Abstract: A fan control board having a central low voltage wiring center as well as a safety interlock for electric heaters. The interlock uses diodes to insure proper fan operation in the event of miswiring of the heater sequencers. Another feature is a quick connect for the time delay relay which permits easy insertion and removal thereof for replacement and/or cleaning. Diode circuits are provided in both the circuit to normally power the fan motor as well as in the circuit to power the PTC resistor which closes the fan motor circuit with the circuit which powers the PTC resistor also being connected across the fan motor circuit to provided rectified power to the fan circuit and permit the fan motor to turn on concurrently with the application of power to the PTC resistor to prevent the heater from being turned on prior to the fan.

Abstract: A fan control board and circuit having a central low voltage wiring center as well as a safety interlock for electric heater in which the interlock uses diodes to ensure proper fan operation in the event of miswiring of the heater sequencers. Another feature of the invention is a quick connect for a time delay of the circuit which permits easy insertion and removal thereof for replacement and/or cleaning.