Community Forums

djtentman · 01-23-2018, 06:45 PM

I have a 2002 Bounder 39R with two Atwood 8520 IV DCLP furnaces. The rear furnace has some problems. It does run, but it doesn't always light. Also, after it runs for a while, the burner stops (even though the thermostat calls for heat) and the fan keeps running. Eventually, the burner will start again. The air coming from the vents does not seem to be as warm as it should be. Also, when it burns, there is a propane odor outside the coach. It seems to me that it is not burning as cleanly as it should be. I've checked to be sure that there are no restrictions in the exhaust. I've also checked to be sure that nothing is restricting the internal heat pipes. I suspect that the orifice needs to be cleaned or replaced, but I have been unable to find any instructions for doing this. I'm fairly handy. So, I think I should be able to do this myself.

Jthigh · 01-24-2018, 08:47 AM

We have a 2002 coach with an Atwood 8535-IV. It had a hard time starting in really cold weather with a lot of condensation and when raining. It would ignite but burner would go out after about 30 seconds or so. It would restart 2 more times and still go back out, then you have to reset thermostat to try 3 more times. Built in safety feature. Replaced igniter / temp sensor. Igniter and sensor combined into 1 part. Solved problem and easy to change. Only 13 bucks on Amazon. Temp sensor was shutting down furnace. Also, our units cycle the burner on and off even when calling for heat. Furnace has temp regulator on internal heat exchanger of furnace to keep it from overheating. Cuts burner back in once heat exchanger temp drops to safe level. Fan runs the intire time burner cycles on and off to get heat out of heat exchanger.

If you have 2 furnaces like we do you can swap the igniter control board and igniter/temp sensor to find out which one is the problem.

djtentman · 02-05-2018, 02:47 PM

Thanks for your advice. I've switched the working control board from the front furnace to the rear. I've also replaced the igniter/sensor. It still cycles on and off frequently and the air coming from the vents is warm, but not as warm as the air coming from the front vents. Maybe it's cycling off because it's getting warm enough, but it doesn't seem to heat the rear of the RV as well as I'd expect.

ALLOY · 02-05-2018, 03:40 PM

Quote:

Originally Posted by djtentman

Thanks for your advice. I've switched the working control board from the front furnace to the rear. I've also replaced the igniter/sensor. It still cycles on and off frequently and the air coming from the vents is warm, but not as warm as the air coming from the front vents. Maybe it's cycling off because it's getting warm enough, but it doesn't seem to heat the rear of the RV as well as I'd expect.

If the overtemp switch is shutting the burner off and the fan keeps running there is not enough air circulation to cool the heat exchanger. This means heat that should go into the RV is going out the exhaust.

Make sure the fan is clean and check the ducting to make sure there are no kinks or collapsed (hose) ducts and the registers are clear. You can even add another duct.

djtentman · 03-13-2018, 03:09 PM

As far as I can tell there is no blockage anywhere, but the rear of the RV doesn't warm up very well.

nosticks · 03-14-2018, 06:12 AM

http://bryantrv.com/docs2/docs/hflamefurn04.pdf

MSHappyCampers · 03-15-2018, 12:32 PM

Hi !

Welcome to IRV2! We're sure glad you joined the gang!

I would clean the orifice/burner and see what happens. Soak the orifice/burner in 91% alcohol for several hours and use compressed air to blow it out. DO NOT use more than 35-40 lbs pressure or you will be buying a new orifice!

Keep her between the ditches!

Good luck, happy trails, and God bless!

djtentman · 11-19-2018, 05:05 PM

It's getting worse. The burner barely runs any of the time. It just blows cold air now.

erikdjensen · 11-20-2018, 08:49 PM

I hope some one can help me figure out what is going on. We have had on and off problems with our furnace. We live in the Pacific Northwest and I understand about the rain and water issues on the control board. However, the other night while in the RV we went to bed and all seemed well with the furnace. We got up to 32 degree temperature and it was cold in the RV. The vents were putting out luke warm air. I turned the furnace off for a while, turned it back on and no improvement. Later I went out to take a look at the exhaust - it just didn't sound right. There was smoke coming out of the exhaust and it was covered with soot. The smoke had a strong pungent smell. Later I ran home and got some tools that I didn't have with me (we were only about 20 miles from home). Took the front cover off, pulled the exhaust, replaced the exhaust without the front cover and restarted the furnace. Right away a strong pungent smell, soot, and smoke. The squirrel cage in the front seemed to be operating okay. I think the problem is behind the firewall looking block. Any ideas what would be causing this?

djtentman · 11-24-2018, 09:25 AM

I've replaced the burner assembly and I've done a bit more troubleshooting. I don't believe the flame goes out from the overheating. I believe it's not burning properly. When it is burning, it doesn't sound like a smooth, clean flame. It goes out and I can smell unburned propane. Then it tries to relight and sometimes takes a while. Any ideas what I could do to get a better burn?

Dale70 · 11-25-2018, 04:04 PM

I would be looking at the gas valve orifice as suggested by MSHappyCampers.

It seems to not be getting good combustion by some of the things you describe -- soot /smoke/cutting on and off --etc.

Since you said you replaced the burner, I would check that orifice.

thx Dale

Skiddy · 11-25-2018, 04:18 PM

had a similar issue last week. after it would start blowing cold air. I would light the stove and the flame would slowly die out. wait a little while and the stove would light with a strong flame. then turn on the furnace and would work just fine for a while. then in the middle of the night it done it again. what I figured is the regulator on the tank getting weak. replaced the regulator and worked fine for the rest of the week.

djtentman · 11-26-2018, 02:51 PM

Quote:

Originally Posted by Dale70

I would be looking at the gas valve orifice as suggested by MSHappyCampers.

It seems to not be getting good combustion by some of the things you describe -- soot /smoke/cutting on and off --etc.

Since you said you replaced the burner, I would check that orifice.

thx Dale

I have one on order. I'll see how that works.

djtentman · 10-19-2019, 01:38 PM

I replaced the orifice and now it burns nicely, but it still shuts off frequently. I took it to an RV repair shop and they replaced the igniter/temp sensor and wire (which I had replaced before). It still has the same issue. Any more ideas?