RV Furnace Sputters And Goes Out -- Troubleshooting Tips -- My RV Works

My RV Works, Inc., Certified RV Technician, Darren Koepp, continues to answer viewer questions about common RV issues.

In this episode, Greg writes to us with a report that his Dometic DMF30111 furnace won't stay lit. It starts, fires, sputters and goes out, and then about 15-20 seconds later, will repeat the process.

Greg has replaced the circuit board, inspected the burner assembly, corrected a gap on the burner head, and checked the solenoids, but the issue still persists.

Join Darren as he demonstrates what a likely cause of this problem is, how to address it, and get some good furnace tips along the way!

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Timestamps
00:00 Intro
00:51 Description of Problem
02:20 Attempted Corrections
04:00 Troubleshooting Tips
07:40 Outro

Want to keep your furnace going strong? Check out our furnace annual service video here!
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Products
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Topic: RV Furnace Flame Sputters And Goes Out - Furnace Won't Stay Running
System: Dometic DMF-30111
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Film Date: 10/18/2022
Location: Joyce, Washington

Camera:
Samsung ZFold3
Samsung Note8
Olympus TG-4

Audio:

Lighting:

Music:
"My RV Works-Jam"
Composed by Steve Patry - Four Faces Band

As an Amazon Associate I earn a small commission on qualifying purchases, at no extra cost to you.

[lanedelker]

The Muppets rule! Great information, Darren. Thank you.

[timberg]

Really appreciate you getting right to the point, using great photos and arrow pointers, and having everything ready to show us (not spending time on the video tediously removing screws, etc. Along with sharing your years of experience, you are fun to listen to!

[cary]

Thank you for sharing your knowledge. You help a lot more people out than you may think.

[diverm]

Always Awesome Darren.
Hope you can keep their vids going all winter

[dougolson]

Based on your description I took the burner out of my Dometic furnace and removed the orifice. I did not see anything interfering with the opening but I blew on it, tapped the gas valve in case something would drop out of the openings, but saw nothing. There was still some very fine dust inside & outside the burn chamber left over from a horrendous dust storm we had in AZ two years ago (although the furnace has worked well after that). When I put it back together I thought the gap between igniters and burn chamber was too large so I adjusted the gap smaller. Anyway, after putting it all back together the furnace seems to be working just fine now. Hopefully it stays that way. Thanks for your suggestions.

[JohnG-rjib]

Fantastic ! Thanks for sharing your knowledge !!!

[europro]

Turned wrenches for almost 50 years. I had the same symptoms on my Atwood furnace. I noticed my cooktop burners were not as high a flame as a few years earlier. My propane regulator full of oil and damaged. Didn’t have to use a Manometer to figure that out. LOL. Replaced my regulator. Cooktop flames got magically higher and Furnace worked every time!!

[BruniFamilyTV]

I'm having a similar issue with mine. Going to check it out when I get the chance.

[J.Cameron.Stuart.Adams.]

Excellent info. My neighbors furnace sounds like a Mack truck idling once the gas ignites. The dang thing wakes me up at least ten times a night. Now I'll be able to approach them with a possible diagnosis and offer my assistance to try to fix it.

[somedayistodayrv]

Another new subscriber as well and I am learning some newer things to help in maintenance and diagnosis of issues, thank you for the videos. Take care. Dave.

[twloughlin]

New subscriber here. This is a pretty awesome channel and I am learning a lot. I'm working now to solve a 12v DC issue where I seem to be losing voltage. Your other videos have been helpful so far in learning more about my system. Thanks.

[RoyBower-ud]

Great video so I learned a lot about the gas valve and igniter. However, my problem was our furnace would start, ignite and then in one second or so, the flame quit. I understand the igniter system serves as a thermocouple, too. Could you do a video on that, too?

[keithgoodrich]

Thank you Darren, that was a big help

[kirkfarley]

New issue creating that problem on Suburban heaters. The fan's are defective. Amp draw MUST be within specs. Otherwise it won't keep the sail switch closed tight.

[bigofishon]

I have watched many of your videos and find them very helpful. Keep up the good work. I've checked everywhere and can't find an answer to my issue. Hopefully you have some insight. The furnace in our Jayco 5th wheel is a Dometic DFLD40 and it works fine. However, it heats the RV to temp setpoint and the living space cools down right away. I found the furnace return is part of the steps to the bedroom. Looking behind the return vents leads to my cargo bay, plumbing, electrical, etc. (a very large area). In other words, there is no ducting from the return air vent to the furnace. When the furnace is not heating, cold air comes through the return air vent cooling the RV living space.

My first thought was to seal off the return air vent. because there is plenty of open space in the cargo bay. But I'm sure if that would be safe.
Next, I'm thinking to build a sealed box behind the return air vent and connect ducting from the box to the furnace. But there's no input on the furnace except the slots around the furnace fan.

[jeffwebb]

I’ve been searching through and watching your excellent and helpful videos. Can’t come across discussion on the issue I’m having though. My Suburban furnace makes a backfire “poof” type sound upon initial shutdown when thermostat set temp is reached. Fan continues to run for cooldown cycle then shuts down completely. Furnace seems to operate normally other than this. Don’t recall hearing this last season. This is in a 2023 Stryker toy hauler. Anything to be concerned with? What could be causing it also? Thanks!

[RyanMcAnulty-igpt]

Hey this refers to the other video with the bad sylinoids so my furnace does everything but I don’t hear a click just the igniter ticking but I think your right it’s gonna be the gas valve or the sylinoids

[iTookMyShot]

This scenario sounds fairly familiar. I, too, was an appliance tech for over 40 years. My Dometic furnace ( DFMD35141) would fire, not sputter, just extinguish and roughly 15 seconds start again, go out again. No fault codes, no break in the 12v (except after flame out), it would just repeat over and over. Sometimes, after multiple tries, ot would seem to heat "normally" but now, If I take the blower end of my vacuum, and blow air into the blower wheel area (near the burner) it will stay on, as long as I add the air. Also, it seems to do this more at higher altitudes. Presently in Colorado at 7, 200 feet. I have not tested with a MaNomiNaa... manometer
Spark gap is good, no bugs or debris in orifice, plugged into 110v.
Possible restriction in burner intake?

[TomasFlores-gmxq]

or the vent maybe covered with something like a floor mat. Vents could be closed. ext.

[patrickstiltner]

Hey Darren, I've seen you use both types of manometers and a slack tube. Which do you prefer?