Abstract
The efficient fan controller includes a microprocessor receiving at least one signal input from thermostat/equipment control terminals to control a fan relay to operate a system fan. The microprocessor monitors a thermostat call for cooling/heating duration and determines a variable fan-off delay based on the cooling/heating cycle duration, and at an end of a cooling/heating cycle energize the fan relay to operate the system fan for the variable fan-off delay. The fan controller avoids false thermostat activation signals and includes a common wire adapter to provide continuous power to a smart communicating thermostat and is configured to evaluate floating, zero, rectified, false positive and active input signals. The fan controller can be embodied on a forced-air-unit control board or thermostat. The fan controller installation methods ensure the system fan/blower operates at high speed for heating and cooling to improve thermal comfort, efficiency and satisfy the thermostat sooner to save energy.
Claims
1. A fan controller for a Heating Ventilation Air Conditioning (HVAC) system (100), the fan controller comprising: a microprocessor (304); at least one electrical input configured to receive an electrical signal from a thermostat or equipment control terminal (201) or a smart communicating thermostat (800), wherein the electrical input is selected from the group consisting of: 1) a fan signal input (214) configured to connect to a thermostat G signal terminal (204) for the microprocessor (304) to monitor for an active G signal, 2) an Air Conditioning (AC) signal input (215) configured to connect to a thermostat Y signal terminal (207) for the microprocessor (304) to monitor for an active Y signal, and 3) a heat signal input (216), configured to connect to a thermostat W signal terminal (208) for the microprocessor (304) to monitor for an active W signal; a first switching device (301) electrically connected to the microprocessor (304) to receive a control signal from the microprocessor (304); a common wire adapter (815), comprising at least one electrical component selected from the group consisting of: an HVAC element (814) providing at least two HVAC control signals to the HVAC system, a thermostat element (806) receiving at least two HVAC control signals from a thermostat, at least one electrical connection (808) between the thermostat element and the HVAC element carrying at least two HVAC control signals, and a second switching device (836) in the HVAC Element to respond to the negatively rectified signals on the single electrical connection (808) to re-create HVAC control signal 818; and a fan relay signal output (212) from the first switching device (301); and wherein the microprocessor (304) is configured to perform at least one action selected from the group consisting of: monitor an output (272) from a power supply (303) and an output (828) of an optoisolator (824) to provide a signal (832) to the second switching device (836) to provide a continuous AC waveform to output (818) to signal the HVAC system if the input (808) has a negatively rectified signal; monitor a duration of a cooling cycle and determine a variable fan-off delay time based on the duration of the cooling cycle, and at an end of the cooling cycle, either energize or continue to energize the fan relay signal output (212) to operate a system fan/blower (206) for the variable fan-off delay time to deliver additional cooling energy to a conditioned space wherein the variable fan-off delay time is determined in order to improve energy efficiency, and monitor a duration of a heating cycle and determine the variable fan-off delay time based on the duration of the heating cycle, and at an end of a heating cycle, either energize or continue to energize the fan relay signal output (212) to operate the system fan/blower (206) for the variable fan-off delay time to deliver additional heating energy to the conditioned space wherein the variable fan-off delay time is determined in order to improve the energy efficiency.
2. The fan controller of claim 1, wherein the electrical inputs to the fan controller have at least one zener diode between the electrical input signal and an optoisolator to eliminate false positive stray voltage signals and establish a minimum threshold active voltage signal to deliver to the microprocessor as an active control signal.
3. The fan controller of claim 1, wherein the microprocessor (304) is configured to determine at least one signal on the output (808) from the thermostat element 806 of the common wire adapter (815) terminal from the group consisting of: a floating signal, a zero voltage signal, a false positive stray voltage signal, an active voltage signal (350), and the positively rectified signal (351); the microprocessor is further configured to recognize the floating signal, the zero voltage signal, the false positive stray voltage signal, the active voltage signal, and the positively rectified signal and only provide a low voltage control signal to the fan control output 212 to control the system fan/blower (206) when the input signal (808) has at least an active positively rectified voltage signal.
4. The fan controller of claim 1, wherein the microprocessor (304) is configured to determine at least one signal on the output (808) from the thermostat element (806) of the common wire adapter (815) terminal selected from the group consisting of: a floating signal, a zero voltage signal, a false positive stray voltage signal, an active voltage signal (350), and the negatively rectified signal (351); the microprocessor is further configured to recognize the floating signal, the zero voltage signal, the false positive stray voltage signal, the active voltage signal, and the negatively rectified signal and only provide a low voltage control signal to output (818) to the HVAC Equipment Control Terminal (804) when the input signal has at least an active negatively rectified voltage signal.
5. The fan controller of claim 1, wherein the apparatus and methods are embodied on a Forced Air Unit (FAU) control board (293) or a thermostat (201).
6. The fan controller of claim 1, wherein the fan controller is installed on the HVAC system (100) to improve thermal comfort, energy efficiency and satisfy the thermostat sooner to save energy by controlling the system fan/blower (206) to a high speed using at least one method selected from the group consisting of: installing a 24-volt wire jumper (840) from a fan only tap to a high-speed or cool speed tap of the system fan/blower (206) to enable the thermostat G signal wire to control high speed fan operation, installing a high-voltage Y-adapter (842) combining the two high voltage signal outputs from a Forced Air Unit (FAU) control board (238) to the high speed tap 15 of the system fan/blower (206) to enable high speed fan operation in cooling and heating modes, using a dip switch or other electrical control switching device (844) on the FAU control board to enable high speed system fan/blower operation when the thermostat G terminal is energized in cooling or heating modes, using wired or wireless (WIFI) software application commands (846) to control a switching device to enable high speed system fan/blower operation when the thermostat G terminal is energized in cooling or heating modes, and using an electrical signal waveform (848) identified by a controller to enable high speed system fan/blower operation when the thermostat G terminal is energized in cooling or heating modes.
7. The fan controller of claim 1, wherein a load resistor (852) is provided between the transformer common and the electrical inputs to the fan controller to provide a low impendence path to common for the thermostat signals to make the fan controller transparent to the thermostat and avoid false thermostat activation signals for the system fan/blower (206).
8. The fan controller of claim 1, wherein the microprocessor performs a fan-only Fault Detection Diagnostic (FDD) procedure for a HVAC thermostat fan control having AUTO and ON or fan-only schedule settings, and the microprocessor corrects a fan-only operating fault by de-energizing a fan relay to override the ON setting and turn off the HVAC thermostat fan control when it is accidentally turned to the ON setting, the microprocessor: monitors signals present or absent on a thermostat or an equipment terminals to determine if the HVAC fan control has been accidentally set to the ON setting which results in continuous fan operation; detects the presence of a fan-only operation based on 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; if the fan-only operation continues until a Threshold Fan-only Time (TFT), then the microprocessor performs at least one action selected from the group consisting of: de-energizes the fan relay to override the ON setting and turn off the HVAC fan, and monitors the HVAC system parameters during the off cycle; and if the HVAC fan control turns off prior to reaching the TFT, then the microprocessor performs at least one action selected from the group consisting of: de-energizes the fan relay and turning off the HVAC fan, and monitors the HVAC system parameters during the off cycle; if the heating signal or the cooling signal are detected or the thermostat call for heating or the thermostat call for cooling are detected during what was previously the fan-only operation and prior to reaching the TFT, then the microprocessor performs at least one action selected from the group consisting of: energizes the fan relay to continue energizing the HVAC fan, and monitors the HVAC system parameters, waits for the completion of either the duration of the heating cycle or duration of the cooling cycle P3 while continuing to energize the HVAC fan, upon completion of either the duration of the heating cycle or duration of the cooling cycle P3, the microprocessor performs at least one action selected from the group consisting of: calculates a fan-off time delay P2, energizes the fan relay to continue energizing the HVAC fan for the fan-off time delay P2, waits for the completion of the fan-off time delay P2, and de-energizes the fan relay to turn off the HVAC fan at the end of the fan-off time delay P2.
9. The fan controller of claim 8, wherein the fan controller Threshold Fan-only Time (TFT) can vary from 0 to 60 minutes or longer.
