This is generic description of RV furnace operation and applies to most DSI (direct spark ignition) type furnaces.
1. The Thermostat calls for heat, sending DC (12 volt) current to the furnace.
2. A Time Delay Relay is energized and passes battery DC power to the blower motor.
3. The blower motor and fans spin, pulling air from the Air Return and generating a stream
of air through the Heat Exchanger and out the Ducts. At the same time another fan pulls
air from the Combustion Air Intake into the Combustion Chamber and out the Exhaust.
4. The fan air stream causes the Sail switch to close as the blower gets near full speed.
5. Power flows to the High Limit Switch and onward to the Control Circuit Board.
6. The Control Circuit Board opens the gas valve and generates a spark at the DSI Igniter.
7. The Burner ignites, building heat in the Combustion Chamber.
8. Heat passes through the Heat Exchanger, warming the air circulating through the Ducts.
9. The Thermostat reaches the Set Temperature and opens.
10. Power is removed from the Control Board and the Burner shuts down.
11. The fan continues to run to cool the furnace, until the Time Delay Relay opens again.
For a Pilot Light model of furnace, the operation is similar but ignition does not depend on a
control board to trigger an igniter. Once the pilot is lit (manually), it stays lit and is the ignition
source. The furnace cycles on/off by control of the gas flow alone, with the gas valve opening or
closing in response to the thermostat demand.
An RV furnace runs strictly on 12 volt power (12 VDC) and does not depend on shore power or
generator to operate. As long as the RVís batteries have sufficient voltage and amps, and there is
a supply of propane to produce heat, the furnace will function.
FOR SALE 2014 BOSS 6.2L F350
2012 Surveyor SV264