Troubleshooting an RV Suburban Furnace
Suburban manufactures physically small but powerful furnaces for motor homes, fifth-wheel trailers and conventional travel trailers. The furnace in a recreational vehicle, or RV, typically heats air by burning propane gas supplied under pressure from an on-board or remote storage tank. Although the propane is burned to create the heat, the furnace comprises many electrical components integral in its function. An adequate flow-through of fresh combustion air, exhaust gasses and heated air is also necessary to the furnace's proper function. All of these variables must be tested in a logical sequence when troubleshooting a non-functioning Suburban furnace in an RV.
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Instructions
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Use your voltage meter to check that the circuit breaker that serves the furnace is functional and switched on.
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Have your licensed propane supplier check the gas pressure at the Suburban furnace test nipple. If your storage tank is full but the pressure at the nipple is low, a blockage is in the gas line.
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Use a voltage meter to test for low voltage from the battery. An ideal reading is between 11 volts and 13.5 volts. If the voltage is low, the fan cannot run at its optimum speed, and this might interrupt the ignition sequence.
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Check inside the combustion chamber to ensure the burner assembly is free from contamination, such as rust flakes that might have settled downward from the exhaust chimney. Consult your owner's manual to ensure the ignition electrode gap is correct, and test that the electrode is firing.
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Inspect the vents through which fresh air is drawn into the furnace. If they are blocked, either by atmospheric dust or by objects that have fallen against them while the RV was underway, the flow-through will be reduced. This might result in a noticeable decrease in performance or an automated shut-down of the furnace.
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Visually inspect the vents through which exhaust gasses are expelled from the furnace. Obstruction might result in a noticeable decrease in performance or an automated shut-down of the furnace.
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Use your voltage meter to test the time delay relay. One terminal should have a constant supply of power from the circuit breaker board, one terminal should become live when the thermostat initiates a demand, and the third terminal should become live 20 seconds after the thermostat terminal does. The terminals should be marked by embossing in the relay's case.
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Tips & Warnings
There are more complex components in many furnace control systems, such as sail switches and temperature control limit switches. These are controlled by printed circuit boards that seldom have user serviceable components.
These troubleshooting tips involve close proximity to 120-volt electricity and inflammable propane gas, which becomes explosive when it leaks and ponds. Exercise all appropriate safety precautions when troubleshooting an RV furnace.
References
Resources
- Photo Credit furnace image by sumos from Fotolia.com
