Furnace black soot

cwbysfan76 · 02-09-2021, 12:13 PM

I have a 2015 Jayco Eagle 5th wheel and a few week's ago we noticed a horrible exhaust smell inside the RV when using the furnace and black soot around the exhaust along with a heavy fume smell. Pulled the furnace and cleaned it (compressed air)..it had lots of soot and a few mud daubers nest in it. Put it back together and it ran fine for a few days and now it's back to the same issue. After some research I have come to the conclusion that it's a combustion issue and that the problem is either with the gas burner head or the gas valve has clogged or dirty jets. Has anyone had this issue and if so how did you fix it? Any help or tips would be greatly appreciated....I'm pulling the furnace out again this evening.

eagleback · 02-09-2021, 12:33 PM

Are you using your tanks or ones that exchange. The reason i ask is i had a tank exchange once from blue rhino, And it was full of oil from a test tank and it caused the soot issue but not on my unit but a portable heater.

ALJO · 02-09-2021, 12:34 PM

Check for a blockage in the air-chamber!

jeffmcpa · 02-09-2021, 12:43 PM

spider web in the burner tube...

bansai · 02-09-2021, 12:44 PM

You wouldn't happen to be parked next door to these guys would you?
https://www.jaycoowners.com/forums/f...-new-post.html

cwbysfan76 · 02-09-2021, 02:13 PM

Quote:

Originally Posted by eagleback

Are you using your tanks or ones that exchange. The reason i ask is i had a tank exchange once from blue rhino, And it was full of oil from a test tank and it caused the soot issue but not on my unit but a portable heater.

I've been using the same tanks refilled from the same place for the past 2 years.

SmokerBill · 02-09-2021, 02:45 PM

It's worrying that you got a strong smell of exhaust inside the RV. That makes me think that it's possible that the heat exchanger may be cracked. That could easily lead to carbon monoxide poisoning.

mini4mw · 02-09-2021, 02:49 PM

found this online:
##########
When you burn propane, water vapor and carbon dioxide are produced. These molecules are colorless and they cannot be seen by the naked eye. Propane that is burned straight without incorporating oxygen into the process will emit black smoke which leaves soot.
The burner ports have relatively small diameters, which makes them susceptible to becoming clogged up with debris. In some cases, such restrictions prevent the burner port from generating flame at all. In other cases, the restriction alters the air-fuel ratio of that particular port. As a result, clogged burner ports may produce excessive levels of soot.
##########

Since you found mud daubers in there and soot is created from unburned or poorly burned propane (which may explain the smell too) it sounds like it just needs to be cleaned again. I'd double check you are getting good air flow to burner and the holes the propane comes out are good and clean. Perhaps air flow/propane flow caused some more debris to clog up somewhere and cause the inefficient burning which is causing the soot/smell.

cwbysfan76 · 02-10-2021, 09:34 AM

just an update..

I got the furnace out, home and taken apart. There are no cracks, breaks or holes in the heat exchanger. The furnace burner head is good, no clogs or cracks in it. So that leaves me to believe the issue is in the gas valve. I removed the jet on the gas out end and cleaned it, I didn't really see anything that was obstructing it. I guess I need to remove the fitting on the gas in side and see if that is clogged. Other than that I am at a loss...I guess after this I will put it back together and put the furnace back in and test run it....if it's still doing the soot I will replace gas valve

RogerR · 02-10-2021, 09:52 AM

Before you throw parts at your furnace call your local LP dealers. Not the tank filler guys but the ones that deliver to houses. Many of them have trained LP furnace repair people who would be able to identify your problem(s).

Also, make sure your carbon monoxide detector is in date and good working order. The furnace fumes from incomplete combustion probably contain lethal amounts of CO and it could blow back or leak into your RV.

cwbysfan76 · 02-10-2021, 11:28 AM

Quote:

Originally Posted by RogerR

Before you throw parts at your furnace call your local LP dealers. Not the tank filler guys but the ones that deliver to houses. Many of them have trained LP furnace repair people who would be able to identify your problem(s).

Also, make sure your carbon monoxide detector is in date and good working order. The furnace fumes from incomplete combustion probably contain lethal amounts of CO and it could blow back or leak into your RV.

Well, at this point I'm fairly certain the problem is the gas valve, I'm going to hook up a 12volt current to it and get it to engage the solenoids so I can blow some air through the gas valve and test if it is clogged or not. I'm not sure if having 1 bad solenoid would cause my problem or not but I'll test those with an ohm meter. The CO detector works I know that for a fact but with the weather right now we are home for 2 weeks anyways :P...good time to sort this issue out.

ALJO · 02-10-2021, 11:49 AM

Black soot means always Air fuel mixture incorrect. It can be restriction of fuel: back pressure combustion chamber; burner airflow adjustment

Jagiven · 02-10-2021, 12:32 PM

Couple thoughts. Hopefully you added a witness mark to your gas air mix chamber before you did any adjustments. This will allow you to get it back to factory settings. Once it is set, it should never change unless something else physically changes.

Being you said it worked fine until the mud daubers, I doubt the issue is with the gas valve. I suspect the jet (some call it the venturi), and check it, I suspect it is partially obstructed. Remove the jet, you should be able to see through it. Use a very thin piece of wire to clean it. DO NOT drill it out, Do NOT over side the jet.

I also start off with a good cleaning of the entire flame chamber. Air/fuel mix (spiders are horrible in this area). Then clean the rest of the system.

When all done, install a bug screen.

Here is a link that might help you test your gas valve. https://www.rvtravel.com/guide-to-tr...nace-problems/

JayNo1 · 12-29-2023, 01:22 PM

I have the same issue, but without any debris dirt dobbers or any bad corrosion in the burner chambers, I pulled the screen cleaned it, cleaned the orifice and still same issue, what was the eventual fix? Gas valve? Thanks

Grumpy · 12-29-2023, 01:33 PM

The valve shouldn't be the issue. Black soot means too much gas, not enough air. A bad valve would reduce the gas flow.

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