Furnace will not ignite

[C Pennison]

Earlier this year (January) we were in Roswell, NM and I got a call from the wife saying that the heater was broken. She turned it on and the blower would start but the burner would not kick on.

We found a "mobile tech" and had her come out to check it out. first thing she said it was most likely the control board and she would order one. While I was at work she pulled out the furnace and replaced the board tested it and it "worked" fine.

After reinstalling the furnace into its cozy little home she turned the heat on again... same problem! fan comes on but the burner will not ignite. This time she replaces the sail switch and puts the old (and I guess functional) control board back on and returns the furnace to its home.

Well that did not work either and at this point she scratches her head and basically says "I don't know that much about the heaters, so I'm not real sure what it could be".

We make it through the cool months with an electric heater with no major issues, but now we find ourselves in Indiana and it looks like we will be here for the winter.

I have pulled the furnace out, cleaned and tested the sail switch (it works) and while the unit is sitting on the floor the everything works as it should, blower starts and then the burner will fire up. As soon as I get put back in and buttoned up the burner will not ignite.

My only thought it the blower may not be getting enough return air and thus it's not able to push the sail switch???

Has anyone had this problem or know of anyone that has and what was the fix?

[MtBiker]

What year, make, model RV and heater?

[C Pennison]

Originally Posted by MtBiker

What year, make, model RV and heater?

2018 Shasta Oasis 310k with a a Atwood AFSD20 furnace. I knew I was forgetting something lol.

[Skip12]

I would check the battery. Be sure its healthy, even on shore power. Not saying that fits your symptoms exactly, but that's what I'd do.

[MR.M]

Originally Posted by MtBiker

What year, make, model RV and heater?

try this when you pull the furnace out there is a plastic plate covering the gas valve where the exhaust tube come out . remove this . pull and clean the igniter reinstall . leave the plastic cover peice off and then give it a try . also check your gas pressure s/b between 12/13 wc into the furnace . this is a combustion air issue .

[TitanMike]

Dumb question but is the furnace actually getting gas (Propane). if for some reason the supply line is kinked or plugged you can replace everything, including the whole furnace, and it won't work.

I had a similar problem with another gas appliance on my 2018 TT and it turned out that the hose supplying gas to it was kinked where it had been pulled at a 90 degree angle where it joined the main line from the regulator.

Several possible reasons for "no gas" but it bears checking before throwing a bunch of parts at it.

[rockfordroo]

Wonder if you have a crushed or restricted heater line that is limiting flow? When you pull the furnace out, without the heater lines attached, it works. Put it back in, the crushed heater line limits air flow, the sail switch won't pick up.

Just a thought.

Try leaving it in place, but remove the heater lines and see if it fires up.

[Brother Les]

2018? If this was going on in January, Did you call the Dealer that you bought it from and ask for suggestions. Looks like you went straight to a 'Tech' that did no testing but replaced good 'parts' and did not find the cause.


Load test your battery and if any cell is bad... replace. If battery good, put a hard charge on it from a battery charger, not just the camper converter.

[rockfordroo]

Originally Posted by Brother Les

2018? If this was going on in January, Did you call the Dealer that you bought it from and ask for suggestions. Looks like you went straight to a 'Tech' that did no testing but replaced good 'parts' and did not find the cause.


Load test your battery and if any cell is bad... replace. If battery good, put a hard charge on it from a battery charger, not just the camper converter.

His 2018 could very well have been built and delivered in April, 2017, making it 21 months old in January.

You might think my 2016 Mini Lite would only be 3 yrs old, but it was built 4/7/15, so it will be 4-1/2 yrs old in about 2 weeks. And weirder yet, it's seen FIVE seasons (2015, 2016, 2017, 2018 and 2019).

[Old Islander]

I had a similar issue with our Atwood.

There is another 'fail safe' sensor in there called a 'limit switch' -- it'll be installed near the 'sail switch'. It monitors the internal temperature of the furnace, and won't permit it to ignite, if it thinks it's too warm, deep inside the furnace. Replacing this switch in our furnace solved our problem and it's run flawlessly since.

The only other thing I can think of is battery health... I've read that a failing battery can prevent a stove from running, but no personal experience with that...

Good luck...

Edit: something else just occurred to me. Is there any chance the wall thermostat could be faulty? Maybe unscrew it from the wall, and simply twist together the two leads, thereby closing the circuit. If the furnace symptoms stay the same, then the thermostat is OK.

[KyDan]

Is it trying to light? After the blower starts and runs several seconds do you hear a ticking sound?
Not sure about the sail switch..... is it in the exhaust air stream or the "heated inside air" stream??
If it's the inside air then you may be onto something about restricted air flow.

