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4 taco valves w/ 50va transformer

just added a forth zone to my house.Replaced the old 40va trans with a 50.Wired just like the old.Three zones wiork perfect.One zone is wild Valve opens when the boiler fires and will not shut off.The others work fine.Do I have a bad head or is there a differant way to wire the 4 zones other than diagram on the valve head.Taco shows using 2-40's.I used 1-50.I think the wiring must be the same or am I wrong.Thanks


  • carol_3
    carol_3 Member Posts: 397

    (message from Antarctica) Here's the simple math. Multiply the amp draw of one valve (they're all the same, right?) by 24V for the VA of one valve. Then multiply that by 4 for 4 valves. That needs to be less than your 50VA.

    Then make sure that your new valve is in a circuit made up the valve, its thermostat, and the transformer. The other valves and thermostats connect to the same transformer, but not to anything else.
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