Furnace operation at 7000' on 2015 Classic

[TonyGuyer]

We just purchased a new 2015 Classic a few weeks ago and did the first "shakedown" trip with it this past weekend. We camped up in the mountains at a 7000 foot elevation.

The primary problem we encountered with the new unit was that the Gas Furnace would not stay ignited at this elevation even though it worked fine down in the desert at 2000 feet. It would ignite for 3-4 seconds then go out followed by another similar cycle after Approx. 30 seconds and repeat over and over again. The thermostat was set far above the internal temperature at the time. All of other gas appliances worked fine including the Hot Water Heater. I'm guessing it's probably a fuel/air mixture problem. Has anyone encountered this, and if so, where can you adjust this or how did you solve the problem?

I also spoke with the Atwood (the furnace manufacturer and they also indicated a regulator adjustment (external to the furnace) would be needed for elevations over 4500 feet.

Any help would be greatly appreciated.

[idroba]

At one time about 10 to 15 years ago furnace and water heater makers said their equipment would not work above xxxx feet, usually in the 7000' range. That didn't go down well with western campers, and it seemed to quietly disappear from their manuals. I have not heard much about it lately, so I thought they had solved the issue. I know that I have not had it up to about 8000' in my rigs.

I will be interested to see what others say about it.

[bbdo]

We have a 2014 30' BH and the furnace works perfectly at our house, which is right at 8K feet in Colorado. Purchased from a Detroit dealer, and I can assure you that they didn't do anything to prepare it for our altitude.

[dznf0g]

I'll bet your regulator is set low. Mine was.

[jt1911man]

Originally Posted by dznf0g

I'll bet your regulator is set low. Mine was.

So how do you fix it?

[dznf0g]

You have to get a low pressure gauge. Install it at the stove with the proper fittings. Turn on all the rest of the gas appliances and adjust the regulator to 11 inches. The adjustment screw is under a black cap on the regulator.

[TonyGuyer]

Thanks for the help.

Since my original post, I had found an information tag attached to the regulator at the propane tanks that contained a short statement on how to adjust the pressure as you had described which led me to the conclusion that this may very well fix the problem.

Once you have adjusted it to 11 inches, will it work at lower elevations (say down to a 1000') or is this something you kind of have to tweek depending on the elevation you are at?

[dznf0g]

Should be fine at both. I adjusted mine when I got home from the Rockies, but haven't been back yet.

[KJRitchie]

I was in North Rim Grand Canyon today and ran the furnace fine at 8200ft. I wonder if only the new furnaces have this limitation. I doubt the previous owner of my AS left Austin, TX during the years they owned it.

Kelvin

[cwf]

Replace regulator. You can have it tested for proper "pressure"...before but easier to change... Compare the flame output in stove to "before/after".... Our was "low pressure" until replaced....

[dznf0g]

But I'm not confident they are properly calibrated off the shelf

[ghaynes755]

Tony I am having the same issue and not just at higher elevations. Already deep into trouble shooting. Pretty simple system and getting into a local service center, well there are 8-10 week waits. Here's what I have found so far.

1. This is new furnace from Atwood and no one has manuals or parts.
2. Attaching the manual to this post.
3. Found that the electrode (starts and checks for flame) was misadjusted by 5mm. Carefully adjusted that.
4. Replaced the main circuit board.
5. Checked pressure. Was too high by 3 inches. Replaced pressure regulator with a Marshall.

This did not fix the issue.

Talked with Atwood, good support though you may be on hold for awhile. They are sending a new electrode. The electrode, besides being the spark for ignition, senses heat. If it has failed or is failing then it says to the board no heat after start and shuts down the gas solenoid. Then goes into a 15 second restart cycle.

If that fixes it great. If not really the only other thing easily replace is the the limit switch when senses and over temp. Again if it is failing that too could shut off the solenoids.

Never had a problem at higher elevations with my 2014 FC25. And coming back from Colonial to Colorado don't remember an issue.

And as I mentioned I've called a Camping World and another local Atwood dealer and they don't even have a manual nor parts/numbers or prices at this point.

Will post again if I get it fixed and reliable. Last resort will be an early fall trip back to Jackson Center.

