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Wiring change on Taco relay and triple aquastat ?

Thank you, for bringing this topic up. The change in wiring is to prevent the boiler from firing when the boiler is shutoff using a safety switch. If the ZR/ZR terminals are connected, and the switching relay is using another power source not connected to the safety switch the burner could still fire. For your reference I attached the published safety notice.
Joe Mattiello
N. E. Regional Manger, Commercial Products
Taco Comfort Solutions


  • I think this started a few months ago ?

    When integrating a triple aquastat with a Taco multizone relay , it used to be as simple as connecting a wire from ZR to ZR and ZC to ZC .

    Now you have to run ZR of the aquastat to X of the relay , and ZC of the aquastat to the other X of the relay , with a jumper to ZR .

    Why the change in wiring ?
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