Efficient Fan Controller
20170268797 · 2017-09-21
Inventors
Cpc classification
G05D23/1951
PHYSICS
F24H9/2064
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F24F11/77
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F24F11/76
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F24H9/2071
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F24F11/61
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F24D19/1084
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F24F11/46
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Y02B30/70
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
International classification
F24F11/00
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F24D19/10
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Abstract
Apparatus and methods are disclosed for controlling a cooling ventilation fan after the thermostat call for cooling has ended by providing a variable fan-off delay time based on cooling system parameters including but not limited to the cooling system operating time, duration of the thermostat call for cooling, relative humidity, temperature split, thermostat temperature rate of change, or thermostat temperature reaching a minimum inflection point or crossing a fixed or variable thermostat differential or differential offset. Apparatus and methods are disclosed for controlling a heating ventilation fan after the thermostat call for heating has ended by providing a variable fan-off delay time based on heating system parameters including but not limited to the heating system operating time, duration of the thermostat call for heating, temperature rise, thermostat temperature rate of change, or thermostat temperature reaching a maximum inflection point or crossing a fixed or variable thermostat differential or differential offset.
Claims
1. A method for efficiently controlling a cooling ventilation fan, the method comprising: a thermostat initiating a thermostat call for cooling and turning on a cooling source and the cooling ventilation fan; the thermostat terminating the thermostat call for cooling and turning off the cool source; determining a variable fan-off delay time P2 based on at least one cooling system parameter; continuing energizing the cooling system ventilation fan for the variable fan-off delay time P2, and de-energizing the cooling system ventilation fan after the variable fan-off delay time P2.
2. The method of claim 1, further including: monitoring the thermostat call for cooling; determining a cooling system operating time P4 as a length of time from when the thermostat is initiating the call for cooling until when the thermostat is terminating the call for cooling; and determining the variable fan-off delay time P2 as function of the cooling system operating time P4, and energizing the cooling system ventilation fan for the entire variable fan-off delay time P2, and de-energizing the cooling system ventilation fan after the variable fan-off delay time P2.
3. The method of claim 2, wherein the variable fan-off time delay time P2 is zero if the cooling system operating time P4 is less than a minimum amount of time required for a minimum amount of water vapor to condense on the evaporator coil and be stored as cold water on the evaporator.
4. The method of claim 2, wherein the variable fan-off time delay time P2 is zero if the cooling system operating time P4 is a time selected from the group consisting of: less than about 2 minutes, and if the current duration of cooling system operating time P4 is less than about 4 minutes and a previous cooling system operating time P4 is about 5 minutes, thereby indicating the cooling system has a short cycling fault.
5. The method of claim 2, wherein a heat pump reversing valve control signal is unchanged on the reversing valve throughout the duration of time while the thermostat is calling for cooling and for the variable fan-off delay time P2, the method further comprising: monitoring the heat pump reversing valve control signal to the reversing valve while the thermostat is calling for cooling, generating and providing the heat pump reversing valve control signal to the reversing valve as provided to the reversing valve while the thermostat is calling for cooling during the cooling system operating time P4, continuing to generate and provide the heat pump reversing valve control signal to the reversing valve as provided to the reversing valve while the thermostat is calling for cooling during the cooling system operating time P4, throughout the variable fan-off delay time P2 after the cooling system operating time P4 has ended, performing at least on action to the reversing valve signal from selected from the group consisting of: de-energize the heat pump reversing valve control signal to the reversing valve after the variable fan-off time delay time P2; leaving the heat pump reversing valve control signal in the same state as it was last driven.
6. The method of claim 1, wherein the length of the variable fan-off delay time P2 is determined to be sufficient to evaporate moisture from a cooling evaporator coil, thereby providing preventative maintenance by reducing moisture or ice formation on the cooling evaporator coil which blocks or reduces a cooling system ventilation fan airflow.
7. The method of claim 1, further including determining the variable fan-off delay time P2 based on monitoring at least one cooling system parameter from the group consisting of: a length of time from when the thermostat is initiating the thermostat call for cooling until when the thermostat is terminating the thermostat call for cooling, a cooling system operating time P4, an off-cycle time P11, a return air drybulb temperature, a return air wetbulb temperature, a return air relative humidity, a supply air wetbulb temperature, a supply air relative humidity, a temperature split across the evaporator defined as the return air drybulb temperature minus the supply air drybulb temperature, a thermostat drybulb temperature measured in a conditioned space, a thermostat wetbulb temperature measured in the conditioned space, a thermostat relative humidity measured in the conditioned space, an outdoor air drybulb temperature, an outdoor air wetbulb temperature, an outdoor air relative humidity, a computed rate of change of the thermostat drybulb temperature with respect to time (dT/dt), a computed rate of change of the thermostat wetbulb temperature with respect to time (dTw/dt), a computed rate of change of the thermostat relative humidity with respect to time (dTrh/dt), an off-cycle thermostat drybulb temperature, and a computed rate of change of the off-cycle thermostat drybulb temperature with respect to time (dT/dt-off).
8. The method of claim 1, wherein the method is embodied in at least one device selected from the group consisting of: a thermostat used to control a fan relay controlling a fan motor driving the cooling system ventilation fan, an external fan controller used to control the fan relay controlling the fan motor driving the cooling system ventilation fan, a controller in a fan motor driving the cooling system ventilation fan, an economizer controller, a forced air unit controller used to control the fan relay controlling the fan motor driving the cooling system ventilation fan, and a packaged unit controller used to control the fan relay controlling the fan motor driving the cooling system ventilation fan.
9. The method of claim 8, wherein determining a variable fan-off delay time P2 as function of the cooling system parameters comprises: measuring a relative humidity in at least one location selected from the group consisting of: a conditioned space served by the cooling system, a return air duct or plenum entering a cooling system evaporator from the conditioned space, and a supply air duct or plenum leaving the cooling system evaporator to the conditioned space; and determining the length of the variable fan-off delay time P2 further based on at least one cooling system parameter selected from a group consisting of: the relative humidity, a temperature split across the evaporator defined as the return air drybulb temperature minus the supply air drybulb temperature, a thermostat drybulb temperature measured in a conditioned space, a computed rate of change of the thermostat drybulb temperature with respect to time (dT/dt), a computed rate of change of the off-cycle thermostat drybulb temperature with respect to time (dT/dt-off), the duration of time from when the thermostat is initiating the call for cooling until when the thermostat is terminating the call for cooling, and the cooling system operating time P4.
10. The method of claim 8, wherein determining the variable fan-off delay time P2 as function of the cooling system parameters comprises: measuring a dry-bulb temperature in at least one location selected from the group consisting of: a conditioned space temperature, a return temperature entering an evaporator from a conditioned space, and a supply air temperature leaving the evaporator to the conditioned space; operating the cooling system ventilation fan for the entire variable fan-off delay time P2 after the thermostat has been satisfied and the call cooling has been terminated based on a duration of time selected from the group consisting of: the duration of time for a measured temperature split to reach a selected minimum temperature split setpoint across the evaporator where the measured temperature split is based on the difference between a return air temperature entering the evaporator from the conditioned space and a supply air temperature leaving the evaporator, the duration of time for the supply air temperature to reach a selected maximum supply air temperature setpoint leaving the evaporator to the conditioned space, the duration of time for the conditioned space temperature to reach an inflection point, the duration of time required from when the conditioned space temperature is decreasing and first crosses a lower thermostat cooling differential satisfying a thermostat setpoint and terminating the call for cooling and continuing, until the time when the conditioned space temperature reaches an inflection point and continuing until the time when the conditioned space temperature is increasing towards the lower thermostat cooling differential a second time, and the duration of time from when the conditioned space temperature is decreasing and first crosses the lower thermostat cooling differential satisfying the thermostat setpoint and terminating the call for cooling and continuing, until the time when the conditioned space temperature reaches an inflection point and further continuing until the time when the conditioned space temperature crosses a thermostat cooling differential or thermostat differential offset above or below the thermostat cooling differential.
11. The method of claim 8, wherein at the beginning of the variable fan-off delay time P2, positioning the economizer dampers to a position selected from the group consisting of: a fully closed position; and a minimum position.
12. The method of claim 8 wherein upon receiving a peak electricity demand reduction signal from a system operator, positioning the economizer dampers to a position selected from the group consisting of: a fully closed position; and a minimum position.
13. The method of claim 8, wherein the method further includes installing an external fan controller apparatus including first steps of: physically disconnecting a first electrical connection between a thermostat G terminal (204) on a thermostat or equipment control terminals (201) and a fan relay terminal (205) used to control the cooling system ventilation; connecting a second electrical connection between the thermostat G terminal (204) on the thermostat or equipment control terminals (201) to a first fan controller terminal (214) on a fan controller (211); connecting a second fan controller terminal (212) on the fan controller (211) to the fan relay (205) used to control the cooling system ventilation fan (206); monitoring a cooling system operating time P4 defined from when the thermostat is initiating a call for cooling and energizing the thermostat G terminal until when the thermostat is terminating the call for cooling and de-energizing the thermostat G terminal; determining a variable fan-off delay time P2 as a function of the cooling system operating time P4; and the fan controller (211) continuing cooling system ventilation fan operation for the variable fan-off delay time P2.
14. The method of claim 13 wherein the call for cooling is present when the thermostat or equipment G terminal is energized.
15. The method of claim 13, wherein the method further includes: connecting a electrical connection between a thermostat Y terminal (207) on the thermostat or equipment control terminals (201) and a fan controller terminal (214); and determining the cooling system operation P4 as the length of time from when the thermostat or equipment Y terminal is energized until the thermostat or equipment Y terminal is de-energized.
16. A method for efficiently controlling a heating ventilation fan, the method comprising: turning on a heating system when a thermostat initiates a call for heating defining the beginning of a heating system operating time; turning on the heating ventilation fan by at least one control device selected from the group consisting of: the thermostat, the heating system, and an external fan controller; monitoring the thermostat call for heating; after the thermostat initiates the call for heating, performing at least one action selected from the group consisting of: turning on the ventilation fan after an initial delay to circulate air through the heating system, energizing the fan relay normally controlled by the thermostat G terminal to circulate air through the heating system, and turning on the ventilation fan to circulate air through the heating system and waiting a first period of time P1 with the ventilation fan operating, and after the period of time P1, energizing the fan relay normally controlled by the thermostat G terminal to circulate air through the heating system; continuing to circulate air through the heating system and the thermostat continuing calling for heating until a selected thermostat set point temperature is satisfied; determining the heating system operating time P3 based on the length of time from when the thermostat is initiating the call for heating until when the thermostat is terminating the call for heating; performing at least one action selected from the group consisting of: de-energizing the ventilation fan after the thermostat turns off the heating system, if the heating system operating time P3 is less than a period of time where no significant amount of heat has been stored in a heat exchanger of the heating system, and continuing energizing the heating ventilation fan for a variable fan-off delay time P2, and de-energizing the heating ventilation fan after the variable fan-off delay time P2 has ended, wherein the variable fan-off delay time P2 is determined based on at least one heating system parameter selected from a group consisting of: the heating system operating time P3, the length of time from when the thermostat is initiating the call for heating until when the thermostat is terminating the call for heating, and the length of time required for the temperature rise across the heat exchanger to reach a minimum threshold value wherein the temperature rise is defined as the supply air temperature minus the return air temperature.
17. The method of claim 16, wherein the minimum threshold value for the temperature rise varies from 0 to 40 degrees Fahrenheit.
18. The method of claim 16, wherein the variable fan-off delay P2 is based on the heating system operating time P3.
19. The method of claim 16, wherein energizing the fan relay signal switches the ventilation fan to a higher speed than when the fan relay signal is not energized.
20. The method of claim 16, wherein energizing the fan relay signal comprises energizing the fan relay and turning the ventilation fan from a low speed to a high speed after the heating system is operated for sufficient time to provide useful heating, wherein the high speed is higher than a low heater ventilation fan speed achieved before the fan relay is energized, and continuing at the high speed for the entire variable fan-off delay time P2.
21. The method of claim 16, further including energizing the fan relay, thereby turning the ventilation fan to a high speed higher than a low heater ventilation fan speed controlled by the heater, during the heating system operating time P3 following the first period of time P1.
22. The method of claim 16, wherein a heat pump reversing valve control signal is unchanged on the reversing valve while the thermostat is calling for heating and for the variable fan-off delay time P2, the method further comprising: monitoring the signal to the reversing valve while the thermostat is calling for heating; generating and providing the same signal to the reversing valve as provided to the reversing valve while the thermostat is calling for heating during the heating system operating time P3; continuing to generate and provide the same signal to the reversing valve as provided to the reversing valve while the thermostat is calling for heating during the heating system operating time P3, throughout the variable fan-off time delay time P2 after the thermostat call for heating has ended; and performing at least on action to the reversing valve signal from a group consisting: de-energize the signal to the reversing valve after the variable fan-off delay time P2; and leaving the reversing valve signal in the same state as it was last driven.
23. The method of claim 16, wherein the method is embodied in at least one device selected from the group consisting of: a thermostat used to control a fan relay controlling a fan motor driving the cooling system ventilation fan, an external fan controller used to control a fan relay controlling the fan motor driving the heating ventilation fan, a controller in a fan motor driving the heating ventilation fan, a forced air unit controller used to control the fan relay controlling the fan motor driving the heating ventilation fan, and a packaged unit controller used to control the fan relay controlling the fan motor driving the heating ventilation fan.
24. The method of claim 23, wherein the method further includes: measuring a dry-bulb temperature in at least one location selected from the group consisting of: a conditioned space temperature, a return temperature entering the heat exchanger from the conditioned space, and a supply air temperature leaving the heating exchanger to the conditioned space; operating the heating ventilation fan for the entire variable fan-off delay time P2 after the thermostat has been satisfied and the call heating has been terminated based on a duration of time selected from the group consisting of: the duration of time for the measured temperature rise to reach a selected minimum temperature rise setpoint across the heat exchanger where the measured temperature rise is based on the difference between the supply air temperature leaving the heat exchanger and the return air temperature entering the heat exchanger from the conditioned space, the duration of time for the measured supply air temperature to reach a selected minimum supply air temperature leaving the heat exchanger to the conditioned space, the duration of time for the measured conditioned space temperature to reach an maximum inflection point, the duration of time required from when the conditioned space temperature crosses an upper thermostat heating differential satisfying the thermostat setpoint and terminating the call for heating and continuing until the time when the conditioned space temperature reaches a maximum inflection point and continuing until the time when the conditioned space temperature is decreasing towards the thermostat heating differential, and the duration of time from when the conditioned space temperature crosses the upper thermostat heating differential satisfying the thermostat setpoint and terminating the call for heating and continuing until the time when the conditioned space temperature reaches a maximum inflection point and further continuing until the time when the conditioned space temperature crosses a thermostat heating differential or thermostat differential offset above or below the thermostat heating differential.