[almcguire]

Originally Posted by C Pennison

2018 Shasta Oasis 310k with a a Atwood AFSD20 furnace. I knew I was forgetting something lol.

.
Look to see if the OEM installed the proper exhaust vent. The AFSD20 does not have a good history. I know the supplier replaces several with AFSD25 more dependable. Air flow.

[Larry-NC]

Originally Posted by KyDan

Is it trying to light? After the blower starts and runs several seconds do you hear a ticking sound?
Not sure about the sail switch..... is it in the exhaust air stream or the "heated inside air" stream??
If it's the inside air then you may be onto something about restricted air flow.

If you hear the ticking sound, the sail switch is okay. Some techs like to replace it because it's the only part whose function they understand.

[Larry-NC]

Originally Posted by C Pennison

Earlier this year (January) we were in Roswell, NM and I got a call from the wife saying that the heater was broken. She turned it on and the blower would start but the burner would not kick on.

We found a "mobile tech" and had her come out to check it out. first thing she said it was most likely the control board and she would order one. While I was at work she pulled out the furnace and replaced the board tested it and it "worked" fine.

After reinstalling the furnace into its cozy little home she turned the heat on again... same problem! fan comes on but the burner will not ignite. This time she replaces the sail switch and puts the old (and I guess functional) control board back on and returns the furnace to its home.

Well that did not work either and at this point she scratches her head and basically says "I don't know that much about the heaters, so I'm not real sure what it could be".

We make it through the cool months with an electric heater with no major issues, but now we find ourselves in Indiana and it looks like we will be here for the winter.

I have pulled the furnace out, cleaned and tested the sail switch (it works) and while the unit is sitting on the floor the everything works as it should, blower starts and then the burner will fire up. As soon as I get put back in and buttoned up the burner will not ignite.

My only thought it the blower may not be getting enough return air and thus it's not able to push the sail switch???

Has anyone had this problem or know of anyone that has and what was the fix?

We had a very similar problem on a Suburban SF-20. It turned out to be the propane regulator. Your gas range and water heater are pretty tolerant about the gas pressure--the range has a secondary internal regulator which helps. But if the pressure isn't exactly right, the furnace won't light. You will hear the ticking sound, indicating that the furnace has purged and is sparking (the ticking sound) to attempt to light the gas.

On a Suburban, if it gets this far, there are really only three things to check:
1) Are the intake and exhaust tubes clear, or full of mud from mud dauber bees? Very common. Bees love the smell.
2) Is the gas shut-off solenoid working? Can you measure voltage across it when the lighting cycle takes place? And if you disconnect it with furnace off, can you measure continuity (finite ohms) across it?
3) What is the pressure measured in inches of water column from the regulator? It took me a couple of days of checking other things before I finally built a pressure gauge and discovered the regulator was bad.

Interestingly, before replacing the regulator, the Suburban would light if I removed the plenum cover which changed the speed of the two blowers.

I hope these suggestions apply to your Atwood.

[C Pennison]

Originally Posted by Brother Les

2018? If this was going on in January, Did you call the Dealer that you bought it from and ask for suggestions. Looks like you went straight to a 'Tech' that did no testing but replaced good 'parts' and did not find the cause.


Load test your battery and if any cell is bad... replace. If battery good, put a hard charge on it from a battery charger, not just the camper converter.

I did call the dealership and talked to the head tech there, in fact I called them before calling the mobile tech lol. It was kind of like talking to a tree, well no a tree probably would have been more responsive and had more personality. All he kept saying was bring the trailer in... We were 500 miles away.

The control board for the hot water heater went out a week after we bought it but we were still in the area so I stopped by there and kind of pinned him down. He gave me a new board saying "I bet it will be this, they had a bad batch and we was wondering if yours was going to go bad".

We live in our trailer full time with a cat and a dog while traveling with my job so it's kind of inconvenient to put the trailer in the shop that's way I wanted to try a fix it myself.

I am going to load test the battery today since I got like four replies saying something about the battery.

[TheWolfPaq82]

Being as you're "Living in your Trailer", you're probably not Boondocking, connected to "Shore Power" I really-really doubt you have any kind of "Battery" trouble. Could you describe in more detail exactly what is does from when you turn it on until it shuts back down. Igniter working/not working, burner lights and immediately goes out....things like that will help.

[rockfordroo]

It worked when "out." It won't work when "in." I assume both ways was on the battery. So I don't think the battery is your problem (unless you had a separate power supply). I still believe it's your air flow.