Exterior soot by furnace vent

[LRPorter]

Any explanation for soot accumulating about the furnace vent. Had my furnace removed and bench tested before leaving for Alaska in 2006. Furnace bench tested fine and worked fine. I began using the furnace in Kansas first night after leaving Tulsa, Ok and noticed soot build up in Shelby, Montana about a week later. The soot kept accumulating and got quite thick. My RV repair guy claims it was the difference in altitude from Oklahoma to Montana. Any advice. The furnace is a Suburban on my 1076 Argosy. It heats fine and thermostat works perfectly. Any ideas comments or advice?

[Janets Husband]

Originally Posted by LRPorter

Any explanation for soot accumulating about the furnace vent. Had my furnace removed and bench tested before leaving for Alaska in 2006. Furnace bench tested fine and worked fine. I began using the furnace in Kansas first night after leaving Tulsa, Ok and noticed soot build up in Shelby, Montana about a week later. The soot kept accumulating and got quite thick. My RV repair guy claims it was the difference in altitude from Oklahoma to Montana. Any advice. The furnace is a Suburban on my 1076 Argosy. It heats fine and thermostat works perfectly. Any ideas comments or advice?

If it tested OK on the bench you now need to look at the installation. Start it up and look at the color of the flame of the burner. Should be Blue no yellow. If it is yellow/orange it will produce soot. You will have to check the airflow to the burner box and adjust air flow for a blue flame. If you can't do that you might have low gas pressure. This will require a set of gauges. Most people will have to bring it in to have it checked and analyzed as to why the pressure is low.

[Inland RV Center, In]

Originally Posted by LRPorter

Any explanation for soot accumulating about the furnace vent. Had my furnace removed and bench tested before leaving for Alaska in 2006. Furnace bench tested fine and worked fine. I began using the furnace in Kansas first night after leaving Tulsa, Ok and noticed soot build up in Shelby, Montana about a week later. The soot kept accumulating and got quite thick. My RV repair guy claims it was the difference in altitude from Oklahoma to Montana. Any advice. The furnace is a Suburban on my 1076 Argosy. It heats fine and thermostat works perfectly. Any ideas comments or advice?

What is the LPG presuuer?

It must be within 11-13 inches of water column pressure.

If you travel in mountains very often then set it to about 12.5 inches.

After that the only culprit is the air mixture.

Contrary to opinion, the flame will make a "roaring noise," when correctly adjusted. If not, then the burner is not getting enough air, and will burn inefficiently, causing soot.

Andy

[Excella CM]

Soot is only produced when the mixture is rich(not enough oxygen to burn all the fuel. Look for obstructions on or around the air intake for the burner. Baring obstructions, adjust the burner per Andy's advice.

[LRPorter]

My furnace does not seem to have an easy way to adjust anything. Are there aftermarket controls that can be added? Do the new furnaces solve this problem?

[Shacksman]

Originally Posted by LRPorter

Any explanation for soot accumulating about the furnace vent. Had my furnace removed and bench tested before leaving for Alaska in 2006. Furnace bench tested fine and worked fine. I began using the furnace in Kansas first night after leaving Tulsa, Ok and noticed soot build up in Shelby, Montana about a week later. The soot kept accumulating and got quite thick. My RV repair guy claims it was the difference in altitude from Oklahoma to Montana. Any advice. The furnace is a Suburban on my 1076 Argosy. It heats fine and thermostat works perfectly. Any ideas comments or advice?

The furnace in my 73 Argosy did the same thing, soot all over the exterior wall every day. I took it out and pulled the burner out. The slots in the burner were plugged with soot. I took a hacksaw blade and cleaned the slots out then washed everything clean. Re-assembled and it works like new.

[Inland RV Center, In]

Originally Posted by LRPorter

My furnace does not seem to have an easy way to adjust anything. Are there aftermarket controls that can be added? Do the new furnaces solve this problem?

What make and model furnace do you have?

Or, what year is your trailer, and is it an Airstream or Argosy, and what length?

Different appliances are used for different models and different years.

Your question is an easy one, but cannot be answered unless what you have is known.

Andy

[LRPorter]

Andy I assumed you remembered my trailer and me since I have bought so many parts from Inland RV. Just joking.

It is the original furnace and my service center tells the pressure everything was fine when it left the shop. I had some trailer "experts" on the trip tell me that it was obvious that the furnace needed to be replaced and was dangerous. I was also told that spider webs cause this problem. Lots of apparently bogus advice.

I saw the furnace when it was out of the trailer. The firebox looked in like new shape. It is an old trailer and I expected to purchase a new one but the tech assurred me it was it good shape. We put the furnace back in a rebuilt the tambor door and surrounding hardware. This was completed and glued in place. If you are familiar with the setup getting the tambor door together and working is quite a task. I would not have done this if I would have known that the furnace was not going to last for at least 3 years.

Any advice on how I can modify the furnace without tearing out the tambor door?

[Excella CM]

Actually, the spider web bit isn't "bogus" advice. Gas appliances to mix the correct amount of air with the gas to burn cleanly by using gentle venturi action. Anything that restricts fresh air gettng into the burner downstream of the gas orfice will give you a "rich " mixture and thus soot. It doesn't take much. A piece of paper, a leaf, a dead rodent or insect or the posterior abdominal secreations of some members of arachinida will all suffice. My guess is that you don't need to remove or disassemble the heater, but merely direct some compressed air into the burner air intake, maybe even a vacuum cleaner exhaust. Something has more than likely set up housekeeping in your furnace.

[LRPorter]

Thanks to all. I guess it is just another of the many benefits of having a warm place to sleep. My take away is to give the furnace a good cleaning with the compressor I bought. Perhaps my wife will forgive me now.

[Davey Jay]

I have a 1974 Suburban nt 16 that i use at 10000 ft. I shut mine off for about a week trying to figure out the black soot problem as well. Thanks to Todd@vintsream.com, he told me that this was a result of the high altitude and an possibly as obstruction in thie intake. Don't trust yahooanswers.com! I bought a scrubber that you use for cleaning dishes and some non flammable cleaner and cleaned the exhaust vent as well as I could. It works very well now, only thing is, sometimes it goes out in the middle of the night. I figure as long as my CO detector isn't going off, I'm fine. Any thoughts on the not staying lit issue?

[LRPorter]

Is it safe to get your compressor and blow in and about the furnace each year. I think Lewster admonished us to be careful and not damage seals. Any help out there?

[flitzwhopper]

I had a problem with a fill on one of my propane tanks where the attendant did not properly evacuate the tank. I had soot for awhile. The hot water heater would blow itself out. After I replaced the tank with a properly filled one the soot went away. My guess is that air/fuel mixture is important in the NT-22 models.
btw... I rebuilt my NT-22 and it works great. The biggest problem was finding a new motor. When I did it came with a new crossover hose.

All is good now