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  1. #27
    Join Date
    Feb 2009
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    My fireplace does the same thing but we have a t-couple. No electrics involved. I've replaced the thermocouple and it worked fine for about 4 months but now has started shutting off after about 5 minutes. I've even moved the thermocouple into the main flame so it's staying hot. I cleaned it and so far same prob.

    There is a screw to the pilot line it's in tight. I was wondering what it did. Is it a flow regulator or something else? If I back it off there seems to be no change in the gas flow so I just left it in tight how I found it

    Thank you

  2. #28
    Join Date
    Aug 2007
    Cleveland, Ohio (geauga County)
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    Does your DV have safety switches on the glass?? I just ran across one that would drop out and I found the glass safety switch not making good contact. JB

  3. #29
    Join Date
    Dec 2017
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    Quote Originally Posted by oil lp man View Post
    Did the mv drop below 279 when it finally cut out?

    200- 250 mv is about as low as you would want to see when the main valve is on. I would try replacing the wall switch. If that doesn't help then you are only out a few bucks and a little time.

    Typically the wall switch for the fireplace used is the incorrect one, (for 120 volt), not the millivolt (with silver contacts) and the resistance gets worse over time because it is not designed for a fraction of a volt.

    95% of the time its not the gas valve thats the problem.

    If that doesn't solve it and he replaces the gas valve I would hope they will eat that time replacing a good gas valve.

    It could be any number of things as pointed out by others here.

    I'm a newbie homeowner, but found this tread very useful and wanted to express appreciation for the information here. I have a 20-year old FMI direct-vent gas fireplace that developed two problems:
    First, the main burner would not stay on for more than one minute, and
    Secondly (and subsequently, the pilot flame would not stay on when I released the lighting control.

    I had an very competent technician in, do some gas furnace work for me that was successful on my equally old furnace. He had a quick look at my fireplace and said the pilot problem was the thermocouple. I replaced this with some effort and care to turning gas off on the main supply, etc. This resolved the fireplace pilot issue, but not the main burner. I had measured the thermopile voltage and knew that it was sufficient (750mv). After reading this site and a number of others, it occurred to me that contact corrosion on that low-voltage thermopile wiring could be the problem. I cleaned the contacts on my wall switch with emery cloth and that solved the problem. Main fireplace burner has been on for hours now! I live in Canada and the fireplace is a nice supplement to the furnace on our bitterly cold morning.

    So, if you have a similar problem with an old fireplace like mine, you might try this. Good luck!

    Thank you all!

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