10. A fan controller for a Heating Ventilation Air Conditioning (HVAC) system (100), the fan controller comprising: a microprocessor (304); at least one electrical input configured to receive an electrical signal from a thermostat or equipment control terminal (201) or a smart communicating thermostat (800), wherein the electrical input is selected from the group consisting of: 1) a fan signal input (214) configured to connect to a thermostat G signal terminal (204) for the microprocessor (304) to monitor for an active G signal, 2) an Air Conditioning (AC) signal input (215) configured to connect to a thermostat Y signal terminal (207) for the microprocessor (304) to monitor for an active Y signal, 3) a heat signal input (216), configured to connect to a thermostat W signal terminal (208) for the microprocessor (304) to monitor for an active W signal, and 4) a temperature sensor input, configured to connect to a temperature sensor to monitor at least one temperature selected from the group consisting of: a conditioned space temperature, a return air temperature and a supply air temperature; and a first switching device (301) electrically connected to the microprocessor (304) to receive a control signal from the microprocessor (304); a common wire adapter (815), comprising at least one electrical component selected from the group consisting of: an HVAC element (814) providing at least two HVAC control signals to the HVAC system, a thermostat element (806) to receive at least two HVAC control signals from a thermostat, at least one electrical connection (808) between the thermostat element and the HVAC element carrying at least two HVAC control signals, and a second switching device (836) in the HVAC Element to respond to the negatively rectified signals on the single electrical connection (808) to re-create HVAC control signal 818; and a fan relay signal output (212) from the first switching device (301); and wherein the microprocessor (304) is configured to perform at least one action selected from the group consisting of: monitor an output (272) from a power supply (303) and an output (828) of an optoisolator (824) to provide a signal (832) to the second switching device (836) to provide a continuous AC waveform to output (818) to signal the HVAC system if the input (808) has a negatively rectified signal; monitor a duration of a cooling cycle and determine a variable fan-off delay time based on the duration of the cooling cycle, and at an end of the cooling cycle, either energize or continue to energize the fan relay signal output (212) to operate a system fan (206) for the variable fan-off delay time to deliver additional cooling energy to a conditioned space wherein the variable fan-off delay time is determined in order to improve energy efficiency, monitor a duration of a heating cycle and determine the variable fan-off delay time based on the duration of the heating cycle, and at an end of a heating cycle, either energize or continue to energize the fan relay signal output (212) to operate the system fan/blower (206) for the variable fan-off delay time to deliver additional heating energy to the conditioned space wherein the variable fan-off delay time is determined in order to improve energy efficiency, and monitor the temperature sensor input, and at an end of the cooling cycle or heating cycle either energize or continue to energize the fan relay signal output (212) to operate a system fan/blower (206) for the variable fan-off delay time to deliver additional cooling or heating energy to a conditioned space wherein the variable fan-off delay time is determined based on at least one threshold temperature selected from the group consisting of: the conditioned space temperature, the return air temperature and the supply air temperature.
11. The fan controller of claim 10, wherein the temperature threshold is based on at least one temperature threshold selected from the group consisting of: a supply air temperature threshold less than the conditioned space temperature for cooling, a supply air temperature threshold greater than the conditioned space temperature for heating, a supply air temperature threshold less than the return air temperature for cooling, a return air temperature threshold less than the supply air temperature for heating, a temperature split threshold for cooling defined as the return air temperature minus the supply air temperature, a temperature rise threshold for heating defined as the supply air temperature minus the return air temperature, a conditioned space temperature decreases below a heating threshold for heating, a conditioned space temperature increases above a cooling threshold for cooling, and a threshold inflection point where the rate of change of the conditioned space temperature with respect to time equals zero plus or minus a confidence interval tolerance.
12. The fan controller of claim 11, wherein the conditioned space temperature threshold for heating is 0.5 degrees Fahrenheit plus or minus a confidence interval tolerance below the end-of-cycle conditioned space temperature at the end of the thermostat call for heating which is equivalent to the upper limit thermostat differential temperature.
13. The fan controller of claim 11, wherein the conditioned space temperature threshold for cooling is +0.5 degrees Fahrenheit plus or minus a confidence interval tolerance above the end-of-cycle conditioned space temperature at the end of the thermostat call for cooling which is equivalent to the lower limit thermostat differential temperature.
14. The fan controller of claim 10, wherein the electrical inputs to the fan controller have at least one zener diode between the electrical input signal and an optoisolator to eliminate false positive stray voltage signals and establish a minimum threshold active voltage signal to deliver to the microprocessor as an active control signal.
15. The fan controller of claim 10, wherein the apparatus and methods are embodied on a Forced Air Unit (FAU) control board (293) or a thermostat (201).
16. The fan controller of claim 10, wherein a load resistor (852) is provided between the transformer common and the electrical inputs to the fan controller to provide a low impendence path to common for the thermostat signals to make the fan controller transparent to the thermostat and avoid false thermostat activation signals for the system fan/blower (206).
17. The fan controller of claim 10, wherein the microprocessor performs a fan-only Fault Detection Diagnostic (FDD) procedure for a HVAC thermostat fan control having AUTO and ON or fan-only schedule settings, and the microprocessor corrects a fan-only operating fault by de-energizing a fan relay to override the ON setting and turn off the HVAC thermostat fan control when it is accidentally turned to the ON setting, the microprocessor: monitors signals present or absent on a thermostat or an equipment terminals to determine if the HVAC fan control has been accidentally set to the ON setting which results in continuous fan operation; detects the presence of a fan-only operation based on 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; if the fan-only operation continues until a Threshold Fan-only Time (TFT), then the microprocessor performs at least one action selected from the group consisting of: de-energizes the fan relay to override the ON setting and turn off the HVAC fan, and monitors the HVAC system parameters during the off cycle; and if the HVAC fan control turns off prior to reaching the TFT, then the microprocessor performs at least one action selected from the group consisting of: de-energizes the fan relay and turning off the HVAC fan, and monitors the HVAC system parameters during the off cycle; if the heating signal or the cooling signal are detected or the thermostat call for heating or the thermostat call for cooling are detected during what was previously the fan-only operation and prior to reaching the TFT, then the microprocessor performs at least one action selected from the group consisting of: energizes the fan relay to continue energizing the HVAC fan, and monitors the HVAC system parameters, waits for the completion of either the duration of the heating cycle or duration of the cooling cycle P3 while continuing to energize the HVAC fan, upon completion of either the duration of the heating cycle or duration of the cooling cycle P3, the microprocessor performs at least one action selected from the group consisting of: calculates a fan-off time delay P2, energizes the fan relay to continue energizing the HVAC fan for the fan-off time delay P2, waits for the completion of the fan-off time delay P2, and de-energizes the fan relay to turn off the HVAC fan at the end of the fan-off time delay P2.
18. The fan controller of claim 17, wherein the fan controller Threshold Fan-only Time (TFT) can vary from 0 to 60 minutes or longer.
Description
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0076] 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:
[0077] FIG. 1 shows a fan controller according to the present invention for installation at a thermostat or at the HVAC equipment terminal block.
[0078] FIG. 2 shows the fan controller according to the present invention connected to an HVAC system with gas furnace, electric resistance, or hydronic heating coils.
[0079] FIG. 3 shows the fan controller according to the present invention connected to a heat pump HVAC system with reversing valve energized for cooling.
[0080] FIG. 4 shows the fan controller according to the present invention connected to a heat pump HVAC system with reversing valve energized for heating.
[0081] FIG. 5 shows elements of the efficient fan controller according to the present invention for HVAC systems with direct-expansion air conditioning, gas furnace, heat pump, electric resistance, or hydronic heating.
[0082] FIG. 6 shows a graph of delivered gas furnace heating efficiency for a known HVAC system fan control and the fan control according to the efficient fan controller.
[0083] FIG. 7 shows a graph of direct-expansion air conditioning sensible cooling efficiency for the known HVAC fan control and the fan control according to the efficient fan controller.
[0084] FIG. 8 shows a graph of delivered heat pump or hydronic heating efficiency for the known HVAC fan control and the fan control according to the efficient fan controller.
[0085] FIG. 9 shows a first method for determining what type of system is connected and what operational mode to execute, according to the present invention.
[0086] FIG. 10 shows a method for determining variable fan-on and fan-off time delays based on the heat mode operational time, according to the present invention.
[0087] FIG. 11 shows a method for determining variable fan-on and fan-off time delays based on the cooling mode operational time, according to the present invention.
[0088] FIG. 12 shows the signals coming from the thermostat and going to the microprocessor with pull up resistors used to facilitate the processor interpreting three distinct states of the input signals, active, floating, or off.
[0089] FIG. 13 shows the connections between a Smart Communicating Thermostat and the HVAC Equipment Control Terminals without a common wire input 802 connected to the thermostat which will not provide reliable electric power to the Smart Communicating Thermostat.
[0090] FIG. 14 shows a Common Wire Adapter 815 comprised of a Thermostat Element 806 and an HVAC Element 814 where the HVAC Element 814 is an integrated element of the Efficient Fan Controller (EFC) (811) embodiment. The Thermostat Element 806 inputs are connected to the thermostat G and thermostat Y terminals on one side and connected to input 808 of the HVAC Element 814 on the other side. The Efficient Fan Controller 811 output 212 connects to the ran relay 205 and output 818 connects to the Y terminal.
[0091] FIG. 15 shows a Common Wire Adapter 815 comprised of a Thermostat Element 806 and an HVAC Element 814 where the HVAC Element 814 is an integrated element of the Efficient Fan Controller (EFC) (811) embodiment. The Thermostat Element 806 inputs are connected to the thermostat G and thermostat W terminals on one side and connected to input 808 of the HVAC Element 814 on the other side. The Efficient Fan Controller 811 output 212 connects to the ran relay 205 and output 818 connects to the W terminal.
[0092] FIG. 16 shows an embodiment of the present invention of a common wire adapter 815 comprised of a Thermostat Element 806 and an HVAC Element 814. The HVAC Element uses optoisolators and a microprocessor to trigger switching devices to create a full AC waveform from a positively or negatively rectified input signal (see FIG. 19) to allow a pre-existing wire to be repurposed and provide an electrical path to carry the common signal 802A of the system transformer 210 to the smart communicating thermostat 800.
[0093] FIG. 17 shows the Y-adapter used to connect the outputs from the fan relay and furnace relay to the high-speed tap of the system fan/blower.
[0094] FIG. 18 shows the detail of the signal conditioning circuitry in FIG. 5.
[0095] FIG. 19 shows the exemplary AC waveforms 350, 351 and 352 that can be present on a wire between the thermostat element and the HVAC element of the Common Wire Adapter 815 comprising HVAC Element 814 and Thermostat (Tstat) Element 806.
