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 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.

An electronic cigarette includes a shell and a mouthpiece. The external wall of the shell has an air inlet. An atomizer and a liquid-supply are in contact with each other. The air inlet, atomizer, and an aerosol passage are interconnected.

A control system for controlling a gas powered appliance includes a hot surface igniter, an igniter relay, and an integrity detection circuit. The integrity detection circuit is configured to be coupled to a power source, the igniter relay, and the hot surface igniter to produce an output indicative of the integrity of the hot surface igniter and the igniter relay. The integrity detection circuit is configured to output a first voltage when the igniter relay is closed and output a second voltage different from the first voltage when the hot surface igniter is in a non-short circuit failure condition.

A combined housing for temperature control of a space has a top face, a bottom face, a left side face, a right side face, a front face, and a rear face. A heating assembly formed in the housing has a recess centrally positioned in the front face and a radiant heating element extending laterally within the recess. A cooling assembly formed in the housing has an input aperture formed in the rear face equally spaced from the left and right side faces, a first output aperture formed in the front face between the recess and the left side face, and a right output aperture formed in the front face between the recess and the right side face.

A combined housing for temperature control of a space has a top face, a bottom face, a left side face, a right side face, a front face, and a rear face. A heating assembly formed in the housing has a recess centrally positioned in the front face and a radiant heating element extending laterally within the recess. A cooling assembly formed in the housing has an input aperture formed in the rear face equally spaced from the left and right side faces, a first output aperture formed in the front face between the recess and the left side face, and a right output aperture formed in the front face between the recess and the right side face.

A high turndown furnace for an air handling system. In one example, the furnace includes a plurality of tubes divisible by four with a first modulating valve supplying gas to of the tubes and a second modulating valve supplying gas to of the tubes. In one aspect, the furnace is capable of providing a 16:1 turndown. In one aspect, the furnace is capable of providing seamless turndown operation throughout the entire firing range.

An electrical heater assembly, fluid treatment assembly, and method of manufacturing same are disclosed. The electrical heater assembly includes a heater body including a resistive portion and a plurality of slits in the resistive portion. The slits electrically disconnect sections of the resistive portion from each other to define a serpentine current-carrying path through the resistive portion. An electrode attachment portion us connected at an end of the serpentine current-carrying path. An electrode is included that includes a first end that is electrically connected to the heater body at the electrode attachment portion. The first end extends in a transverse direction from the heater body.

A holding device for at least one heating element, in particular for a PTC heating element or a mica heating element, including at least two oppositely arranged holding elements, which are spaced apart from one another by a gap, which extends along a longitudinal direction of the holding device and is adapted for receiving at least one heating element, and including a heat transfer body with at least two chambers, which respectively form an inner region, through which a gaseous medium can flow, wherein the opposite holding elements are arranged between the two chambers and the gap connects the inner regions of the chambers.

The disclosed technology includes systems and methods for detecting an at least partially obstructed air filter in a furnace. The disclosed technology can include a system and method that can receive temperature data from a flame sensor configured to detect a temperature of a flame in a burner, determine that an air filter associated with the burner is at least partially obstructed by determining that the temperature data indicates the flame temperature is greater than or equal to a threshold temperature, and output an alarm signal indicating that the air filter is at least partially obstructed.