RV Furnace Valve caught fire!

[gsuty17]

I lost the blower motor on one of my motorhome furnaces so I figured as long as I’m in that deep, might as well replace the burner and ignitor, etc. Same valve though.

Anyway, I replace everything and it had a faint scent of propane so I tore it appear, re-seal it and fire it up. Runs consistently but sounds a little inconsistent, put tools away and come back to it aflame!

Anybody seen anything like this? I can’t imagine it is coincidence, but I can’t tell you how I caused the valve to leak, or if it wasn’t the valve how/what else caught fire. I’m confident it wasn’t the fittings.

For reference- it is an Atwood 8525-IV-DCLP

 

[bonneyman]

No direct experience on RV furnaces but propane/LP gas was always "snakey" to me. The tiniest leak or crack always caught fire. The stuff is just so easy to burn - it doesn't take much.

 

[Chuckster in NJ]

Is this an atmospheric or power vent?

 

[gsuty17]

Is this an atmospheric or power vent?

Power.

 

[Firebrick43]

This is why we do gas checks with a manometer or Dwyer gage and the must pass before lighting things up. I would suggest you do one as well before putting the system back into service. A manometer can be made for a few dollars in vinyl tubing and a scrap board if you don’t want to spend the money.

Also get a leak detection spray. The tiniest of leaks can be found as the bubble like crazy.

 

[toplessHO]

scary stuff

If you get going fast enough it will be on the news as another comet sighting

 

[Chuckster in NJ]

This is why we do gas checks with a manometer or Dwyer gage and the must pass before lighting things up. I would suggest you do one as well before putting the system back into service. A manometer can be made for a few dollars in vinyl tubing and a scrap board if you don’t want to spend the money.

Also get a leak detection spray. The tiniest of leaks can be found as the bubble like crazy.

THIS! ^ Is the best advice on any gas system, especially with LP……. A manometer doesn’t lie!
Also check for proper operation on the power vent.……. I have seen vents blocked by bird nests, raccoon babies and I also found a bird stuck in the flue damper.

 

[gsuty17]

This is why we do gas checks with a manometer or Dwyer gage and the must pass before lighting things up. I would suggest you do one as well before putting the system back into service. A manometer can be made for a few dollars in vinyl tubing and a scrap board if you don’t want to spend the money.

Also get a leak detection spray. The tiniest of leaks can be found as the bubble like crazy.

Always solid advice. I checked the static side, and it was leak free. The leak only occurred after the valve was energized. When installed checking the other side of the valve for leaks between the valve body and actual burner is nearly impossible.

I’m going to replace the valve. Will a sniffer test alert when the unit is operating in normal conditions? i.e. will the exhaust set it off?

 

[Firebrick43]

Always solid advice. I checked the static side, and it was leak free. The leak only occurred after the valve was energized. When installed checking the other side of the valve for leaks between the valve body and actual burner is nearly impossible.

I’m going to replace the valve. Will a sniffer test alert when the unit is operating in normal conditions? i.e. will the exhaust set it off?

Do be honest I don’t know about a sniffer working when there is a flame burning nearby, I have never done it.

 

[bonneyman]

Also get a leak detection spray. The tiniest of leaks can be found as the bubble like crazy.

Here's the bubbles I've used.

Best Bubble Leak Detector for HVAC and Plumbing - Big Blu

Big Blu leak detector is used by Manufacturers and Industry Professionals Worldwide. Big Blu Finds the smallest leaks and can be used with any type of gas.

www.refrigtech.com

Fluorescent Gas Leak Detector Nu-Calgon

www.nucalgon.com

Shop NLDF - Leak Detector - NRP - URI

NLDF - Leak detector, liquid, fluorescent dauber, 8 oz.

www.uri.com

 

[BillK]

I looked at this thread before but didn't comment. Are you absolutely sure that damage is from a leak in the valve ? Is it possible the wires burnt up due to a bad connection ? Is the valve 24 volts or 120 ?

Could it be "back flashing" for lack of a better term, from the part on the right ? Looks like maybe an igniter there ?

What brand is the igniter ? I would certainly be on the phone with them and ask them also. Matter of fact that would be my first call.

 

[gsuty17]

Customer service has categorically been so poor across the board for so long I don’t even consider that an option anymore, but you are certainly right. I also can’t see how or where the valve leaked but for the small expense of the new valve, I’m replacing it anyway.

It only ran for literally long enough for me to put tools away after initial startup; maybe a minute or two.