Atwood 8525 furnace overheating, gas pressure too high?

[frostylemonade]

Hello Friends,

The Atwood 8525-III in my Bigfoot truck camper has been giving me issues since I purchased it a little over a year ago. Last fall, I replaced the control board with a dinosaur board and all was well.

Fast forward to now, and I'm having trouble getting the furnace to light (again). I begin checking everything and had read some about checking the propane orifice to make sure that was clear. Yesterday I took the gas valve assembly out, got the orifice out. Looked good but I cleaned it up anyway. Unfortunately, I also saw shiny brass screw on the side of the valve that I couldn't resist taking out to make sure all that was clean... it was like a carburetor jet, but when I removed the inner (plastic?) screw and I spring came out I realized I may have made a big mistake.

My problem this time ended up being the igniter electrode gapped too far. Fixed that and she fires right up, but now appears to be running too hot. I notice intense heat from the vents, and after a few minutes of running, the limit switch trips. After some research I believe that I increased the propane pressure and am turbocharging the unit...

My question now is, does anybody know the correct setting of the "jet screw" inside the valve? I understand that measuring the gas pressure would be the best, but I can't find the spec for the regulated pressure even if I could get a way do measure it. Or did this become an expensive lesson in not touching screws that you don't know what they do?

I'm a fairly competent DIY'er, but sometimes don't know when to stop. I'm feeling like I might be in a little over my head. Worst case, I think I should be able to replace the valve and hopefully fix everything. I just hate to replace a valve over one screw being out of adjustment. Diagnosis at the RV center will cost more than a new valve.

Thank you for reading. Any thoughts or advice are greatly appreciated!

[BFL13]

If your part is like the one in this photo to the left, from an 8531- ll or lll, not sure which now, and your screw is in the middle of the white part behind there in the photo, then the white part circle says 25M16V Type 701, 12vDC .480A, Max press 1/2 PSI

The screw is in what looks like three washers stacked with all of the three showing equal depth, and the screw driver slot in the top of the screw is about 2/3 the way down in depth towards the top of the top "washer"

Sorry the photo does not show where I am trying to explain, but that's what I have.

[wolfe10]

Start by verifying that air return and all ducts are open and not crimped, etc.

If that doesn't do it, next step is to check propane pressure with a MANOMETER or just replace the propane regulator.

Can't help with what you need to do to properly reassemble or replace the parts you dismantled.

[Old-Biscuit]

Gas Valve is NOT adjustable

Gas pressure is controlled by Main LP Regulator
Orifice meters the flow of gas

How did you clean the orifice?
No poking anything thru it OR blowing high pressure air thru it
THAT will damaged the laser cut meter hole
Orifice should just be soaked in alcohol and air dried


Overheating can be result of damaged orifice
High LP SYSTEM Pressure
Blocked Combustion Exhaust
Blocked room air return
Ducts collapsed, blocked or too many registers closed
Room air wheel missing vans