Furnace Dometic issues

[Orian]

Furnace Not working at an elevation of 3668 feet
Have a issue with the following.
Dometic furnace model DFSAD12131
2020 escape
Never use the furnace summer months .
First experienced failure in the fall of November 2020
At an elevation of 3668 feet
It went through the initial startup procedure, fired up then quit .
Would ignite then quit constantly .
Cleaned sail switch no luck
Got home fired up at an elevation of 465 feet ran like a champ

This year 2021 didn’t need use the furnace till September, again at the same
Elevation of 3668 feet same issues as 2020 pulled the sail switch again ,
Did reset Got a flash code of one flash ,meaning ,air flow /limit fault
Got home again same elevation of 465 feet again ran like a champ
Anyone have similar problems ?

[davidmurphy02]

The altitude shouldn't have any effect on the sail switch so that is not likely the issue. Are your other propane appliances working OK at the higher altitude? Does the stove or cooktop burner have a good blue flame, fridge burner sounds good - no sputtering? I wonder if your regulator could be faulty or just set way off specs and even at a slightly higher altitude it's not enough pressure (or too much pressure) for the furnace to burn properly. Without a manometer / test gauge it would be difficult to tell, but that would certainly be the next thing to check. You can get a digital or analog manometer/gas pressure gauge pretty inexpensively online (<$50) and it will plug into the test port on the right side of the regulator (there is a bolt head in that port that is visible).

When it ignites but then quits at altitude, are you on shore power or running on batteries? If on batteries, do they have a full charge? These furnaces are sensitive to air flow and if your batteries were low the blower might not run fast enough and that could trip the sail switch and shut it down.

[Orian]

Thanks for the reply
Running off battery power fully charged have solar
Boon docking
Fridge ,hot water , all working fine
At home now running furnace. Not a hiccup
Started up right away battery power

[davidmurphy02]

Kind of figured that was the case but at least it rules more things out.

I went through a similar problem last spring, it would only ignite sporadically, sometimes after numerous attempts. After exhausting just about every other possibility and replacing the sail switch and circuit board to no avail, I replaced the gas valve and it immediately began firing up as soon as the igniter began clicking. That must mean that something was wrong with my original gas valve and although it let gas flow, it wasn't letting gas flow strong enough and many times that wasn't enough for ignition.

All of the other propane appliances have a gas/air mixture flowing out of the burner that is easily ignited. But in the furnace, the blower is operating so there is a strong air current blowing across the burner. I suspect that if the gas flow is low, it dissipates too quickly in that air flow to ignite, and since a new gas valve corrected my problem I can only assume something in the original one wasn't opening fully or was somehow obstructed. I've never heard of anyone else having this problem, though, and unfortunately it's not a quick job to replace the gas valve like it is replacing a sail switch or circuit board.

[ChuckBC]

David, I wonder if the gas regulator had oil in it to gum up operation. I remember in my Pleasure Way motorhome the 2 stage regulator was horizontal and it was plagued by dirty propane fouling up operation. I also noted that the Fairview regulator was a poorer quality than the Marshall Excelsior I replaced it with.
Here is a review i noted online. https://www.rvtalk.net/best-rv-propa...lator-reviews/

[Tam2004]

Originally Posted by davidmurphy02

Kind of figured that was the case but at least it rules more things out.

I went through a similar problem last spring, it would only ignite sporadically, sometimes after numerous attempts. After exhausting just about every other possibility and replacing the sail switch and circuit board to no avail, I replaced the gas valve and it immediately began firing up as soon as the igniter began clicking. That must mean that something was wrong with my original gas valve and although it let gas flow, it wasn't letting gas flow strong enough and many times that wasn't enough for ignition.

All of the other propane appliances have a gas/air mixture flowing out of the burner that is easily ignited. But in the furnace, the blower is operating so there is a strong air current it worked blowing across the burner. I suspect that if the gas flow is low, it dissipates too quickly in that air flow to ignite, and since a new gas valve corrected my problem I can only assume something in the original one wasn't opening fully or was somehow obstructed. I've never heard of anyone else having this problem, though, and unfortunately it's not a quick job to e season thatreplace the gas valve like it is replacing a sail switch or circuit board.

David and all —.

Thank you for this!! We have a history like yours with 2018 - I will write more in a couple of hours but your gas valve sounds like what we need . Back later

[davidmurphy02]

Let me know how it goes. I did a post with pics and details of the gas valve replacement in May but am traveling and can't find it, should turn up on a search of furnace problem threads.

[rubicon327]

Originally Posted by davidmurphy02

Let me know how it goes. I did a post with pics and details of the gas valve replacement in May but am traveling and can't find it, should turn up on a search of furnace problem threads.

This should be the link:
https://www.escapeforum.org/forums/f...ing-20805.html

[Tam2004]

David and all -

Our furnace is a DFSAD12131 in a 2018 Escape19 which we picked up September 2018.

For the first few days of the trip in 2018, the furnace worked well. It even worked at 7000 feet. But in less than a week we began to have issues that resulted in so many attempts at different stages in our journey that we were given a new furnace by Dometic at the end of our journey. I understand this is rare, but we were a particularly dramatic story at the time.

So this replacement furnace worked well through the 2019 and 2020 season with just some normal issues – like the battery can’t be low.

2021 season resulted in the furnace failing to fire. Our RV shop couldn’t find anything wrong, but Dometic had produced a new version of the sailswtich so even though the furnace fired just fine for them (the shop is at about 3500 feet BTW) we had them replace the sailswitch in July 2021.

Everything was fine until this trip from Oregon to Colorado to visit our 102 year old Aunt. Two days ago the furnace – boondocking with full battery power (we have solar panels) – started with the fan (high blower speed) – paused then did one good click – then paused for quite awhile before trying one or two more clicks. We tried a number of times over two days – sometimes there were fewer clicks -but never very many. The fan never shut down.

Sept 29,2021- today - we arrive at camp at 6670 feet and tested the furnace right away before plugging in to electricity. IT STARTED RIGHT UP. And continues to do so on each test. What the hey??

These terrible furnaces have resulted in all sorts of theories about what is wrong – most partially correct I am sure – but we heard about fluff, altitude, batteries, sail switches, control boards – but never about the GAS VALVE. We are thrilled!! We will look for your May posting to figure out where the gas valve is and what to do. THANK YOU. We mostly boondock and are motivated to learn more of this to do ourselves!

Tam and Jim

[rubicon327]

Originally Posted by Tam2004

We will look for your May posting to figure out where the gas valve is and what to do.

Link in post #8.

[Orian]

I’m in the process of booking my trailer into a shop
Unfortunately my mobile guy has relocated a few hundred miles away .
Unreal the wait time to get a rv into a shop
Looking at a months time !
Fired the furnace up the other day in the driveway
Elevation 465 feet
Purrs like kitten

And always has at that elevation

[cpaharley2008]

Originally Posted by Orian

I’m in the process of booking my trailer into a shop
Unfortunately my mobile guy has relocated a few hundred miles away .
Unreal the wait time to get a rv into a shop
Looking at a months time !
Fired the furnace up the other day in the driveway
Elevation 465 feet
Purrs like kitten

And always has at that elevation

So what is the issue, does everything work?

[Orian]

Not yet
Going to do a wc test