25. The method of claim 23, wherein the method further includes: installing an external fan controller apparatus including first steps of: physically disconnecting a first electrical connection between a thermostat G terminal (204) on a thermostat or equipment control terminals (201) and a fan relay terminal (205) used to control the cooling system ventilation; connecting a second electrical connection between the thermostat G terminal (204) on the thermostat or equipment control terminals (201) to a first fan controller terminal (214) on a fan controller (211); connecting a third electrical connection between second fan controller terminal (212) on the fan controller (211) to the fan relay (205) used to control the heating ventilation fan (206); and connecting a fourth electrical connection between a thermostat W terminal (208) on the thermostat or equipment control terminals (201) to a third fan controller terminal (216) on the fan controller (211); monitoring a heating system operating time P3 defined from when the thermostat is initiating a call for heating and energizing the thermostat W terminal until when the thermostat is terminating the call for heating and de-energizing the thermostat W terminal; and the fan controller (211) continuing heating ventilation fan operation for a variable fan-off delay time P2 based on the heating system operating time P3.
26. The method of claim 25, wherein the method further includes: determining the heating system operating time P3 as the length of time from when the thermostat or equipment W terminal is energized until the thermostat or equipment W terminal is de-energized; or determining a heat pump heating system operation P3 as the length of time from when the thermostat or equipment Y terminal is energized with the reversing valve signal indicating a call for heat until the thermostat or equipment Y terminal is de-energized.
27. A method for controlling a Heating Ventilating Air Conditioning (HVAC) system and ventilation fan with a variable differential thermostat, the method comprising: detecting the thermostat temperature decreasing below a thermostat differential for heating and energizing a heating terminal (208) or the thermostat temperature increasing above a thermostat differential for cooling and energizing a cooling terminal (207) and a fan terminal (204); initiating the monitoring and storing of at least one parameter selected from the group consisting of: an HVAC system type and mode of operation; a thermostat call for heating defining a heating system operating time P3, a thermostat call for cooling defining a cooling system operating time P4, a thermostat temperature measured in a conditioned space, a thermostat relative humidity measured in the conditioned space, a temperature rise (TR) across the heat exchanger defined as a supply air temperature minus a return air temperature, a temperature split (TS) across the evaporator exchanger defined as a return air temperature minus a supply air temperature, a computed rate of change of the thermostat temperature with respect to time (dT/dt), a computed rate of change of the off-cycle thermostat temperature with respect to time (dT/dt-off), and waiting until the thermostat temperature first reaches at least one threshold from a group consisting of: a first heating differential above the heating setpoint to de-energize the heat source, a second variable heating differential above the first heating differential to de-energize the heat source where the second variable heating differential is based on the heat source operating time P3, a first cooling differential below the cooling setpoint to de-energize the cool source, and a second variable cooling differential below the first cooling differential to de-energize the cool source where the second variable cooling differential is based on the cool source operating time P4; determining a variable fan-off time delay differential threshold or variable fan-off delay time P2 based on the HVAC system type and mode of operation and at least one parameter selected from the group consisting of: the heating system operating time P3 based on the duration of time the thermostat is calling for heating, the cooling system operating time P4 based on the duration of time the thermostat is calling for cooling, the off-cycle time P11, the TR, the TS, the thermostat temperature, the thermostat relative humidity, the rate of change of the thermostat temperature with respect to time (dT/dt), a second variable heating differential offset above or below the first heating differential setpoint to de-energize the fan relay where the second variable heating differential offset is based on the heating system operating time P3, and a second variable cooling differential offset above or below the first cooling differential setpoint to de-energize the fan relay where the second variable cooling differential offset is based on the cooling system operating time P4, performing at least one action at an end of the heating system operating time P3 or the cooling system operating time P4, selected from the group consisting of: energizing a fan relay to continue energizing the heating ventilation fan or the cooling ventilation fan for the variable fan-off delay time P2, energizing an economizer to enable the economizer to position the economizer dampers, and de-energizing an economizer to enable the economizer to close the economizer dampers; continuing to operate the heating or cooling ventilation fan for a variable fan-off delay time P2 based on at least one parameter from a group consisting of: the heating system operating time P3 based on the duration of time the thermostat is calling for heating; the cooling system operating time P4 based on the duration of time the thermostat is calling for cooling; the TR, the TS, the thermostat temperature, the thermostat relative humidity, the duration of time for the thermostat temperature to cross the first heating differential temperature a second time, the duration of time for the thermostat temperature to cross another heating differential offset above or below the first heating differential, the duration of time for the thermostat temperature to cross the first cooling differential temperature a second time, and the duration of time for the thermostat temperature to cross another cooling differential offset above or below the first cooling differential setpoint; performing at least one action at the end of the variable fan-off delay time P2 selected from the group consisting of: de-energizing the fan relay, and de-energizing an economizer to enable the economizer to close the economizer dampers.
28. The method of claim 27, wherein the heating differential or cooling differential or differential offsets are adjusted based on at least one time period selected from a group consisting of: the thermostat call for heating defining a heating system operating time P3, the thermostat call for cooling defining a cooling system operating time P4, the off-cycle time P11, and the variable fan-off delay time P2.
29. The method of claim 27, further including a user adjusting at least one variable selected from the group consisting of: a target TR, a target TS, the heating differential to increase or decrease the duration of time the thermostat is calling for heating in response to the thermostat calling for heating, the cooling differential to increase or decrease duration of time the thermostat is calling for cooling in response to the thermostat calling for cooling, the heating differential offset to increase or decrease the heating variable fan-off delay time P2, and the cooling differential offset to increase or decrease the cooling variable fan-off delay time P2.
30. A fan controller (211) for a Heating Ventilation and Air Conditioning (HVAC) system (100) including a direct-expansion air conditioner and at least one of a gas furnace, a Heat Pump (HP), an electric heating element, and a hydronic heating element, the fan controller comprising: electrical inputs configured to receive electrical signals from an HVAC thermostat or equipment control terminals (201), the electrical inputs configured to receive electrical signals from an HVAC thermostat or equipment control terminals (201), the electrical inputs comprising at least one of: 1) a fan controller fan signal input (214), 2) a fan controller heat source or HP reversing valve signal input (216), 3) a fan controller AC or HP (AC/HP) compressor signal input (215), 4) a fan controller HP Detection (HPD) signal input (234); a microprocessor (304); a switching device (301) electrically connected to the microprocessor (304) to receive a control signal from the microprocessor (304); a low-voltage DC power source electrically connected to the microprocessor (304), the DC power source selected from at least one of: a low-voltage battery (306), an AC-DC converter (303), and a super capacitor (312); and a fan controller fan relay signal output (212) from the switching device (301) configured to electrically connect to a fan relay (205) to provide a low-voltage fan relay signal to control the fan relay (205); the microprocessor programmed to monitor and calculate a variable fan-off delay time P2 as a function of at least one of: a heating system operating time P3, a thermostat call for heating time duration, a cooling system operating time P4, and a thermostat call for cooling time duration; the microprocessor programmed to operate a system blower/fan (206) for a variable fan-off delay time P2 at the end of at least one of: the heating system operating time P3, the thermostat call for heating, the cool system operating time P4, and the thermostat call for cooling.
Description
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0091] The above and other aspects, features and advantages of the fan controller will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein:
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[0136] Corresponding reference characters indicate corresponding components throughout the several views of the drawings.
DETAILED DESCRIPTION OF THE INVENTION
[0137] The following description is of the best mode presently contemplated for carrying out the present invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing one or more preferred embodiments of the invention. The scope of the invention should be determined with reference to the claims.
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[0139] The fan controller 211 includes input signal wires 213 through 216 are configured to receive signals from thermostat or equipment control terminals 201 (
[0140] The thermostat 200 shown in
[0141] The humidity sensor 17 is used to measure relative humidity to enable the variable fan-off delay time for cooling to be based on the amount of moisture on the evaporator when the conditioned space relative humidity is above a minimum relative humidity threshold of approximately 35 to 45 percent for enough water vapor to condense on the evaporator to provide sufficient evaporative cooling by the fan after the cooling compressor turns off to support longer variable fan off delay times greater based on the duration of cooling compressor operational time based on the duration of time the thermostat is calling for cooling.
[0142] The thermostat 200 display 1 shows other embodiments of the invention including a maintenance symbol (cog with a wrench inside) to indicate maintenance is required, a Cooling Satisfaction Time (CST) symbol indicating a method used to calculate a fan-off delay time P2 as a function of the cooling system operating time P4 defined as the duration of time from when the thermostat initiates a call for cooling until the thermostat terminates the call for cooling. A Heat Satisfaction Time (HST) symbol indicates a method used to calculate a fan-off delay time P2 as a function of the heating system operating time P3 defined as the duration of time from when the thermostat initiates a call for heating until the thermostat terminates the call for heating. The “dT/dt” symbol indicates a method of calculating the fan-off delay time P2 based on a computed rate of change of the thermostat temperature with respect to time (dT/dt) defined as the total thermostat heating differential plus overshoot divided by the heating operational time P3 compared to an off-cycle rate of change of thermostat drybulb temperature with respect to time (dT/dt-off) defined as the total off-cycle thermostat drybulb temperature differential plus overshoot divided by an off-cycle time P11.
[0143] The thermostat 200 display 1 also shows an Unoccupied Fan Controller (UFC) symbol indicating an occupancy sensor 9 and a UFC diagnostic method are active. The UFC indicates an embodiment wherein the thermostat 200 monitors the fan signal and in the absence of an occupancy signal, cool-source signal or heat-source signal, in this embodiment the thermostat 200 de-energizes the G terminal connected to fan relay 205 and turns off the system fan/blower 206 after a minimum fan-only time period to save energy when the fan has been accidentally left on by itself.
[0144] The fan controller 211 includes unique features to receive electric power and determine an HVAC system type and a heating or a cooling mode of operation. Based on the HVAC system type and mode of operation, the fan controller 211 monitors signals on the thermostat or equipment control terminals 201 to determine a variable fan-off delay time P2 as a function of heat-source operational time P3 or cool-source operational time P4.
[0145] The fan controller 211 determines HVAC system type and heating or cooling mode of operation, for direct-expansion air conditioning systems and gas furnace, heat pump, electric resistance, and hydronic heating systems. For gas furnace heating systems, the apparatus and methods include energizing the heater blower fan from the low speed used for heating to the high speed used for cooling after delay time period P1 to deliver more heating output to satisfy the thermostat sooner and save heat-source energy. For heat pump, electric resistance, and hydronic heating systems, the apparatus and methods include energizing the fan relay after a short fan-on time delay P0 as a function of the previous HVAC system 100 off-cycle time duration P11. For each specific HVAC system 100 type and cooling or heating mode of operation, the apparatus and methods uniquely vary the extended fan-off delay time P2 as a function of air conditioning compressor cool-source operational time P4 or heat-source operational time P3 based on signals present on thermostat or equipment terminals. For a gas furnace, the extended fan-off delay time P2 is increased when the heat-source operational time P3 increases based on signals present on thermostat or equipment terminals. For heat pump, hydronic, or electric, resistance heating systems the extended fan-off delay time P2 is decreased when the heat-source operational time P3 increases based on signals present on thermostat or equipment terminals due to lower outdoor air temperatures and increased heating loads which reduce the temperature increase delivered by heat pump, hydronic, or electric, resistance heating systems. Heat pump heating capacity and temperature rise are directly proportional to outdoor air temperature. Lower outdoor air temperatures cause longer heat pump operation and less heat available to support a variable fan-off delay time. Hydronic heating coils receive hot water from water heaters. Low outdoor air temperatures cause longer hydronic heater operation and the water heater cannot keep up with demand causing lower water heating supply temperatures which cause less heat available to support a variable fan-off delay time. Electric resistance heating elements are ineffective at storing heat and with longer operation due to cold weather less heat is available to support a variable fan-off delay time.
[0146] The fan controller 211 apparatus and methods may be incorporated within a thermostat 200 or incorporated into an HVAC system 100 such as a control board 101 or incorporated into an HVAC system 100 with an economizer to perform the fan controller 211 methods disclosed herein.
[0147] An embodiment of the thermostat 200 of the present invention may provide variable fan-off time delays as a function of current or previous cool-source or heat-source operational times and off-cycle times based on signals present on thermostat or equipment control terminals 201. The thermostat display 1 shows “EFC” indicating the variable fan-off delay method is enabled based on cooling or heating system parameters. The thermostat display 1 shows “VDT” indicating the variable differential thermostat method is enabled where the thermostat differential varies as a function of cooling or heating system parameters. The thermostat display 1 shows “dT/dt” indicating the variable fan-off delay is based on the thermostat temperature rate of change with respect to time. A variable fan-off time delay may also be based on the thermostat temperature rate of change with respect to time (dT/dt) using a resistance temperature detector (RTD) or other type of temperature sensor (see
[0148] An embodiment of the thermostat 200 of the present invention may provide a variable fan-off delay time based on the heat-source operational time P3 or the cool-source operational time P4. The variables P3 and P4 are the times required for the heating or cooling apparatus to satisfy the thermostat call for heating or cooling.
[0149] The Heating Satisfaction Time (HST) is defined as the duration of time from when the thermostat initiates a call for heating until the time when the thermostat terminates the call for heating equivalent to the time required for the heating apparatus to increase the thermostat temperature from the setpoint minus the differential to the setpoint plus the differential. The Cooling Satisfaction Time (CST) is defined as the duration of time from when the thermostat initiates a call for cooling until the time when the thermostat terminates the call for cooling equivalent to the time required for the cooling apparatus to decrease the thermostat temperature from the setpoint plus the differential to the setpoint minus the differential. The Off Time (OT) is the time between heating or cooling cycles. The cooling fan-off delay time is a function of the CST and OT and the heating fan-off delay time is a function of the HST and OT. Long CST or HST combined with short OT indicate a faulted system where the fan-off delay time decrease with increasing CST and HST. Short CST or HST and long OT indicate a non-faulted system where the fan-off time increases with increasing CST or HST. For hydronic and heat pump heating systems, the fan-off delay time generally increases from zero to a maximum and then decreases to a minimum or zero as a function of HST and OT. For gas furnace heating systems, the fan-off delay time generally increases from zero to a maximum and then decreases slowly to a minimum as a function of HST and OT. For direct-expansion air conditioning systems, the fan-off delay time generally increases from zero to a maximum and then decrease to a minimum or zero as a function of CST and OT.
