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  1. #1
    I am trying to understand a Rheem 80 Plus. The transformers keep failing. I have been using standard 24v 40va transformers although they are not the factory original. A local service company swapped it out with what he had on his truck. He modified the wiring slightly. Rheem calls for a 24v 40va but one lasted a year and another one lasted three days. Is the 40va simply under sized? I have never heard of transformers failing like fuses before?

  2. #2
    Join Date
    Sep 2002
    I don't know
    Having transformers blow is not a problem, it's a symptom.

    You have a low voltage wiring/control issue. Call a different company for service.

  3. #3
    There are two types of class 2 transformers used, one that's inherantly energy limiting (A shorted secondary will just heat up the transformer some) and the other that has some protective device built in (A shorted secondary pops the built-in protection device). You seem to have the latter where the transformer winding is blowing to protect the fuse.

    Transformer is likely intermittantly overloaded and not class 2 compliant. Not easy to fix.

    But then neither is a 15 KV @ 1A vaccum tube shunt regulated power supply. Fix has lasted 20+ years or so and counting. Used to blow a few components on the control board about every 6 months. When I inherited the problem, I said enough is enough and fixed it. Found the cause: loose connections, a 1 Meg 200 W bleeder resistor was popped and a few resistors in the divider where out of spec.

  4. #4
    Join Date
    Jul 2006
    NW burbs of Detroit
    So saying, we then found the 60k micro mhz Xmtr had to be re-calibrated to the duplex squelch gain control that subsidized the out put of the transceiver side. but when we fired it up we got a Dolby sound oscillation that created a sensible flux field around the 100k long-wire string assembly that let us talk to Pluto. (arf arf)
    That pissed off Mini who slugged Mickey who kicked Goofy in the ass for starting a family feud with Warner Bros with hated Popeye for doing Olive Oyl who had Sweetpea that Wimpy stole to buy a hamburger

  5. #5
    Join Date
    Nov 2006
    If a qualified tech cannot find the assumed intermittent ground which is killing the xformer, have him add an inline fuse and provide you with some spares.

  6. #6
    Join Date
    Dec 2006

    Thumbs up xformer

    put a fuse on each relay (wire), whichever fuse blows
    check that circuit for your problem,
    or put an amprobe around control wires
    and see which relay is drawing unusual ammounts of amps,
    if that dont work change the multiplex demodulator

  7. #7
    Join Date
    Apr 2005
    new jersey
    useing the voltmeter simply find the short.remove the low voltage wiring from the control board going to the t the problem external or internal.

  8. #8
    transformer ::= ersatz fuse

  9. #9
    Join Date
    Jun 2006
    You have an intermittant short in the output to one of the relays. If a tech simply replaces it, it will not solve the problem. He should first put a 1.0 amp fuse in the output of the new transformer after finding the wiring problem. At least, if it happens again you will blow the fuse which is a lot easier and acheaper to replace.

  10. #10
    I had the similar problem. Blew 2 tranformers before I found out what the problem was.

    I had a Electric thermostat go bad. It was not just closing the circut but somehow Powering up the line and blowing the tranformer.

  11. #11
    Join Date
    Mar 2003
    short in the defrost controls!

    oops what are we talking about.

  12. #12

    So your the guy that writes the unintelligible messages that try to get by the SPAM filters.

    You should have a guilty conscience by now.

    Shame on you.

  13. #13
    You could replace the furnace and find out that the problem is still there.

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