Provided is an RPM control method for an inducer for a gas furnace that induces a flow of combustion gas produced in a burner from a heat exchanger to an exhaust pipe. The RPM control method for an inducer for a gas furnace includes: (a) initiating a heating operation for the gas furnace; (b) determining whether the operation time during which the heating operation is performed is equal to or longer than a first time period; (c) if it is determined that the operation time is equal to or longer than the first time period, detecting whether a pressure switch is turned OFF; and (d) if the pressure switch is detected as turned OFF, increasing the RPM of the inducer by a first value.

The present disclosure relates to a condensate trap for a gas furnace for collecting and discharging condensate generated in a heat exchanger and an exhaust pipe, the condensate trap including: a first inlet through which the condensate generated in the heat exchanger is introduced; a second inlet through which the condensate generated in the exhaust pipe is introduced; a first passage through which the condensate introduced from the first inlet passes; a second passage through which the condensate introduced from the second inlet passes; a discharge port through which the condensate, having passed through the first passage and the second passage, is discharged outside; and a backflow prevention device disposed on the first passage and configured to prevent backflow of air, wherein the backflow prevention device includes: a housing; and a core which is movably disposed in the housing, and which in response to an amount of the condensate introduced from the first inlet being less than or equal to a predetermined amount, prevents backflow of the air by closing the first passage.

A method of determining presence of a flame in a furnace of a heating, ventilation, and air conditioning (HVAC) system. The method comprises determining, using a controller, whether a processor signal (G) is active, responsive to a determination that the processor signal (G) is active, determining, using the controller prior to assertion of a flame-test input control signal, an output state of a first comparator, responsive to a determination that the output state of the first comparator is high, determining, using the controller prior to assertion of the flame-test input control signal, an output state of a second comparator, and responsive to a determination that the output state of the second comparator is low, transmitting, using the controller, a notification that a flame is present.

An HVAC system with a refrigerant gas sensor is provided. In one embodiment, an HVAC system includes a heat exchanger coil installed within a housing. The heat exchanger coil is operable to exchange heat with air in the housing via a refrigerant passing through the heat exchanger coil. The system also includes an HVAC sensor assembly installed within the housing. The HVAC sensor assembly includes a refrigerant gas sensor and an orientation sensor positioned to detect an orientation of the refrigerant gas sensor. The HVAC system may also or instead include a position sensor to detect the position of the refrigerant gas sensor within the system. Additional systems, devices, and methods are also disclosed.

Methods and related systems for operating a furnace are disclosed. In an embodiment, the method includes activating a burner assembly and a first fan of the furnace to combust fuel and air and circulate combustion gases along a flow path extending through a heat exchanger of the furnace. In addition, the method includes operating a second fan of the furnace to circulate air across an external surface of the heat exchanger of the furnace and produce a conditioned airflow. Further, the method includes monitoring one or more parameters of a motor of the second fan indicative of an airflow rate of the conditioned airflow, and deactivating the burner assembly, whereby combustion of the fuel and air in the furnace ceases, in response to the one or more parameters indicating that the airflow rate is less than a minimum airflow rate.

Provided is a condensate water trap for a gas furnace that collects and discharges condensate water produced in a heat exchanger and an exhaust pipe. The condensate water trap includes: a first inlet through which the condensate water produced in the heat exchanger is introduced; a second inlet through which the condensate water produced in the exhaust pipe is introduced; a first flow path through which the condensate water coming from the first inlet passes; a second flow path through which the condensate water coming from the second inlet passes; an outlet through which the condensate water introduced through the first and second inlets is discharged; a third flow path into which the residual condensate water passed through at least one of the first and second flow paths but not discharged through the outlet is introduced; and a sensing mechanism that senses if the amount of residual condensate water introduced into the third flow path is greater than or equal to a given amount.

A variable capacity furnace includes a variable capacity fuel valve configured to supply a fuel to a burner, where the variable capacity fuel valve is configured to be controlled to a target setting over a range of settings to modulate an amount or flow rate of the fuel supplied to the burner. The variable capacity furnace also includes a control assembly having processing circuitry and memory circuitry. The memory circuitry includes instructions stored thereon that, when executed by the processing circuitry, cause the processing circuitry to execute a control algorithm to determine, based on whether an indoor temperature is progressing toward a set point over time and based on a temperature differential between the set point and the indoor temperature, a target setting of the variable capacity fuel valve. The instructions also cause the processing circuitry to control the variable capacity fuel valve to the target setting.

This invention relates to a heater. A combustion air blower feeds combustion air to a burner device. The burner device burns a gas-air mixture from the combustion air and a fuel and serves for heating air. A circulating air blower discharges heated air from the heater. A control device acts on at least one component of the heater, wherein a night mode parameter set associated with an operation of the heater in a night mode and a default parameter set are stored in a data storage device. After an activation of the night mode, the control device accesses the night mode parameter set and uses the same for acting on the component. The night mode parameter set effects a reduction of background noise generated by the heater.

The flameless heater system includes an energy source comprising a diesel engine configured to create volumes of air, a hydraulic system to control engine loading for heat generation and for air moving, and a control system, operatively coupled with the energy source and the hydraulic system to control at least one of a speed of the diesel engine, a loading of the diesel engine, or a fan speed.