[0150] An embodiment of the present invention may provide fault detection diagnostics (FDD) of “low cooling capacity” by detecting whether or not the cool source operating time P4 is longer than 50 to 60 minutes for two cycles in a row with the fixed −1° F. lower hysteresis. The present invention provides an indication of a “low cooling capacity fault” to check for the following faults: dirty air filters, blocked evaporator/condenser coils, iced evaporator, low refrigerant charge, faulty expansion device, restrictions, non-condensables, or low thermostat setpoint.
[0151] An embodiment of the present invention may provide fault FDD of “short cycling” by detecting whether or not the cool source operating time P4 is less then or equal to 5 minutes for two cycles in a row with the fixed −1° F. lower hysteresis, then the present invention thermostat would provide an indication of a “short cycling fault” to check for low differential (<0.5° F.), defective thermostat, thermostat located near a register, low airflow due to blocked or dirty air filters, refrigerant overcharge, defective compressor, insufficient line voltage, failed blower wheel, defective run/start relay, contactor or capacitor, refrigerant restriction, condenser coil blockage, closed registers, or damaged ducts.
[0152] An embodiment of the thermostat 200 of the present invention may improve efficiency and reduce short-cycling losses by varying the cooling or heating operational time based on calculating the current thermostat satisfaction time equal to the difference between thermostat temperature and setpoint temperature plus default differential divided by dT/dt, and if thermostat satisfaction time is less than the optimal steady-state efficiency operational time for cooling or heating, then the thermostat continues to operate the cooling or heating until the optimal steady-state efficiency operational time has been reached. If the thermostat differential to end cooling or heating operation is increased, then the thermostat differential to begin cooling or heating operation is proportionately increased to maintain a consistent setpoint. If the cooling or heating operational time is considerably longer than an optimal steady-state cooling or heating operational time greater than an upper limit of continuous operation (i.e., greater than 1.5 hours) or short-cycling (i.e., less than or equal to 5 minutes operation), then the thermostat displays a maintenance symbol (cog with a wrench inside) to indicate maintenance is required for dirty air filter, dirty or blocked evaporator or condenser coil, low refrigerant charge, excess outdoor air, duct leakage, restriction, non-condensables, faulty contactor or capacitor, or other fault.
[0153] An embodiment of the thermostat 200 of the present invention may optimize cooling or heating energy efficiency and operational time by varying the heating thermostat temperature differential based on the previous heat source operational time P3 or by varying the cooling thermostat temperature differential based on the previous cooling system operating time P4. The thermostat temperature differential can also be based on the current dT/dt times the difference between a minimally optimal efficiency operational time and the current operational time. If the thermostat differential to end cool- or heat-source operation is increased, then the thermostat differential to begin cool- or heat-source operation is proportionately increased to maintain a consistent setpoint. This embodiment provides the same cooling or heating setpoint as a known thermostat, but the temperature differential varies to optimize heat-source or cool-source energy efficiency.
[0154] An embodiment of the present invention thermostat 200 may provide a variable heating fan-off delay time based on a variable thermostat differential based on the current or previous heat source operational time P3 where the heat source is turned off when the thermostat temperature reaches the upper variable differential a first time and the heating ventilation fan continues to operate for a variable fan-off delay time P2 to heat the air causing the thermostat temperature to increase above the first upper differential and when no additional heat is available the thermostat temperature decreases to the same differential a second time whereupon the fan is de-energized. In another embodiment of the present invention, heat source is turned off when the thermostat temperature reaches the upper variable differential a first time and the heating ventilation fan continues to operate for a variable cooling fan-off delay time P2 to heat the air causing the thermostat temperature to increase above the first upper differential and when no additional heating is available the thermostat temperature decreases to a thermostat differential offset or a fixed thermostat differential below the upper thermostat differential whereupon the fan is de-energized. In another embodiment of the present invention, the thermostat 200 can also provide a variable cooling fan-off delay time P2 based on the current heat source operational time P3.
[0155] An embodiment of the thermostat 200 of the present invention may provide a variable fan-off delay time based on the current dT/dt being less than a previous cooling off-cycle dT/dt. For heating, the thermostat can extend the variable fan-off time delay based on the current dT/dt being greater than a previous heating off-cycle dT/dt. The embodiment may also provide a decreasing fan-off delay time if the cool- or heat-source operational time is greater than a maximum and the off-cycle time is less than a minimum threshold to adjust the fan-off delay time to account for faults that might reduce cooling or heating capacity and efficiency resulting in less cooling or heating energy available for recovery during the fan-off delay time.
[0156] An embodiment of the present invention thermostat 200 may provide a variable cooling fan-off delay time based on a variable thermostat differential based on the current or previous cooling system operating time P4 where the cool source is turned off when the thermostat temperature reaches the lower variable differential a first time and the cooling ventilation fan continues to operate for a variable fan-off delay time P2 to cool the air causing the thermostat temperature to decrease below the first lower upper differential and when no additional cooling is available the thermostat temperature increases to the same differential a second time whereupon the fan is de-energized. In another embodiment of the present invention, cool source is turned off when the thermostat temperature reaches the lower variable differential a first time and the cooling ventilation fan continues to operate for a variable fan-off delay time P2 to cool the air causing the thermostat temperature to decrease below the first lower differential and when no additional cooling is available the thermostat temperature increases to a thermostat differential offset or a fixed thermostat differential above the lower thermostat differential whereupon the fan is de-energized. In another embodiment of the present invention, the thermostat 200 can also provide a variable cooling fan-off delay time P2 based on the current cooling system operating time P4.
[0157] An embodiment of the present invention may provide a method to continue operating the cooling ventilation fan after the thermostat call for cooling is terminated where the method for determining the cooling ventilation fan variable fan-off delay time P2 is determined based on at least one cooling system parameter selected from a group consisting of: the duration of time from when the thermostat is initiating the call for cooling until when the thermostat is terminating the call for cooling, the cooling system operating time P4, an off-cycle time P11, a return air drybulb temperature, a return air wetbulb temperature, a return air relative humidity, a supply air drybulb temperature, a supply air wetbulb temperature, a supply air relative humidity, temperature split across the evaporator defined as the return air drybulb temperature minus the supply air drybulb temperature, a thermostat drybulb temperature (T) measured in a conditioned space, a thermostat wetbulb temperature (Tw) measured in the conditioned space, a thermostat relative humidity (Trh) measured in the conditioned space, a computed rate of change of the thermostat drybulb temperature with respect to time (dT/dt), a computed rate of change of the Tw temperature with respect to time (dTw/dt), a computed rate of change of the Trh with respect to time (dTrh/dt), an off-cycle thermostat drybulb temperature, and computed rate of change of the off-cycle thermostat drybulb temperature with respect to time (dT/dt-off).
[0158] An embodiment of the thermostat invention can determine the heating start-up time S1 defined as the time required for the heating system to satisfy the thermostat setpoint after a period of inactivity such as a heating thermostat setback period or a period of time where the heating thermostat control was turned off. An embodiment of the thermostat invention can determine the cooling start-up time S2 defined as the time required for the cooling system to satisfy the thermostat setpoint after a period of inactivity such as a cooling set forward period or a period of time where the cooling thermostat control was turned off. If the heating start-up period S1 or cooling start-up period S2 are longer than a maximum threshold of about 60 minutes then the thermostat will
determine whether or not the system has low heating or cooling capacity and display fault alarm information on the thermostat device or on a software application on an electronic device, cell phone, internet, or computer system to alert a user about the cooling or heating system not operating properly or delivering less than optimal performance. If the length of the heat-source operational time P3 or cool-source operational time P4 are longer than 60 minutes, then the thermostat embodiment can determine whether or not the system has low heating or cooling capacity and display fault alarm information on the thermostat device or on a software application on an electronic device, cell phone, internet, or computer system to alert a user about the cooling or heating system not operating properly or delivering less than optimal performance.
[0159] If the length of the heat-source operational time P3 or cool-source operational time P4 are less than 4 minutes, then the thermostat embodiment can determine whether or not the system has a short cycling fault and display fault alarm information on the thermostat device or on a software application on an electronic device, cell phone, internet, or computer system to alert a user about the cooling or heating system not operating properly based on short cycling. The present invention thermostat embodiment 200 can also correct short cycling faults due to low differential (<0.5° F.) by increasing the thermostat differential based on a short-cycle heating operational time P3 or a short-cycle cooling operational time P4 to lengthen subsequent operational times to improve thermal comfort and energy efficiency.
[0160] An air conditioner can turn on and off frequently or short cycle if it is oversized or if its thermostat has low hysteresis (<0.5° F.) or if its thermostat is located near a register or if it has the following faults: low airflow due to blocked or dirty air filters, failed blower wheel, failed fan contactor or capacitor, refrigerant restriction, condenser coil blockage, closed registers, or damaged ducts. Short-cycling for a furnace, heat pump or hydronic heating system can be caused by the system being oversized or by low thermostat hysteresis (less than 0.5° F.), thermostat location (near register), low airflow due to blocked or dirty air filters, failed blower wheel, failed fan contactor or capacitor, closed registers, or damaged ducts. Short-cycling for a heat pump can also be caused by a failed reversing valve or an iced condenser in heating mode.
[0161] The embodiment of the thermostat 200 or fan controller 211 may also provide a zero fan-off delay time if the heat-source operational time P3 or the cool-source operational time P4 is less than a minimum indicating the insufficient heating is available in the heat exchanger or insufficient cooling is available in the evaporator to support a fan-off delay time.
[0162] An embodiment of the fan controller 211 monitors the fan signal and in the absence of a cool-source or heat-source signal, the fan controller 211 de-energizes the fan relay 205 and turns off the system fan/blower after a minimum fan-only time period to save energy when the fan has been accidentally left on by itself (see
[0163] An embodiment of the thermostat 200, monitors the fan signal and in the absence of an occupancy signal, cool-source signal or heat-source signal, the thermostat 200 de-energizes the G terminal connected to fan relay 205 and turns off the system fan/blower 206 after a minimum fan-only time period to save energy when the fan has been accidentally left on by itself.
[0164] An embodiment of the thermostat 200 of the present invention may maintain a heat pump reversing valve position continuously throughout both the compressor operational time and fan-off time delay for cooling and heating mode of operation to ensure maximum energy recovery from the heat pump indoor coil. Known thermostats do not maintain a heat pump reversing valve position continuously throughout the compressor operational time and fan-off time delay and which can cause a loss of cold refrigerant stored in the evaporator at the end of the compressor operational cycle and less cooling energy available to recover during the fan-off delay time period (see
[0165] Known HVAC systems leave moisture on the evaporator coil at the end of an air conditioning cycle. This moisture can be frozen in place at the beginning of the next air conditioning cycle causing a blockage of air flow through the coil. With little to no air flow, the thermostat will never be satisfied, and the system will run continuously. The present invention leaves the coil dry at the end of the fan-off delay P2 and prevents the icing condition.
[0166] For HVAC systems 100 with economizers, an embodiment of the present invention may use wired or wireless communication technology to receive a demand reduction signal from a system operator and implement a peak demand reduction method by partially or completely closing economizer dampers during a peak demand event to reduce cooling or heating loads to reduce energy consumption. The degree of closing may be determined based on the quantity of outdoor airflow delivered by the HVAC economizer dampers during normal operational time.
[0167] For HVAC systems 100 with economizers, an embodiment of the fan controller 211 may also monitor economizer operation to determine when it is advantageous to partially or completely close the economizer dampers during normal operation to deliver a required minimum amount of outdoor airflow to satisfy indoor air quality requirements and also deliver more sensible cooling or heating capacity to satisfy the thermostat sooner and reduce energy use.
[0168] For HVAC units with economizers, an embodiment of the fan controller 211 may also monitor cool-source and heat-source operational time and partially or completely close the economizer dampers at the end of the cool-source or heat-source operational time and implement a fan-off time delay with the economizer dampers closed to recover additional sensible cooling or heating capacity and deliver additional cooling or heating capacity to the conditioned space to improve energy efficiency, lengthen the off cycle time, and reduce energy use.
[0169]
[0170]
[0171] 1) Fan signal “G” on terminal 204 transmits voltage signals to the fan controller 211 through fan input lead 214;
[0172] 2) optional cooling signal AC “Y” on terminal 207 transmits voltage signals to the fan controller 211 through AC input lead 215 (indicated by dashed line 277);
[0173] 3) heat-source signal HEAT “W” on terminal 208 transmits voltage signals to the fan controller low-voltage heat-source or HP reversing valve signal input 216;
[0174] 4) system transformer 210 common 24 VAC signal is connected to the fan controller 211 through Hot input lead 221;
[0175] 5) system transformer Hot “R” on terminal 209 is connected to the fan controller 211 by Hot lead 213;
[0176] 6) an optional Heat Pump Detection (HPD) input lead 234 is shown on fan controller 211 with a dashed line to enable connection to the Hot leg 210b to enable control of a fan relay 205 and system blower/fan 206 for a heat pump system (see
[0177] 7) fan controller fan signal output 212 connected to fan relay 205 to control system fan/blower 206.
[0178]
[0179]
[0180]
[0181]
[0182]
[0183]
[0184]
[0185] The diode 275 shown in
[0186] When installed on most gas furnace HVAC systems in heating mode, the fan controller activates the 24 VAC low-voltage signal output 212 which causes the high-speed relay 205 to drive the fan/blower 206 at the high-speed used for cooling. On some gas furnace HVAC systems the fan relay 205 on the OEM blower controller 238 might be connected to the low or medium speed tap on the system fan/blower 206 and the system fan/blower 206 then operates at the low or medium speed. To achieve optimal performance in gas furnace heating mode, the fan controller 211 can be configured to include a high-voltage relay to directly drive the high-speed tap of the fan/blower 206 and circumvent the OEM blower controller board 238 default fan speeds and operate the fan/blower 206 at the high-speed used for cooling after the time P1 has expired, and continue operating the fan/blower at high speed throughout the heat-source operational time P3 and the extended fan-off delay time period P2.
