Suburban furnace model NT-12S - Page 3

MrHenrietta · 10-08-2016, 04:50 PM

Just wanted to chime in as I just fixed my Suburban NT-12S furnace today. I was having trouble getting my furnace to heat up. It would work intermittently. I would be able to get it to fire up but then after getting to temp, turning off then turning back on again is where I was having the issue. My problem was a dirty heating element and igniter. When I took it apart it there was a lot of debris on the element and the igniter was having trouble making contact with the element. When reading the manual I noticed that Suburban highly recommends that you clean the chamber once a year. All good now : )

phlite · 12-19-2018, 09:41 PM

Hi Guys,

I too have been having this issue where my furnace does not turn on in the middle of the night. It's so frustrating! We get the same symptom, three attempts, and then no light. Only thing to do is to turn the furnace off and retry. It is no fun to wake up cold and try and dick around with the furnace.

I decided to dive in and look at it today as we are taking the van camping this weekend and will need the furnace. My thought was to try and clean the ignitor as that is what i do to my home furnace when it has trouble lighting. After looking at it i realized that I could take the cover off by removing part of the surrounding walls. It's tight in there, and had to remove the water line fitting to access some of the screws. See pictures. After removing the left wall, I could access the metal cover and remove it by unscrewing two screws holding it on.

After removing the access panel the ignitor terminal is in view. After removing two more screws to the ignitor, the ignitor can be removed. I noticed that my ignitor was rusty, and sooty. I took some steel wool and cleaned it by rubbing it quite a bit. This is how i clean my home furnace ignitor.

After vacuuming the surroundings, and putting everything back together, things seemed ok. The furnace turned on as i had hoped. But then I tried turning the furnace on again and thats when the retched issues returned. The furnace did not turn on after three tries. I tried the furnace on over and over again and it would not light. This is three times turning the furnace on and off for a total of 9 ignite attempts.

But then i remembered a couple posts I read where folks suspected that part of the problem of the furnace not lightning may be due to low voltage coming from the cabin battery. So to test this i turned on the van's engine. This of course will instantly apply full power to everything.

Now trying the furnace again ... it turned on instantly! I tried powering the furnace off and on over and over for 5 times and the furnace turned on instantly each time.

So, it seems that likely the cause of the issues could be a combination of things. Dirty ignitor, and what may be the most important issue, low voltage going to the ignitor.

My cabin battery is probably on it's way out. I'd give it a good to fair rating. It will last over 24 hours with fridge, and sparing indoor light use. May be time for a new one :/.

Anyhoo guys, hope this help!

JoeH · 12-19-2018, 10:15 PM

Strong work Phlite! I think I might have mentioned it previously but if your in the market for a house battery and want to stick with a Lifeline 4D I got a pretty good deal at AZ Wind and Sun. No tax since it's presumably for a solar application.

I never chimed back in on this thread by my furnace issue turned out to be a mud dauber wasp nest.