Abstract: An electronic safety circuit for a portable gas heater includes a transformer and half wave rectifier connected in parallel with a fan motor for charging a capacitor, and a solid state switching circuit, which may be either a pair of cascaded transistors, an SCR, or a Darlington switch, for applying a reverse polarity voltage across the solenoid of a solenoid operated gas valve to immediately turn off the gas valve in the event of loss of power to the combustion fan motor. The electronic safety circuit may be conveniently mounted on a PC board and enclosed in the combustion fan motor.

Abstract: A fuel burning furnace includes a number of energy efficient features. The furnace includes a heat exchanger in which combustion air is preheated by hot discharge gases. Diverters are provided in the heat exchanger to continually urge hot combustion gases toward the interior portions of the heat exchanger to improve its heat transfer characteristics. The furnace incorporates a number of features to determine malfunction and indicate inefficient operation. A humidification control system for the humidification or dehumidification of circulated air also is provided. The furnace also includes a blower motor system which compensates for loss of tension in driving belts and makes correction for blower speed in response to temperature variations.

Abstract: A fuel burning furnace includes a number of energy efficient features. The furnace includes a heat exchanger in which combustion air is preheated by hot discharge gases. Diverters are provided in the heat exchanger to continually urge hot combustion gases toward the interior portions of the heat exchanger to improve its heat transfer characteristics. The furnace incorporates a number of features to determine malfunction and indicate inefficient operation. A humidification control system for the humidification or dehumidification of circulated air also is provided. The furnace also includes a blower motor system which compensates for loss of tension in driving belts and makes correction for blower speed in response to temperature variations.

Abstract: An electrically-operated gas valve in a gas furnace is pulsated between the fully-open and fully-closed position in response to a series of electrical pulses of selectable frequency and duty cycle. The pulses are generated by an electronic timer, which is user-adjustable to select a frequency and duty cycle from a range of frequencies and duty cycles. A switch in series with the gas valve alternately energizes and deenergizes the valve in response to the pulses, whereby the valve is fully-open when energized and fully-closed when deenergized.

Abstract: A fluid shut-off device is provided which comprises a non-magnetic casing having a fluid passage therein, a metallic valve body movably disposed in the casing to close the passage at one operative position, and a magnetic member slidably disposed outside the casing and magnetically attracting the valve body. The magnetic member takes an inoperative position against a spring force and is locked at this position. The lock is released by a bimetallic strap deformable by supply of an electric current. When the lock is released, the magnetic member is moved by the action of the spring force, so that the valve body magnetically attracted by the magnetic member is also moved to the operative position to shut off the flow of fluid material through the passage.