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.

Disclosed are a gas furnace and an air conditioner having the same. The gas furnace includes: a burner for burning fuel; a manifold providing the fuel to an entry of the burner; a heat exchanger spaced apart from an exit of the burner and providing a passage for combustion gas generated by the burner; an inducer for causing a fluid to flow through the burner and the heat exchanger; a blower for causing a flow of air passing around the heat exchanger; and an air shutter positioned between the manifold and the entry of the burner. The air shutter includes: a housing having an inner space that communicates with the manifold and the entry of the burner; and a primary hole formed to penetrate the housing and able to be opened and closed.

Disclosed are a gas furnace and an air conditioner having the same. The gas furnace includes: a fuel valve; a manifold providing a passage of fuel passing through the fuel valve; a plurality of burners provided to burn fuel provided from the manifold and spaced apart from each other in one direction; a plurality of heat exchangers providing a passage of combustion gas generated by the plurality of burners; and a blower for causing a flow of air passing around the heat exchanger. The manifold includes: a first tube having one end connected to the fuel valve and forming a first passage; a second tube extending in the one direction, forming a second passage, and facing at least one of the plurality of burners; a third tube extending in the one direction, forming a third passage, and facing remaining burners of the plurality of burners; and a three-way valve connected to the first tube, the second tube, and the third tube.

A room heater is operated on receiving an on-command from a thermostat when a detected temperature detected by a second room-temperature detector falls below a first reference temperature, and is stopped on receiving an off-command when the temperature detected by the second room-temperature detector is above a second reference temperature that is set higher than the first reference temperature or when the thermostat is manually operated to be switched off. A setting temperature for temperature control to be carried out when the on-command is received again is updated according to a difference between the set temperature and the temperature detected by the first room-temperature detector on receiving the off-command. When the off-command is received before passing a predetermined period of time after receiving the on-command, the updating of the set temperature is prohibited if the temperature detected by the first room-temperature detector is below a predetermined minimum lower reference temperature.

A stove for indoor use includes a housing having a bottom wall, a top wall and one or more side walls defining a combustion chamber adapted to retain a fire, and an air supply system for supplying air to the combustion chamber. The air supply system includes a primary air conduit for supplying air to the combustion chamber from below through the bottom wall and a secondary air conduit for supplying air to the combustion chamber from above. A valve is arranged in the primary air conduit or in a branching between the primary and secondary air conduits. The valve is controlled by a bimetal whereby the valve is in a maximum open position when the prevailing temperature is below a first predetermined temperature during start-up of a fire and in a maximum closed position when the prevailing temperature is above a second predetermined temperature after start-up of the fire.

One or more techniques and/or systems are disclosed for a portable heater that may be used in an area used for human occupancy, to provide heat to that area. Such a heater can be portable, and comprise an environmental detector that senses ambient air conditions, and may provide data used to shut down the heater in threshold conditions. In one implementation, a portable heater for use in high altitudes can comprise a housing configured for portability, in which a combustion region and a fuel supply component are disposed. The heater can comprise an environmental detector with a flameless sensor configured to detect an ambient level of a constituent of the atmosphere, and generate a signal indicative of the constituent level; and a sensor interface that can control flow of fuel from the fuel supply, based at least upon a signal received from the sensor.

One or more techniques and/or systems are disclosed for a vent-free heater that may be installed in an area used for human occupancy, to provide heat to that area. Such a heater can comprise an environmental detector that senses ambient air conditions, and may provide data used to shut down the heater in predetermined threshold condition. In one implementation, a vent-free heater for installation in high altitudes can comprise a combustion region and a fuel supply component. The heater can comprise an environmental detector with a flameless sensor configured to detect an ambient level of a constituent of the atmosphere and generate a signal indicative of the constituent level; and a sensor interface that can control flow of fuel from the fuel supply, based at least upon a signal received from the sensor.

A balanced high efficiency outdoor heater is provided to increase the heat radiation area, and to improve the stability of the structure. The heater includes a burner provided at an upper end of a standing column, a bottom base provided at a lower end of the standing column, and a beam is set between the burner and the standing column. The beam and the standing column are connected by pipe fittings. An ignition control device is equipped inside the base and is connected to the burner. An electrode rod and a thermocoupler are connected to the ignition control device under the burner. A first reflector is fixedly connected to the lower end of the burner and a gas valve is equipped in the bottom base. Compared with the prior art, the burner uses sintered felt and a heating surface of the burner faces upside down to improve thermal efficiency.

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.

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.