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Boiler transformer 24v but only getting 17 to reLay coil

Dairon421 Member Posts: 80
Hello guys Im getting 26 volts at the transformer. But when I test the wire going to the honey well relay I'm only getting 17v. Is the wiring messed up or do I have a weak transformer?


    EBEBRATT-Ed Member Posts: 15,764
    If your getting 26 at the transformer the trans is probably ok. Also check the 120 to the trans, should be 110-120 approx.

    You will have to trace the 24 volt circuit from the transformer to the relay. I would disconnect the two wires to the relay coil (with the power off of course) otherwise you will get backfeeds which will make troubleshooting more difficult.

    Put one meter lead on the transformer with the power on on one wire and follow the other wire with your meter lead until you get to the realy coil. If no problem follow the other wire. Could be thermostat, vent damper etc.
  • Jamie Hall
    Jamie Hall Member Posts: 23,554
    Keep in mind that low voltage at the relay can be caused by poor connections anywhere along the line, as well as switches which are compromised. However, there is another possibility. If the transformer is overloaded on current draw, it may not necessarily burn out, but the output voltage will drop. This is caused by internal resistance in the transformer itself, and can only be fixed by eliminating the excess load or replacing the transformer with one rated for the load.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England