Discussion in 'HVAC Heating & Cooling' started by g4s, May 9, 2010.

  1. g4s

    g4s New Member

    May 9, 2010
    I installed a new thermostat last night without turning the power off, and i have read that doing so may cause the transformer to short out. How do i tell where the transformer is and if that is the problem?
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    If you have a multimeter, it should be fairly easy. If I remember properly, measure between the red and white wires...if you have 22-30vac, it should be fine.
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  4. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona
    You would only damage the transformer if you shorted the lines while installing the new thermostat. Just touching two or more wires together would NOT necessarily short out the transformer unless it was the "wrong" two wires. Even then it would normally only happen if the transformer had an internal, or external, fuse. You probably have a miswired thermostat if it is not working.
  5. jimbo

    jimbo Plumber

    Aug 31, 2004
    San Diego, CA
    As to WHERE it is, if you have a forced air unit, air handler, or gas furnace, the transformer is inside that unit.
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