[0187]
[0188]
[0189] The switch 301 acts as a direct control of the fan relay 205 and indirect control of the system fan/blower motor 206. It is indirect because the switch 301 controls the fan relay 205, and the fan relay 205 controls the high-voltage signals going directly to the system fan/blower motor 206. Switch 301 works for systems where the default fan speed is the high speed used for cooling. For systems where the default fan speed is the low or medium speed used for heating, a high-voltage switch allows the fan controller 211 to directly control the system fan/blower motor 206. A double-pole double-throw relay could be in place of switch 301. The normally closed contacts could connect the furnace fan control board output to the low speed tap on the system fan/blower 206. The normally open contacts could connect 120/240 VAC to the high-speed used for a cooling tap. For gas furnace heating systems, the microprocessor activates the relay at the end of time period P1 and the system fan/blower 206 is controlled by the fan controller 211 to go from the low-speed used for heating to the high-speed used for cooling after time P1. For air conditioning systems where the default fan speed is the low or medium speed, the fan controller microprocessor 304 activates the high-voltage switch for the system fan/blower 206 to operate at the high-speed used for cooling after the fan-on time delay P0 (if applicable), continue through the cool-source operational time P4 or heat-source operational time P3, and then continue through the extended fan-off delay time period P2. This provides increased cooling or heating capacity in order to satisfy the thermostat in less time and save energy. In this way, the fan controller 211 directly controls the system fan/blower speed, rather than indirectly as with switch 301 and fan relay 205.
[0190] The embodiments shown in
[0191] The fan controller 211 receives the following signal inputs from the thermostat:
[0192] fan input 214 from the thermostat “G” terminal 204;
[0193] AC compressor input 215 from the thermostat “Y” terminal 207;
[0194] heat-source input 216 from the thermostat “W” terminal 206 or from the thermostat “O” terminal 235 or thermostat “BR” terminal 236; and
[0195] HPD mode input 234 from the thermostat “R” terminal 209 or the system transformer Hot 210b.
[0196] The fan controller 211 has a single output 212 which is the signal to enable the fan relay 205.
[0197] The signal inputs 214, 215, 216, and 234 and an output of the zero crossing detector 302 pass through a signal conditioning circuit 308 before being passed to the microprocessor 304. The signal conditioning circuit 308 shifts the level of the thermostat inputs to a level that does not harm the microprocessor 304. The microprocessor 304 is used to control switching devices 301 and 309. The microprocessor 304 also has an input from a zero crossing detector 302. This zero crossing detector 302 may monitor either the current feeding through the fan relay 205 via signal output 212 or a neutral leg 210b (see
[0198] The zero crossing detector 302 then presents a zero crossing signal 272 to the microprocessor 304 which enables the microprocessor to determine when the system transformer signal input 221 passes above zero volts and below zero volts. This information is used to count cycles for timekeeping purposes and to determine when to activate the switching device 301. The zero crossing times are also required when the switching device 301 is a triac. To operate the triac as a switch, the triac must be fired at all zero crossing transitions.
[0199] The AC-DC converter 303 has inputs from the system transformer 221 as well as the thermostat signal outputs for heat-source enable signal 216, compressor enable signal 215, and fan enable signal 212. Any of these signals can be rectified in the AC-DC converter to provide DC power to the microprocessor 304 and to keep an optional battery 306 charged or supercapacitor 312.
[0200] The switching device 301 is controlled by the microprocessor 304 and connects the fan controller 211 input 213 to the fan relay control line 212 which in turn, energizes the fan relay 205. The output of switching device 301 is routed through the normally closed relay 309 which when operating properly is switched by the microprocessor 304 to the normally open position allowing a complete circuit from the switching device 301 to the fan relay control output 212.
[0201] There is also an optional user interface 305 which may be used to configure the microprocessor 304 to perform in an alternate manner. An optional battery 306 is also shown which could be used in the event that common wire 221 is not present and the switching device 301 is not a triac.
[0202] The wire 265 shown in
[0203] The diode 275 shown in
[0204] The microprocessor 304 performs several major functions. In terms of timing, the microprocessor 304 keeps track of seconds and minutes by either monitoring the output from the zero crossing detector 302, or by counting microprocessor clock cycles. Each positive zero crossing accounts for 1/60th of a second; therefore, sixty positive crossings occur each second. The seconds are then accumulated to measure the time of operation or non-operation. The negative crossings are also monitored to provide timing for the switching device 301.
[0205] The fan controller 211 draws power through the HVAC thermostat or equipment terminal block C common 223 of the 24 VAC transformer 210 (see
[0206] The microprocessor 304 continuously monitors all inputs to determine if there is any change to the current system operation. In one embodiment, the microprocessor 304 contains FLASH memory, which allows the unit to store the programming instructions and data when there is no power applied to the unit.
[0207] The microprocessor 304 monitors the duration of the fan 205, AC compressor 203, and/or heater 202 operation by the thermostat 201, and adjusts the delay accordingly. If the AC compressor 203 or the heat-source 202 are operated for a short period of time and there is not much condensation on the evaporator or heat in the heat exchanger, then the fan 205 time is extended for a shorter period of time. Likewise, if the AC compressor 203 or the heat-source 202 have operated for a longer period of time, allowing for more condensate or heater 202 runs longer creating more heart soak, then the fan controller 211 causes the fan 205 to run for a longer period of time after the AC compressor 203 or the heat-source 202 have stopped. Timing table and/or algorithms may be modified for particular HVAC system 100, environments, user preferences, and the like.
[0208] In the embodiment of the fan controller 211 using a triac as the switching device 301, the microprocessor 304 does not enable the triac at exactly the zero crossing of the 24 VAC signal. Instead, the microprocessor 304 delays an amount of time into the positive going cycle and allows the positive going waveform to provide a small amount of charge into the AC/DC circuitry. After a small charge has been accumulated, the microprocessor 304 enables the triac to pass the remainder of the power through to the fan relay 205. The AC waveform rises for a short period and then completely shorts out for the duration of the cycle, which passes this energy on to the fan relay 205 and thus actuates it. In this way, the fan relay 205 gets the majority of the AC waveform and actuates, while enough charge is stored by the AC/DC circuitry to keep the microprocessor 304 running until the next positive going cycle of the AC waveform.
[0209] In another embodiment of the fan controller, a battery 306 is used to supply power to the microprocessor 304 when the fan controller 211 is actuating the fan relay 205. In this embodiment, the 24 VAC signal is passed to the fan relay 205. This method is less complex but increases the cost of the invention and adds an item (the battery 306) that requires maintenance and periodic replacement.
[0210]
[0211]
[0212]
[0213]
[0214]
[0215]
[0216] The fan controller curve 24 for a heat pump at 47 degrees Fahrenheit OAT provides a final heating temperature rise of seven degrees Fahrenheit at the end of a P2 variable fan-off delay time of 1.5 minutes based on based on heat-source operational time P3 of 10 minutes. The fan controller curve 26 for a heat pump at 17 degrees Fahrenheit OAT provides a final heating temperature rise of seven degrees Fahrenheit at the end of a P2 variable fan-off delay time of 0.7 minutes based on a heat-source operational time P3 of 10 minutes. The fan controller curve 27 for a heat pump at 0 degrees Fahrenheit OAT provides a final heating temperature rise of seven degrees Fahrenheit at the end of a P2 variable fan-off delay time of 0.33 minutes based on a heat-source operational time P3 of 10 minutes.
[0217]
[0218]
[0219]
[0220]
[0221]
[0222]
[0223]
[0224]
[0225]
[0226] Test 4 curve 76 shows a TS of 21.3° F. at the end of 15 minutes of cool-source operational time P4. At the end of an 8.5-minute fan-off delay time, the measured TS was 0.15° F. The 8.5-minute fan-off delay time (additional 4.5-minutes) reduced sensible efficiency to 6%, increased the thermostat temperature by more than 1° F. above the set point and caused the compressor to turn on and eliminate the off-cycle.
[0227] Test 3 curve 74 provides the practical upper limit 4-minute fan-off delay time followed by an 11.5-minute off-cycle period. For this example, a fan-off delay time longer than 4 minutes reduces efficiency and shortens the off-cycle period.
[0228] Impractical and excessively long fan-off delay times disclosed in the CEC '056 report reduce latent recovery and sensible efficiency and also reduce or eliminate the compressor off-cycle time. Hundreds of field and laboratory tests were performed on numerous HVAC units to determine the practical upper limit of the fan-off delay time and develop the variable fan-off delay time P2 based on AC/HP compressor cool-source operational time P4.
[0229]
[0230]
[0231]
[0232]
[0233]
[0234]
[0235] At Step 503 the fan controller determines (e.g., accumulates) the off-cycle time P11 where the HVAC system 100 has been idle between heating or cooling periods. P11 is used when there is a fan-on time delay P0 for the start of the fan, or to adjust the fan-off time delay P2 in combination with the previous or current cool-source operational time P4 or heat-source operational time P3. In some systems, the fan start time is delayed by the fan-on time delay P0 before being energized while the heat or cooling source is brought to operational temperature.
[0236] At Step 505 the fan controller determines whether or not the fan controller fan signal input 214 is active based on the presence or absence of the low-voltage fan signal on a thermostat “G” terminal 204, or whether or not the fan controller AC/HP signal input 215 is active based on the presence or absence of the low-voltage AC/HP signal on a thermostat “Y” terminal 207. If the fan controller fan signal input 214 is not active, or the fan controller AC/HP signal input 215 is not active, then the fan controller proceeds to Step 510.
[0237] At Step 510, the fan controller sets the Fault Detection Diagnostic (FDD) Fan-only Time Accumulation (FTA) variable F6 to zero. F6 variable is used to accumulate fan-only time and is used in the FDD method to close the economizer dampers when F6 is greater than a Threshold Fan-on Time (TFT). In one embodiment the TFT time limit is 10 minutes or adjustable based on Outdoor Air Temperature (OAT), TR, TS, occupancy sensor signals, an indoor air quality requirement, or user inputs.
[0238] At Step 510, the fan controller also sets the FDD Fan-on Override (FO) variable F7 to zero. The FO F7 variable is set at the end of all heating or cooling cycles, if the fan is accidentally left on, to indicate that the fan ON signal 214 needs to be overridden to turn the fan OFF when it has accidentally been turned ON.
[0239] At Step 510, the fan controller and sets the Fan Accidentally ON (FAO) variable F8 to zero. The F8 variable is used in the FDD method to indicate that the fan is ON by itself prior to a heat-source operational time period P3 or a cool-source operational time period P4. The fan controller examines the FAO F8 variable at the end of all heating or cooling cycles to determine if the cycle was entered from a condition where the fan was accidentally left on. The FO F7 variable is used in the FDD method to turn off the fan if the fan has accidentally been left on at the end of any heat-source or cool-source operational time where the fan was turned ON prior to the heat-source or cool-source operational time.
[0240] At Step 512, if the fan controller determines the fan is operating simultaneously with a thermostat call for heating or cooling for a heat pump or hydronic system, then the fan controller proceeds to Step 513. Fan-only operation is defined as the presence of a fan signal and the absence of a heating signal or a cooling signal on the thermostat or equipment terminals or the presence of the HVAC fan control ON setting without a thermostat call for heating or a thermostat call for cooling. At Step 512, if the fan controller determines the fan is operating simultaneously with a thermostat call for heating or cooling for a heat pump or hydronic system, then the fan controller proceeds to Step 513.
[0241] At Step 513 the fan controller determines whether or not fan controller signal input 234 is detecting a signal. If fan controller signal input 234 is not detecting a signal, then the fan controller proceeds to Step 515. At Step 515, if fan controller signal input 216 from the thermostat heat “W” signal on terminal 208 is active simultaneously with fan controller signal input 214, then the fan controller sets the HVAC system mode to a hydronic or electric resistance heating system operating in heating mode and sets the mode to heating at Step 517. The fan controller then proceeds to Step 519 and goes to Step 701 fan controller hydronic/electric heating methods (
[0242] At Step 516, if the fan controller is connected to a hydronic or electric resistance system then the fan controller proceeds to Step 533 and sets the system type to a hydronic or electric HVAC system 100 operating in cooling mode. The fan controller then proceeds to Step 537 and goes to Step 901 fan controller cooling methods (
[0243] At Step 506 the fan controller determines whether or not fan controller signal input 234 is detecting a signal through either a wire connection 265 (
[0244] At Step 506, if fan controller signal input 234 is not detecting a signal, then the fan controller proceeds to Step 507 to determine whether or not fan controller signal input 216 is active from thermostat signal heat “W” on terminal 208. If fan controller signal input 216 is active, the fan controller determines that the system type is a gas furnace HVAC system 100 operating in heating mode at Step 509. The fan controller then proceeds to Step 511 and goes to Step 601 fan controller gas furnace heating methods (
[0245] At Step 505, if fan controller signal input 214 is active from the thermostat fan signal 204 or the compressor signal on terminal 207, and then through Step 512 to Step 513 fan controller HPD signal input 234 is not detecting any type of signal, and at Step 515 fan controller signal input 216 from the thermostat heat “W” signal on terminal 208 is not active, and the fan controller is connected to a gas furnace HVAC system 100 at Step 516, then the fan controller proceeds to Step 531 and sets the system type to gas furnace HVAC system 100 operating in cooling mode. The fan controller then proceeds to Step 537 and goes to Step 901 fan controller cooling methods (
[0246] The HPD input 234 is used to detect a heat pump HVAC system 100 by connecting the HPD input 234 to the hot side of the system transformer 210b or thermostat terminal 209 through wire 265 for a heat pump with reversing valve “O” normally energized for cooling (see
[0247] If at Step 513 the fan controller determines that input 234 is detecting a signal, then at Step 521, if the fan controller determines that the input signal 234 is rectified (i.e. indicating a diode 275 is present), and if at Step 525 the fan controller determines that the input 216 from thermostat signal HP REV “BR” 236 is active, then at Step 527 the fan controller determines that the system type is a heat pump HVAC system 100 operating in heating mode. The fan controller then proceeds to Step 529 and goes to Step 801 fan controller heat pump heating methods (
[0248] At Step 525, if the fan controller does not detect an active input on fan controller signal input 216 from thermostat signal HP REV “BR” 236, then at Step 535 the fan controller determines that the system type is a heat pump HVAC system 100 operating in cooling mode. The fan controller then proceeds to Step 537 and goes to Step 901 fan controller cooling methods with cooling source ON (
[0249] If the fan controller determines the HPD input 234 signal is detecting a signal at Step 513, either rectified or unrectified, and Step 521 determines the HPD input 234 signal is not rectified (no diode is connected), and Step 523 detects a floating signal on fan controller input 216 from thermostat signal HP REV “O” 235, then at Step 527 the fan controller determines the heat pump HVAC system 100 is operating in heating mode. The fan controller then proceeds to Step 529 and goes to Step 801 fan controller heat pump heating methods (
[0250] At Step 523, if the fan controller detects an active input on 216 from thermostat signal HP REV “O” 235, then at Step 535 the fan controller determines the heat pump HVAC system 100 is operating in cooling mode, and at Step 537, the fan controller proceeds to Step 901 fan controller cooling methods with cooling source ON (
[0251]
[0252] At Step 605 the fan controller accumulates (i.e., measures) gas heat-source operational time P3. At Step 605, for HVAC systems with an economizer, the fan controller optionally measures OAT, MAT, SAT, and TR.
