'77 GMC Motorhome Furnace Repair
ฝัง
- เผยแพร่เมื่อ 12 ก.พ. 2022
- The furnace hasn't worked since we got the coach. Our coach has a Duo-Therm furnace, other years and models may have other furnaces. The fan would come on but there was no spark and no ignition. I found some bug nests in the air intake and exhaust but it didn't seem to be restricting the flow too much. I went through some troubleshooting steps to find out why we didn't have spark. I have included some links that I found helpful.
Classic video covering operation and troubleshooting. • MH-25 GMC Motorhome D... - ยานยนต์และพาหนะ
Well done! My furnace (also a '77) was a Sol-aire brand and it too had problems. The coil had failed so we got no sparking at the igniter, so I replaced it. It did work - after a fashion (not entirely predictable 😄) which is almost as bad as not working at all. While researching the furnace I also discovered the old Sol-aires had problems with CO leaks, and were considered unsafe. That solidified my decision to replace the furnace so I fitted a new Atwood unit. Because of the rather radical differences in the design and dimensions of the new unit, installation was not without it's own challenges - but I too now have a reliable source of heat. 😉
Every project is an adventure :-) I think the Duo-Therm models are fairly reliable, we'll see over time. I did look at the combustion chamber and heat exchanger to make sure it wasn't too rusty or showing signs of leaks. It's always good to have a CO sensor too, just in case.
It took me a few weeks to get my Duotherm furnace operational.. When I first got my GMC motorhome it worked for a few days, then shut down. I found a paper wasp nest had dropped inside the exhaust and was blocking it, which of course shut down airflow. I am very happy it did- because I found the exhaust pipe stub rusted through on the inside, meaning I was venting exhaust into the coach! In any case, I fully disassembled the unit, burners, firebox, everything, and made new gaskets with silicone sheet (1/16"& 1/8"IIRC from McMaster-Carr), new exhaust and intake stubs from a piece of auto parts store exhaust pipe (Note- you will need to expand the pipes on the main furnace, as newer pipe is a hair larger, as well as the very end of th epipe to accomodate the end piece) and reassembled everything after cleaning mudwasp nest from the intake fan housing, and two of the three burner sections! After reassembly, it has been working well but has developed a popping recently: It still runs well, but pops time to time, sounding like a restart. I did have a problem on a 40 degree night when I lost it all together, and after following the troubleshooting guide in the TM, got frustrated and just repeatedly kept cycling it, and it started working again- I think there was air in the line, and I had to get it through... All in all, a nice unit. I am glad to hear dinosaur has replacement boards: Could you add a link, so I can get one to have on hand? Thanks! I enjoy all your videos, and I am currently living in my coach, in preparation for a life change trip to a few states to decide where to relocate to form the northeast.
Thanks for the comment! I ended up getting my furnace working with a good cleaning...although when I tried to use it last fall, it didn't work :( Looks like I'll have another project this year. Here is a link to the Dinosaur boards www.dinosaurelectronics.com/Ignitor_boards.htm I think our furnaces will use either the UIB S or the UIB S Post.
Good to see you got it working with just some cleaning. But wow things have moved on in terms of HVAC.
I don't expect to be doing lots of cold weather camping but I like to have things work they way they are supposed to so we'll see how long this furnace lasts...45 years and counting!
Great job! Free fixes are the best! I've wondered if a newer, quieter, more energy-efficient fan could be swapped into the old furnace to make it even better?
I like to keep things original when I can. I have heard that newer furnaces require a lot of custom install work to fit the curved outer wall. We don't camp in cold weather very often but I like the option if we needed.
Not a huge fan of our Motorhome's furnace. So noisy. That said, it is a godsend to turn it on before climbing out of bed on a frosty morning. Happy for you!
It's really noisy, I'm going to try and quiet down the blower that pushes air to the back of the coach. I'm looking forward to being able to warm the place up before I have to get out of bed :)
@@MrGMCMotorhome I have the same furnace in my 78 Palm Beach and its pretty quiet. However the auxiliary fan behind the stove that pushes warm air to the bathroom is terribly loud. You can turn that fan off, there should be some type of toggle switch in the cabinet with the fuse boxes and battery charger .
@@yoshstudio Thanks for the comment! I don't have a switch for my fan but I think I may add one. The fan is loud and I don't think I always need the extra air movement or battery drain.