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  1. #1
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    thermopiles/gas valves

    and a complaint that the gas valve doesn't turn on.

    Assuming the wiring and everything else is good and without knowing anything else or making any measurements, what are the odds that it's the thermopile?

  2. #2
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    50/50

  3. #3
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    Quote Originally Posted by Senior Tech View Post
    50/50
    Thanks.

  4. #4
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    I say 10%. Chances are it needs to be cleaned. I've cleaned and taken reads on thousands during my career and found most of the time cleaning would do it. Always take reads on millivolt system. Your meter is your best friend. Also you must know pilot generator values. 250, 320, 750 you must know which is which and if it is the proper one for the sytem you are working on. So often a h.o changes the tstat and installs the wrong one or doesn't set the right one up properly.

  5. #5
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    Quote Originally Posted by mike3 View Post
    I say 10%. Chances are it needs to be cleaned. I've cleaned and taken reads on thousands during my career and found most of the time cleaning would do it. Always take reads on millivolt system. Your meter is your best friend. Also you must know pilot generator values. 250, 320, 750 you must know which is which and if it is the proper one for the sytem you are working on. So often a h.o changes the tstat and installs the wrong one or doesn't set the right one up properly.
    If it's only 10% then the common HO strategy of changing out the pile by default only makes sense if the pile costs 10% of the valve.
    And it might, I guess.

    You have links to spec's for the 250 mV and 320 mV piles? How 'bout to gas valves where they show the coil resistance or current?

  6. #6
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    Quote Originally Posted by WhoIsThat? View Post
    If it's only 10% then the common HO strategy of changing out the pile by default only makes sense if the pile costs 10% of the valve.
    And it might, I guess





    You have links to spec's for the 250 mV and 320 mV piles? How 'bout to gas valves where they show the coil resistance or current?
    No i don't at this time, however G250-251 are used in wall furnaces, as are 750's more commonly known as PG-9. The G250 is a low input type pilot and it gets dirty very easily. The PG-1 (320mv) has been around at least 70 years I would guess, and it is used in B-60 type systems where there is only an operator to energize, no pilot safety involved. The PG-9(750mv) also has been around at least 50 years, it was to be the replacement for the PG-1. In fact when you purchased a PG-9 it would have an adapter plate available, so the mounting would mimic the PG-1. The PG-9 is used for controls that also incorporate a pilot safety. Remember these values are for factory fresh and open reads. I'll see what I can dig up.

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