[0253] At Step 606 the fan controller determines whether or not the fan-on delay time period P1 has expired. The fan-on delay time period P1 is based on field and laboratory test data for how long it takes for the heat exchanger to reach a useful heating temperature required to deliver warm air to the conditioned space when the fan controller transitions the fan speed from the low speed used for heating to the high speed used for cooling.
[0254] In a preferred embodiment the fan-on delay time period P1 is 4 minutes, but P1 can vary or equal the heat-source operational time P3. For an embodiment where P1 is equal to P3, the fan controller output signal 222 is not energized until the thermostat is satisfied and the heat-source operational time P3 has ended. This is a default embodiment of a fan controller for a gas furnace HVAC system 100 with a one-speed fan/blower motor or a gas furnace HVAC system 100 where the low-voltage signal from the thermostat or equipment control terminal 204 controlling the fan relay 205 cannot switch the system fan/blower motor to the high fan speed used for cooling.
[0255] At Step 607, if the fan controller determines the HVAC system requires a high speed relay to operate the system fan/blower at high speed and the fan controller goes to Step 609 to energize the High-Speed Output (HS OUT) signal 232 to turn ON the system fan/blower 206 to high speed and de-energize Low-Speed Output (LS OUT) 252. Fan controller signal 232 connects the normally open contacts on switching device 316 and connected the high-voltage line input 233 to fan controller output 232 which then turns ON the high speed tap 15 to operate the system fan/blower 206 at the high speed used for cooling. At step 607, if a high speed relay is not required, the fan controller proceeds to Step 608 and energizes signal 212 to turn on the fan relay 205 and the system fan/blower 206. At Step 610, the fan controller continues to a loop to accumulate (or otherwise measure) heat-source operational time P3 until the thermostat 201 is satisfied and discontinues the call for heating. At Step 611 the Fan Controller checks if input 216 from a gas furnace heat-source on terminal 208 is ON. If Fan Controller input 216 is ON, the fan controller continues to accumulate heat-source operational time P3.
[0256] If at Step 611, the fan controller input 216 is OFF, then at Step 613 the fan controller determines that the gas furnace satisfies the thermostat and the heat-source is OFF. At optional Step 614 if the fan controller is connected to an HVAC system with an economizer and occupancy sensor, the fan controller turns OFF output Occupancy Output (OCC OUT) 242 to close the economizer dampers to reduce outdoor airflow into the economizer and HVAC system during the fan-off time delay P2 in order to maximize heat recovery from the heat exchanger and deliver as much heating capacity as possible to the building conditioned space. At Step 615 the fan controller stores the furnace heat-source operational time P3.
[0257] In
[0258] At Step 619 a loop provides the extended fan-off delay time P2 until P2 has expired. At optional Step 620, the fan controller examines the FAO F8 variable to determine if the gas furnace heating method 601 was entered from a condition where the fan was accidentally left on. If the fan was accidentally left on, the FDD method set the variable FAO F8 to “1”. If the FAO F8 is a “1” the fan controller proceeds to Step 621. In Step 621 fan-on override, FO F7 variable is set to “1” which will later be used by the FDD method to turn off the fan. Step 621 proceeds to Step 622. If the FAO F8 variable is not set to “1” the fan controller proceeds to Step 622.
[0259] At Step 622, after P2 has expired, the fan controller de-energizes signal output signal 232 (HS OUT) and signal 252 (LS OUT) if using a high speed relay or de-energized FAN OUT 212, turning OFF the system fan/blower 206, and returns to Step 501 for the next cycle (
[0260]
[0261] At Step 653 the fan controller accumulates (i.e., measures) gas heat-source operational time P3. At Step 653, for HVAC systems with an economizer, the fan controller optionally measures OAT, MAT, SAT, and TR.
[0262] At Step 655 the fan controller checks if input 216 from the gas furnace heat-source on terminal 208 is ON. If fan controller input 216 is ON, then the fan controller continues to accumulate heat-source operational time P3. If at Step 655, the fan controller input 216 is OFF, then at Step 657 the fan controller determines that the gas furnace satisfied the thermostat based on an absence of a low-voltage signal on fan controller heat input 216, and the heat-source is OFF. At Step 659, after the gas furnace heat-source operational time P3 has expired, the fan controller energizes switch 301 which takes over control of the low-voltage fan signal from the thermostat“G” terminal (204) and provides a 24 VAC signal to fan controller output 212 which in turn activates the fan relay 205 and turns ON the system fan/blower fan 206. At optional Step 660 wherein the fan controller is connected to an HVAC system with an economizer and occupancy sensor, the fan controller turns OFF Occupancy Output (OCC OUT) 242 to close the economizer dampers to reduce outdoor airflow into the economizer and HVAC system during the fan-off time delay P2 in order to maximize heat recovery from the heat exchanger and deliver as much heating capacity as possible to the building conditioned space.
[0263] At Step 661, the fan controller stores the furnace heat-source operational time P3.
[0264] At Step 663, the fan controller calculates the variable fan-off delay time P2 based on at least one of: 1) gas furnace heat-source operational time P3 based on signals present on thermostat or equipment terminals, 2) OAT, 3) MAT, 4) SAT, and 5) TR and the rate of change of these temperatures.
[0265] At Step 665, a loop provides the extended fan-off delay time P2 until P2 has expired. At optional Step 666, the fan controller examines the FAO F8 variable to determine if the gas furnace heating fan-off delay time only method 651 was entered from a condition where the fan was accidentally left on. If the fan was accidentally left on, the FDD method set the variable FAO F8 to “1”. If the FAO F8 is a “1” the fan controller proceeds to Step 667. In Step 667, fan-on override, FO F7 variable is set to “1” which will later be used by the FDD method to turn off the fan. Step 667 then proceeds to Step 668. If the FAO F8 variable is not set the fan controller proceeds to Step 668.
[0266] At Step 667, after P2 has expired, the fan controller de-energizes signal output 212, turns OFF the fan relay 205 and fan 206, and goes to Step 501 for the next cycle (
[0267]
[0268] At Step 703, the fan controller accumulates heat-source operational time P3. At Step 703, for HVAC systems with an economizer, the fan controller optionally measures OAT, MAT, SAT, and TR.
[0269] At Step 705, the fan controller determines whether or not the fan-on delay time P0 has expired based on the prior off-cycle duration P11. In one embodiment, if the hydronic or electric resistance heating system has been OFF for less than 5 minutes, then the fan-on delay time P0 is set to zero, and if the hydronic or electric resistance heating system has been OFF from 5 minutes to 30 minutes or longer, then the fan-on delay time can vary from 5 seconds minimum to 15 seconds maximum. The fan-on time delay P0 is increased from 0 to 15 seconds maximum based on off-cycle duration P11 because it takes longer for the heating coil (or electric resistance elements) to reach a useful heating temperature required to deliver warm air to the conditioned space. In another embodiment, the fan controller may set the fan-on time delay P0 to zero for any HVAC system 100 or mode of heating or cooling operation. In another embodiment, the fan controller may set the gas furnace heater fan-on time delay P1 to the heat-source operational time P3.
[0270] At Step 707, after the fan-on delay time P0 has expired, the fan controller energizes the switch 301 which provides a 24 VAC signal to fan controller output 212 which in turn activates the fan relay 205 and turns ON the blower fan 206. At Step 709 the fan controller initiates a loop that runs continuously to accumulate heat-source operational time P3 until the thermostat 201 is satisfied and discontinues the call for heating. At Step 711, the fan controller checks if the input signal 216 from terminal 208 is ON. If the fan controller input signal 216 is ON, the fan controller accumulates heat-source operational time P3. If fan controller input 216 is OFF, at Step 713 the fan controller determines that the hydronic or electric heating satisfies the thermostat. At Step 715 the fan controller stores heat-source operational time P3. At optional Step 716 wherein the fan controller is connected to an HVAC system with an economizer and occupancy sensor, the fan controller turns OFF output occupancy output (OCC OUT) 242 to close the economizer dampers to reduce outdoor airflow into the economizer and HVAC system during the fan-off time delay P2 in order to maximize heat recovery from the heat exchanger and deliver as much heating capacity as possible to the building conditioned space.
[0271] At Step 717, the fan controller calculates the variable fan-off delay time P2 based on at least one of: 1) hydronic or electric heat-source operational time P3 based on signals present on thermostat or equipment terminals, 2) OAT, 3) MAT, 4) SAT, and 5) TR and the rate of change of these temperatures.
[0272] At Step 719, the fan controller initiates a loop to operate the extended fan-off delay time until P2 has expired and when P2 has expired. At optional Step 720, the fan controller examines the FAO F8 variable to determine if the hydronic or electronic heating method 701 was entered from a condition where the fan was accidentally left on. If the fan was accidentally left on, the FDD method set the variable FAO F8 to “1”. If the FAO F8 is a “1” the fan controller proceeds to Step 721. In Step 721, fan-on override, FO F7 variable is set to “1” which will later be used by the FDD method to turn off the fan. After Step 721, the fan controller proceeds to Step 722. If the FAO F8 variable is not set the fan controller proceeds to Step 722.
[0273] At Step 722, after the extended fan-off delay time P2 has expired, the fan controller de-energizes signal output 212, turns OFF the fan relay 205 and the fan 206, and returns to Step 501 for the next cycle (
[0274]
[0275] At Step 803, the fan controller accumulates heat-source operational time P3. At Step 803, for HVAC systems with an economizer, the fan controller optionally measures OAT, MAT, SAT, and TR.
[0276] At Step 805, the fan controller determines whether or not the fan-on delay time P0 has expired based on prior off-cycle duration P11. In one embodiment, if the heat pump heating system has been OFF for less than 5 minutes, then the fan-on delay time P0 is set to zero, and if the heat pump heating system has been OFF from 5 minutes to 30 minutes or longer, then the fan-on delay time can vary from 5 seconds minimum to 15 seconds maximum. The fan-on time delay P0 is increased from 0 to 15 seconds maximum based on off-cycle duration P11 because it takes longer for the heating coil to reach a useful heating temperature required to deliver warm air to the conditioned space. In another embodiment, the fan controller may set the heat pump heating fan-on time delay P0 to zero.
[0277] At Step 807, after the fan-on delay time P0 has expired, the fan controller energizes switch 301 which drives a 24 VAC signal to fan controller output 212 which in turn activates the fan relay 205 and turns ON the blower fan 206. At Step 809 the fan controller initiates a loop which runs continuously to accumulate heat-source operational time P3.
[0278] At Step 811, the fan controller checks for the presence of a signal on at least one of: 1) fan input 214 from thermostat fan “G” terminal 204; and 2) AC/HP input 215 from the thermostat AC “Y” terminal 207. If either signal input 214 or 215 are ON, then the fan controller accumulates heat-source operational time P3 by continuing to loop through Step 811 and Step 809 until the thermostat 201 is satisfied and heating is discontinued.
[0279] If the heat pump enters a defrost cycle during heating mode, the fan controller signal inputs 214 (fan signal from thermostat “G” terminal 204) and 215 (AC/HP compressor signal from thermostat “Y” terminal 207) continues to be energized, but the reversing valve signal changes from heating to cooling mode (energized for “O” and de-energized for “BR”) to operate the refrigeration cycle in reverse to defrost the outdoor coil. The fan controller allows the system to operate during the defrost cycle and continue to accumulate heat-source operational time P3. Defrost operation occurs when outdoor air temperatures are less than freezing (i.e., 32° F.). Lower outdoor air temperatures increase building heat losses and reduce heat pump condenser indoor-coil temperatures and heating energy available for heat recovery from extended fan operation after the heat-source has been de-energized (see
[0280] If the fan controller determines that either of the fan controller signal inputs 214 or 215 are not energized, then the fan controller continues to Step 813 where the heat pump heating system satisfies the thermostat and the heat-source is OFF and the fan controller signal detects the absence a low-voltage signal on inputs 214 and 215.
[0281] At Step 815, the fan controller stores heat-source operational time P3.
[0282] At optional Step 816, wherein the fan controller is connected to an HVAC system with an economizer and occupancy sensor, the fan controller turns OFF output occupancy output (OCC OUT) 242 to close the economizer dampers to reduce outdoor airflow into the economizer and HVAC system during the fan-off time delay P2 in order to maximize heat recovery from the heat exchanger and deliver as much heating capacity as possible to the building conditioned space.
[0283] At Step 817, the fan controller calculates the fan controller variable fan-off delay time P2 based on at least one of: 1) heat pump heat-source operational time P3 based on signals present on thermostat or equipment terminals, 2) OAT, 3) MAT, 4) SAT, and 5) TR and the rate of change of these temperatures.
[0284] At Step 819, the fan controller initiates a loop to operate the extended fan-off delay time until P2 has expired.
[0285] At optional Step 820, the fan controller examines the FAO F8 variable to determine if the heat pump heating method 801 was entered from a condition where the fan was accidentally left on. If the fan was accidentally left on, the FDD method set the variable FAO F8 to “1”. If the FAO F8 is a “1” the fan controller proceeds to Step 821. At Step 821, Fan-on Override, FO F7 variable is set to “1” which will later be used by the FDD method to turn off the fan. After Step 821 the fan controller proceeds to Step 822. If the FAO F8 variable is not set the fan controller proceeds to Step 822.
[0286] At Step 822, when P2 has expired, fan controller de-energizes fan signal output 212, to turn OFF the fan relay 205 and the fan 206, and returns to Step 501 for the next cycle (
[0287]
[0288] At Step 903, the fan controller accumulates cool-source operational time P4. At Step 903, for HVAC systems with an economizer, the fan controller optionally measures relative humidity (RH), TS, OAT, MAT, and SAT.
