Disclosed is a gas furnace for indoor heating. The gas furnace includes a burner to generate high-temperature exhaust gas, an exhaust flow path, a blower to suction indoor air through a recovery flow path, a supply flow path to guide the indoor air to the indoor space after undergoing heat exchange in the exhaust flow path, and a fuel supply unit including a fuel supply line and a fuel discharge line, configured to supply fuel to the burner, and a valve between the fuel supply line and the fuel discharge line. The valve includes a step motor, and a blocking member coupled to a rotating shaft of the step motor and configured to move straight via by driving of the step motor, and an opening degree of the valve between the fuel supply line and the fuel discharge line is adjusted by the straight movement of the blocking member.

An air conditioning system includes a heat pump having a refrigerant radiator, a gas furnace unit having a heating section to heat passing air, a blower generating air flow through the radiator and the heating section, and a controller controlling operation of the heat pump unit, the gas furnace unit, and the blower. The controller has a first operating mode in which the gas furnace unit operates alone as a heat source unit, a second operating mode in which the heat pump unit operates alone as a heat source unit, and a third operating mode in which the gas furnace unit and the heat pump unit operate at the same time as a heat source unit. The controller is configured to select the operating modes based on a parameter relating to outside air temperature that is the temperature of outside air.

A furnace including a combustion chamber for burning fuel can have increased fuel burning efficiency, increased heating efficiency, and decreased harmful emissions of combustion byproducts. A combustion air delivery system delivers primary and secondary combustion air to the combustion chamber. Primary and secondary combustion air may be delivered at amounts that increase burning efficiency. An amount of secondary combustion air can be controlled by a valve system. A heat transfer device efficiently transfers heat from products of combustion for heating an enclosed space.

A system and method of operating a gas fuel valve control circuit are disclosed. The gas valve control circuit includes a gas valve assembly configured to control a flow of a fuel gas to a load and a switch assembly including a switch in each leg of a plurality of legs of a power supply to the gas valve assembly. The switch assembly is configured to supply power and a return to the gas valve assembly in a first position and to open the plurality of legs of the power supply to the gas valve assembly in a second position. The switch assembly is configured to indicate a position of the switch assembly.

Systems and methods for providing a personal heater are disclosed. In some embodiments, the personal heater comprises a housing, a heating element, and a controller. The housing is configured with an opening for receiving one or more feet. The controller is configured to cause the heating element to heat one or both of an interior and an exterior of the housing based on whether the one or more feet are inside the housing.

A portable forced air heater including a housing, a heating element located within the housing, a sensor configured to sense a characteristic of the portable heater, a communications device configured to communicate with an external device, and a controller having an electrical processor and memory. The controller is configured to receive, from the sensor, the characteristic of the portable heater, and output, via the communications device, a signal indicative of the characteristic of the portable heater to the external device.

An HVAC controller may wirelessly communicate with a mobile wireless device that provides a user interface for interacting with the HVAC controller. In some cases, the communication module wirelessly receives a sensed parameter from a remote wireless sensor in a living space of the building and receives a wired input from a return air sensor. A controller may be operatively coupled to the communication module and may control the HVAC system based at least in part on the sensed parameter from the remote wireless sensor when the sensed parameter from the remote wireless sensor is available and, in some cases, control the HVAC system based at least in part on the return air parameter when the sensed parameter from the remote wireless sensor is not available.

A forced airflow drying apparatus includes a body including a pair of air inlets to receive inlet air which is channeled to an upstream side of a filter unit, a pair of body airflow generators to generate a first forced airflow, each body airflow generator having a first end and a second end, where the first end of each body airflow generator is opened to a downstream side of the filter unit, a pair of thermoelectric devices configured to control a temperature of the first forced airflow, and a first air outlet, in communication with the second end of each body airflow generator, to receive the forced airflow from the body airflow generators and to expel the forced airflow out of the body. The forced airflow drying apparatus further includes a bar and a drive apparatus configured to movably drive the bar relative to the body, the bar including a second pair of airflow generators to generate a second forced airflow, a pair of resistance heaters to control a temperature of the second forced airflow prior to being expelled from the second air outlet, and a second air outlet to expel the second forced airflow from the bar.

Techniques for use with vent covers of furnace ductworks are described herein. A vent cover may include a fan to actively pull air from the ductwork and into a room at least in part in response to a number of open or closed vents in ductwork to which the vent cover is connected. Active air movement through the vent cover may lower air pressure and/or temperature within the ductwork and increase airflow through heat exchangers of the furnace, thereby compensating for zones created by closed vent covers. A system may monitor factors consistent with a furnace over-temperature event, such as furnace operation, closed vent covers, high air pressure or temperature in ductwork, etc. A fan of a vent cover may be turned on to actively draw air through a vent covered by the vent cover. The fan may turn off after conclusion of at least one of the monitored factors.

A furnace including a housing and a firebox in the housing having a combustion chamber. The furnace includes a combustion air delivery system for delivering combustion air to the combustion chamber. The combustion air delivery system includes a manifold mounted outside the combustion chamber and extending vertically along the front face of the combustion chamber from a lower end to an upper end. An air blower is mounted on the manifold. The combustion air delivery system includes a primary combustion air passage for delivering air from the air blower to a primary combustion air outlet at the front face of the combustion chamber. The combustion air delivery system includes a secondary combustion air passage for delivering air to a secondary combustion air outlet positioned inside the combustion chamber adjacent the top face of the combustion chamber.