The invention relates to a water heating device, comprising a burner (20) and a flame current measuring device (100) for measuring a flame current, which measuring device comprises two electrodes and a voltage source (14), wherein each of the poles (18, 19) of the voltage source is connected to one of the electrodes. The water heating device further comprises a heat exchanger (40) which is electrically insulated relative to the burner. The burner and the heat exchanger here form the electrodes of the flame current measuring device. The heat exchanger functioning as electrode can be earthed (41). The measured flame current can be used to determine the excess air factor of the combustion. The water heating device can further comprise an air/fuel controller for controlling the air/fuel ratio, wherein the air/fuel controller uses the determined excess air factor to control the air/fuel ratio. The invention also relates to a method for measuring a flame current in a flame.

A motor controller for a draft inducer motor that operates an inducer blower in a furnace is provided. The motor controller includes a communication interface operable to receive a signal from a system controller. The signal represents a command to operate the draft inducer motor. The motor controller includes a processor operable to operate the draft inducer motor in accordance with a predefined motor speed profile during at least one of an ignition stage and a combustion stage of the furnace.

A furnace system of a heating, ventilation, and/or air conditioning (HVAC) system includes a burner assembly having a burner enclosure configured to receive a fuel for ignition to generate heated combustion byproducts. The furnace system also includes a controller configured to detect a value associated with a wave signal transmitted through the burner enclosure and operate the furnace system based on a comparison between the value and a threshold value.

A furnace system includes a heat exchanger and a burner assembly including a burner enclosure fluidly coupled to the heat exchanger. The burner assembly is configured to receive a fluid, ignite the fluid to produce combustion byproducts, and direct the combustion byproducts to the heat exchanger. The furnace system also includes a pressure sensor configured to detect a pressure within the burner enclosure. The furnace system is configured to operate based on the pressure detected by the pressure sensor.

A furnace system of a heating, ventilation, and/or air conditioning (HVAC) system includes a burner assembly having a burner enclosure configured to receive a fuel for ignition to generate heated combustion byproducts. The furnace system also includes a controller configured to detect a value associated with a wave signal transmitted through the burner enclosure and operate the furnace system based on a comparison between the value and a threshold value.

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.

Example furnaces and methods related thereto are disclosed herein. In an embodiment, the furnace includes a burner box including at least one burner configured to combust a fuel/air mixture. In addition, the furnace includes a first blower including an inlet nozzle having an air inlet and fuel inlet. The inlet nozzle is configured such that operation of the first blower is to pull air and fuel into the inlet nozzle to produce the fuel/air mixture at a fuel/air ratio that is configured to produce flue products having less than 14 Nano-grams per Joule of nitrogen oxides when combusted. Operation of the first blower is configured to push the fuel/air mixture into the burner box. Further, the furnace includes a heat exchanger assembly fluidly coupled to the burner box through a vestibule, and a second blower configured to pull the flue products through the heat exchanger assembly.

Example furnaces and methods related thereto include a burner box including at least one burner configured to combust a fuel/air mixture. In addition, the furnace includes a first blower including an inlet nozzle having an air inlet and fuel inlet. The inlet nozzle is configured such that operation of the first blower is to pull air and fuel into the inlet nozzle to produce the fuel/air mixture at a fuel/air ratio that is configured to produce flue products having less than 14 Nano-grams per Joule of nitrogen oxides when combusted. Operation of the first blower is configured to push the fuel/air mixture into the burner box. Further, the furnace includes a heat exchanger assembly fluidly coupled to the burner box through a vestibule, and a second blower configured to pull the flue products through the heat exchanger assembly.

A heating, ventilation, and/or air conditioning (HVAC) system includes a control system configured to initiate an operating cycle of a furnace of the HVAC system at an initial operating stage in response to a call for heating, monitor a duration of time associated with the operating cycle of the furnace to satisfy the call for heating, adjust the initial operating stage to provide an adjusted initial operating stage of the furnace based on the duration of time, and initiate a subsequent operating cycle of the furnace at the adjusted initial operating stage.

A portable heater includes a housing enclosing a combustion region, a first connector for connecting with a fuel source, a first supply line in fluid connection with the first connector for supplying fuel to the combustion region when the fuel source is connected with the first connector, a second supply line in fluid connection with a second connector for supplying fuel to a fuel-fired accessory when the fuel source is connected with the first connector and the fuel-fired accessory is connected with the second connector, and a valve arrangement operable to selectively supply fuel to the first and second supply lines when the fuel source is connected with the first connector.