[0289] At Step 905, the fan controller determines whether or not the fan-on delay time P0 has expired based on prior off-cycle duration P11. In one embodiment, if the cooling system has been OFF for less than 5 minutes, then the fan-on delay time P0 is set to zero, and if the cooling system has been OFF from 5 minutes to 30 minutes or longer, then the fan-on delay time can vary from 5 seconds minimum to 15 seconds maximum. The fan-on time delay P0 is increased from 0 to 15 seconds maximum based on off-cycle duration P11 because it takes longer for the cooling coil to reach a useful cooling temperature required to deliver cool air to the conditioned space. In another embodiment, the fan controller may set the cooling fan-on time delay P0 to zero.
[0290] At Step 907, after the fan-on delay time P0 has expired, the fan controller energizes switch 301 which drives a 24 VAC signal to fan controller output 212 which in turn activates the fan relay 205 and turns ON the blower fan 206.
[0291] At Step 908, for thermostats or controllers that de-energize the heat pump reversing valve at the end of the AC/HP compressor cooling operational time, the fan controller can optionally energize switch 304 which drives a 24 VAC signal to fan controller output 222 which in turn activates reversing valve 263 to maintain the normally energized position of the heat pump reversing valve 263 for the entire duration of the AC/HP compressor cool-source operational time and the fan-off delay time time period to maximize energy recovery.
[0292] At Step 910, the fan controller initiates a loop which runs continuously. If the ECO Y1I 231 signal is not energized, the economizer is using outdoor air to cool the conditioned space. At Step 910, if the fan controller determines outdoor air is being used, the fan controller skips to Step 921 and does not accumulate cooling system operating time P4. In Step 910, if the fan controller determines that the compressor is ON, by detecting ECO Y1I 231 is energized, the fan controller proceeds to step 911 to accumulate cool-source operational time P4 until the thermostat 201 is satisfied and discontinues the call for cooling. At Step 912, the fan controller checks for the presence of a signal on at least one of: 1) fan input 214 from thermostat fan “G” terminal 204; and 2) AC/HP input 215 from the thermostat AC “Y” terminal 207. If either signal input 214 or 215 are ON, then the fan controller accumulates cool-source operational time P4. If the fan controller determines both signal inputs 214 or 215 are not energized, then the fan controller continues to Step 913 where the cooling system satisfies the thermostat and the cool source is OFF and the fan controller signal detects the absence a low-voltage signal on inputs 214 and 215. At Step 914 the fan controller stores cool-source operational time P4.
[0293] At Step 914, the fan controller can also optionally store the final relative humidity (RH), TS, OAT, MAT, and SAT measurements.
[0294] At optional Step 915, the fan controller checks the economizer Y1 (ECO Y1) input signal indicating whether or not the AC compressor is de-energized in economizer mode. If ECO Y1 is de-energized (i.e., N), then the fan controller will go to Step 921 and provide no fan-off delay time since the evaporator would not be operating due to the economizer cooling the conditioned space without compressor cooling. At optional Step 915, if the ECO Y1 is energized (i.e., Y) then the fan controller goes to optional Step 916.
[0295] At optional Step 916 wherein the fan controller is connected to an HVAC system with an economizer and occupancy sensor, the fan controller turns OFF output occupancy output (OCC OUT) 242 to close the economizer dampers to reduce outdoor airflow into the economizer and HVAC system during the fan-off time delay P2 in order to maximize cooling recovery from the evaporator and deliver as much evaporative cooling capacity as possible to the building conditioned space.
[0296] At Step 917, the fan controller calculates the variable fan-off delay time P2 based on at least one of: 1) cool-source operational time P4 based on signals present on thermostat or equipment terminals, 2) relative humidity (RH), 3) TS, 4) OAT, 5) MAT, and 6) SAT and the rate of change of these temperatures.
[0297] At Step 919, the fan controller initiates a loop to operate the extended fan-off delay time P2 until it has expired. At Step 921, after P2 has expired, the fan controller de-energizes signal output 212, turns OFF the fan relay 205 and the fan 206.
[0298] At optional Step 921, the fan controller examines the FAO F8 variable to determine if the cooling method cool source on 901 was entered from a condition where the fan was accidentally left on. If the fan was accidentally left on, the FDD method set the variable FAO F8 to “1”. If the FAO F8 is a “1” the fan controller proceeds to Step 922. In Step 922 fan-on override, FO F7 variable is set to “1 which will later be used by the FDD method to turn off the fan. After Step 922, the fan controller proceeds to Step 923. At Step 923, if the FAO F8 variable is not set to “1” the fan controller proceeds to Step 923. At Step 923, the fan controller can optionally de-energize output signal 222 to de-energize heat pump reversing valve 263.
[0299] At Step 925, the fan controller goes to Step 501 for the next cycle (
[0300]
[0301] At Step 957, if the FO F7 variable is not set to “1”, the fan controller energizes switch 301 which drives a 24 VAC signal to fan controller output 212 which in turn activates the fan relay 205 and turns ON the blower fan 206.
[0302] At Step 959, the fan controller determines if the fan-on time has exceeded the Threshold Fan-on Time TFT, in one embodiment, the TFT could be set to 10 minutes. If so, the fan controller proceeds to Step 967. If not the fan controller continues to Step 961.
[0303] At Step 961, the fan controller determines if there is a call for heating or cooling and if so, proceeds to Step 969. If there is not a call for heating or cooling, the fan controller continues to Step 963.
[0304] At Step 963, the fan controller determines if the fan signal input 214 is still energized and if so loops back to Step 953. If the fan switch input 214 is not active, the fan controller proceeds to step 969 and goes to Step 501 to determine system type and heating or cooling mode (
[0305] At Step 965, if the FDD fan-on override variable FO F7 examined in Step 955 is set to a value of “1”, based on a previous heating or cooling cycle where F7 is set to “1” to indicate that the fan 206 is accidentally turned ON with no call for heating or cooling and needs to be turned OFF. The fan controller in Step 965 de-energizes the output 212 which de-energizes the fan relay 205 and turns the fan 206 OFF. The fan controller then proceeds to Step 961 and continues the loop until there is a call for heating, a call for cooling, or the fan switch input 214 is de-energized. In this way, the fan controller will turn the system fan/blower 206 off if the thermostat fan switch is accidentally left in the ON position. For HVAC systems with economizers, the fan is turned off to save energy and prevent unconditioned outdoor air from entering the building through the economizer dampers which are automatically opened to the minimum damper position when the fan is operating to meet minimum outdoor air ventilation regulatory requirements. For HVAC systems without economizers, the fan is turned off to save energy and prevent unconditioned outdoor air from entering the building through fixed dampers which are always open to meet minimum outdoor air ventilation regulatory requirements. During the cooling season, operating the fan continuously will cause frequent short cycling of the air conditioning compressor due to hot unconditioned outdoor air entering the building causing the indoor air temperature to increase above the thermostat set point. During the heating season, operating the fan continuously will cause frequent short cycling of the heat source due to cold unconditioned outdoor air entering the building causing the indoor air temperature to decrease below the thermostat set point.
[0306] At Step 959, the fan controller examines variable F6 and if the fan has been left on for greater than, a maximum fan-on threshold, MFT, for example 10 minutes, or some other threshold amount, then the fan controller will de-energize the OCC output 244 at Step 967. This operation causes the economizer 220 to close the outdoor air dampers and save energy by reducing unconditioned outdoor air from entering the building if the thermostat fan switch is accidentally left in the ON position.
[0307] Step 961 checks if the thermostat detects a call for heating or cooling. Step 963 checks if the fan input signal 214 is energized. This is the only exit from the fan-on fault detection diagnostics loop. At Step 969, the fan controller goes to Step 501 to determine system type and heating or cooling mode (
[0308]
[0309] The fan controller 211 has a high-voltage input 233 that connects to the line voltage. The input 233 is then connected to the normally open contacts of a switching relay to the output 232. During the time period P1, the fan controller 211 keeps both relays de-energized. This connects the furnace fan controller output 247 through the normally closed contacts to output 252 to the system fan/blower 206 low-speed tap 11. After time period P1 has expired, the fan controller 211 energizes both relays. This operation disconnects the high-voltage signal 247 from the furnace fan controller from the fan 206 low-speed tap 11, and connects the line voltage signal from fan controller 211 input 233 through normally open relay contact 232 to the fan 206 high-speed tap 15. This switches the fan 206 from low speed to high speed directly, rather than indirectly as in
[0310]
[0311]
[0312] The economizer controller 220 energizes the cool source HP compressor control 203 using economizer signal AC1 Y1 229. The fan controller 246 monitors the system signals HPC Y1 215, REV O 216 FANI BK 214 and HPD 234 to determine if the system is in heating, cooling, or fan-only mode.
[0313] In cooling mode the fan controller 246 monitors the AC1 Y1 237 signal from the economizer controller 220. If the fan controller input signal ECO Y1I 231 is not energized when the thermostat is calling for cooling, then the fan controller determines that the economizer controller 232 is enabling economizer cooling only without the compressor operating. At the end of the cooling cycle the fan controller can either add additional time to the fan-off delay time period P2 to supply more cool air to the occupied space or terminate the cooling cycle with no additional fan-off delay time period P2.
[0314] If the fan controller input 231 is energized when the thermostat is calling for cooling, then the fan controller determines that the HVAC system is using mechanical cooling to satisfy the thermostat. In this event, the fan controller waits until the thermostat has been satisfied and then de-energizes the OCC OUT 242 signal to close the economizer dampers while energizing the FANO G 212 signal for the entire fan-off delay time period P2. De-energizing the OCC OUT 242 output removes the signal from the economizer input OCC W/G 245 and signals the economizer that the conditioned space is unoccupied to close the dampers during the variable fan-off delay time period P2 after the cooling system operating time P4.
[0315] Closing the dampers during the fan-off delay time period P2 allows the fan controller to recover more evaporatively cooled air from the air conditioning evaporator coil with only outdoor airflow that leaks into the economizer dampers when they are closed.
[0316] In one embodiment of the invention the economizer perimeter gap 126 of the economizer frame where it connects to the HVAC system cabinet can be sealed to prevent unintended, uncontrolled, and unconditioned outdoor airflow from entering the economizer, HVAC system, and conditioned space whether or not the ventilation fan is operating. The electrical power must be disconnected to the HVAC unit and the economizer hood must be removed in order to properly seal the economizer perimeter gap. In one embodiment of the present invention, sealing around the perimeter gap 126 of the economizer frame, where the economizer connects to the HVAC system cabinet between the economizer frame and a system cabinet, can be performed with at least one material selected from the group consisting of: adhesive tape sealant, adhesive sealant, mastic sealant, and weatherstripping. In one embodiment of the present invention, sealing the economizer perimeter gap will reduce untended outdoor air leakage through the economizer perimeter frame and allow the HVAC system to provide more cooling and heating capacity, and also allow the fan controller to recover more heating capacity from the heat exchanger or evaporatively cooled air from the air conditioning evaporator coil during the variable fan-off delay time period P2.
[0317] Sealing the economizer perimeter gap 126 involves locating the economizer perimeter gap between the economizer frame and the system cabinet, where the economizer perimeter gap is generally provided to facilitate easy installation and removal of the economizer from the HVAC system and generally left un-sealed to facilitate easy removal and replacement of the economizer, wherein the economizer perimeter gap allows outdoor air to be unintentionally drawn into the HVAC system by a heating or cooling ventilation fan and where the unintended outdoor airflow mixes with a return airflow causing increased heating and cooling loads when the economizer dampers are closed or in a minimum economizer damper position to provide a minimum outdoor airflow to meet a minimum indoor air quality recommendation. Sealing the economizer perimeter gap involves cleaning a metal surface on both sides of the economizer perimeter gap specifically between the economizer frame and the system cabinet prior to sealing the economizer perimeter gap between the economizer frame and the system cabinet; applying a material over or into the economizer perimeter gap between the economizer frame and the system cabinet to reduce unintended outdoor airflow and mixing of the outdoor airflow drawn through the economizer perimeter gap by the heating or cooling ventilation fan with the return airflow, the material selected from the group consisting of adhesive tape sealant, adhesive sealant, mastic sealant, and weatherstripping.
[0318] In another embodiment, the fan controller 245 OCC OUT 244 signal can be connected to the economizer HOT R input 226. This configuration is used for economizers without an occupancy input. In another embodiment, the fan controller 245 OCC OUT 244 signal can be connected to the actuator control 232 HOT R input which when de-energized, will cause the actuator control to use an internal spring return mechanism to fully close the dampers.
[0319] When the HVAC system is operating in heating mode, the economizer opens the dampers to a minimum open position for the duration of the heat source operational time P3. When the fan controller determines that the system is in heating mode, the fan controller energizes the FANO G 212 and the OCC OUT 242. When the heat source operational time P3 has ended, the fan controller de-energizes the OCC OUT 242 to close the economizer dampers. Closing the dampers during the fan-off delay time period P2 allows the fan controller to recover more heat from the heat exchanger during the fan-off delay time period P2 following the heat source operational time P3.
[0320] If the fan controller uses Fault Detection Diagnostics (FDD) to determine whether or not the HVAC system fan is operating continuously prior to the thermostat calling for cooling or heating. If the fan is operating continuously prior to the thermostat calling for heating or cooling, then the economizer opens the dampers to a minimum open position to provide unconditioned outdoor airflow into the HVAC system and building. This can cause the building conditioned space temperature to increase above the thermostat set point in cooling mode or cause the conditioned space temperature to decrease below the thermostat set point in heating mode. If the outdoor air temperature is 20 degrees Fahrenheit (F) above the cooling set point or 20 F below the heating set point and the fraction of outdoor airflow is 15 to 60% of the total system airflow, then the cool source or heat source can turn ON and OFF frequently causing a well-known fault referred to as “short cycling” characterizing an ON-OFF frequency of approximately 5 minutes. The fan controller uses FDD to de-energize the OCC OUT 242 and as outlined above, closes the dampers to a fully closed position, after a Threshold Fan-on Time (TFT). In one embodiment the TFT is approximately 10 minutes or adjustable based on Outdoor Air Temperature (OAT), TR, TS, occupancy sensor signals, an indoor air quality requirement, or user inputs. With the dampers closed, less unconditioned outdoor air is drawn into the economizer dampers, HVAC system, and building conditioned space when the fan is operating and this reduces the frequency and duration of cool-source operational time P4 and heat-source operational time P3.
