My gas fireplace failed to light this year, although the pilot was fine. I put my multimeter on the terminals and got about 150 mV. This was obviously too low, so I cleaned it and got maybe 160.

So I bought a new one and installed it. It give me 180 mV.

The pilot flame is right on the thermo, and by wiggling it and poking a bit I got a clearer flame and it went up to 200.

To make sure the thermo worked I put my BBQ lighter on it and it shot right up to 380. But it goes back down again as soon as I take it off.

Can anyone offer a suggestion on what I might do to get the values up?

  • 1
    What is the make and model of fireplace? How old is it?
    – wallyk
    Nov 15, 2016 at 0:01
  • Is the pilot burning cleanly/correctly? Nov 15, 2016 at 0:27
  • The pilot is working fine, at least visually, it is clean burning and stable. There is a screw that appears to be an adjustment for the pilot size, but doesn't seem to work. The fireplace is an Arrow DM10 built in 1993. Nov 15, 2016 at 14:10

1 Answer 1


So the problem was actually the gas pipe, not the thermo. I guess it was corroded inside or had some dirt, but basically it was nothing more than not enough gas coming out. I put in a new line and presto, everything's perfect.

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