Atwood Furnace 2015.pdf

[dznf0g]

Originally Posted by ghaynes755

Tony I am having the same issue and not just at higher elevations. Already deep into trouble shooting. Pretty simple system and getting into a local service center, well there are 8-10 week waits. Here's what I have found so far.

1. This is new furnace from Atwood and no one has manuals or parts.
2. Attaching the manual to this post.
3. Found that the electrode (starts and checks for flame) was misadjusted by 5mm. Carefully adjusted that.
4. Replaced the main circuit board.
5. Checked pressure. Was too high by 3 inches. Replaced pressure regulator with a Marshall.

This did not fix the issue.

Talked with Atwood, good support though you may be on hold for awhile. They are sending a new electrode. The electrode, besides being the spark for ignition, senses heat. If it has failed or is failing then it says to the board no heat after start and shuts down the gas solenoid. Then goes into a 15 second restart cycle.

If that fixes it great. If not really the only other thing easily replace is the the limit switch when senses and over temp. Again if it is failing that too could shut off the solenoids.

Never had a problem at higher elevations with my 2014 FC25. And coming back from Colonial to Colorado don't remember an issue.

And as I mentioned I've called a Camping World and another local Atwood dealer and they don't even have a manual nor parts/numbers or prices at this point.

Will post again if I get it fixed and reliable. Last resort will be an early fall trip back to Jackson Center.

Attachment 240491

3" too high with all gas appliances on or off? 14" is just about right with all the appliances off. I adjusted to 11" with everything (but the stove, since that's where the gauge is installed) on. After shutting everything off I have 14" static pressure.

[dznf0g]

Here's a step by step procedure:

How to Measure Propane Regulator Pressure | eHow

[Plan-B]

My 1997 Excella never had an issue running the furnace above 6,000 feet and up to 8,000 (never ran it higher than this). But I did find an interesting quirk with starting that drove me nuts till I realized why sometimes it wouldn't fully start (similar to your symptoms). Disclaimer, I really don't know if this is a design built in or just a fluke of my 97 Excella, and it did this every year for 16 years). When testing heater out before taking trips, if my inside AS temperature was pretty warm the heater would go through its staring fits and never stay lit. If I waited till the evening, thus cool outside and inside, it would fire up and stay lit. I don't know, but I am not making this one up. I take delivery next week of my 2016 25 FC, I hope it works above 6,000 feet because in two weeks that will be my lowest altitude for 4 weeks. Good luck!

[Reg Mary]

So glad to see this post. We had the same problem while camping in the Big Horns this May. The furnace worked fine when we got back to lower elevations.
Thanks, Reg

[ghaynes755]

Rich it was 3 inches to high with the appliances running.

Got the new electrode from Atwood and will install in the next day or so.

Can anyone recommend a good not overly expensive manometer so that I can more testing? Tech did the the original testing and probably wouldn't be a bad piece of gear to have.

[Ahab]

????? Ours works fine at 10,000'.

[TonyGuyer]

I wanted to provide a quick update on my original problem of the furnace not operating above 7000 feet elevation. I was advised by several people (both on the forum and at multiple dealer service departments) that I would need to make an adjustment to the set screw on the trailer regulator to lean out the propane for high elevations. Prior to trying this, the Service Department calibrated the setting (measured and adjusted for the appropriate pressure) at the current location (1000' elevation). On our second trip in the new trailer, we tried making adjustments with no success. The furnace continued to ignite for a couple of seconds and then go out. The regulator adjustment had no effect at small incremental changes throughout the full range of the adjustment (both fully leaned out as well as fully "richened" out. In fact there was no perceptible change in stove flames when making these adjustments as well (or in operation of a generator connected to the external LP connection).

We then returned the trailer to the service department after the second trip. They examined the LP Lines and the furnace itself and found some foreign debris in the lines and in the furnace. In addition, they replaced the regulator and calibrated it again.

On our 3rd trip up to 7500' elevation (just completed today) the furnace worked great with no further adjustments needed - SUCCESS!

Unfortunately by making both changes we cannot specifically point to which item (or if it was the combination of the two) which corrected the problem.