I maintain Air Supply Houses at a local car plant and have little/no residential experience. My uncle installed a funace at his hunting cabin and it doesn't run right. Of course I was called to save the day, and I failed. Danged thing has me baffled.
It is an LP Comfort Maker GUA. Way to big for his 500 square foot shack, 64k btu's. It was going out on high temp. I had him put some more openings in the supply. This helped out a some as it does not drop out all the time. I turned the "fan on" limit way down, but that forces the "fan off" limit so low that it will never shut off. The over temp is set up all the way. I also tried regulating the gas way down, figuring the fan would have enough time to keep the exchanger cool, but that did not work.
I conceeded defeat and he did have a residential guy out there to look at it and he could not figure it out either. I figured the fan limit was bad and had the guy replaced it. The original fan limit and the replacement have a max of 200 degrees for the high temp shut off. Is this the correct one for the unit?
Does anyone have a manual or diagrams for these units?
One last note, at work, I can access the roof tops from a PC. I can see all the sensors, troubles, damper positions, etc without having to leave the desk. LOL. No wonder I am lost!
Thanks for the help!
Was the gas valve factory set up for LP?
How about gas pressure what was it?
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My uncle got it from the resort he works at. It was already set up for LP and working great. The cabin it came from was just a little larger than the hunting shack he put it in. The cabin was being knocked down to make way for a larger house, that is why it was available.
The tech that came and looked at it while I was there was amazed at how clean it was. The only thing that puzzeled him was a little soot in the burner compartment.
Another symptom I just remember is that when it is cold, it will start right up and heat everytime. Once the exchanger is warm, that is when it starts to act up.
what is the model number?
GUA080A016AIL for the model number.
0000246444-P41-0045 SERIAL NUMBER
I did not check gas pressure. Neither did the tech. He said the flame "looked" nice and blue.
that unit is an 80,000 btuh input with a 4 ton drive. That being in a 500 sf cabin is the problem. Too much heat and blower. That furnace was a bulletproof 80% unit back in it's time.
My uncle got the unit running. I was wrong, size of the furnace was not making it trip.
My uncle talked with some residential HVAC guys he knows. The service guy that came out to replace the fan limit didn't have the same unit on his truck.The one he had was a little shorter, he said they work the same.
Uncle bought the correct size limit(as suggested by his buddies) from the hardware store, installed it and it cycled perfectly. He said the probe was not sticking past the end of the tube.
The original limit did not move smooth. It would jump as the temperature stepped up and down. The one the service guy stuck in did the same. My uncle said the one that he put in moved smooth as the temperature rose and fell.
Hopefully this will help anyone with similar problems. Have you guys run into this before?