Atwood 8531-IV-DCPL Furnace

Farmboy666 wrote:

newman fulltimer wrote:
bad propane regulator

Then why does everything else work fine. Read the posts.

because the heater requires more presure

newman fulltimer wrote:

Farmboy666 wrote:

newman fulltimer wrote:
bad propane regulator

Then why does everything else work fine. Read the posts.

because the heater requires more presure

Thanks for the info. Why do both manuals, water heater and furnace say 11 ? W.C. (27mbar)? Are you saying the water heater would run if it was lower but the furnace would not? Also, to my original reply, how do you have this checked? I have never used a U-Tube Manometer.

OK so you get the fan come on, then the click or two and Boom!- it lights-THEN it keeps clicking like it does not know it lit, and then it shuts off the gas and then as usual the fan shuts down a bit later?

So you have gas. That takes away some possibles. So the other ideas are what to work with.

I would bet on a rusted out burner on that age furnace.

BFL13 wrote:
OK so you get the fan come on, then the click or two and Boom!- it lights-THEN it keeps clicking like it does not know it lit, and then it shuts off the gas and then as usual the fan shuts down a bit later?

So you have gas. That takes away some possibles. So the other ideas are what to work with.

Yes exactly. It does that the three or four times like it should and lights each time but if you are outside you can hear it still clicking (sparking) like it does not know it is lit.

Chris Bryant wrote:
I would bet on a rusted out burner on that age furnace.

I thought of that yesterday after looking at a few videos of people removing the gas valve/burner assembly. They all seemed pretty tusted. That might explain why it worked fine at home (RV was sitting for several months) but after hitting the road and a few pretty bumpy roads it now stopped working. If it was rusted bad maybe a few pieces broke off.

I ordered a board and electrode yesterday that will be here today. Once I get it apart if the burner looks bad I guess I will get that too. I believe the burner is part number 36043 for this unit? If ayone can verify that would be great.

As Newman says, it could be related to your pressure regulator. Icing can occur that will cause the regulator to deliver lower pressure. Your water heater will work because it has a pilot that "bathes" the thermocouple in flame, so it can operate at lower pressure. But, if you don't have enough pressure to get an initial flame big and hot enough to heat the thermocouple/flame detector in your furnace burner, the furnace won't light or stay lit. You might try heating the gas regulator and gas bottle valves (warm towels, hair dryer) and see if it makes a difference. Doesn't cost anything to try. Another reason I suggest this... I just replaced the pilot assembly on a gas fireplace. I had the glass front panel off of the fireplace, and attempted to test the operation. It appeared the pilot flame was covering the thermocouple and thermopile just fine... but the darn thing would shut off after a few minutess of operation. The fix was to put the glass panel back on, which slowed the draft through the fireplace, and allowed the pilot flame to keep the two thermal elements heated properly. I've concluded these thermal flame detectors are a bit finicky or at least sensitive (they only generate millivolts), and you need to check anything that can inhibit their operation. I doubt your bottle pressure is low, but there is a chance the line pressure is low in cold weather, and it doesn't cost anything to try and remedy gas bottle valve or regulator issues. I'd sure try this before I started ordering parts (well, practice what I preach.... I always order parts and now have plenty of spares!) This might explain why you get a flame, but it isn't supplied well enough to get hot enough to keep the furnace from trying to relight.

Steve

Steve 83406 wrote:
As Newman says, it could be related to your pressure regulator. Icing can occur that will cause the regulator to deliver lower pressure. Your water heater will work because it has a pilot that "bathes" the thermocouple in flame, so it can operate at lower pressure. But, if you don't have enough pressure to get an initial flame big and hot enough to heat the thermocouple/flame detector in your furnace burner, the furnace won't light or stay lit. You might try heating the gas regulator and gas bottle valves (warm towels, hair dryer) and see if it makes a difference. Doesn't cost anything to try. Another reason I suggest this... I just replaced the pilot assembly on a gas fireplace. I had the glass front panel off of the fireplace, and attempted to test the operation. It appeared the pilot flame was covering the thermocouple and thermopile just fine... but the darn thing would shut off after a few minutess of operation. The fix was to put the glass panel back on, which slowed the draft through the fireplace, and allowed the pilot flame to keep the two thermal elements heated properly. I've concluded these thermal flame detectors are a bit finicky or at least sensitive (they only generate millivolts), and you need to check anything that can inhibit their operation. I doubt your bottle pressure is low, but there is a chance the line pressure is low in cold weather, and it doesn't cost anything to try and remedy gas bottle valve or regulator issues. I'd sure try this before I started ordering parts (well, practice what I preach.... I always order parts and now have plenty of spares!) This might explain why you get a flame, but it isn't supplied well enough to get hot enough to keep the furnace from trying to relight.

Steve

Thanks for the info. Our water heated does not have a pilot light. It has the same type electronic ignition as the furnace. Where if it does not detect the flame it shuts off. Had an issue with it once and had to reposition the ignitor/thermocouple to get it to stay lit. One time, I just warmed it up slightly with a long BBQ lighter and then started it and it ran fine as the water heater ignitor is right there in the flame tube so easy to access.

As for the parts, I agree but they are fairly cheap and since this is a 1999 furnace I figured if I pull it all apart I might as well change a few parts while in there. The board, ignitor and burner were around $100 total so not too bad.

jsuvman wrote:
... The board, ignitor and burner were around $100 total so not too bad.

You got some real good prices there. I had a board on a HWH go out on me while on the road. Local RV shop had one all dusty and sun-bleached that he would "let go" for $200. I install, no warranty.

John&Joey wrote:

jsuvman wrote:
... The board, ignitor and burner were around $100 total so not too bad.

You got some real good prices there. I had a board on a HWH go out on me while on the road. Local RV shop had one all dusty and sun-bleached that he would "let go" for $200. I install, no warranty.

Thats what I love about Amazon. Decent if not good prices. Sometimes you pay a few dollars more but worth it if you are a Prime member due to the free two day shipping on most products. Got the board already yesterday. Rest coming today.