Heating problem 300C

Urban350

Well-known member
I have a question about my furnace because I do not think this is right. My furnance comes on fan runs starts heating the coach then it hits the high limit switch, 160 degrees, burner shuts of fan keeps running. Burner cools to 120 and lights again and keeps going in this circle till the coach heats up. With the furnace running this way it takes about 5 hours for the trailer temp to raise 20F or 10C. I have air out of all the ducts and can't see any blockage without ripping the trailer apart and it is still winter here (snowing) and no dealer can look at till the end of May. My question is this the way the furnace should work???
 

Rickhansen

Well-known member
No.

I would guess one of 3 things.

1. Restricted or lack of "house" airflow, as opposed to combustion airflow.
2. A supply duct feeding hot air back into the return air intake, could be caused by an open duct or disconnected supply duct near the furnace.
3. Too much gas supply, regulator pressure set too high.

Sounds like you've verified the temperatures, ruling out a defective high temperature limit-switch. Trace your supply ducts to make they are all connected and unobstructed. Remember that that flexible ducts are easily crushed or crimped, they need to be straight and not sagging. The only other thought is the "under-belly of most rigs are heated by a 2" duct off the furnace for freeze protection. It should be routed deep into the belly near water and drain lines, yours might be laying up near the furnace. you might want to check the plenum of the furnace for any openings not connected to a duct.

Hope this helps, keeps us posted.
 

Urban350

Well-known member
Thanks Rick I did check at the furnace plenum for missing ducts or obstruction, I guess and I sort of thought, I am going to have to take panels off. I would assume, hate that word, the one to the underbelly is ok because no frozen water lines. Thanks Steve I did not think it should work that way but before I rip things out or take it to the dealer I want to be sure.
 

wdk450

Well-known member
Urban:
Maybe its time to talk to the service department at the factory. Also, if your Heartland dealers can't get to it immediately, you could always go to a 3rd party RV servicer in your area (with service department pre-approval). They might have some names of servicers they have worked with in your area, or maybe you could ask Suburban Propane Appliances.
Say, I seem to remember something about a "sail switch" that senses furnace airflow, and will shut it down intermittently if the switch isn't closed.
I found the Suburban website, and it looks like there are 3 authorized servicers within about 30 miles of your hometown. Here is a link to that page: http://www.rvcomfort.com/suburban/service/repairs.php
 

Urban350

Well-known member
Left a phone mesg. with Dustin in service today no reply yet, but not sure if he will be any help I talked to him last week and he did not have much to say. I am looking into other dealers but no luck so far before June.

On edit thanks Bill
 

Urban350

Well-known member
Dustin never got back to me but the dealer did and has fixed my problem by relocating the heat passage for the garage. I have not picked it up yet so I hope he is right.
 

Rickhansen

Well-known member
Hope you've gotten it fixed. Keep us posted.

BTW, What is a "heat passage?" - I can only envision a flexible duct.
 

Urban350

Well-known member
Another update furnace still hitting high limit switch dealer wants to try another flexible duct out of furnace to move more air out of the furnace. I guess I will be loosing more airflow to the bedroom.
 

Urban350

Well-known member
Ok 3" flexible duct added to furnace into living area and a third high limit switch and it seems to be fixed.
 
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