Flame shot out of Furnace NT-32

[ronsgto]

I hope this is proper to do. I have asked a couple of questions about my furnance but I just added the question to the end of other post. I though I would try and start from scratch. Its on a 1974 Overlander and it has a Suburban NT-32. I was surprized because I thought they had NT-22's in them. Anyway when I lite the pilot gas builds up in the back of the heat exchanger and a flame shot right out of the pilot access whole. I checked to make sure the thermostat was off and it is. How can gas leak in the back or anywhere for that matter. Others I know have had similar problems but I don't know if they ever found the problem. I don't know if there is any access to the inside of the heat exchanger. I could sure use some help on this one.

[Inland RV Center, In]

Originally Posted by ronsgto

I hope this is proper to do. I have asked a couple of questions about my furnance but I just added the question to the end of other post. I though I would try and start from scratch. Its on a 1974 Overlander and it has a Suburban NT-32. I was surprized because I thought they had NT-22's in them. Anyway when I lite the pilot gas builds up in the back of the heat exchanger and a flame shot right out of the pilot access whole. I checked to make sure the thermostat was off and it is. How can gas leak in the back or anywhere for that matter. Others I know have had similar problems but I don't know if they ever found the problem. I don't know if there is any access to the inside of the heat exchanger. I could sure use some help on this one.

The furnace needs to be overhauled every few years.

Take it out of it's case.

Disassemble it on a bench.

Notice the large amount of dirt you remove.

Clean everything including the inside of the combustion chamber, by tapping on it, and then dumping the dirt out.

Clean the burner log.

Reassemble with all new gaskets.

Bench test it with LPG, using a regulator.

You will understand much better why it flashed back, once you remove all the internal dirt.

After it functions correctly on the bench, then reinstall it.

Andy

[ronsgto]

Thanks much Andy that's just want I am going to do.

[Smokin Camel]

Just want to add one item.....look over the heat exchanger. If there are any pinholes of severe irregularities, get a new exchanger. Older furnaces need to be periodically checked for bad exchangers. You may want to put a new nozzle in as well.

When LP is burned there is water in the combustion by-products ( exhaust gas). That water can be a corrosion medium that when combined with the heat - well you get holes after awhile--usually quite a while.

I guess I should mention that if you have holes in the heat exchanger you can be putting Carbon Monoxide into the trailer.

[Mike Leary]

Both correct posts, but from personal experience, replace the unit. The new furnace should fit in the old enclosure. Might as well have them put a Dinosaur board in at the same time.

[ronsgto]

Well I pulled the unit out cleaned it and yes it was dirty inside but not that much rust. It had wasp nest in the exchanger. Looking in the heat exchange it looks pretty good not much rust it may not have been used that much. Any way still have a problem. I ran it on the bench and managed to get it working some what. But I am still having some flash back. In fact it will blow out the pilot. For those that may be experenced with these does it sound like maybe the gas valve is leaking gas at the main port? If so does anyone know where I might get a gas valve. BTW don't have a budget to replace the furnace right now. Thanks much.

[derf]

Mike,
What is the correct replacement model Number for the NT 32a?
Derf

[ronsgto]

Sorry I don't have that info I never replaced mine. You should be able to find the info on the forum if you searched.

[Lumatic]

Originally Posted by derf

Mike,
What is the correct replacement model Number for the NT 32a?
Derf

FYI I replaced my NT22a with a NT30s. I had to do a little modification to get the intake /exhaust tubes to line up, but it was not that bad. There are a couple of old threads about the process.

Dump the old furnace, you will be a happy camper. They work easier and better.

[darryl97420]

Not to rehash an old topic but are gaskets available for these furnaces? If I can save my furnace that would be great.

When I first bought my trailer I was told to replace the furnace when I asked about how to service it. I can't stand the thought of throwing away the furnace. It may be 35 years old but it still looks great.

[Inland RV Center, In]

Originally Posted by darryl97420

Not to rehash an old topic but are gaskets available for these furnaces? If I can save my furnace that would be great.

When I first bought my trailer I was told to replace the furnace when I asked about how to service it. I can't stand the thought of throwing away the furnace. It may be 35 years old but it still looks great.

Yes, gaskets are available, but make super sure of the model number when you order them.

Andy

[darryl97420]

Andy, do you have the caps?

[darryl97420]

Andy, Looks like I will be ordering the gaskets in the next week or so. Is there a gasket set? Also wondered if you have the little screw on caps that you can see through? What are they called so I ask for the right item? My furnace is the NT-22 C.

Thank you for your help.