Abstract: A duty cycling switch for use with a furnace which mounts onto the exterior wall of the furnace plenum and opens and closes in response to the temperature of the plenum wall. The switch is adjusted to deactivate the burner when the plenum wall heats up to a temperature caused by the continuous operation of the burner for a predetermined period of time. The duty cycling switch acts to reactivate the burner when the plenum cools down below this temperature. A duty cycling switch for use with an air conditioner is also disclosed which mounts onto the plenum wall and opens and closes in response to the temperature of the plenum wall. It is adjusted to deactivate the compressor of an air conditioner unit when the plenum wall cools down to a temperature caused by continuous operation of the compressor for a first predetermined period of time and reactivates the compressor after the plenum wall exceeds this temperature. The furnace duty cycling switch is preferably an adjustable bimetal switch which opens on rise.

Abstract: A quartz heater, an elongated, rectilinear heating element which lies in a horizontal position in front of a reflector in an improved housing designed to enable the outer surface of the housing to remain cool during operation without the aid of an active cooling system such as a fan or water cooling system. This is accomplished by drawing cooling air from beneath the heater to bathe both front and rear surfaces of the reflector and further preventing air in the front of the heater from being drawn into the heater. The cooling air upon entering the interior of the housing is divided into two flow paths, one of which exhausts at approximately a 45.degree. angle toward the front of the heater and the second exhausts directly from the top of the heater.