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Constantly replacing thermocouple

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Petey Pete
Petey Pete Member Posts: 13
in THE MAIN WALL
What can be the cause of having to replace a thermocouple at least twice a heating system? On a standing pilot, gas fired, steam boiler..

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  • Steve Whitbeck
    Steve Whitbeck Member Posts: 669
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    pilot

    If the pilot flame is too big OR too much thermocouple is in the flame it will burn it out.

    ONLY the tip ( 3/8 " ) is supposed to be red.
  • The Steam Whisperer (Formerly Boilerpro)
    The Steam Whisperer (Formerly Boilerpro) Member Posts: 834
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    Yep,

    that's the most common problem.  If you have a multimeter with millivolts, you can check output between the end of the thermocouple and the outside of the wire when holding pilot valve down for a couple of minutes.  The output should be about 27 to 30 MV.  Also, the tip should be a dull red, not bright red after being heated by the pilot.  Almost all pilots need to be adjusted down at installation because the factory typically leaves them full open at the factory.

    There was an error rendering this rich post.

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