[0096] FIG. 20 shows a graph of heating efficiency, outdoor air temperature, indoor thermostat temperature, and rate of change of indoor thermostat temperature versus time of operation for a gas furnace heating system with known control where the heat source is turned off when the thermostat temperature reaches the setpoint hysteresis differential a first time and the heater ventilation fan operates for a fixed fan-off delay time after the heat source is turned off
[0097] FIG. 21 shows a graph of cooling efficiency (i.e., Energy Efficiency Ratio, (EER)), cooling system power, outdoor air temperature, indoor thermostat temperature, and rate of change of indoor thermostat temperature versus time of operation for a direct-expansion air conditioning cooling system with known control where the cool source and cooling ventilation fan are turned off when the thermostat temperature decreases to the minimum setpoint hysteresis a first time.
[0098] FIG. 22 shows a method for turning off a fan if it has been left accidentally on.
[0099] Corresponding reference characters indicate corresponding components throughout the several views of the drawings.
DETAILED DESCRIPTION OF THE INVENTION
[0100] The following description is of the best mode presently contemplated for carrying out the fan controller 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.
[0101] FIG. 1 shows a fan controller 211 according to the present invention for installation at a thermostat or at an HVAC equipment terminal block. The efficient fan controller 211 includes leads 212-222.
[0102] FIG. 2 shows the efficient fan controller 211 connected to an HVAC system with AC compressor control (203) for direct-expansion cooling and heat source (202) for gas furnace, electric resistance, or hydronic heating. The following existing thermostat or equipment control terminals (201) are connected and transmitting low-voltage signals to the efficient fan controller (211): [0103] 1) Fan signal G 204 transmits voltage signals to the efficient fan controller 211 through input lead 214; [0104] 2) cooling signal AC Y 207 transmits voltage signals to the efficient fan controller 211 through input lead 215; [0105] 3) heat source signal HEAT W 208 transmits voltage signals to the through input lead 216; [0106] 4) system transformer (210) common 24 VAC signal is connected to the efficient fan controller 211 through input lead 221; and [0107] 5) system transformer Hot R 209 is connected to the efficient fan controller 211 by lead 213 or optionally connected to efficient fan controller 211 lead 234 for connecting to enable control for a heat pump system.
[0108] The dashed line 217 indicates where the original thermostat fan signal wire to the fan relay (205) has been disconnected in order to route this signal to the efficient fan controller 211 and transfer control of the fan relay 205 to the efficient fan controller 211. The efficient fan controller 211 transmits a low-voltage control signal to the fan relay 205 through efficient fan controller 211 output signal 212.
[0109] FIG. 3 shows the efficient fan controller 211 connected to an HVAC system with AC compressor control 203 for direct-expansion cooling and heat pump reversing valve 263 energized for cooling. The efficient fan controller 211 is connected directly to the following existing thermostat or equipment control terminals 201 connected and transmitting low-voltage signals to the efficient fan controller 211: [0110] 1) FAN G 204 transmits voltage signals to the efficient fan controller 211 through input lead 214; [0111] 2) AC Y 207 transmits voltage signals to the efficient fan controller 211 through input lead 215; [0112] 3) reversing valve REV O 235 transmits voltage signals to the efficient fan controller 211 through input lead 216; [0113] 4) system transformer (210) common 24 VAC is connected to the efficient fan controller 211 through input lead 221; and [0114] 5) system transformer Hot R 209 is connected to the efficient fan controller 211 by lead 213 and connected to efficient fan controller 211 lead 234.
[0115] When the efficient fan controller 211 detects current flowing in both the positive cycle and negative cycle on the lead 213, the efficient fan controller 211 responds to control for a heat pump system by energizing the reversing valve 263 for cooling mode. The dashed line 217 indicates where the original thermostat fan signal wire to the fan relay (205) has been disconnected in order to route this signal to the efficient fan controller 211 input 214. The efficient fan controller transmits a low-voltage control signal to the fan relay 205 through efficient fan controller 211 output signal 212.
[0116] FIG. 4 shows the efficient fan controller 211 connected to an HVAC system with AC compressor control (203) for direct-expansion cooling and heat pump reversing valve energized for heat (264). The efficient fan controller 211 is connected directly to the following existing thermostat or equipment control terminals (201) connected and transmitting low-voltage signals to the efficient fan controller (211): [0117] 1) FAN G 204 transmits voltage signals to the efficient fan controller 211 through input lead 214; [0118] 2) AC Y 207 transmits voltage signals to the efficient fan controller 211 through input lead 215; [0119] 3) reversing valve REV BR 235 transmits voltage signals to the efficient fan controller 211 through input lead 216; [0120] 4) system transformer (210) common 24 VAC is connected to the efficient fan controller 211 through input lead 221; and [0121] 5) system transformer Hot R 209 is connected to the efficient fan controller 211 by lead 213 and also connected to efficient fan controller 211 lead 234 with a diode 275.
[0122] The diode 275 only allows current to flow to the efficient fan controller 211 on positive cycles of the system transformer hot signal (209). By seeing current flowing only during the positive cycle and not on the negative cycle, the efficient fan controller 211 is commanded to control for a heat pump system with reversing valve energized for heating mode. The dashed line 217 indicates where the original thermostat fan signal wire to the fan relay (205) has been disconnected in order to route this signal to the efficient fan controller 211 input 214. The efficient fan controller transmits a low-voltage control signal to the fan relay 205 through efficient fan controller 211 output signal 212.
[0123] FIG. 5 shows components of the efficient fan controller 211 used for systems with gas furnace, electric resistance, heat pump or hydronic heating. A switch 309 is a normally closed relay which connects the input lead (214) signal from the thermostat to the fan relay control (212). In this way, if the efficient fan controller 211 device fails, the FAN G 204 is connected to the fan relay 205 and the system will perform as if the efficient fan controller 211 was not in the control loop.
[0124] In normal operation, when the efficient fan controller 211 is controlling the fan relay 205, the relay 309 is enabled and the switching device 301 output is presented to the fan relay control signal 212. The efficient fan controller 211 has the following input signals from the thermostat: [0125] fan enable 214, A/C compressor enable 215; [0126] heat source enable 216; and [0127] heat pump mode 234.
[0128] The efficient fan controller 211 has a single output 212 which is the signal to enable the fan relay 205.
[0129] The input signals 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 will 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 output signal 212 or a neutral leg 210b (see FIG. 2) of the system transformer 210. When monitoring the signal 212, which is normally an output of the efficient fan controller 211 to the fan relay 205, the fan relay 205 has the leg opposite signal 212 tied to the neutral leg 210b of the system transformer 210. Current can flow from that neutral leg 210b, up through the fan relay 205 and into the efficient fan controller 211 since the efficient fan controller 211 ground is referenced to the hot leg 210b of the system transformer 210.
[0130] 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 input signal 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.
[0131] The AC-DC converter 303 has inputs from the system transformer 221 as well as the thermostat output signals 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.
[0132] The switching device 301 is controlled by the microprocessor 304 and connects the efficient 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.
[0133] 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. A Heat Pump (HP) signal 234 is passed through the signal conditioning 308 element before being passed to the microprocessor. By nature of the zero crossing detector 302, the microprocessor 304 knows when thermostat signals should be above ground and below ground. If the HP signal 234 is not connected to the system transformer 210 as shown in FIG. 2, the microprocessor 304 detects the HP signal 234 is floating and performs like it is connected to a conventional HVAC system. If the HP signal 234 is connected to the system transformer 210 as shown in FIG. 3, the microprocessor 304 sees the HP signal 234 driven above and below ground and preforms like it is connected to a heat pump system with the reversing valve driven for cooling.
[0134] When a diode 235 is introduced as shown in FIG. 4, the HP signal 234 is driven during the positive cycle and floats because of the direction of the diode 275, during the negative cycle where the signal is rectified. The microprocessor 304 detects this state and performs like it is connected to a heat pump system with a reversing valve driven for heating. Because the microprocessor 304 is powered by the AC to DC converter 303, using an AC signal, the system is free to define hot and neutral as the opposite of what the original installation intended. The efficient fan controller 211 basically floats electronically and as a result is able to use the only wire coming to the thermostat (Hot) as a ground. As discussed above, the microprocessor 304 is configured to detect five low-voltage electrical input signal states: 1) a ground or zero VAC signal (104), 2) a 24 VAC signal (108), 3) a floating signal (102), a false positive stray voltage signal (108) and 5) rectified signal (110). The signal conditioning element 308 processes the input signals to detect all 5 states. The signal conditioning detail is shown in FIG. 18.
[0135] 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 keep track of minutes. The negative crossings are also monitored to provide timing for the switching device 301.
[0136] The efficient fan controller 211 draws power through the HVAC thermostat or equipment terminal block C common 223 of the 24 VAC transformer 210 (see FIG. 2, FIG. 3, or FIG. 4). The switching device 301 could be standard relay type device, a reed relay or some other electro-mechanical device, and could also be a solid state device such as an FET switch or a triac. In the event that an electro-mechanical switch was used, either an optional battery would be added to power the microprocessor 304 or the inputs 215, 216 or 221 could provide power through the AC-DC converter when the switch is closed. A preferred embodiment of the fan controller uses only the 24 VAC Hot 213 from the system transformer 210 and a triac 301 and does not require a battery.
