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Wiring a DPDT relay for a thermostat

Discussion in 'Electronic Basics' started by Pigcorn, Nov 1, 2003.

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  1. Pigcorn

    Pigcorn Guest

    Problem: I need to know how to wire a DPDT relay:


    My 2 wire heat system does not provide enough power to my 24vac home
    automation Thermostats. Basically all is fine until the thermostat
    calls for heat and then my zone relay uses too much power on the line
    to signal the boiler and end result is that my thermostats die and
    then reset and never finish the call for heat.

    Solution: to my problem above is to wire in a 24vac transfomer to the
    Red (power wire) of my thermostat and put it on a relay so that it
    only receives 24vac when it calls for heat. Otherwise the 24vac is
    constant and it heats up the thermostats and they then tell the wrong
    temperature since they are heating up!

    Question: I know I only need a SPDT relay for this and I am not asking
    an HVAC question. That solution is already solved. What I am asking is
    on my Omron MJN DPDT General Relay I have these terminals

    1 3 (1/7 connected 3/9 connected)
    4 6 (N\C)
    7 9
    A B (Coil Wire)

    How do I wire this. on the thermostats the R terminal is power and the
    White terminal is the trigger that calls for heat.

    Any idea?
  2. Hmmm, better dumb it down a bit so's we can understand what you are saying.
    Wiring a relay ain't much but all that "Thermostats using too much power"
    indicates a bit of a communication problem.
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