Water Heater Air Shutter catching fire

[RyanSargent]

Im new to the rv life ive got a 1994 winnebago adventurer chevy and i recently just lit the WH pilot for the first time last night and while the size of the flame surprised me ive read that its fairly normal however my Air Shutter kept catching fire and im not sure what to do about that as itll burn the wires in the control box if left on. Any ideas as to what the issue is and how to fix it?

[83Itasca]

I am NOT a pro. I replaced pilot light assembly on mine because lines were clogged with rust and wouldn’t light.

POSSIBLY on yours the orifice is to large and letting too much gas through. Extremely dangerous. Who tinkered with it before you?

If you don’t know or have doubts call in a professional. It is not worth the risk.

In my case I had a good idea of what the issue was and I KNEW what the fix was.
My furnace was a different story… I paid a pro to come and service it. Money well spent and peace of mind ( for my wife that it wouldn’t blow up…)

[83Itasca]

Owners manual will help with unit ID and standard operating procedure with maybe a little trouble shooting. Your trouble sounds more serious.
I’m leaving a lot unsaid. I don’t always listen to sound advice

[RyanSargent]

Thank you so much what kind of professional would you recommend like i said im new at this so im not sure if i call a plumber or?

[Sun_Seeker]

Originally Posted by RyanSargent

Im new to the rv life ive got a 1994 winnebago adventurer chevy and i recently just lit the WH pilot for the first time last night and while the size of the flame surprised me ive read that its fairly normal however my Air Shutter kept catching fire and im not sure what to do about that as itll burn the wires in the control box if left on. Any ideas as to what the issue is and how to fix it?

I had the same thing...blue flame blow back out of the air shutter. What it turned out to be, was spider webs and prey cocoons were in the down tube. I used three tobaccos pipe cleaners. to put them into the air shutter and move them in and out and the spider webs and other silk debris came out where the flame should blast in the channel. After doing that...I tried to start the gas W.H. burner and it came on, with no further flame back out of the air shutter. I had a good hot blue blasting flame towards the wrap around air passage. So...first off...check for any INSECT debris in the burner tube. I'll bet you will find some...(usually spider debris...but could also be hornets trying to use the burner tube as a home...and building a nest, or trying to.

[Morich]

First step is often air flow and that brings the question of whether there is a screen over the vents? If there is not a screen it is just a matter of time before some type wasp, mud dauber or spiders find it as a home.
So if no screen I would first look at all the air flow and clear it. It sounds like the reason it is coming out in the wrong ploace is that it can go up and out like it should.

Orifice is only likely if somebody tried to "fix" it and got it too large and then it requires a new orifice but unlikely. If there is an adjustment on the air flow gadget, it may help to loosen the screws and move it very small amounts to get the best blue flame going.

[83Itasca]

Wiser heads prevail.
So to clarify…
Are you saying it is not just the pilot flame but when the burner lights that flame comes back out the air mixture tube???
For those that have had that issue, did you have to take the tube out to clean it?

Mark where things are before taking anything apart or moving it

RV Service center couldn’t (or wouldn’t ) help with my old heap but recommended a mobile rv repair that were actually reasonable. I did the disassembly and cleaned the mud dauber nests out and they replaced circuit board and bench tested.

[Morich]

The thing that is often missed on the fire in RV water heaters is how simple the gas flow!
It really is more like a blowtorch in a barrel and not real complex, so if we look at how the gas comes in at the orifice, mixes with air of the right amount and then moves on into the space where it should burn, there are limited things to go wrong.

The gas amount does come in through the orifice but that is not too often a problem if we keep it keep as the fire is a pretty long space away, to it doesn't take much abuse and lasts a really long time but that is only true if nobody tries really hard to clean and improve it as that is one way to make the hole too big!

If we keep the tube clear so the gas/air mix moves into the "barrel" where is should burn and if we keep the "barrel" clear things should work okay once the gas/air mix is close to right. One way to make the flame come back out of the space inside the heater is if that "barrel" space is full of something else like mud dauber nests! The gas doesn't go in and burn inside if the thing is half full of mud, so a good look and stirring a heavy wire around in the barrel may tell you if it has junk in it. I'm always amazed at how hard and durable they can build those nests.

It can be worth the time to take a few screws out and look at the small parts like the pilot and igniter and replace them when they get really burned or bent too far out of line but cleaning the tube and the space is often all that is needed. Then when you are putting it all back together, do a check of the flame and you want mostly blue color if the air/gas mix is right but it is not real touchy as it really is just a "blowtorch in a barrel"!

[Ray,IN]

Originally Posted by Sun_Seeker

I had the same thing...blue flame blow back out of the air shutter. What it turned out to be, was spider webs and prey cocoons were in the down tube. I used three tobaccos pipe cleaners. to put them into the air shutter and move them in and out and the spider webs and other silk debris came out where the flame should blast in the channel. After doing that...I tried to start the gas W.H. burner and it came on, with no further flame back out of the air shutter. I had a good hot blue blasting flame towards the wrap around air passage. So...first off...check for any INSECT debris in the burner tube. I'll bet you will find some...(usually spider debris...but could also be hornets trying to use the burner tube as a home...and building a nest, or trying to.

Bingo! Spiders are attracted to the odorant in LP.

[RTrider]

As suggested by Sun Seeker, there is a good chance it simply spider webs in the venturi. For some reason, spiders like the smell of propane. Today almost all gas grills have a screen over the air inlet for that exact reason. I worked in the gas appliance industry and about the only thing that will cause flame to come out at the air shutter/air inlet area is some kind of resistance to flow down stream and the most likely is in the venturi area.

[mikee409]

My water heater did the same thing.
Inspected the tube where the flame blows to heat the tank. Found a big clod of mud restricting the tube.
Mud daubber had built a nest in there.
After that I put screen wire over the openings on the cover to keep them out.
Mikee