Tempermental Furnace (Saga Continues)

[Rossue]

Many keep spares for important systems. I keep a spare sail switch, water pump(last spare was used for my van build) previous propane regulator, and original thermostat.

Best of luck getting the heater reliably working(for the first time)!

The current level of after sale service reminds me of Clark Howard and his No Customer Service label for companies that engage in that practice.

[chesaka]

I got pre-approval from Dometic to take the trailer to an RV repair place on Oct. 5. Hopefully this will be an easy and permanent fix. Everything else about the trailer has been very nice and works well. But this furnace issue has been a disappointment. I need heat at night here in Alaska and not comfortable with running the Buddy Heater all night long with window open. By mid-October I will be winterizing the trailer, if not earlier. So, I lost a lot of time when I could have been enjoying my new trailer. It is what it is.

[AZ Escaper]

I've been dealing with Atwood furnace problems (AFSAD 12121) since we brought our 17B down from Chilliwack to AZ in 2018. It worked perfectly on that journey, but when we camped at 8,000 ft the next summer, the furnace kept cycling, even though it hadn't reached the set temperature.

I thought it might be running too rich, so I went to a smaller propane orifice – no help. Flame sensor? Limit switch? Circuit board? (The sail switch tested good.)

Well this little furnace goes in with the circuit board and LED fault indicator installed against the outside wall of the trailer, where you can't see it! Big help there.

This year I finally got fed up and decided to do a “bench test,” where I could monitor the LED. I cut the wires; pulled the unit out; connected to a 20 lb propane bottle and 12V battery, and joined the two thermostat wires to create the “on” signal. When I moved the reset switch to on, the LED illuminated momentarily, and the furnace ran perfectly – no faults!

So for some reason, I then remembered a post here about restricted airflow into the cabin causing cycling, so I put my hand over the furnace outlet, and sure enough, the propane valve closed, and the unit cycled.

Another light went off in my head – I had noticed a faint but annoying sound of something “fluttering”or “bouncing” in the furnace – THE SAIL SWITCH. It wasn't defective, but perhaps some back pressure was causing it to move enough to interrupt the circuit.

It wasn't easy because there is only 3” from the furnace to the air register (which also happens to be about an inch above the furnace outlet), but I removed the flex duct and “hard piped” it. Now at 6,000 ft, it's running perfectly, and I do not hear any fluttering from the sail switch.

I did make one other change. Somewhere I read the trailer propane pressure should be 11” of water, but the regulator from my test bottle was putting out 12. Since Atwood recommends 10-14” for the furnace, I went ahead and upped the trailer regulator to 12” and everything is running fine at 6,000 ft.

What a fussy system. If not for you people posting your insights, I would have never figured out why a perfect furnace wasn't working. Thank you so much, and hopefully this helps some other Escape owners.

AZ Escaper

[Rossue]

One of the more truly enlightening posts on the subject. Thanks.

[BrooksWade]

Originally Posted by AZ Escaper

What a fussy system. If not for you people posting your insights, I would have never figured out why a perfect furnace wasn't working. Thank you so much, and hopefully this helps some other Escape owners.

AZ Escaper

This begs the question: why does ETI continue using the DFSAD 12 furnace?

[BrooksWade]

Just sayin'.

[Rossue]

Originally Posted by BrooksWade

This begs the question: why does ETI continue using the DFSAD 12 furnace?

Another question: do other OEM'S have similar problems or could it be unique to Escape due to size of cabinet the unit is installed in for example?

I am aware that Gen1 trailers with a Dometic 8555 did not have the Dometic exterior grill. They used a much smaller Norcold as it probably was deemed more aesthetic. To what degree this had an effect on widely reported less than desirable performance will probably never be known.

There is one member here who did enlarge the outside opening with a Dometic grill. Perhaps they can chime in on that.

[ChuckBC]

I am now wondering that the possible cause of Attwood/Dometic furnace problems is the ability of the blower to hold the sail switch open with a steady flow of air? My Atwood was hit and miss in igniting and I even had a new sail switch, tested okay, not work. I put a slight bend in my switch paddle arm and now it has worked for my month trip. That said I did add a 2” vent to bathroom and maybe this could have improved intake/exhaust flow for blower?