[0137] 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.
[0138] The microprocessor 304 monitors the duration of the following thermostat or equipment terminal signals 201: fan G 204, AC compressor Y 207, and/or heat W 208 and adjusts the variable fan-off delay accordingly. If the AC compressor 203 or heat source 202 are operated for a short period of time and there is not much condensation stored on the evaporator or heat stored in the heat exchanger, then the fan relay 205 and system fan/blower 206 operating time will be extended for a shorter period of time or not at all. Likewise, if the AC compressor 203 operates allowing more condensate to be stored on the evaporator, or heater 202 operates longer storing more heat in the heat exchanger, then the efficient fan controller 211 will energize the fan relay 205 and operate the system fan/blower 206 to run for a longer fan-off delay period of time after the AC compressor 203 or heat source 202 have stopped. Timing table and/or algorithms may be modified for particular HVAC system, environments, user preferences, and the like.
[0139] In the embodiment of the efficient 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.
[0140] In another embodiment of the fan controller, a battery 306 is used to supply power to the microprocessor 304 when the efficient fan controller 211 is actuating the fan relay 205. In this embodiment, the 24 VAC signal would be 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.
[0141] FIG. 6 shows a graph comparing delivered heating efficiency for the known HVAC fan control 4 and efficient fan control 6. The efficient HVAC fan control 6 improves heating system efficiency and reduces gas furnace operation by increasing fan speed from the low speed used for heating to the high speed used for cooling after time period P1 after the heat exchanger reaches maximum temperature. The efficient HVAC fan control 6 also maximizes heat recovery from the heat exchanger after the heat source is turned off with an extended variable fan-off delay based on the heating cycle duration P3 defined as the heating on time from when the thermostat initiates a call for heating until the thermostat terminates the call for heating or the heating cycle duration is defined as the heating off time defined from when the thermostat terminates the call for heating until the thermostat initiates the call for heating plus the heating on time. Known fixed-time or temperature fan-off delay control 4 wastes more energy by leaving the heat exchanger with significantly higher temperatures of 260 to 380 degrees Fahrenheit ( F.). FIG. 6 shows the efficient HVAC fan control 6 improving heating efficiency and savings 15% compared to known control 4.
[0142] FIG. 7 shows a graph comparing sensible cooling efficiency for the known HVAC fan control 8 and efficient fan control 10. The efficient fan controller 211 control 10 monitors and controls the HVAC fan improves cooling system efficiency and maximizes sensible cooling recovery from the evaporator after the AC compressor is turned off with an extended variable fan-off time delay based on the cooling cycle duration P3 defined as a cooling on time from when the thermostat initiates a call for cooling until the thermostat terminates the call for cooling or the cooling cycle duration defined as the cooling off time from when the thermostat terminates the call for cooling until the thermostat initiates the call for cooling plus the cooling on time. Known fixed-time delay control 8 is slightly more efficient at the beginning of the cycle due to an initial wet coil due to water left on the evaporator coil with no delay. The efficient fan controller 10 operates the fan for an extended variable fan-off delay based on P3 providing evaporative cooling at the end of the cycle delivering more sensible cooling and thermal comfort and extending the P11 off cycle to reduce compressor operation and save 10% compared to known control 8.
[0143] FIG. 8 shows a graph comparing heat pump (HP) or hydronic heating efficiency for the known fan control 12 and the efficient fan controller 14. The efficient fan controller 14 monitors and controls the HVAC fan and calculates a short fan-on delay P0 based on the previous heating off-cycle duration P11. The efficient fan control 14 improves heating efficiency and maximizes heat recovery from the heat pump coil or hydronic heat exchanger after the thermostat call for heating has ended with an extended variable fan-off time delay based on the heating cycle duration P3 defined as the heating on time from when the thermostat initiates a call for heating until the thermostat terminates the call for heating or the heating cycle duration defined as the heating off time from when the thermostat terminates the call for heating until the thermostat initiates the call for heating plus the heating on time. Known fixed-time delay control 12 wastes energy by leaving the heat pump or hydronic heat exchanger with unrecovered sensible heating energy and higher heat exchanger temperatures of 110 F. for heat pumps and 130 to 160 F. for hydronic heating systems. FIG. 8 shows the efficient fan control 14 improving saving 10% compared to known control 12.
[0144] FIG. 9 shows a first method for the efficient fan controller used to determine what type of system is connected and what operational mode to execute. Step 501 is the reset point of the software and the point which is used once the variable fan-off delay P2 is completed. If not already done, switch 309 is moved from the normally closed position to the normally open position to connect the fan output signal 212 to the switch 301. Step 502 is used to keep track of the amount of time the duration of the heating or cooling cycle off time P11. This time is accumulated to P11 and is referenced when there is a fan-on time delay P0 for the start of the fan. In some systems, the fan start time is delayed by P0 before being energized while the heat or cooling source is brought to operational temperature. Thermostats connect at least one output signal to the transformer hot 209 when calling for either heating or cooling. Since the invention uses the transformer hot 209 as ground, the invention detects an active or on signal by detecting the signal is connected to ground or a digital 0. Any state of the input other than ground is inactive or off. The microprocessor detects three input signal states, active or ground, 24 VAC or inactive, or floating also inactive. The two inactive states are generated when the thermostat is not calling for either heating or cooling. The 24 VAC state occurs when the input to the microprocessor is pulled to the system transformer neutral line through the controlled element such as the fan relay 205, the AC compressor control 203, or the heat source control 202. The floating state occurs when the input signal has no reference to ground. The method for detecting and acting on these three states is described in the discussion of FIG. 12. Step 503 is used by the efficient fan controller to determine if the fan signal 204 received by efficient fan controller input 214 or the compressor signal 207 received by efficient fan controller input 215 is on or active. If either signal is active, the efficient fan controller then determines whether the heat source is active simultaneously which would indicate either a heat pump, electric heat, or hydronic heat. If the fan signal 204 is not active, then the efficient fan controller drops to Step 504 to determine if it is configured for heat pump operation by connecting input HP 234 to the hot side of the system transformer 210b through wire 265 for a heat pump with reversing valve normally energized for cooling (see FIG. 3) or a wire with a diode 275 for a heat pump with reversing valve normally energized for heating (see FIG. 4). Step 504 is used to determine if HP 234 is connected to the hot side of the system transformer 210b. If HP 234 is connected to the hot side of the system transformer 210b, either with a wire 265 or a diode 275, then the efficient fan controller knows it is connected to a heat pump. If the efficient fan controller is connected to a heat pump, and the fan signal 204, or compressor signal 207 are not active, then the efficient fan controller can ignore the signal on the Heat W 208 since the main driver of a heat pump is the compressor and the efficient fan controller will determine that the compressor is not energized. Step 505 is enabled after the efficient fan controller determines that the HP 234 input is floating and not connected to the hot side of the system transformer 210b. Step 505 is then used by the efficient fan controller to check if the Heat W signal 208 to input 216 is active. If heat signal 208 to input 216 is active and no other inputs are active, then the efficient fan controller knows the system is a gas furnace and the thermostat is calling for heating. Step 506 sets a flag to indicate that the system is a gas furnace in heating mode. Step 507 is the entry into the loop that accumulates the duration of the heating cycle P3 while the gas furnace is operating before the fan-on time delay P1 has expired. The fan-on time delay P1 is used to activate the system fan. Step 508 determines whether or not the fan-on time delay P1 has expired. If time P1 has not expired, then the efficient fan controller continues to accumulate the duration of the heating cycle P3. If fan-on delay time P1 has expired, the efficient fan controller immediately jumps to Step 509 and Step 601 for heating fan control procedures (see FIG. 10). Step 602 activates the switch 301 which drives a 24 VAC signal to the output 212 which in turn activates the fan relay 205 and turn on the system fan.
[0145] Step 510 is entered after the efficient fan controller 211 has detected that either the fan signal 204 or compressor signal 207 are active in Step 503. Step 510 checks if the HP reversing valve signal REV 235 to input 216 is active as well (see FIGS. 3 and 4). If the REV signal 235 to input 216 is not active, then the efficient fan controller knows the system is either in cooling mode or fan only mode and jumps to Step 516 and Step 701 to continue with cooling fan control procedures. If the REV signal 235 to input 216 is active simultaneously with the fan signal 204 to input 214 or compressor signal 207 to input 215, then the efficient fan controller proceeds to Step 511 and examines the HP 234 signal. Step 511 checks to see if the fan controller 211 is connected to a heat pump by the HP signal 234 connected to the system transformer hot signal 210b. If the HP 234 signal is connected to the hot side system transformer 210b, then the efficient fan controller goes to Step 517 to set a flag to indicate the efficient fan controller is connected to a heat pump system in heating mode and the thermostat is actively calling for heat. If the HP 234 is floating, then the efficient fan controller has determined it is connected to an electric or hydronic heating system and heat is being called for by the thermostat 201. Step 512 sets a flag indicating that the efficient fan controller is in electric or hydronic heating mode. Step 513 is the entry for a loop used to accumulate the duration of the heating cycle P3 for a fan-on delay time P0 based on the previous off-cycle time P11 during which the heating element is allowed to reach operational temperature. Step 513 accumulates the duration of the heating cycle P3 prior to expiration of the fan-on delay time P0. Step 514 is used to determine whether or not the fan-on delay time P0 has expired. If the system has been off for a longer period of time, then the fan-on time delay P0 is increased as it would take longer for the heating element (or heating coil) to reach a useful heating temperature required to deliver warm air to the conditioned space. The efficient fan controller may set the heating fan-on time delay P0 to zero. In Step 514, after the fan-on delay time P0 has expired, the efficient fan controller immediately jumps to Step 515 and Step 601 for heating fan control procedures (see FIG. 10). Step 602 activates the switch 301 which drives a 24 VAC signal to the output 212 which in turn activates the fan relay 205 and turn on the system fan.
