Saturday, September 30, 2023


Quick RV Tech Tip: Furnace runs too long. What’s the problem?

Dear Dave,
Our furnace runs longer than it should. If it’s an air filter, where is it? — Joy H.

Dear Joy,
The furnace operation is controlled by the thermostat, which monitors the temperature and creates a closed condition that supplies the furnace control board with 12-volt power. If you set the temperature at 70 degrees, once the inside temp drops below that temperature +/- 5 degrees, it sends 12-volt power to the module board and the motor/fan starts until it raises the sail switch and then the gas valve opens and it lights the burner assembly. When the temperature gets to 70 +/- 2 degrees it shuts off.

I would suggest getting a thermometer and verifying what the temperature is at the thermostat. This will tell you if the furnace is actually performing as designed or really is running too long.


Dave Solberg
Dave Solberg
Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club. He has been in the RV Industry since 1983 and conducts over 15 seminars at RV shows throughout the country.


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dale p
1 year ago

And why not give reason of why this would happen ?
Example High Temperature sensor bad. Bad connection of said sensor to shield.

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