Propane Furnace won't ignite

[OwenTrail]

I have a older 1996 TM with a Suburban Gas Furnace. Was working fine the last time I used it this spring, but when I went to use it a week ago this fall, it would not ignite.
The thermostat is working a-okay, it will kick the fan on and then can here the igniter try to light the gas, but with no luck. Any direction on where to track down the problem will be appreciated.
All other gas appliances work, Stove and water heater.
The unit is a Suburban furnace, model #NT-16SE

Thanks - OwenTrail

 

[jagizzi]

I have the service manual for the furnace with a troubleshooting section in it. Give me your email address and I can send it over. I don't know how to attach a file here.

 

[jagizzi]

Got it figured out. Here is the Suburban Furnace Service Document. FWIW I replaced my furnace this summer and it was very straightforward. Disconnect the propane line and electric and then slide the unit out into the TM. The shell stays in place. You'll have to do this anyway to replace components I would think. Good luck!

 

[OwenTrail]

Jim and Kelli, thank you so much. This should do the trick. Happy Trails

 

[Kidkraz]

I had my camper out and found my heater wasn't working either. Your posting was perfect timing for me. Love this forum and all the great people on it.
Thank you for posting the manual.

 

[Shane826]

Kidkraz & OwenTrail- Please be sure to post here when you figure out the problem! This forum only continues to grow when people share their solution and how they got to that solution.

 

[Wavery]

It's most likely an air flow issue. The furnace has a "Sail switch" in the air intake and the exhaust outlet. If there is any airflow disturbance when the fan kicks off, the gas valve will shut off immediately.

It could be spider webs, mud dobber nests or a host of other obstructions. Those furnaces are pretty indestructible and very serviceable. They seldom need replacing.

Having said all that, we never use ours. They are so noisy and they put out so mush heat that they fire-up, warm the space quickly causing the thermostat to turn it off. 5-minutes later, the camper has cooled down and the thermostat turns it back on (about the time that we fall asleep). so it goes all night long.

We bought a Mr Buddy heater. It's silent and does an amazing job of heating the camper. We've used ours in +15* temps.

 

[Shane826]

Agreed on the use & noise but I think the sail switch is working correctly because it’s calling for ignition. I’m guessing a gas blockage.

 

[Kidkraz]

different issue

Unlike Owentrail, I'm not sure I have power to the furnace. The only sounds was from the mechanical switch at the thermostat. Water heater and stove both worked with the gas. I'll definitely post what I find. I thank Waverly on reminding me to check for blockages, cause the camper sat for 2 year before this year and it's only been used two different trips. I've seen & found way too many spiders for my liking.
Not sure when I'll be checking it out, but will give info on whatever I find.

 

[Shane826]

Sorry I forgot there were two separate furnaces being discussed!

Kidkraz- Even if the thermostat clicks it can still be bad, especially if it’s the original mechanical tstat. Disconnect the two wires at the tstat and twist them together. Does the furnace start and run? Bad thermostat. I’d replace it with a simple non-programmable heat-only tstat.

https://a.co/d/34UF2FB

https://a.co/d/08U2bWz

 

[Kidkraz]

Shane, thanks for the tip. I'll check that first.

 

[LoveToCamp-TMO]

Well, I no longer have a TM (loved them!), but I MAY be able to help solve the ignition problem. Or, at least give you something else to look at.

I have an Atwood furnace in my current trailer. It has similar problems as all other TT furnaces. I have replaced the sail switch a few times, and messed with it (key point!) on our last trip. I had a backup, and put it in. The backup had a hard plastic guard over the sail, so I tried bending the old sail back to that shape. I put the old sail switch back in, and it worked, temporarily. So, I turned-up the thermostat and went outside so I could look for the error code.

The unit fired-up (which it wouldn't do if the sail switch was not working), and was not staying ignited. It would re-ignite without the blower turning off, and did this a few times. Then, I saw a backfire flame come out the exhaust port. HMMM!

