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Mendocino, California. Delivery all over Northern California. Call or text (909) 259-7837

Free RV manual

How an RV Furnace Works

A propane furnace with a 12 volt fan. How it starts, why it drains the battery and what to check when it blows cold air.

How it starts

An RV furnace burns propane and blows the heat through ducts with a fan. The fan runs on the 12 volt battery.

When you turn up the thermostat, the fan starts first. After about 15 to 30 seconds the burner lights and warm air follows. If it does not light after a few tries, it locks out. Turn the thermostat down and back up to try again.

Watch the battery

The fan uses more battery than anything else in most rigs. A cold night off the grid can drain a battery by morning. When the battery gets low, the fan slows and the furnace will not light. Run the generator or plug in if you can.

Never use the stove or oven to heat the rig. They are not vented outside and can fill it with carbon monoxide.

If it blows cold air

  1. Check that the propane tanks are open and have gas. Light the stove to be sure.
  2. Check the battery voltage. Below about 12 volts the furnace may not light.
  3. Look at the vent outside. Wasps and mice love to nest in it. Clear it with the furnace off and cool.
  4. Make sure no floor vents are closed or covered. Too little air flow shuts the burner off.
  5. Try it two or three times. Air in the propane line after a tank change can take a few tries to clear.

Care

Fit a screen over the outside vent for storage to keep bugs out. Take it off before you use the furnace. Test the furnace before a cold trip, not the night you need it.

Some air conditioners have a heat pump. It warms the rig on shore power without propane when it is not too cold out. The furnace takes over when it gets colder.

When to call a shop

Call a shop if you smell propane, see soot around the outside vent, the carbon monoxide alarm goes off, or the burner lights and then goes out again and again.

The maker's own manuals

These guides cover how most RVs work. Your own rig may differ, so check the manual for your make and model.

Renting from us? Call or text 909-259-RVDR before you try a fix. We would rather talk you through it than have you guess, and it is free.

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