[0146] FIG. 10 shows a method for heating according to the present invention. Step 601 is the beginning of the method for heating fan control procedures. Step 602 activates switch 301 which connects 24 VAC to the output 212. This in turn connects 24 VAC to the fan relay 205 which activates the system fan 206. Step 603 is the entry of a loop that runs continuously while the thermostat 201 is calling for heat, regardless of system type. The duration of the heating cycle P3 is accumulated until the thermostat 201 is satisfied and discontinues the call for heating. Step 604 is used to check if the system is connected to a gas furnace or one of the other system configurations such as a heat pump, electric heating, or hydronic heating based on previous flag settings. If connected to a gas furnace, the efficient fan controller proceeds to Step 605, and if the gas furnace signal 208 to input 216 is still active, the efficient fan controller keeps looping and accumulating the duration of the heating cycle P3. If the efficient fan controller is not connected to a furnace, it uses the compressor signal 207 to input 215 or the fan signal 204 to input 214 to continue in the loop and accumulate the duration of the heating cycle P3. Step 606 is entered when the thermostat 201 call for heating has been satisfied and the gas furnace heat source has been de-activated. Step 606 now has all the necessary information to calculate the fan-off time delay P2 based on the duration of the heating cycle P3, and the fact that the efficient fan controller is connected to a gas furnace. Step 607 continues to operate the system fan 206 for the variable fan-off time delay P2 until the time delay P2 has expired. After the time delay P2 has expired the efficient fan controller proceeds to Step 608 and turns off the switching device 301 which removes the 24 VAC from the efficient fan controller output 212 which in turn deactivates the fan relay 205 and the system fan 206. Step 609 stores the duration of the heating cycle P3 of the heat source for later use. Step 610 is entered when all the housekeeping is completed for the system heating mode and fan operation, and the system returns to the start Step 501 (see FIG. 9).
[0147] Step 611 is entered when the efficient fan controller is connected to either a heat pump, electric heater, or hydronic heat system and the thermostat 201 is calling for heating. Step 611 looks to see if the compressor signal 207 to input 215 or the fan signal 204 to input 214 are still active. At least one of these signals is active during the entire heating cycle. If either signal is active, then the efficient fan controller loops to accumulate the duration of the heating cycle P3. Step 612 is entered when the thermostat 201 on the heat pump, electric, or hydronic system has been satisfied and de-energizes the heat source. Step 612 further determines if the just completed cycle was for a heat pump by examining the heat pump flag. The fan-off time delay P2 is then determined based on the type of system that called for heating. Step 613 is entered when the thermostat 201 has been satisfied and turns off the heat pump. Step 613 now has all the information necessary to calculate the fan-off time delay P2 based on the duration of the heating cycle P3, and the efficient fan controller has determined that the controller is connected to a heat pump. Step 614 is entered when the thermostat 201 has been satisfied and turns off the electric or hydronic heat source. Step 614 now has all the information necessary to calculate the fan-off time delay P2 based on the duration of the heating cycle P3, and the efficient fan controller has determined that it is connected to an electric or hydronic heat source.
[0148] FIG. 11 shows a method for cooling fan control according to the present invention. Step 701 is the entry point for cooling or fan only operation of all types of systems. Step 702 is the entry point for a loop which accumulates the duration of the cooling cycle P3. Step 703 evaluates whether or not the fan-on delay time P0 has expired based on the current cycle P3 and the previous cooling cycle off time P11. Step 703 is used to check if the delay time P0 has expired and if not, continue to accumulate the duration of the cooling cycle P3 for the entire duration of the cooling cycle. The efficient fan controller may set the cooling fan-on time delay P0 to zero. Step 704 activates switch 301 which connects 24 VAC signal to the output 212. This in turn connects 24 VAC to the fan relay 205 which activates the system fan 206. Step 705 is the entry of a loop that runs continuously while the thermostat 201 is calling for cooling. Step 705 continues to the duration of the cooling cycle P3 until the thermostat 201 temperature is satisfied and discontinues to call for cooling. Step 706 checks the compressor cooling signal 207 to input 215 and fan signal 204 to input 214 to determine if cooling is still active, and if so continues to loop and accumulate the duration of the cooling cycle P3. Step 707 is entered when the thermostat 201 temperature setting has been satisfied and turns off the cooling compressor. Step 707 now has all the information necessary to calculate the fan-off time delay P2 based on the duration of the cooling cycle P3. Step 708 continues to operate the system fan 206 for the variable fan-off delay time P2 until the fan-off time delay P2 has expired. Step 709 turns off the switching device 301 which removes the 24 VAC from the efficient fan controller output 212 which in turn de-activates the fan relay 205 and the system fan 206. Step 710 stores the duration of the cooling cycle P3 for later use. Step 711 is entered when all the housekeeping is completed for the system cooling mode and fan operation, and the system returns to the start step 501 (see FIG. 9).
[0149] FIG. 12 shows the elements of the invention to detect three distinct states of the signals from the thermostat 201. The three states are active (ground), 24 VAC, and floating. The Fan Controller 211 this invention draws power either through the fan relay input/output 212 or the system transformer 210. This allows the creation of a +5-volt DC signal to power the fan controller circuit. The pull-up resistors 826A, 826B, and 826C shown in FIG. 12 pulls the inputs to microprocessor up to a known state (+5) when the input signal floats (i.e., neither ground nor 24 VAC). The microprocessor uses a software zero crossing detector shown as block 302 in FIG. 5. The AC-DC converter 303 converts the 60 Hz 24 VAC input to the power supply into a 60 Hz 5V square wave which is an input 272 to the microprocessor 304. This is also disclosed in the Walsh U.S. Pat. No. 8,763,920 ('920 patent) to application claims priority and the '920 patent is incorporated herein by reference in its entirety. See, e.g., Walsh '920 at Col. 6, lines 14-41. The zero crossing detector is used to sense when the 24-volt AC power supply input from the transformer 210 or the fan relay input/output 212, transitions from a positive voltage to a negative voltage and from a negative voltage to a positive voltage, for timing to sample the thermostat outputs 204, 207, and 208. The thermostat 201 connects one or more of the thermostat outputs to the transformer hot 209 if heating, cooling, or fan operation is required. Since the invention uses the transformer hot 209 as the system ground, any input signal that appears as a ground is active. This discussion focuses on the fan 204 thermostat output but the processor samples all outputs in a similar manner. If the fan signal input 204 is ground or active, the microprocessor senses that the fan signal input 204 is ground or a digital 0 at the positive and negative transitions of the power supply output 272. If the fan input 204 is 24 VAC, then the microprocessor Input/Output (IO) pin input is positive, digital 1, after the zero crossing detector signals a positive transition and digital 0 after a negative transition. Finally, if the input is in a floating state, the pull-up resistor 826B creates a +5-volt signal, digital 1 in both the positive and negative transitions and thus the microprocessor 304 detects all input conditions.
[0150] FIG. 13 shows prior art thermostat wiring when only 4 wires are available in the wiring harness. This case is prevalent in existing buildings which were built before Smart Communicating Thermostats were available. Most thermostats prior to Smart Communicating Thermostats simply connected the Hot R terminal 209 to the appropriate output based on whether the thermostat was set for heating or cooling. For cooling, the standard thermostat connects the Hot R terminal 209 to both the Fan G terminal 204 and the AC Y terminal 207. This activates the compressor and the system fan. For heating, the thermostat connects the Hot R terminal 209 to the Heat W 208 terminal. With these 4 wires, a standard thermostat can control the HVAC system to heat or cool a building. Smart Communicating Thermostats generally require an additional wire to bring a Common 802A signal to the thermostat Com B input 802. Without the fifth wire included in the original wiring harness, a solution is required to use one of the existing 4 wires to carry two signals and free one of the other wires to supply the transformer 210 common wire to the thermostat Com B 802 input.
[0151] FIG. 14 shows a common-wire adapter comprising Thermostat Element 806 and HVAC Element 814 according to the present invention used to create a common signal path with only four wires between the Smart Communicating Thermostat 800 and HVAC equipment 804. The Smart Communicating Thermostat 800 has for example the Fan G terminal 204 and the AC Y terminal 207 signals going into the Thermostat Element 806. A single wire 808 comes out of the Thermostat Element 806. This single wire 808 can be either the existing Yellow wire 207 or the existing Green wire 204. FIG. 14 shows the Green wire indicated by a dashed oval 810 used for both the Green and Yellow wire signals. With two signals now on a single wire 808 the Yellow wire in the harness is available to be reconnected at the HVAC Equipment Terminals 804 to the Com B terminal 802. The Yellow wire is repurposed with a new function to carry the Common signal from the HVAC Equipment Control Terminals to the Smart Communicating Thermostat Com B input. The new function is represented by the dashed oval 812. At the Smart Communicating Thermostat 800, the Yellow wire is connected to the Com B terminal 802. The output of the Thermostat Element 808 goes to the input of the HVAC Element 814. The function of the HVAC Element 814 is to reproduce the signals routed through the Thermostat Element 806 to the HVAC Equipment Control Terminals 804 with full fidelity.
