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  1. #1

    Two Bad Millivolt Generators

    Hello all. I use to be a swimming pool tech. many years ago and know something about gas heaters. A friend is about to get his 3rd Generator that I ordered online. I'm concerned if I just give it to him without ohm-ing everything out he'll just toast this one also.

    So, can the system short out the millivolt generator and ruin it?

    He took the book back to his house so I don't have the numbers here. Can someone give me a quick run down on what to look for and how TP , TC , and other things should be tested and how they work.

    I just know he'll want to install it right away and not give me a chance to scan the book again and figure out what is wrong with this fireplace before we have another dead generator.

    Thanks, part and labor are free for this guy.

  2. #2
    Join Date
    May 2005
    Location
    Madison, WI
    Posts
    1,078
    I dont know how one could fry a TP unless you hook it up to high voltage...

  3. #3
    Join Date
    Nov 2008
    Location
    port-land OR
    Posts
    111
    first off depending on the unit, some have both a thermopile and a thermocouple, if u have the thing apart and are replacing one might as well do the other as well, but as a free acct thats ur call.

    secondly whats happening that u think its frying? thats pretty hard to accomplish. they're typically pretty resilient creatures.

    a thermopile is simply a bunch of little thermocouples connected in series inside the thermopile. thus increasing voltage from 30 millivolts or so to 750 mv or whatever urs is.

    as far as testing...light the pilot, be sure its properly in the flame and check voltage at the connections. should be near the rated voltage of the tp/tc.

    test a t-couple the same way just put ur probes on the tip n ring on the end that plugs into the GV. u can get one of those little tester deals that plugs in between the t-couple and the GV but they come apart and i think they're a waste of time personally.

  4. #4
    Join Date
    Aug 2004
    Location
    S.E. Pa
    Posts
    6,049

    Exclamation qualified tech?

    I would not be ordering parts for someone else to install. You would be responsible should something go wrong.

  5. #5
    Join Date
    Nov 2005
    Location
    London, Ontario, Canada
    Posts
    268
    Some pilot assemblies can cook a t-pile. I have seen it once before. After 3 t-piles replaced I called the manufacturers distributor and they knew all about it and sent me a new pilot assembly which solved the problem.

  6. #6
    Join Date
    Apr 2002
    Posts
    1,383
    I'd get someone out there who can diagnose the actual problem, of which there could be several. Guessing and supposing doesn't seem to be cutting it.

  7. #7
    Join Date
    Apr 2002
    Posts
    1,383
    You also have my sympathies for working on swimming pool boilers. I generally hated that equipment, which was often poorly maintained and heavily corroded due to exposure to swimming pool chemicals, water and such.

  8. #8
    Join Date
    Feb 2004
    Posts
    2,456
    Quote Originally Posted by My77GMC View Post
    first off depending on the unit, some have both a thermopile and a thermocouple, if u have the thing apart and are replacing one might as well do the other as well, but as a free acct thats ur call.

    secondly whats happening that u think its frying? thats pretty hard to accomplish. they're typically pretty resilient creatures.

    a thermopile is simply a bunch of little thermocouples connected in series inside the thermopile. thus increasing voltage from 30 millivolts or so to 750 mv or whatever urs is.

    as far as testing...light the pilot, be sure its properly in the flame and check voltage at the connections. should be near the rated voltage of the tp/tc.

    test a t-couple the same way just put ur probes on the tip n ring on the end that plugs into the GV. u can get one of those little tester deals that plugs in between the t-couple and the GV but they come apart and i think they're a waste of time personally.


    Sorry, but I must disagree. Taking an open read may show a tcouple read of say 20mv, when in reality it is 0-2 or 3 under load. Also you need to take a dropout read on the valve power unit. The same apply's for PG's
    Your meter is your best friend.

  9. #9
    Join Date
    Dec 2006
    Location
    Portland, OR
    Posts
    18
    Yeah, I've seen quite a few TP's and several TC's tht failed only under load, and have to be tested into a load to see the fault on a meter.

    To save time, I made a little 2ohm shunt resistor on a 2 prong banana plug adapter that I can plug into my meter, then plug my probes into that.

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