Heat from RV furnace reaches 195 degrees at closest vent. Is this too hot?

Dear Dave,
The air coming out of the closest vent from the heater is 195 degrees. The flame goes out and the fire box cools down a little. Then the flame comes back on and finishes the cycle. Is 195 too hot? —Bobby, 1999 Nomad

Dear Bobby,
Yes, 195 degrees is too hot. Most limit switches are set at 160 degrees to prevent overheating and damaging the furnace and other components. The switch actually creates an open circuit, similar to turning off a light switch, and shuts the power off to the furnace.

It seems the switch is working properly and you have an issue somewhere else that is creating the excess heat.

Troubleshooting the problem

Start by making sure all other vents are open and not covered up. Restricted airflow causes the hot air to take the path of least resistance and go to a vent that is open. In your case, it sounds like it is the closest vent to the furnace.

With proper airflow, hot air will be distributed throughout the vents and maintain a safe temperature.

What to check next

I would assume your unit has the corrugated vent lines that supply the vents. The next step would be to make sure none of these are kinked or collapsed.

It’s not uncommon to shove items under a bed or sofa and push these to the point where there is restricted airflow.

Last year, an RVtravel.com reader had a similar situation. One of the vents coming out of his furnace was designed with a sharp 90-degree turn that had to be modified.

Next step

If you have proper airflow to all the vents, the next step would be to inspect the burner assembly. If it is rusted or corroded, it will cause the flame to be excessive and should be replaced.

One more possible issue

One more issue could be the blower motor is not running fast enough to get the airflow. However, most of the time the sail switch will not get to the right height and the furnace will not start at all.

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DAVE HAS ANSWERED MORE THAN 1,000 readers’ maintenance and repair questions. Read a directory here. There is so much to learn!

Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”

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