[0152] FIG. 15 is similar to FIG. 14 with the exception being the Thermostat Element 806 is connected to the G 204 and the W 208 terminals of the thermostat. These two signals are then combined using the diodes 820 and 822 (see FIG. 16), and the single signal is sent to the HVAC element via connection 808. The HVAC element output 818 is connected to the HVAC Equipment Control Terminals W input 208A. The W 208 wire from the thermostat now makes an uninterrupted connection to the HVAC Equipment Control Terminal W input 208A. This drawing discloses that the only connection to the thermostat element that is required is the G input 204. The other input could be any 24 VAC signal from the thermostat including the W 208, Y 207, or if present, the reversing valve signal.
[0153] FIG. 16 shows a Common Wire Adapter 815 (dashed line) comprised of a Thermostat Element 806 and an HVAC Element 814. The HVAC Element uses optoisolators and a microprocessor to trigger switching devices to create a full AC waveform from a positively or negatively rectified input signal (see FIG. 19) to allow a pre-existing wire to be repurposed and provide an electrical path to carry the common signal 802A of the system transformer 210 to the smart communicating thermostat 800. Two diodes 820 and 822 are connected to the Smart Communicating Thermostat 800 Fan G 204 and the AC Y 207 outputs. The anode of diode 820 is attached to the Fan G 204 terminal. The cathode of diode 822 is attached to the AC Y 207 terminal. The invention does require one of the diodes to be connected to the Fan G 204 terminal, but does not limit which output terminal of the Smart Communicating Thermostat 207, or 208 is attached to the other diode. This embodiment shows Fan G 204 and AC Y 207 as examples. The invention does not limit which output terminal is attached to the anode or cathode of each diode. The only restriction is that the diodes must be attached to the thermostat outputs in opposing polarity. That is to say, one anode goes to one signal, and the cathode of the other diode goes to another thermostat output signal. In this way, the output signal 808 from the Thermostat Element 806 will carry either a positively rectified AC waveform 351 through diode 820, a negatively rectified waveform 352 through diode 822, or a full AC waveform 350 if both diodes are conducting in the case where both thermostat outputs are simultaneously active.
[0154] In one embodiment, a microprocessor 304 and an optoisolator 824 create the signals to trigger the switching devices 301 and 836. In other embodiments individual diodes may replace the optoisolator. This embodiment also uses a simple AC-DC power supply 303 to provide a 5 volt signal 270 (see FIG. 5) to the microprocessor and the pull up resistor 826. The power supply 303 also provides a timing signal 272 that signals to the microprocessor 304 of the presence of the rising edge of the 60 Hz input from the system transformer 210. The signal 272 is used by the microprocessor 304 to determine when to look at the output 828 of the optoisolator 824. The output of the optoisolator 828 will be a zero if the input signal 808 is positively or negatively rectified. The microprocessor 304 samples the output 272 from the power supply 303 for a positive edge of the 60 Hz input and then samples the output 828 of the optoisolator. If the output of the optoisolator 828 is zero after a rising edge of the 60 Hz input 272 is detected, then the processor activates output 832 to trigger the switching device 836 which passes the Hot R 209 signal to the output 818 which signals to the HVAC Equipment Control Terminals 804 that the Fan G input 204A is active. The microprocessor 304 monitors the output 828 from the optoisolator 824 to detect every rising edge and keeps the signal 832 active to the switching device 836 until the output from the optoisolator is high at the 60 Hz rising edge which would indicate that the call for the FAN G 204 has gone away. If the switching devices were a triac, the microprocessor would trigger the gate at both the positive and negative zero crossing events. In this way the switching device is continuously triggered to provide a continuous AC waveform for output 818.
[0155] In the same way, the output 828 from the optoisolator 824 is zero with a negatively rectified input 808. The microprocessor 304 samples the input 272 from the power supply and monitors for a transition from a positive input to a zero input. This transition indicates that the Hot R 209 signal has transitioned from a positive voltage level to a negative voltage level. The microprocessor then monitors the output 828 from the optoisolator 824. If the voltage is zero at this transition, then the optoisolator 824 is receiving a negatively rectified signal 352 from the input 808. Receiving a zero from output 828 indicates to the microprocessor 304 that a negatively rectified waveform 352 input is being received and the processor triggers switching device 836 with a gate signal 832 which causes the Hot R 209 signal to be transmitted to the output 818. If the switching device is a triac, the microprocessor would trigger the gate at both the positive and negative zero crossing events. In this manner, a negatively rectified signal waveform 352 from the thermostat element 806 would be used to conduct a full AC waveform 350 to the output 818 until such time as the output 828 from the optoisolator 824 was positive during a negative transition of the 60 Hz input signal 272.
[0156] In the event that a Common Wire Adapter 815 is not required, the invention will function as a standard fan controller 211 by connecting the input wire 808 to the Fan G terminal of the thermostat 800. A full sinusoid signal will present itself to the optoisolator 824 and the microprocessor 304 will activate both switching devices. The switching device 301 will be activated with the energy efficiency delays per the standard fan controller 211 functionality. The switching device 836 will also be activated but since the AC Y 207 uses the yellow wire in the existing harness and is connected to the HVAC equipment control terminals 804 input 207A, there is nothing connected to output 818 and activating the switching device causes no effect.
[0157] FIG. 17 shows the Y-adapter element 842 used to connect the output from the fan relay 205 and the furnace relay 239 together and the combined signal is connected to the high-speed tap 15 of the system fan/blower 206. In this way, when either relay 205 or 239 are activated, the system fan/blower will operate at a high speed.
[0158] FIG. 18 discloses how the invention is able to properly process signals that have a voltage that is neither 24 VAC nor 0 VAC but some voltage that is approximately 10 VAC. This stray voltage appears due to thermostats power stealing current, faulty gas valves, faulty contactors, faulty fan relays, or induced voltage due to a wiring issue. When a stray voltage occurs, some devices interpret this 10 VAC signal as an indication that the thermostat is calling for heating or cooling when in actuality, it is not. In order to create a threshold voltage over which the signal must be in order to actually be interpreted as a command from the thermostat, the current invention takes an innovative approach to solve an unresolved problem. As shown in FIG. 18, Dual zener diodes 850 and 851 are placed in series with the input signal with opposite polarity. The signal then passes through a optoisolator. The optoisolator output is pulled up to the power rail through a pull up resistor 854. This essentially subtracts the rated value of the zener, forward bias of a zener, and the forward bias of the LEDs in the optoisolator from the input signal. If both diodes 850 and 851 have a value of 15 volts, then approximately 16.7 volts will be subtracted from the input signal before the microprocessor will receive an input other than a 5 volt signal from the pull up resistor. Employing this method eliminates any stray voltage from being considered an active signal until it surpasses 16.7 volts. A resistor 852 shown in FIG. 18 is connected between the input pin to the transformer common. The purpose of the resistor 852 is to provide a current path to the thermostat in the event the signal is disrupted by the presence of the fan controller 211 such as the fan 204 signal. The value of this resistance is such that the load into the thermostat is similar to an actual fan relay so the fan controller 211 is transparent to the thermostat.
[0159] FIG. 19 show the 24 VAC waveforms that can be sent from the thermostat element 806 via the wire 808 to the HVAC element 814. The unrectified waveform 350 is received by the HVAC element 814 when both the Y signal 208 and the G signal 204 are active. The positive half originates with the G signal 204 and the negative half originates with the Y 207 signal. Both combined create the full AC waveform. The positively rectified signal 351 with no negative component is created by the G signal 204 as it passes through the diode 820. There is no negative component if the Y signal 207 is inactive. When a positive waveform is received by the HVAC element 814 a full AC waveform is created by switching device 301 which is output to the HVAC equipment control terminals 804 input 204A to activate the system fan/blower 206. The negatively rectified signal 352 with no positive component is created by the Y signal 207 passing through diode 822. There is no positive component when the G signal 804 is inactive. When a negative waveform is received by the HVAC element 814 a full AC waveform is created by switching device 836 which is output to the HVAC equipment control terminals 804 input 207A to activate the system compressor. If the system is calling for cooling, the signal will resemble curve 350 since the Y 207 and G signals are active simultaneously. The G 204 signal must always be connected since the present invention uses this signal to determine the cooling operation time. The second signal described above as the Y 207 signal could instead be the W 208 or the reversing valve signal.
