Furnace running very hot...

[groundhogy]

So I have been noticing that my vent air has been notceably hotter.
Like too hot.
So I went to the furnace and put my hand on it. It is also too hot.

It is not triggering the over temperature sensor.

It is a 1 year old Attwood/Dometic 30k btu. The new model they are selling.

What types of things can cause this?

The air is blowing just as fast as ever.

[NRALIFR]

The furnace should have a rating label on it somewhere that lists all the specs for your model. Plenum temperature and temperature rise should be on that label. The normal temperature rise will be about 50 degrees. I would start with that measurement and go from there.

:):)

[larry_cad]

If there is a crack in the heat exchanger as has been suggested, you can get a battery operated CO (carbon monoxide) detector which will beep if you have CO leaking from the combustion chamber into the RV. It is unlikely a crack is your problem.


It is also highly unlikely that your combustion air passage is clogged with either cat hair or any other obstruction. If that passage is clogged or even partly obstructed, the furnace has a "sail switch" that monitors airflow and prevents the burner from igniting if the air flow is obstructed. That is not your problem.


I am still wondering how hot is "too hot". That statement is too vague. It would be nice to have some real numbers that you could verify with the factory.

[opnspaces]

He's saying there is possibly a crack in the heat exchanger (the tube where the flame lives) allowing combustion air inside the coach. This would be a bad thing as along with the combustion air you will get carbon monoxide, a colorless odorless deadly gas.

[groundhogy]

“you are getting HOT flue gasses into the inside loop.”

Please explain further

[groundhogy]

Its the inside vents that i am talking about.

I pulled out the stove today to uncover the furnace. And I pulled off the cover outside of rhe RV.
I started thinking that maybe the intake vents might be somewhat blocked with cat hair or something.
This would slow the air flow, and increase temperature.
I saw no real obstructions.

The only other ways i can think of to get a hotter furnace is to either blow less air, or burn more propane..right?

Do you think its supposed to run this hot?
I mean i cant keep my hand on the furnace enclosure.

[Sam_Spade]

groundhogy wrote:
So I have been noticing that my vent air has been notceably hotter.
Like too hot.

Which "air vent" ?
The one producing heat for YOU or the one expelling exhaust to the outside ??

If it is the inside air, this could be REALLY important as it might indicate that you are getting HOT flue gasses into the inside loop.
Also a partially plugged flue can do that. Also an unusually high gas pressure can too.

Unless you stumble across something obvious, I suggest a professional repair visit is necessary.

Any chance that it's just hotter than you remember from last year ?

[time2roll]

Airflow is key. Do you have any ducts to the underbelly or other compartments that may have become partially blocked? Otherwise if the burner runs continuous through the heat cycle you should be fine.

[larry_cad]

You would have to define what you mean by "too hot". Measure a specific temperature, and either check the owner manual or contact dometic. If it truly is "too hot", they will want to know and will most likely correct the problem before they end up in a nasty lawsuit.