Provided is a gas furnace including a primary heat exchanger and a secondary heat exchanger through which a combustion gas produced by the combustion of a fuel gas flows. The gas furnace includes: a coupling box serving as an intermediary to connect the primary heat exchanger and the secondary heat exchanger; a collect box connected to the secondary heat exchanger, for letting in the combustion gas passed through the secondary heat exchanger; an inducer connected to the collect box, for inducing a flow of the combustion gas; and a bypass pipe connected to one side of the coupling box and including a bypass pipe for guiding the combustion gas passed through the primary heat exchanger to a hot water supply tank for supplying hot water to an indoor space.

A collection of methods for monitoring the operation of a heating system configured to heat a space is provided. One method includes obtaining, by one or more computing devices, data from a fuel sensor for a period of time, the fuel sensor configured to detect an amount of fuel within a fuel supply for a furnace of the heating system. The method further includes determining, by the one or more computing devices, an adjustment to the operation of the heating system based, at least in part, on the data obtained from the fuel sensor. The method additionally includes adjusting, by the one or more computing devices, the operation of the heating system according to the adjustment.

A method for controlling a gas furnace that performs a heating operation by receiving a first heating signal; calculating a certain heating capacity smaller than a maximum heating capacity of the gas furnace, according to the first heating signal; and operating a heating of the gas furnace with the calculated certain heating capacity. The calculating of the certain heating capacity includes calculating the certain heating capacity according to a difference between an intake air temperature sucked into the gas furnace and a reference temperature.

According to various aspects, exemplary embodiments are disclosed of blow through direct fired heaters including evaporator coils and/or energy recovery ventilation.

A flame sensor for a furnace of a heating, ventilation, and air conditioning (HVAC) system includes a sensor body and an electrically conductive member of the sensor body. The electrically conductive member is configured to be disposed within a flame region of a burner of the furnace and configured to receive electrical current from a controller of the furnace. The flame sensor also includes an anti-oxidation coating disposed on an outer surface of the electrically conductive member and configured to transmit the electrical current from the electrically conductive member. The anti-oxidation coating is configured to contact a flame produced by the burner and expose the electrical current to the flame.

A method of controlling a gas furnace system includes determining a first pressure in a conduit coupled to a draft inducer from signals output by a pressure transducer positioned to sense a pressure within the conduit with a motor of the draft inducer in a stopped condition. A first status of the pressure transducer is determined based at least in part on the first pressure. The motor of the draft inducer is controlled to increase a speed of the motor from the stopped condition in response to a call for heat when the first status does not indicate that the pressure transducer is unreliable, and the motor is maintained in a stopped condition when the first status indicates that the pressure transducer is unreliable.

A method of controlling a gas furnace system includes controlling a motor of a draft inducer to increase a speed of the motor in response to a call for heat, receiving pressure signals output by a pressure transducer, receiving signals indicating whether a pressure switch is in a first state or a second state, and determining a first status of the pressure transducer as reliable, unreliable, or questionable at a first time based on the received pressure signals from the pressure transducer, the signals indicating whether the pressure switch is in the first state or the second state, and a first status of the motor of the draft inducer at the first time. Operation of the motor of the draft inducer is stopped when the first status of the pressure transducer indicates that the pressure transducer is unreliable.

A furnace for a heating, ventilation, and air conditioning (HVAC) unit includes a heat exchange tube configured to flow combustion products therethrough and place the combustion products in a heat exchange relationship with an air flow directed across the heat exchange tube. The furnace also includes a burner assembly fluidly coupled to a first port of the heat exchange tube and configured to generate the combustion products directed into the heat exchange tube via the first port, and a draft inducer blower fluidly coupled to a second port of the heat exchange tube and configured to draw the combustion products through the heat exchange tube. The burner assembly is higher in position than the draft inducer blower relative to a base of the HVAC unit.

A method of controlling a gas furnace comprising a gas valve for supplying a fuel gas to a manifold; a burner through which the fuel gas discharged from the manifold passes; an igniter for igniting a mixture of fuel gas passed through the burner and air; and an inducer for generating a flow in which a combustion gas generated by the burning of the mixture is discharged to an exhaust pipe via a heat exchanger, wherein the gas furnace performs a heating operation according to a heating signal or a heating stop according to a stop signal, includes the steps of: (a) receiving any one of the heating signal or the stop signal; (b) transmitting a signal to operate the inducer when the heating signal is received; (c) operating the igniter; (d) transmitting a signal to open the gas valve; (e) detecting whether the gas valve is opened or closed; (f) detecting a flow rate of the fuel gas in the manifold; and (g) displaying a normal operation of the heating operation, based on information detected in the steps (e) and (f).

Embodiments of the present disclosure are directed to a furnace that includes a blower configured to operate to force a fluid through the furnace, a motor having a rated speed, in which the motor is coupled to and configured to actuate the blower, and a controller configured to receive data indicative of an operating characteristic of the furnace and regulate operation of the motor to be at or below an operational speed limit. The controller is configured to set the operational speed limit based on the data indicative of the operating characteristic of the furnace, such that the operational speed limit is less than or equal to the rated speed of the motor.