I recalled that on the Lance Owners forum, someone had said to check the bottom knockout of the furnace housing. I had done that in the past, and the knockout had fallen out, so I put it back on with duct tape. I looked under my furnace (inside, through the cold-air return), and the knockout had fallen out again. I put it back on (again with duct tape, as that is all I had with me), and tried the furnace again. IT WORKED FINE!

So, the point is, check your furnace housing for a missing knockout. I don't know why that would impact the combustion process, but mine works great if the knockout is in place (I have since put it on with muffler tape, and support it now with a 1" x1" post). Heck, one of my wail switch replacements may have been unnecessary, if the missing knockout was causing the problem back then.

Good luck!

 

[Rolling Thunder-TMO]

Heater Propane Ignition
I’ve had minor heater issue when it’s wet outside, she won’t start up. When rain or dampness subsides, she starts right up. We use her sparingly because of the noise also and carry a silent radiator style oil heater and are usually in full hookup sites.

 

[DiegoWest]

It's most likely an air flow issue. The furnace has a "Sail switch" in the air intake and the exhaust outlet. If there is any airflow disturbance when the fan kicks off, the gas valve will shut off immediately.

It could be spider webs, mud dobber nests or a host of other obstructions. Those furnaces are pretty indestructible and very serviceable. They seldom need replacing.

Having said all that, we never use ours. They are so noisy and they put out so mush heat that they fire-up, warm the space quickly causing the thermostat to turn it off. 5-minutes later, the camper has cooled down and the thermostat turns it back on (about the time that we fall asleep). so it goes all night long.

We bought a Mr Buddy heater. It's silent and does an amazing job of heating the camper. We've used ours in +15* temps.

Hi Wayne,
What model of Mr. Buddy heater do you use? I assume this is a propane model? Does your heater require an open window for venting?
Thanks in advance..

 

[Kidkraz]

I've used the Mr. Heater Portable Buddy Heater MH9BX 4,000-9,000 BTU, version. Which works great in my 2619. I see Mr Heater Buddy has their own 1LB refillable propane tanks. I also have a 5 LB tank I take for sitting outside. That can last me a couple days, verses several hours. Just make sure you use a filter with the large tanks.

 

[Wavery]

Hi Wayne,
What model of Mr. Buddy heater do you use? I assume this is a propane model? Does your heater require an open window for venting?
Thanks in advance..

Our Mr Buddy heater is the same as Kidraz' heater.

We use the 5G (20#) tank with the adapter hose for the heater. The 1# bottles are too expensive. We do leave a window cracked open. We've never had to use the heater on high, even in 15* F temps.

https://www.amazon.com/gp/product/B002G51BZU/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

https://www.amazon.com/gp/product/B092TDYLW5/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

 

[DiegoWest]

Our Mr Buddy heater is the same as Kidraz' heater.

We use the 5G (20#) tank with the adapter hose for the heater. The 1# bottles are too expensive. We do leave a window cracked open. We've never had to use the heater on high, even in 15* F temps.

https://www.amazon.com/gp/product/B002G51BZU/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

https://www.amazon.com/gp/product/B092TDYLW5/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

Thanks Wayne and Kidraz,
Wayne, I assume you are using one of the 20 pound propane tanks that come with the trailmanor as your propane source? How did you route the adapter hose from the outside to the inside of the TM?

 

[Wavery]

Thanks Wayne and Kidraz,
Wayne, I assume you are using one of the 20 pound propane tanks that come with the trailmanor as your propane source? How did you route the adapter hose from the outside to the inside of the TM?

Actually, I carry an extra 20# bottle of propane (when it's predicted to be cold). I set it outside the TM, on the door side and feed the 12' long adapter hose between the slide-out and the body on our 2720SL.

 

[DiegoWest]

Actually, I carry an extra 20# bottle of propane (when it's predicted to be cold). I set it outside the TM, on the door side and feed the 12' long adapter hose between the slide-out and the body on our 2720SL.

Nice solution. Thanks Wayne..

 

[Kidkraz]

You could also run the propane hose where the street side flap seal dead ends at the sink wall. That is if you place the heater on sunk counter.