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AFChap · 10-17-2007, 02:58 PM

It seems one thing leads to another. I noticed recently the WH plug had been dripping slightly. It had been about three months since I last flushed the tank, so today I flushed the tank, put new teflon tape on the plug, and put the plug back in so stop the leak. Then, thinking it had been several months since we have run the WH on gas, I decided to test it. I went inside and turned the LP switch on, then went back outside to verify it was lit as the light inside indicated. As I walked up to the WH door, a bit of smoke came out the vent, then faded. I opened the doors and found a good bit of the insulation melted off most of the wiring above the burner. I have a vent screen over the vent, mothballs in a small ventilated bottle inside the compartment, and don't think there is any spider web, etc in the burner tube. Is there another possible cause of the flashback that obviously happened? (when I flushed the WH, did I get water somewhere I shouldn't have?) ... Or am I just missing a burner tube blockage?

The WH appears to be working find on electric, but now I have some damaged wiring to repair in addition to figuring out the problem...

AFChap · 10-17-2007, 02:58 PM

It seems one thing leads to another. I noticed recently the WH plug had been dripping slightly. It had been about three months since I last flushed the tank, so today I flushed the tank, put new teflon tape on the plug, and put the plug back in so stop the leak. Then, thinking it had been several months since we have run the WH on gas, I decided to test it. I went inside and turned the LP switch on, then went back outside to verify it was lit as the light inside indicated. As I walked up to the WH door, a bit of smoke came out the vent, then faded. I opened the doors and found a good bit of the insulation melted off most of the wiring above the burner. I have a vent screen over the vent, mothballs in a small ventilated bottle inside the compartment, and don't think there is any spider web, etc in the burner tube. Is there another possible cause of the flashback that obviously happened? (when I flushed the WH, did I get water somewhere I shouldn't have?) ... Or am I just missing a burner tube blockage?

The WH appears to be working find on electric, but now I have some damaged wiring to repair in addition to figuring out the problem...

RV Wizard · 10-17-2007, 11:03 PM

Paul, I would start by cleaning the burner venturi tube, gas valve orfice and burner "box" if Atwood "U" tube flame goes into. Retry operating the water heater. DOes it perform well? If not you should have the working gas pressure before and after the gas valve checked. Make repairs to correct gas pressure or flow problems. Retest and if it is working well repair the wiring that was damaged.

AFChap · 10-18-2007, 09:23 AM

Found the problem this morning. I couldn't see anything in the burner tube (know from past history it is almost impossible to get anything inside the tube even with the air gizmo moved), so took the framework it is mounted in off in order to get it off. There was a spider web (complete with spider) at the very end of the tube at the burner box end ...guess my mothballs didn't faze the spider. With a new thermal cut-off in place, the WH works just as it should.