Dometic Furnace would not ignite. What's up?

Discussion in 'A-Frame PopUps' started by biot78, Apr 25, 2021.

  1. biot78

    biot78 New Member

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    hey guys. we bought a 2020 Aliner Classic from so local folks last week. Took it out for a one night trial run...

    chance of showers turned to snow this morning. we were camping at 6,100 feet in the Owyhee Uplands a couple hours SW of Boise, Idaho. Outdoor temp was right at freezing.

    Anyway, furnace worked fine for a bit, then, just stopped prior to us going to sleep. Blower would run, and then it would just shut off. I noticed a red blinking light right as it shut off, and I think it would blink intermittently. Reset/On switch and it would do the same thing. Blower would run for <1 min and then it just shut down. So, I'm thinking it wasn't getting gas or wasn't igniting. stove top worked fine, luckily so we could make some coffee this morning. plenty of gas in the tanks.

    we got back home. I tried to run the furnace again unplugged with the same results. plugged in the shore power via 15 amp puck, and it fired right up.

    is my deep cell battery not strong enough? it was plugged in for a couple days before we headed out.

    Dometic 16121
     
  2. Sjm9911

    Sjm9911 Well-Known Member

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    The blinking red light is a code, see what it blinks then look it up.
    And it could be low voltage. Try it after charging up the battery.
     
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  3. Sjm9911

    Sjm9911 Well-Known Member

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  4. Rik Peery

    Rik Peery Well-Known Member Gold Supporting Member

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    Call the people you bought it from if possible & maybe they can advise...
     
  5. neighbormike

    neighbormike Well-Known Member Gold Supporting Member

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    If the battery is weak, the blower won’t turn fast enough to trip the sail switch. If it works ok on 110, I would start by looking at battery/ voltage.
     
  6. Old_Geezer

    Old_Geezer Well-Known Member

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    The newer Dometic furnaces are very picky about voltage and also operating at an altitude above 5000 ft. The sail switch design is idiotic, both how its placed and the quality of the piece.

    Perhaps replace with a Suburban/Airxcel?
     
  7. Hilldweller

    Hilldweller Well-Known Member

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    The battery was probably not charged or maintained properly and will likely never hold a complete charge.
    I'd start from scratch with a new battery and maintain it meticulously.
     
  8. rabird

    rabird Howdy!

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    as suggested, likely sail switch not closing from low battery.
    also make sure wasps/rats have are not restricting the intake air from outside.
     
  9. davido

    davido Well-Known Member

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    Sail switch. This is exactly the behavior a failed sail switch will exhibit. It's not a particularly expensive repair. I paid someone to do it for me because I didn't want to disassemble more than necessary and discover I made things worse. But it's a pretty standard repair.

    The sail switch detects whether or not the blower is operating. The furnace always turns the blower on first to get the flue venting combustion exhaust, and pulling in combustion air. The sail switch detects that the blower is running. If the blower is running, then the propane flow can be started, and the igniter flicks. With a failed sail switch, the blower won't be detected. The igniter may still flick, but the propane will not be turned on. The reason is to prevent possible CO or low oxygen situations caused by the blower failing. It's a safety mechanism.

    After this failed one time for me, I purchased a Mr Heater Buddy, propane filter, and a long propane hose. In the event of furnace failure, I can run the Mr Heater Buddy off of the main propane tank(s). Mr Heater Buddy is designed to run safely in an RV. But to be extra cautious, turn if off when you go to bed, and break out a few extra blankets for everyone to stay warm in bed.

    I don't consider Mr Heater Buddy to be an alternative to a well working furnace. But it's a failsafe that I can fall back to if the main furnace gives out.
     
