HELP!! Not sure what's wrong - GAS FIREPLACE

[jeff.stai]

Hey everyone let me start off by saying that my gas fireplace is frustrating me. I feel that I'm mechanically inclined, and can usually figure out how to fix most household issues, but this one is baffling me.

I have a 4 year old gas fireplace that worked fine last year, but now the burner won't light, however the pilot lights fine. When I try to turn the pilot adjustment knob to "ON" the pilot light goes out even if when the pilot has been burning for 20 min (hot). The knob in question has three settings - 1. Off, 2. Pilot, 3. On. When I flip the wall switch, I can hear a very faint click so I think everything is getting power and all connections seem to be secure. I also took a closer look at the burner, and I don't see anything blocking any of the holes, etc.

Any help and or advice is appreciated.

Thanks!

-Jeff

[X X]

Should be serviced once every year or two...

[Tony Hwang]

Hi, One thing, have you checked the front glass window interlock switch?

[Joseph Meehan]

I am going to try an off the wall answer.

Is it possible that someone shut off the gas supply last spring? Is it possible they did not get it 100% off. Now when you run just the pilot light enough gas is supplied to light it, but when you turn on the main, it reduces the pressure so much that while some is going to the pilot it is not enough to keep it lit and there is not enough to light the main burners.

[Joe]

Classic symptom of a bad thermocouple. Start with that because it is cheap and easy. If no go, check for 24 V at your gas valve solenoid, then check to see if the gas valve solenoid coil is open. If you don't have a $9.95 Radio Shack meter to test with, now is a good time to acquire one. Good luck.

Joe

[Joseph Meehan]

I almost thought that, but normally under the conditions described a bad thermocouple would not allow the pilot to say on.

[Steven Andrade]

Sounds exactly like the TC to me.

[Joseph Meehan]

In my experience (limited) when the thermocouple is bad, the pilot light will stay on as long as the "button" is pressed. When the (light) button is released about about 30 seconds, with the switch still on Pilot (you can's move it off with the button depressed) the pilot will go out. The thermocouples (as I recall) protect not just the main burner, but will also shut down the pilot. Frankly it has been a long time since I had had to light a pilot light I could be remembering that wrong. If I am then if a pilot blows out, then gas will be released into the room.

[Joe]

You are correct if the thermocouple failure mode is is either a) bad or b) good. Considering how they operate, the dissimilar metal junction actually generates the small voltage to power the pilot gas flow widget and permit the main valve to function (round of applause here for Dr. Peltier!). But there can also be c) intermittant failures (rare) from junction welds going bad. Makes sense then to cheaply eliminate a), b) and c) all at once and then get into the tougher diagnostics if you're unlucky. Kind of like don't overhaul the carburetor unless you know your fuel is fresh and frisky. Cheers,

Joe