Perplexing Furnace Issue

[Captainscott32]

Hello All,

I have a 2010 Thor Freedom Elite 21C. Standard Atwood furnace.

Here is my issue:
I purchased the unit last fall in superb shape. As the unit was from the southwest, the furnace got very little if any use. The propane in the tank could be from some time ago as well as the unit itself was very lightly used.

local temperatures have been between 30 and 45 while I have been doing some projects.

I Start the furnace for the day and it fires up immediately. It will run without a hiccup for about an hour. Then the unit will cycle through the start sequence (multiple clicking) 3 times, fail to light and shut down as prescribed by the safety manual. It will not light for the rest of the day.

The next day, it will light immediately, run fine for about an hour and then fail. I have repeated this scenario at least 8-10 times this winter.

I apologize for the lengthy post, but I am quite perplexed. Do any of you more experienced folks have any thoughts?

Much appreciation!
Scott Ross

[mcr1010]

Could be an over temp signal, bad circuit board, loose connection. try re-seating your connections to the circuit board and check other connections.
Good luck.

[Laco]

It could also be a legitimate over temp, check to make sure ducting, including the return, is free flowing, no sharp corners, or kinks.

[Captainscott32]

I will look at the overtrmp possibility and report back. Thanks for the idea.

Scott

[Captainscott32]

The confusion continues. I removed the exterior cover today to look for error codes. Wiggled some connectors and ensured all was tight. Fired up the furnace and could not duplicate the problem. Ran without a hitch for over an hour. Stopped and started without fail.

The only thing different today. In reading another thread that dealt with flow problems, it mentioned bleed the line at the stove, then open the gas valve very slowly. Opening rapidly could make the regulator stick causing all sorts or gremlin problems. Did I just get "punked" by that post or is it possible that my regulator has been the issue all along? Thoughts?

Thanks in advance Scott

[16ACE27]

I think a regulator problem would show up quicker than an hour. Do you have vents on your outside furnace door? Which way would they allow moisture to flow? To the outside of the door or the inside?

[Captainscott32]

Thanks for the response. I believe the vents are correct to shed water as opposed to introduce water. They look ok from that standpoint, but I will need to look at them with more interest next time it rains.

I'm going to fill my propane tank tomorrow,, not for any other reason than I am below 1/3 of a tank. I don't expect it to make any change but who knows. Thanks again for the responses.

Scott

[airforceret]

It sounds to me that you may have a small amount of air trapped in your propane tank. It's possible it wasn't purged properly at some point and air was trapped in the tank.

[Steve70605]

I had an identical issue to yours this past winter. Even went as far as to remove outside cover and leave off - no issue. When cover reinstalled unit would run for about 15 - 30 minutes and shut off.

Found issue was thermal switch(it is usually a black round "button" mounted on heat box with 2 wires) . As they age they tend to shut down the units at a lower box temperature. Since our units are known for low airflow through the air box since all outlets are generally not used, it can become an issue. It is an easy check using a jumper.

Hope this helps.

[Captainscott32]

Update. So, I filled the propane tank. It was just under 1/3 of a tank. Since, I have not been able to duplicate the issue. I'm not ready to call it solved, but I am feeling a bit more confident, just not sure why. I'm hoping it was just air in the system. Thanks for the responses. I will keep an eye on the thermal switch, I have heard of that issue from others as well. Time will tell!

Thanks again, Scott

[Bob Denman]

Since it hadn't seen much use: perhaps it was just throwing a bit of a tantrum?
Glad to hear that it's working much better!