[0321] If the fan is operating continuously but the fan-only operational time does not reach the TFT before the thermostat calls for cooling or heating, then the fan controller FDD will de-energize the FANO G 212 signal after the fan-off delay time P2 following the cool-source operational time P4 or heat-source operational time P3. This embodiment of the fan controller FDD turns the system fan/blower 206 OFF even though the thermostat fan switch is in the ON position. This saves energy in two ways: 1) the fan is no longer operating and continuously drawing electric power, and 2) the fan is no longer causing unconditioned outdoor airflow into the building through the economizer dampers which can cause unnecessary thermostat calls for cooling or heating or “short cycling.”
[0322] In one embodiment, the fan controller 245 can provide a user interface to select whether or not the fan turns off after a fan-off delay time P2 following a cool-source operational time P4 or a heat-source operational time P3 for maximum energy efficiency. In another embodiment the fan controller 245 can provide a user interface to select whether or not the dampers can be positioned to a fully closed position during continuous fan operation to reduce unconditioned outdoor airflow into the building through the economizer dampers which can cause unnecessary thermostat calls for cooling or heating or “short cycling.”
[0323] In another embodiment, the fan controller 245 can close the dampers as described above during the cool-source or heat-source operation to save even more energy by reducing the introduction of unconditioned outdoor airflow during the cool-source or heat-source operational time. This embodiment can be used in conjunction with wireless or wired demand response technologies to reduce peak cooling or peak heating demand.
[0324] In another embodiment, one or more temperature sensors T1 258, T2 259, T3 260 can be connected to the fan controller 245. The temperature sensors can be placed in locations to measure outdoor air temperature (OAT), mixed air temperature (MAT), and supply air temperature (SAT) and the rate of change of these temperatures. The fan controller can use these temperature sensors to calculate the heating temperature rise (TR) as the difference between SAT and MAT in heating mode and the rate of change of TR. The fan controller can also use these temperature sensors to calculate the cooling temperature split (TS) as the difference between MAT and SAT in cooling mode and the rate of change of TS. In this embodiment, the cooling fan-off delay time P2 can calculated as a function of at least one of the following independent variables: 1) cool-source operational time P4, 2) OAT, 3) MAT, 4) SAT, 5) TS and the rate of change of these temperatures. In this embodiment, the heating fan-off delay time P2 can be calculated as a function of at least one of: 1) heat-source operational time P3, 2) OAT, 3) MAT, 4) SAT, and 5) TR and the rate of change of these temperatures.
[0325] In another embodiment, the fan controller can use these temperature measurements or the difference between these measurements or the rate of change of any or all of these temperature measurements to lengthen or reduce the fan-off delay time period P2 after the cool-source operational time P4 or the heat-source operational time P3.
[0326]
[0327]
[0328]
[0329]
[0330]
[0331]
[0332]
[0333]
[0334]
[0335]
[0336]
[0337]
[0338]
[0339]
[0340]
[0341] At Step 1019, the thermostat determines whether or not the thermostat is connected to an economizer and whether or not the economizer ECO 1 is active or not. If ECO 1 is not active, then the thermostat skips to Step 1027. If ECO 1 is active, the thermostat proceeds to Step 1021. At Step 1021, the thermostat turns off the occupancy sensor output and closes the economizer dampers (or sets the economizer dampers to a minimum damper position) during the variable fan-off delay. At Step 1023, the thermostat calculates the variable fan-off delay P2 based on cooling or heating system parameters including at least one parameter selected from a group consisting of: HSTMO, TT, P3, P4, dT/dt, dT/dt-off, variable thermostat differential, differential offset, TR, TS, OAT, MAT, SAT and rate of change of these variables.
[0342] At Step 1025, the thermostat is waiting for the variable fan-off delay time P2 to expire based on cooling or heating system parameters or the thermostat temperature reaches an inflection point or crosses a fixed or variable thermostat differential or differential offset. For heating, if the thermostat is operating in dT/dt mode, the thermostat will continue the heating variable fan-off delay while the dT/dt is greater than the dT/dt-off times a constant. For cooling, if the thermostat is operating in dT/dt mode, the thermostat will continue the cooling variable fan-off delay while the dT/dt is less than the dT/dt-off times a constant. At Step 1027, the thermostat de-energizes the thermostat G terminal fan 204 to turn off the fan relay 205 and turn OFF the fan 206. At Step 1029, the thermostat sets F6=0, F7=0, and F8=0. At Step 1031, for a heat pump the thermostat de-energizes the thermostat O/BR terminal to de-energize the heat pump reversing valve 235. At Step 1033, the thermostat goes back to Step 1001 to continue.
[0343]
[0344] In accordance with one embodiment of the present invention, a method is provided for sealing an economizer perimeter gap of an HVAC system with an economizer when a perimeter gap of an economizer frame is present between the economizer frame and a system cabinet. The method involves disconnecting electrical power to the HVAC unit, locating the economizer perimeter gap between the economizer frame and the system cabinet, where the economizer perimeter gap is generally provided to facilitate easy installation and removal of the economizer from the HVAC system and generally left un-sealed to facilitate easy removal and replacement of the economizer, wherein the economizer perimeter gap allows outdoor air to be unintentionally drawn into the HVAC system by a heating or cooling ventilation fan and where the unintended outdoor airflow mixes with a return airflow causing increased heating and cooling loads when the economizer dampers are closed or in a minimum economizer damper position to provide a minimum outdoor airflow to meet a minimum indoor air quality recommendation. The method further includes cleaning a metal surface on both sides of the economizer perimeter gap specifically between the economizer frame and the system cabinet prior to sealing the economizer perimeter gap between the economizer frame and the system cabinet. The method further includes applying a material over or into the economizer perimeter gap between the economizer frame and the system cabinet to reduce unintended outdoor airflow and mixing of the outdoor airflow drawn through the economizer perimeter gap by the heating or cooling ventilation fan with the return airflow, the material selected from the group consisting of: adhesive tape sealant, adhesive sealant, mastic sealant, and weatherstripping; and reconnecting electrical power to the HVAC unit.
[0345] In accordance with one embodiment of the present invention, the economizer damper position can be determined using temperature measurements based on sensors installed in the HVAC system including Outdoor Air Temperature (OAT), Mixed Air Temperature (MAT), and Supply Air Temperature (SAT).
[0346] In accordance with one embodiment of the present invention the data from temperature sensor measurements to detect the following economizer faults listed in the California Energy Commission Title 24 building standard which require fault detection diagnostics for economizers: 1) economizer dampers being stuck in the open, minimum, or closed position, 2) bad or unplugged actuator, 3) sensor hard failure, 4) actuator mechanically disconnected, 5) air temperature sensor failure/fault, 6) not economizing when should, 7) economizing when should not, 8) damper not modulating, or 9) excess outdoor air. The present invention can also detect cooling or heating system not operating properly or delivering less than optimal performance.
[0347] Temperature sensor measurements alone cannot be used to determine whether or not economizer dampers are stuck open if the measured Outdoor Air Temperature (OAT) is close to the Return Air Temperature (RAT) returning to the HVAC system from the conditioned space. The outdoor air drawn through economizer dampers mixes with the return air in the return plenum of the HVAC system and the average return plenum temperature is referred to as the Mixed Air Temperature (MAT). Packaged HVAC systems cool the return air by using a fan to draw mixed air through the air filter and cooling evaporator. Packaged HVAC systems heat the return air by using the fan to draw mixed air through the air filter and heat exchanger of a gas furnace, heat pump, hydronic or electric heating system. The air temperature immediately downstream of the evaporator or heat exchanger is referred to as the Supply Air Temperature (SAT). On a hot day if the OAT is 95 degrees Fahrenheit (° F.) and the RAT is the 75° F. and the MAT is close to 95° F., then a faulted condition of a damper stuck open can be detected. If the OAT is 75 to 85° F. and the RAT is 75 to 80° F., then it can be difficult to determine if the economizer damper is stuck open based on air temperature measurements alone. Temperature measurements can only be reliably used to determine if the damper is stuck open if the OAT is 10° F. or more greater than RAT. When the OAT is within 10° F. of the RAT, it is very difficult to determine whether or not the dampers are stuck closed or stuck open, due to unintended outdoor air leakage through the economizer perimeter.
[0348] In accordance with one embodiment of the present invention, methods are provided to position economizer dampers to a minimum position to provide a minimum outdoor airflow during the cooling system operation or the heating system operation or the variable fan-off delay operation for an HVAC system equipped with economizer outdoor air dampers. The minimum position is intended to provide the minimum outdoor airflow to meet but not exceed the minimum outdoor airflow requirements specified in the American Society of Heating Refrigeration and Air-Conditioning Engineers (ASHRAE) Standard 62.1 Ventilation for Acceptable Indoor Air Quality (ASHRAE Standard 62.1). Methods are also provided to fully closed position for the economizer dampers during the variable fan-off delay to recover more evaporative cooling energy from the evaporator or more heating energy from the heat exchanger.
[0349] These embodiments can also be used to provide advanced fault detection diagnostics (AFDD) messages displayed on the thermostat device or displayed on a software application residing on a cell phone, internet, or computer system to alert a user about economizer dampers being stuck open, minimum position, or closed position, bad or unplugged actuator, sensor hard failure, actuator mechanically disconnected, air temperature sensor failure/fault, not economizing when it should, economizing when it should not, damper not modulating, excess outdoor air, or the cooling or heating system not operating properly or delivering less than optimal performance. For example, if the thermostat temperature does not achieve a minimum threshold rate of change or it takes too much time for the thermostat to reach the upper limit setpoint hysteresis during heating operation or the lower limit hysteresis limit during cooling operation, then AFDD messages can be displayed on the thermostat device or displayed on a software application residing on a cell phone, internet, or computer system to alert a user about the cooling or heating system not operating properly or delivering less than optimal performance. The following AFDD fault alarms can displayed: low airflow, low cooling capacity, low heating capacity, dirty air filter, short cycling, unoccupied supply fan operation, heat source or cool source operational faults, refrigerant system faults, heat pump reversing valve faults, refrigerant restriction, noncondensables air or water vapor in the refrigerant system, dirty or blocked condenser or evaporator, fan motor or compressor faults, low battery faults or other system faults.
[0350] While the present invention has been described as apparatus and methods for a fan controller, the apparatus and methods described above may be integrated into a thermostat, an external fan controller, a controller in a fan motor driving the cooling system ventilation fan, an economizer controller, a forced air unit controller used to control the fan relay controlling the fan motor, a packaged unit controller used to control the fan relay, or any device including these apparatus and/or methods as intended to provide similar embodiments of the present invention.
[0351] While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations can be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.
