Very Frustrating Furnace Problem

[Mike L123]

Hello All!

I am stumped by this issue and am not enjoying getting up in the morning, or returning from work to a very, very cold RV interior. I thought at first a propane supply problem, then perhaps a furnace motherboard problem - just don't know and can't pin it down to a cause. Please give me your thoughts.

The furnace will randomly decide to shut itself down and will not start again until I manually turn it off at the thermostat and then back on. Then it will run for a few cycles through the day or evening and then, without rhyme or reason, will just decide to not fire up the next time that heat is called for.

The first few times this happened I thought it was problem with the safety supply portion of the bottle pig tails and I reset the propane bottle hoses and it seemed to work for a while. Then the problem reappeared and I have pretty much for certain verified that the propane supply is working properly.
We have the basic Dometic thermostat for a single zone and I have cleaned the motherboard for it and checked the connections and everything seems to be in good shape.

I am out of ideas on this one and we are not in a position to take the RV to a dealer. What are your thoughts? Any and all input greatly appreciated.

Cheers!

Mike and Carol

[Festus2]

Mike -
You might want to read what other members have posted about issues they have had with their Dometic thermostat and furnace operation. Not sure what kind of Dometic you have - older, manual/digital/ or programmable.

There are scads of posts about "furnace thermostat" already on the forum which can be found by doing a forum search of this topic.

The fault may lie with your thermostat. Many of posts talk about what others have done in the way of replacement. You might want to check these posts out.

[Bluewater]

I had a similar problem and found it was a weak battery and poor conection. Been working perfect since then. Maybe the thermosat is defective...that is quite common. Good luck

[Shelbs]

Originally Posted by Festus2

Mike -
You might want to read what other members have posted about issues they have had with their Dometic thermostat and furnace operation. Not sure what kind of Dometic you have - older, manual/digital/ or programmable.

There are scads of posts about "furnace thermostat" already on the forum which can be found by doing a forum search of this topic.

The fault may lie with your thermostat. Many of posts talk about what others have done in the way of replacement. You might want to check these posts out.

I am leaning toward an issue with your thermostat, if I were to take a guess. I do want to thank Festus2 for using the word "scads" in a meaningful sentence!!! Well played!!!

[Mike L123]

Originally Posted by Shelbs

I am leaning toward an issue with your thermostat, if I were to take a guess. I do want to thank Festus2 for using the word "scads" in a meaningful sentence!!! Well played!!!

So, then, Scads would be the polarization of Smidge?

Just a quick update and thanks for the reads and replies. It seems that our problem is twofold. The auto crossover was very anemic and unable to supply the flow of gas the furnace was demanding and I have replaced the regulator. Now when the furnace calls for ignition gas it fires right up. Part two of the issue is still unresolved. The furnace/thermostat has a mind of it's own with regard to whether or not it will actually call for ignition or not. Of course, it seems to fail at the coldest part of the night and has us waking up to a 40F temperature. Then, when I reset the furnace it fires right up and heats very well thanks to the new regulator. I am going to try and find the mother board for the furnace, inside the furnace itself perhaps? and jiggle some wires or something.

Wish me luck! Cheers!

Mike

[Terrydactile]

It seems to me that you ought to at least replace the lack luster Dometic thermostat. They are notorious to be unreliable.

[therink]

I would strongly recommend going with a household type battery operated digital thermostat. You can get a decent programmable or non programmable one for under $30. The install us very easy, only 4 wires.
Mine works flawlessly for ac and furnace.
Steve

[Mike L123]

I went shopping for a new thermostat yesterday and could not find a digital replacement at the local RV repair store. I then went to our famous Canadian Tire chain of one stop box stores and found numerous T-stats all rated for 24V or higher systems. Where did you find a 12V T-stat that worked in your RV?

I agree that the Dometic should be replaced - I just don't know where to find one in small town rural Alberta.

Thanks for your suggestions.

Mike

[therink]

I bought mine at Lowes. It is powered by 2 AAA batteries, not 12v.

[Festus2]

Mike -

Almost any "stick house" type digital and/or programmable thermostat will work providing -
1) it is battery operated
2) it is not for electric baseboard heaters

Try a cheap Honeywell that has at least these settings:
1) auto 2) Fan (hi/lo) 3) cool/heat 4) temperature

In most connections, only one fan setting is practical..... the Hi setting.

Heck, even rural Alberta places have thermostats - don't they? We have scads of them here in BC...lol

[hankaye]

Mike L123, Howdy.

I had to replace one in my TT, Found one at Wal-Mart for about $15.00.

hankaye