  10. biot78

    biot78 New Member

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    thank you all for the responses. as noted, the furnace worked initially but stopped. it sounds like the 12v deep cell battery may have had a low charge. I have not tested it yet, but will.

    it's a 2020 camper. the original owners kept it in their garage...never used it for camping. not sure if they ever charged the battery while stored.

    that said, I had it plugged in at the house for 2 days (at least) cooling down the fridge. but, I do not have a record of what charge I left with.

    the 20 amp fuse was popped when I backed into our camp spot. so, it wasn't charging on the way (for who knows how long 2-3 hrs max)...and, the fridge was not pulling power from battery once the fuse popped. plus, could have been charging from TV if fuse wasn't busted.

    i have it plugged in at home now. furnace works. will check the charge level with my volt meter (when I can find it).

    hoping it's just the newish battery just being ruined already because previous owners just let it sit for a year, and not something with the furnace not working at altitude and cold weather. that's why we got it!! to extend the camping season.
    PXL_20210424_220522444.jpg
    PXL_20210425_143357128.MP.jpg
     
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  11. Dnodoz

    Dnodoz Member

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    We have a 2018 Classic we purchased new. Recently our furnace was doing the same thing. I bought a new sail switch and limit switch but haven’t installed yet.

    I decided to take off the wasp screen that was added to the exhaust port outside and then blew a can of compressed air in the opening. Fired up after that without putting in the parts I ordered.

    Even when it was working the 1st season it would not light at 8000 feet in CO. We had a late June snow in the mountains without heat.

    Since then and after the latest failure in TX, I don’t trust it anymore. We carry a Wave3 that can plug into our stove quick connect port if we plan on camping without hookups for elec.

    If we have hookups, our Classic has the CoolCat with the heat pump and we always carry an electric heater.
     
  12. biot78

    biot78 New Member

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    have you had any issues at higher elevations (5k+) before? perhaps the air is thinner and the air isn't pushing the sail switch the enough...so, no ignition. I still haven't tested battery for charge, but, will report back when I do.

    kinda sucks for us here in Idaho if this furnace won't operate at higher elevations. We mainly camp at higher elevations, boondocking. And, just wanted some onboard heat. thinking spring ski camping. and, sorta what we did this last weekend.

    we have a Mr. Buddy we will bring as backup emergency heat. We'll also be packing our backpacking stove for emergency coffee. I'm addicted to coffee first thing in the morning.
     
  13. Dnodoz

    Dnodoz Member

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    I’d go down the battery route first on yours. If they left the factory lead acid battery sit without maintenance that could easily be the problem.

    We had 200amps of fully charged lithium batteries so I know electric was not our issue. First failure was at altitude of over 8500 feet in CO. From what I’ve heard, these can be unreliable at altitude. Seemed to be confirmed by lighting right up next time it was needed at low altitude.

    Even the Buddy Heaters have elevation recommendations so I think that validates the assumption. We went with the Wave heater as a backup as it has the highest altitude rating.

    Last time our furnace failed was at low altitude so my first corrective measure was to make sure I had no airflow blockage. That worked for now. We’re going up in the mountains again this year and I will take the replacement sail switch along just in case it quits firing again.

    I’m not really sure how to get into the unit to change the switch but I’m hoping to just remove couple of screws on the vent cover and pull the unit out into the area in front of the sink. That’s last resort but will do it if I have to.
     
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  14. Tait

    Tait Active Member

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    I have a similar issue - but it is intermittent for me. Here is a video that I hope will have been helpful when I try to fix it:


    Another vote here to carry a Mr. Buddy - we used it one time when our main battery died.

    Also, if anybody is wondering, when boondocking, just checking to make sure the refrigerator is running on something other than 12V is a great idea.

    Not that I know from personal experience or anything.
     
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  15. biot78

    biot78 New Member

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    follow up. battery voltage is fine. but, the connections were not tight. this could have been the problem with a poor connection and some battery drain not pushing the fan fast enough.

    heading out to 5k+ elevation again this weekend and will see if there are any issues.
     
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  16. Anthony Hitchings

    Anthony Hitchings Well-Known Member Silver Supporting Member

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    our Atwood 9716-II lit up fine repeatedly at Elev 8392 ft. (which is likely the highest that we have camped).

    And also at 9,000 ft.

    Two different trips.

    Full voltage on our pair of batteries
     
    Last edited: May 26, 2021
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  17. Econ

    Econ Well-Known Member

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    Atwood 7916II works at 6000' multiple times for several years so its just not Anthony's
     

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