LIST OF ELEMENTS
[0352] 1—a display on the thermostat 200 embodiment. [0353] 2—a home button on the thermostat 200 embodiment. [0354] 3—an up button on the thermostat 200 embodiment. [0355] 4—a curve representing the delivered heating efficiency for a gas furnace HVAC system 100 with the known fixed fan-off delay time and low fan speed operation. [0356] 5—a down button on the thermostat 200 embodiment. [0357] 6—a curve representing the increase in delivered heating efficiency for the same gas furnace HVAC system 100 with the fan controller switching the blower fan from the low fan speed used for heating to the high fan speed used for cooling plus extended variable fan-off time delay P2 based on heat-source operational time P3. [0358] 7—a screen button on the thermostat 200 embodiment. [0359] 8—a curve representing the delivered sensible cooling efficiency for a direct-expansion air conditioning system with a known fixed fan-off time delay. [0360] 9—an occupancy sensor on the thermostat 200 embodiment. [0361] 10—a curve representing the increase in sensible cooling efficiency for the same direct-expansion air conditioning system with the fan controller providing a variable fan-off time delay P2 based on cool-source operational time P4. [0362] 11—a high-voltage low-speed tap on the system fan/blower 206 which when activated by line voltage drives the fan to a low speed. [0363] 12—a curve representing the delivered sensible heating efficiency COP for a heat pump or hydronic HVAC system 100 in heating mode with no fan-on time delay representing the negative value in sensible heating that occurs when the system fan/blower is activated before a heat pump or hydronic system has generated useful heat and no fan-off delay time. [0364] 13—a high-voltage medium-speed tap on the system fan/blower 206 which when activated by line voltage drives the fan to a medium speed. [0365] 14—a curve representing the increase in delivered heating efficiency COP for the same heat pump or hydronic HVAC system 100 in heating mode with the fan controller providing a short variable fan-on time delay based on the off-cycle duration P11 and a variable fan-off time delay P2 based on heat-source operational time P3 to increase delivered heating capacity and efficiency for the heat pump or hydronic heating system. [0366] 15—a high-voltage high-speed tap on the system fan/blower 206 which when activated by line voltage drives the fan to a high speed. [0367] 16—a curve representing the temperature rise above the return air temperature generated in a gas forced-air furnace operating for an equivalent heat-source operational time P3 and variable fan-only operational time P2. [0368] 17—a humidity sensor used to check relative humidity in the conditioned space. [0369] 18—a curve representing the temperature rise above the return air temperature generated in a hydronic heating system with supply water temperature of 140° F. operating for 10 minutes of heat-source operational time P3 and variable fan-only operational time P2. [0370] 20—a curve representing the temperature rise above the return air temperature generated in a hydronic heating system with supply water temperature of 130° F. operating for 10 minutes of heat-source operational time P3 and variable fan-only operational time P2. [0371] 22—a curve representing the temperature rise above the return air temperature generated in an electric resistance heating system operating for 10 minutes of heat-source operational time P3 and variable fan-only operational time P2. [0372] 24—a curve representing the temperature rise above the return air temperature generated in a heat pump system with an outdoor air temperature of 47° F. operating for 10 minutes of heat-source operational time P3 and variable fan-only operational time P2. [0373] 26—a curve representing the temperature rise above the return air temperature generated in a heat pump system with an outdoor air temperature of 17° F. operating for 10 minutes of heat-source operational time P3 and variable fan-only operational time P2. [0374] 27—a curve representing the temperature rise above the return air temperature generated in a heat pump system with an outdoor air temperature of 0° F. operating for 10 minutes of heat-source operational time P3 and variable fan-only operational time P2. [0375] 28—a curve representing the temperature rise above the return air temperature generated in a gas forced-air furnace with equivalent heating output to satisfy the thermostat based on varying the heat-source operational time P3 and variable fan-only operational time P2 for the fan control. [0376] 30—a curve representing the temperature rise above the return air temperature generated in a hydronic heating system with supply water temperature of 140° F. with equivalent heating output to satisfy the thermostat based on varying the heat-source operational time P3 and variable fan-only operational time P2 for the fan control. [0377] 32—a curve representing the temperature rise above the return air temperature generated in a hydronic heating system with supply water temperature of 130° F. with equivalent heating output to satisfy the thermostat based on varying the heat-source operational time P3 and variable fan-only operational time P2 for the fan control. [0378] 34—a curve representing the temperature rise above the return air temperature generated in an electric resistance heat furnace with equivalent heating output to satisfy the thermostat based on varying the heat-source operational time P3 and variable fan-only operational time P2 for the fan control. [0379] 36—a curve representing the temperature rise above the return air temperature generated in a heat pump system with an outdoor air temperature of 47° F. with equivalent heating output to satisfy the thermostat based on varying the heat-source operational time P3 and variable fan-only operational time P2 for the fan control. [0380] 38—a curve representing the temperature rise above the return air temperature generated in a heat pump system with an outdoor air temperature of 17° F. with equivalent heating output to satisfy the thermostat based on varying the heat-source operational time P3 and variable fan-only operational time P2 for the fan control. [0381] 40—a curve representing the temperature rise above the return air temperature generated in a heat pump system with an outdoor air temperature of 0° F. with equivalent heating output to satisfy the thermostat based on varying the heat-source operational time P3 and variable fan-only operational time P2 for the fan control. [0382] 50—a curve showing a known fan control with constant fan operation during unoccupied periods of time causing over ventilation and constant fan power consumption and increased heating power consumption. [0383] 52—a curve showing unoccupied fan-off control reduces fan and heating power consumption and energy usage according to an embodiment of the present invention. [0384] 54—a curve showing a known fan control with constant fan operation during unoccupied periods of time causing over ventilation and constant fan power consumption and increased cooling power consumption. [0385] 56—a curve showing unoccupied fan-off control reduces fan and cooling power consumption and energy usage according to an embodiment of the present invention. [0386] 57—a curve representing the energy efficiency of a gas furnace heating system with known control. [0387] 58—a curve representing the energy efficiency of a gas furnace with heater ventilation fan-off delay time operation for as long as the current dT/dt is greater than a constant, C1, multiplied times a previous heating off-cycle dT/dt-off1 according to the present invention. [0388] 59—a curve representing the energy efficiency of a gas furnace with heater ventilation fan-off delay time operation for as long as the current dT/dt is greater than a constant, C1, multiplied times a previous heating off-cycle dT/dt-off2 according to the present invention. [0389] 60—a curve representing indoor thermostat temperature for the on and off cycles of a gas furnace heating system. [0390] 63—a curve representing the energy efficiency of an air conditioning cooling system with known control. [0391] 64—a curve representing the energy efficiency of an air conditioning cooling system with cooling ventilation fan-off delay time operation for as long as the current dT/dt is less than a constant, C2, multiplied times a previous cooling off-cycle dT/dt-off1 according to the present invention. [0392] 65—a curve representing the energy efficiency of an air conditioning cooling system with cooling ventilation fan-off delay time operation for as long as the current dT/dt is less than a constant, C2, multiplied times a previous cooling off-cycle dT/dt-off2 according to the present invention. [0393] 66—a curve representing indoor thermostat temperature for the on and off cycles of an air conditioning cooling system. [0394] 70—a curve representing laboratory test data of cooling temperature split (° F.) across the evaporator (i.e., entering evaporator air dry-bulb temperature minus leaving evaporator dry-bulb temperature) for 5 minutes of cool-source operational time P4 and a 3-minute fan-off delay time P2 providing a 32% efficiency improvement compared to the same unit with no time delay. [0395] 72—a curve representing field test data of cooling temperature split (° F.) across the evaporator for 10 minutes of cool-source operational time P4 and a 4-minute fan-off delay time P2 providing a 15% efficiency improvement compared to the same unit with no time delay. [0396] 74—a curve representing field test data of cooling temperature split (° F.) across the evaporator for 15 minutes of cool-source operational time P4 and a 4-minute fan-off delay time P2 providing a 10% efficiency improvement compared to the same unit with no time delay. [0397] 76—a curve representing field test data of cooling temperature split (° F.) across the evaporator for 15-minutes of cool-source operational time P4 and an 8.5-minute fan-off delay time P2 providing a 6% efficiency improvement compared to the same unit with no time delay. The 8.5-minute (extra 4.5-minutes compared to curve 74) of fan-off delay reduced sensible efficiency by 34%. [0398] 80—a curve representing laboratory test data of sensible EER and total power (kW) for 5 minutes of cool-source operational time and a 3-minute fan-off delay time P2 providing a 32% efficiency improvement compared to the same unit with no time delay. [0399] 82—a curve representing laboratory test data of sensible EER and total power (kW) for 10 minutes of cool-source operational time and a 3-minute fan-off delay time P2 providing a 15% efficiency improvement compared to the same unit with no time delay. [0400] 84—a curve representing laboratory test data of sensible EER and total power (kW) for 15 minutes of cool-source operational time and a 4-minute fan-off delay time P2 providing a 10% efficiency improvement compared to the same unit with no time delay. [0401] 86—a curve representing laboratory test data of sensible EER and total power (kW) for 15 minutes of cool-source operational time P4 and a 8.5-minute fan-off delay time P2 providing a 6% efficiency improvement compared to the same unit with no time delay. The additional 4.5-minute fan-off delay time reduces the efficiency improvement by about 34% due to zero temperature split and sensible cooling delivered at the end of the fan-off delay time. [0402] 88—a curve representing laboratory test data of sensible EER and total power (kW) for 30 minutes of cool-source operational time P4 and a 4-minute fan-off delay time P2 providing a 5% efficiency improvement compared to the same unit with no time delay. [0403] 90—a curve representing a heat pump with reversing valve “O” energized throughout the cool source operational period of time P3 and the fan-off delay time period of time P2. [0404] 92—a curve representing the dry-bulb temperature split with the heat pump with reversing valve “O” energized throughout the cool source operational period of time P3 and the fan-off delay time period of time P2. [0405] 94—a curve representing the application energy efficiency ratio (EER*) with the heat pump with reversing valve “O” energized throughout the cool source operational period of time P3 and the fan-off delay time period of time P2. [0406] 96—a curve representing the application energy efficiency ratio (EER*) with the heat pump with reversing valve “O” de-energized throughout the cool source operational period of time P3 and the fan-off delay time period of time P2. [0407] 100—an HVAC system. [0408] 101—a control board on an HVAC system. [0409] 103—a combustion air inducer on an HVAC system with a gas furnace. [0410] 105—an igniter on an HVAC system with a gas furnace. [0411] 107—a gas valve an HVAC system with a gas furnace. [0412] 109—a burner on an HVAC system with a gas furnace. [0413] 111—a heat exchanger on an HVAC system including a gas furnace heat exchanger, electric resistance coil, or hydronic heating coil. [0414] 113—a pressure switch on an HVAC system with a gas furnace. [0415] 115—a gas manifold on an HVAC system with a gas furnace. [0416] 117—an AC or HP compressor. [0417] 119—an evaporator in cooling mode or a condenser on a heat pump in heating mode. [0418] 121—a condenser in cooling mode or an evaporator on a heat pump in heating mode. [0419] 123—a condenser fan. [0420] 125—an economizer. [0421] 126—a perimeter gap of the economizer frame where it connects to the HVAC system cabinet and this gap allows unintended and uncontrolled outdoor airflow to enter the economizer, HVAC system, and conditioned space whether or not the ventilation fan is operating. [0422] 200—a thermostat. [0423] 201—a thermostat or equipment control terminals. [0424] 202—a furnace heat-source control used to indicate a device that when energized, produces heating for the system. [0425] 203—an AC compressor control used to indicate a device that when energized produces cooling for the system when the system is a direct-expansion cooling system; In a heat pump, this device is energized in both heating and cooling. The heating or cooling mode is determined by the reversing valve 263, and 264. [0426] 204—a FAN “G” terminal of a thermostat energized when the system fan is ON or the thermostat calls for air conditioning. [0427] 205—a high-speed relay used to indicate a device that when energized connects 120 VAC to the high speed tap of the system fan/blower 206. [0428] 206—a system fan/blower used to indicate a multiple speed motor with a low, medium, and high fan speed tap or setting. [0429] 207—an AC compressor thermostat “Y” terminal of the thermostat energized when the thermostat calls for cooling. [0430] 208—a heat thermostat “W” terminal energized when the thermostat calls for heating. [0431] 209—a Hot thermostat “R” terminal connected to the Hot leg 210b of the 24 VAC system transformer 210. [0432] 210—a system transformer used to step down the input voltage of 120 VAC to the 24 VAC system voltage with a neutral leg 210a and a hot leg 210b. [0433] 210a—a neutral or common leg 210a of the system transformer 210. [0434] 210b—a Hot leg 210b of the system transformer 210. [0435] 211—an embodiment of the fan controller 211. [0436] 212—a fan controller output signal to activate the fan relay 205 and when energized turns on the system fan/blower 206 to high speed and when de-energized can either stop the system fan/blower 206 or return control of the system fan/blower 206 to the low-speed relay on the furnace fan controller 238. [0437] 213—a fan Controller input signal connected to the Hot leg 210b of the system transformer where this signal is actually the system ground signal for the fan controller 211. [0438] 214—a fan controller fan signal input used to detect the presence or absence of a low-voltage fan signal on a thermostat “G” terminal 204 to determine system type and cooling or heating mode of operation based on other fan controller inputs, allow measurement of an off-cycle time P11, and used as a proxy to measure cool-source operational time P4 or heat-source operational time P3 in order to calculate a fan-off delay time P2. The fan controller fan signal input 214 is active when the fan is on, or when the AC compressor is on, or for a heat pump when the thermostat is calling for heating or cooling based on the signal to the reversing valve. The fan controller fan signal input 214 can be used as a proxy for the compressor operation and therefore, be used to measure the duration of compressor cool-source operational time P4. For a heat pump system, the fan controller fan signal input 214 can be used to determine the duration of the cool-source operational time P4 or heat-source operational time P3 depending on the status of the signal to the reversing valve 216 and the HPD signal input 234. [0439] 215—an optional fan controller AC compressor input signal used to detect the presence or absence of a low-voltage fan signal on the AC thermostat “Y” terminal 207 to determine system type and cooling or heating mode of operation based on other fan controller inputs, allow measurement of an off-cycle time P11, and used as a proxy to measure cool-source operational time P4 or heat-source operational time P3 in order to calculate a fan-off delay time P2. The fan controller AC signal input 215 is active when the AC compressor is on, or for a heat pump when the thermostat is calling for heating or cooling based on the signal to the reversing valve. The fan controller fan signal input 215 can be used to measure the duration of compressor cool-source operational time P4. For a heat pump system, the fan controller fan signal input 215 can be used to determine the duration of the cool-source operational time P4 or heat-source operational time P3 depending on the status of the signal to the reversing valve 216 and the HPD signal input 234. [0440] 216—a fan controller heat-source or HP reversing valve signal input used to detect the presence or absence of a low-voltage heat signal on the thermostat “W” terminal 208 to determine system type and cooling or heating mode of operation based on other fan controller inputs, allow measurement of an off-cycle time P11, or to allow measurement of a cool-source operational time P4 or heat-source operational time P3 in order to calculate the fan-off delay time P2, or to detect the presence or absence of a low-voltage heat pump reversing valve signal on a thermostat “O” terminal (235) normally energized for cooling or a HP low-voltage reversing valve signal on the thermostat “BR” terminal (236) normally energized for heating. [0441] 217—a dashed line to indicate the disconnection of the FAN G terminal of the thermostat to the fan relay 205. [0442] 219—a fan controller 246 input signal from a building's occupancy sensor. [0443] 220—an economizer control used to control an economizer to provide minimum outdoor airflow into the HVAC system 100 and building conditioned space to meet minimum indoor air quality regulatory requirements and provide maximum outdoor airflow when the outdoor air temperature (or humidity and enthalpy conditions) are less than the economizer change over settings to cool the conditioned building space without direct-expansion compressor cooling. [0444] 221—a fan controller input signal from the system transformer neutral side. [0445] 222—a fan controller output signal to activate the reversing valve 263 or 264 to maintain the position of the reversing valve for the entire duration of HP compressor operational time and fan-off delay time to maximize sensible energy recovery from a heat pump. [0446] 223—a neutral side of the system transformer connected to other elements of the system. [0447] 224—a dashed line to indicate the disconnection of the reversing valve thermostat or equipment terminal 235 or 236 to the reversing valve 263 or 264. [0448] 225—an input to the economizer 220 that supplies power to the economizer through the system transformer 210 neutral leg 210A. [0449] 226—an input to the economizer 220 that supplies power to the economizer through the system transformer 210 hot leg 210B. [0450] 227—a dashed line used to indicate a broken connection between the thermostat 201 occupancy signal output 218 and the economizer 220 occupancy sensor input 245. The economizer 220 occupancy input 245 is connected to the fan controller 246 output 242. [0451] 228—an input to an economizer 220 from the thermostat terminal 207 which is activated if the thermostat calls for cooling. [0452] 229—an output from the economizer 220 which is energized when mechanical cooling is required for the building. [0453] 231—a fan controller 246 input signal which is activated by the economizer 220 output 233 when mechanical cooling is required to cool the building. [0454] 232—an actuator control used to close and open economizer dampers in the HVAC system 100 to provide minimum outdoor airflow into the HVAC system 100 and building conditioned space per indoor air quality regulatory requirements and provide maximum outdoor airflow when the outdoor air temperature and humidity conditions are less than the economizer change over settings to cool the conditioned building space without direct-expansion compressor cooling. [0455] 233—a fan controller line voltage input used to supply power to the system fan/blower 206 high-speed tap 15 through switching device 316. [0456] 234—a fan controller HPD signal input used by the fan controller to detect the presence or absence of a low-voltage signal from the system transformer hot 210b to determine whether or not a heat pump is connected. If the HPD signal input 234 is not connected to the system transformer hot 210b, then the fan controller determines it is connected to a gas, hydronic, or electric HVAC system 100 type in cooling or heating mode of operation depending on the low-voltage signals on other fan controller signal inputs. If the HPD signal input 234 is connected by a wire 265 to the system transformer hot 210b, then the fan controller HPD signal input 216 receives an unrectified low-voltage signal and determine it is connected to a heat pump HVAC system 100 with reversing valve “O” energized in cooling mode and de-energized in heating mode where the mode of cooling or heating operation is detected by the presence or absence of a low-voltage signal on fan controller input 216 based on a connection to the REV “O” thermostat terminal 235 (see waveform 350 in