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.

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.

In a fan apparatus that includes a passage, a switching device, and a control device, on a premise that at a state where an effective sectional area at a predetermined portion of the passage is switched to a predetermined first-area by the switching device, a value of a current flowing to the fan when a rotational speed of the fan is made to a predetermined rotational speed is defined as a first fan-current value, at a state where the effective sectional area at the predetermined portion of the passage is switched to a predetermined second-area which is larger than that of the first area by the switching device, the value of the current flowing to the fan when the rotational speed of the fan is made to the predetermined rotational speed is defined as a second fan-current value, and a ratio of the first fan-current value to the second fan-current value is defined as a detected current ratio, a control device is configured to: memorize as a standard current ratio a detected current ratio that is detected when the fan apparatus is set up; and decide a clogging degree of the passage by comparison of a detected current ratio after detection of the standard current ratio with the standard current ratio.

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.

A temperature control system includes a blower impeller assembly that has a blower impeller, a motor coupled to and configured to drive the blower impeller, and a sensor that is coupled to the motor and configured to measure current drawn by the motor to maintain the blower impeller at a set angular speed. Further, the temperature control system includes a controller that is communicatively coupled to the sensor. The controller electronically detects at least one of a blockage in a vent coupled to the temperature control system and a malfunction of the blower impeller based on an amount of the current drawn by the motor to maintain the blower impeller at the set angular speed.

Method for operating a gas burner appliance (10), the gas burner appliance com-prising: a combustion chamber (11) in which a defined gas/air mixture is combusted after combustion has been started; a mixing device (25) to provide said gas/air mixture by mixing an air flow provided by an air duct (15) with a gas flow provided by a gas duct (16); a fan (14) to provide the air flow or the flow of the gas/air mixture; a gas safety valve unit (19) assigned to the gas duct to open or close the gas duct; a gas flow modulator (18) or a gas flow regulator (28) assigned to the gas duct to keep a mixing ratio of the defined gas/air mixture constant over the modulation range of the gas burner appliance; an absolute pressure sensor (21) positioned between the gas safety valve unit and the mixing device, wherein the gas burner appliance is operated to determine the air flow resistance of the same by executing the following steps before combustion becomes started: Measuring a first absolute pressure by the absolute pressure sensor (21) when the gas safety valve unit (19) is closed and when the fan (14) is stopped. Measuring a second absolute pressure by the absolute pressure sensor (21) when the gas safety valve unit (19) is closed and when the fan (14) is running. Determining a pressure difference between the first absolute pressure and the second absolute pressure. Determining on basis of the pressure difference the air flow resistance of the gas burner appliance.

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.