[0160] FIG. 20 shows a graph of heating efficiency, outdoor air temperature, indoor thermostat temperature 359, and rate of change of indoor thermostat temperature versus time of operation for a gas furnace heating system with known control 355 where the heat source is turned off when the thermostat temperature reaches the setpoint hysteresis differential a first time and the heater ventilation fan operates for a fixed fan-off delay time after the heat source is turned off FIG. 20 also shows a graph of a curve 357 representing the energy efficiency of a heating system with heat source operational until a thermostat temperature reaches the upper limit of the setpoint hysteresis differential 361 a first time and the heater ventilation fan continues to operate for a variable fan-off delay time until the thermostat temperature declines to the same upper limit setpoint hysteresis differential a second time or a hysteresis differential offset 363 or the fan-off time delay P2 is based on the heating cycle duration P3 defined as the heating on time from when the thermostat initiates a call for heating until the thermostat terminates the call for heating or the heating cycle duration is defined as the heating off time defined from when the thermostat terminates the call for heating until the thermostat initiates the call for heating plus the heating on time. In another embodiment the variable fan-off delay time P2 is the time required for the thermostat temperature to reach a maximum temperature where the rate of change of respect to time, dT/dt, reaches an inflection point and is approximately equal to zero plus or minus a confidence interval tolerance shown in FIG. 20 as the heating overshoot (HO) 362. Operating individually or together, these fan-off delay time embodiments can be used to recover and deliver additional sensible heating energy from a heat source to improve efficiency and thermal comfort and reduce heat source operational time to save energy. In this embodiment, the fan controller temperature sensor can monitor and record the end-of-cycle conditioned space temperature at the end of the thermostat call for cooling. The fan controller will then energize or continue to energize the fan relay to operate the system fam/blower for the fan-off delay until the fan controller temperature sensor monitors a conditioned space temperature that is greater than the recorded end-of-cycle cooling temperature whereupon the fan controller will de-energize the fan relay to turn off the system fan/blower and end the fan-off delay.
[0161] FIG. 21 shows a graph of cooling efficiency (i.e., Energy Efficiency Ratio (EER)), cooling system power, outdoor air temperature, indoor thermostat temperature 369, and rate of change of indoor thermostat temperature versus time of operation for a direct-expansion air conditioning cooling system with known control 365 where the cool source and cooling ventilation fan are turned off when the thermostat temperature decreases to the minimum setpoint hysteresis a first time. FIG. 21 also shows a graph of a curve 367 representing the EER of a cooling system with cool source operational until a thermostat temperature reaches the lower limit of the setpoint differential 371 a first time and the cooling ventilation fan continues to operate for a variable fan-off delay time until the thermostat temperature increases to the same lower limit setpoint differential a second time or a differential offset 374 or the fan-off time delay P2 is based on the cooling cycle duration P3 defined as the cooling on time from when the thermostat initiates a call for cooling until the thermostat terminates the call for cooling or the cooling cycle duration is defined as the cooling off time defined from when the thermostat terminates the call for cooling until the thermostat initiates the call for cooling plus the cooling on time. In another embodiment the cooling ventilation fan continues to operate for a variable fan-off delay time P2 until the thermostat temperature decreases to the Cooling Overshoot (CO) 373 defined as the minimum thermostat temperature beyond the CLD after the cool source is turned off where the rate of change of temperature with respect to time, dT/dt, reaches an inflection point and is approximately equal to zero plus or minus a confidence interval tolerance. Operating individually or together, these fan-off delay time embodiments can be used to recover and deliver additional sensible cooling energy from a cool source to improve efficiency and thermal comfort and reduce cooling system operating time to save energy. In this embodiment, the fan controller temperature sensor can monitor and record the end-of-cycle conditioned space temperature at the end of the thermostat call for heating. The fan controller will then energize or continue to energize the fan relay to operate the system fam/blower for the fan-off delay until the fan controller temperature sensor monitors a conditioned space temperature that is less than the recorded end-of-cycle heating temperature whereupon the fan controller will de-energize the fan relay to turn off the system fan/blower and end the fan-off delay.
[0162] FIG. 22 shows a fan controller fan-on fault detection diagnostics method according to the present invention. At Step 951, the fan controller starts the method with the fan ON and no call for heating or cooling. At Step 953, the fan controller accumulates fan-on operational time F6. At Step 953, the fan controller initiates a loop which runs continuously to accumulate the fan-on operational time F6 until the fan controller either receives a call for heating, a call for cooling, or the fan switch input 214 is de-energized. At Step 955 the fan controller determines whether or not the fan_off variable has been set to 1 in step 976.
[0163] At Step 957, if the fan_off flag 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.
[0164] 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.
[0165] 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.
[0166] 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 (FIG. 9).
[0167] At Step 965, if the fan has been on longer than the TFT and the Fan off flag is set to a value of 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.
[0168] Also disclosed in this invention is a method solving an unresolved need for increasing fan speed to improve comfort, efficiency and satisfy the thermostat sooner to save energy. The present invention enables control of the system fan/blower to high speed operation using at least one method selected from the group consisting of: 1) installing a 24-volt wire jumper from the fan only tap to the high-speed or cool tap of the system fan/blower 206 to enable the thermostat G signal wire to control high speed fan operation, and 2) installing a high-voltage Y-adapter 842 combining the two high voltage signal outputs, one from the fan relay 205 and the other from the furnace relay 239 on the Forced Air Unit (FAU) control board 238 to the high speed tap 15 of the system fan/blower 206 to enable high speed fan operation in cooling and heating modes, and 3) using a dip switch other electrical control switching device on the Forced Air Unit (FAU) control board 238 to enable high speed system fan/blower operation when the thermostat G terminal is energized in cooling or heating modes, and 4) using wired or wireless (WIFI) software application commands to control a switching device to enable high speed system fan/blower operation when the thermostat G terminal is energized in cooling or heating modes, and 5) using an electrical signal waveform 848 identified by a controller to enable high speed system fan/blower operation when the thermostat G terminal is energized in cooling or heating modes.
[0169] Some HVAC systems will disregard the activation of the fan signal 212 when heating and continue to operate the system fan/blower at a low speed. In that event the system will be less efficient than operating the fan at a high speed which delivers more heat to the conditioned space and satisfies the thermostat more quickly. By connecting together the output of the fan relay 205 and the output of the relay which is activated when heating using a Y adapter to the high-speed tap of the system fan/blower the fan will operate at a high speed during either heating or cooling. Thus a method for increasing fan speed to improve comfort, efficiency and satisfy the thermostat sooner to save energy has been disclosed.
[0170] The fan controller 211 can include at least one temperature sensor input to connect to a temperature sensor to monitor at least one temperature selected from the group consisting of: a conditioned space temperature, a return air temperature and a supply air temperature. The monitored temperature sensor input can be used at an end of the cooling cycle or heating cycle to either energize or continue to energize the fan relay signal output (212) to operate the system fan (206) for a variable fan-off delay time to deliver additional cooling or heating energy to a conditioned space wherein the variable fan-off delay time is determined based on at least one threshold temperature selected from the group consisting of: the conditioned space temperature, the return air temperature and the supply air temperature. The temperature threshold can be based on at least one temperature threshold selected from the group consisting of: a supply air temperature threshold less than the conditioned space temperature for cooling, a supply air temperature threshold greater than the conditioned space temperature for heating, a supply air temperature threshold less than the return air temperature for cooling, a return air temperature threshold less than the supply air temperature for heating, a temperature split threshold for cooling defined as the return air temperature minus the supply air temperature, a temperature rise threshold for heating defined as the supply air temperature minus the return air temperature, and a threshold inflection point where the rate of change of the conditioned space temperature with respect to time equals zero plus or minus a confidence interval tolerance.
