Furnace Smudge

[traveler of california]

I noticed that at the openings to my MoHo furnace that I am getting a black smudging/residue. What causes this and what is the cure. Should I refrain from using the furnace until I fix it?

Nick, Journey '01

[traveler of california]

I noticed that at the openings to my MoHo furnace that I am getting a black smudging/residue. What causes this and what is the cure. Should I refrain from using the furnace until I fix it?

Nick, Journey '01

[Doug Sage]

It depends on how bad the smudge is. If it is fairly light and can be cleaned off easily then I would go ahead and use it, but if it is pretty dark and heavy then I would worry more. It is caused by an improper fuel mixture and needs to be fixed. My furnace is in the rear wall of my motorhome and is entirely sealed up. This makes it difficult for me to do anything to change the air/fuel mixture. I would definitely take it to a repair shop regardless of how dark the smudge is. It needs to be fixed. You could be lucky and it is simply an obstruction (like an insect nest) in the air intake opening.

[DonGee]

I think the advice is correct, too much fuel and not enough air, which will deplete your propane a little faster. Needs cleaning, don't believe there is an adjustment.

Don W 77041

[tderonne]

Have you been using it at an high elevations? I don't think there's any compensation for the lower ambient pressure, which could stave it for air.

[autofish]

Is the smudge black if it is it is soot so the air fuel mix is too rich not enough air however if it is white it could just be normal water vapor condisation on the cool sides of the rig. Ours does this in cold weather. Hope this helps.

[dstinch]

most likely cause is some kind of nest inside burner tube. You can blow high pressure air into one hole and it will come out the other hole. Don

[traveler of california]

Thanks to all that responded. I'll give you a little update on the problem.

As suggested, I blew some air into the vent holes and I also removed the "bug screens" I had over the vents. Someone said these could restrict air flow. Anyway, after I cleaned the soot I ran the heater for a couple of days and there appeared to be no problem.

However, I was running the furnace while we were traveled and when we stopped for fuel I noticed a soot problem again. Again I removed the soot and turned off the furnace. After arriving home, I again ran the furnace and after 3 days, no sooting/smudging at all.

I will watch it and see if it continues to be OK.

Again, thanks for all the comments.

Nick

[lthrnk]

I would guess that if the problem only showed after using the furnace while travelling that the air flow over the exhaust holes were being starved for air and that resulted in a bad air/fuel mixture.