[0171] While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations could 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
[0172] 4a curve representing the delivered heating efficiency for a gas furnace HVAC system 100 with the known fixed fan-off time delay and low fan speed operation. [0173] 6a 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 a low fan speed used for heating to a higher fan speed used for cooling plus extended variable fan-off time delay P2 based on the duration of the heating cycle P3 including on time or on time plus off time. [0174] 8a curve representing the delivered sensible cooling efficiency for a direct-expansion air conditioning system with a known fixed fan-off time delay. [0175] 10a curve representing the increase in sensible cooling efficiency for the same direct-expansion air conditioning system with the fan controller providing an extended variable fan-off time delay P2 based on the duration of the cooling cycle P3 including on time or on time plus off time. [0176] 11Low speed tap of the system fan/blower. [0177] 12a curve representing the delivered sensible heating efficiency 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 time delay. [0178] 13Medium speed tap of the system fan/blower. [0179] 14a curve representing the increase in delivered heating efficiency 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 an extended variable fan-off time delay P2 based on the duration of the heating cycle P3 including on time or on time plus off time in order to increase delivered heating capacity and efficiency for the heat pump or hydronic heating system. [0180] 15High speed tap of the system fan/blower. [0181] 100Heating Ventilating Air Conditioning (HVAC) System. [0182] 201a thermostat or equipment control terminals. [0183] 202a furnace heat-source control used to indicate a device that when energized, produces heating for the system. [0184] 203an 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. [0185] 204a FAN G terminal of a thermostat energized when the system fan is ON or the thermostat calls for air conditioning. [0186] 205a 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. [0187] 206a system fan/blower used to indicate a multiple speed motor with a low, medium, and high fan speed tap or setting. [0188] 207an AC compressor thermostat Y terminal of the thermostat energized when the thermostat calls for cooling. [0189] 208a heat thermostat W terminal energized when the thermostat calls for heating. [0190] 209a Hot thermostat R terminal connected to the Hot leg 210b of the 24 VAC system transformer 210. [0191] 210a 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. [0192] 210aa neutral or common leg 210a of the system transformer 210. [0193] 210ba Hot leg 210b of the system transformer 210. [0194] 211an embodiment of the fan controller 211. [0195] 212a 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. [0196] 213a 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. [0197] 214a 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 the duration of the cooling cycle P3 or the duration of the heating cycle P3 including on time or on time plus off time in order to calculate a fan-off time delay 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 duration of the AC compressor cycle and therefore, be used to measure the duration of the cooling cycle P3 including on time or on time plus off time. For a heat pump system, the fan controller fan signal input 214 can be used to determine the duration of the cooling cycle P3 or duration of the heating cycle P3 including on time or on time plus off time depending on the status of the signal to the reversing valve 216 and the HPD signal input 234. [0198] 215an 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 to measure the duration of the cooling cycle P3 including on time or on time plus off or the duration of the heating cycle P3 for a heat pump including on time or on time plus off time in order to calculate a fan-off time delay 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 the AC compressor cycle and therefore, be used to measure the duration of the cooling cycle P3 including on time or on time plus off time. For a heat pump system, the fan controller fan signal input 215 can be used to determine the duration of the cooling cycle P3 or duration of the heating cycle P3 including on time or on time plus off time depending on the status of the signal to the reversing valve 216 and the HPD signal input 234. [0199] 216a 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 the duration of the heating cycle P3 including on time or on time plus off time in order to calculate the fan-off time delay 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. [0200] 217a dashed line to indicate the disconnection of the FAN G terminal of the thermostat to the fan relay 205. [0201] 221a fan controller input signal from the system transformer neutral side; [0202] 223a neutral side of the system transformer connected to other elements of the system. [0203] 234a 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 FIG. 11). If the HPD signal input 234 is connected to the system transformer hot 210b with a wire and a diode 275 in either polarity, then the fan controller HPD signal input 216 receives a rectified low-voltage signal and determine it is connected to a heat pump with reversing valve BR 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 BR thermostat terminal 236 (see waveform 351 and 352 in FIG. 11). [0204] 235a heat pump REV O terminal of the thermostat energized for cooling and de-energized for heating. [0205] 236a heat pump REV BR terminal of the thermostat de-energized for cooling and energized for heating. [0206] 238Forced Air Unit (FAU) control board. [0207] 263a reversing valve energized for cooling used to indicate a reversing valve on a heat pump system that is energized for cooling and de-energized for heating and referred to as an Orange (O) reversing valve. [0208] 264a reversing valve energized for heating used to indicate a reversing valve on a heat pump system that is energized for heating and de-energized for cooling and referred to as a Brown (BR) reversing valve. [0209] 265a connection between the system transformer hot 210b and the fan controller HPD signal input 234 when connected with a wire as shown in FIG. 3 where the fan controller signal input [0210] 216is connected to the heat pump REV O thermostat terminal 235 energized for cooling and de-energized for heating. [0211] 270a DC rail voltage that powers the microprocessor and associated circuitry as well as charges a super capacitor 312 where the rail voltage can originate from the AC-DC converter, or the optional battery 306. [0212] 272a signal from the zero crossing detector 302 to the microprocessor 304 indicating a transition on the 24 VAC signal either from a positive voltage to a negative voltage, or from a negative voltage to a positive voltage. [0213] 275a diode used in the path between the system transformer hot 210b and the fan controller HPD signal input 234 where the system transformer Hot leg 210b provides a 24 VAC signal. In the preferred orientation, the diode 275 allows current flow in a positive cycle, and blocks current flow in a negative cycle (see waveform 351 in FIG. 11). The fan controller HPD signal input 234 is designed to accommodate the condition with the diode 275 reversed with current flowing in the negative cycle and blocked in the positive cycle (see waveform 352 in FIG. 11). If the diode were not in place as shown in FIG. 3, then the current into the fan controller HPD signal input [0214] 301a switching device used to indicate a device which connects the fan controller Hot signal input 213 to the fan controller fan signal output 212 to activate the high-speed fan relay 205. [0215] 302a zero crossing detector used to indicate a function that signals to the microprocessor that the 24 VAC input to the fan controller has changed from either a positive voltage to a negative voltage, or from a negative voltage to a positive voltage. [0216] 303an AC-DC converter taking multiple AC inputs and rectifies one or all to create a DC voltage to power the fan controller. [0217] 304a microprocessor with flash memory used to indicate a device that is programmable to carry out the various tasks to enable the fan controller device to function. [0218] 305an optional user interface used to indicate a function that allows a user to interact with the microprocessor. This interaction can be as simple as DIP switches to configure parameters, a key pad and display, or a communication interface such as USB or a wireless communication. [0219] 308signal conditioning used to indicate a function that receives 24 VAC signals and conditions them to a level that can be safely read by the microprocessor 304. [0220] 306an optional battery used to indicate an optional power source in the event the fan controller is unable to generate sufficient power from the input signals. [0221] 309a relay used to connect the thermostat fan G terminal 204 to the high-speed relay 205 which eliminates the dashed line 217 to provide a hard connection. The purpose of this switch is to provide a fail-safe connection in the event the fan controller fails so the HVAC system 100 operates as though the fan controller were not connected to the circuit. [0222] 312indicates an optional super capacitor which can be charged from the AC-DC converter and used to power the fan controller until sufficient voltage can be generated again from the fan controller input signals. [0223] 355a curve representing the energy efficiency of a heating system with known control where the heat source is turned off when the thermostat temperature reaches the setpoint hysteresis 361 a first time and the heater ventilation fan operates for a fixed fan-off delay time after the heat source is turned off. [0224] 350A full sinusoid waveform transmitted from the thermostat element 804 of the common wire adapter if both inputs to the thermostat elements are active. [0225] 351A positively rectified sinusoid waveform transmitted from the thermostat element 804 of the common wire adapter if the G 204 input is active. [0226] 352a negatively rectified sinusoid waveform transmitted from the thermostat element 804 of the common wire adapter if the Y 207 input is active. [0227] 357a curve representing the energy efficiency of a heating system operating until a thermostat temperature reaches the upper limit of the setpoint hysteresis differential 361 a first time and the heater ventilation fan continuing to operate for a variable fan-off delay time until the thermostat temperature declines to the same upper limit setpoint hysteresis differential a second time or a hysteresis differential offset 363 or the fan-off time delay P2 is based on the duration of the heating cycle P3. [0228] 358a curve representing the outdoor air temperature ( F.) during heating. [0229] 360a curve representing the lower thermostat differential for the heating system. [0230] 361a curve representing the lower upper thermostat differential for the heating system. [0231] 362a curve representing the upper thermostat differential for the heating system. Heating Overshoot (HO). [0232] 363a thermostat setpoint +/differential offset for heating. [0233] 365a curve representing the sensible energy efficiency of a cooling system with known control 365 where the cool source is turned off when the thermostat temperature reaches the lower limit of a cooling setpoint differential 369 a first time, and the cooling ventilation fan is turned off at the same time or continues to operate for a fixed fan-off delay time after the cool source is turned off. [0234] 367a curve representing the sensible energy efficiency of a cooling system with cool source operational until a thermostat temperature reaches the lower limit of the cooling setpoint differential 369 a first time and the cooling ventilation fan continuing to operate for a variable fan-off delay time until the thermostat temperature increases to the same lower limit cooling setpoint differential a second time or to a setpoint hysteresis offset 373 or the fan-off delay time P2 is based the duration of the cooling cycle P3. [0235] 368a curve representing the outdoor air temperature ( F.) during cooling. [0236] 370a curve representing the electrical power of a cooling system operating until a thermostat temperature reaches the lower limit of the setpoint differential 371 a first time and the cooling fan continuing to operate for a variable fan-off delay time until the thermostat temperature increases to the same lower limit setpoint differential a second time or differential offset 374 or the fan-off time delay P2 is based on the duration of the cooling cycle P3. [0237] 373a thermostat differential offset for cooling. Cooling Overshoot (CO). [0238] 374a thermostat +/differential offset for cooling. [0239] 800a Smart Communicating Thermostat [0240] 802a Common B input to the thermostat [0241] 802Aa Common B input to the HVAC Equipment Control Terminals [0242] 804HVAC Equipment Control Terminals [0243] 806a Thermostat Element [0244] 808an Output from the Thermostat Element [0245] 810a repurposed wire used to carry the positively or negatively rectified signals from the thermostat [0246] 811a solid-state common-wire adapter [0247] 812a repurposed wire used to carry the common signal to the thermostat [0248] 814an HVAC Element [0249] 815a Common Wire Adapter [0250] 818an output from a switching device [0251] 820a diode attached to a thermostat output [0252] 822a diode attached to a thermostat output [0253] 824an optoisolator used to signal a processor [0254] 826Aa pull up resistor [0255] 826Ba pull up resistor [0256] 826Ca pull up resistor [0257] 828an output from the optoisolator [0258] 832an output from the microprocessor to trigger a switching device [0259] 834an output from the microprocessor to trigger a switching device [0260] 836a switching device [0261] 840a jumper wire to enable high speed fan operation in heating and cooling [0262] 842a high-voltage Y-adapter combining the two high voltage signal outputs from the Forced Air Unit (FAU) control board to the high speed tap of the system fan/blower (206) to enable high speed fan operation in cooling and heating modes. [0263] 844a dip switch or other electrical control switching device on the FAU control board to enable high speed system fan/blower operation when the thermostat G terminal is energized in cooling or heating modes. [0264] 846a wired or wireless (WIFI) software application commands to control a switching device to enable high speed system fan/blower operation when the thermostat G terminal is energized in cooling or heating modes, and [0265] 848an electrical signal waveform identified by a controller to enable high speed system fan/blower operation when the thermostat G terminal is energized in cooling or heating modes. [0266] 850a Zener diode [0267] 851a Zener diode [0268] 852a Load resistor [0269] 854a Pull up resistor [0270] 856an Optoisolator
