Add C wire to Argo AR821-T

Discussion in 'HVAC Heating & Cooling' started by Frederick, Dec 1, 2019.

  1. Frederick

    Frederick New Member

    Joined:
    Dec 1, 2019
    Location:
    MA
    I searched for this topic, and while a few similar questions came up, none of the responses appear to work for me. I have a 30-year old Peerless boiler with 3 zones. In order to add a Ecobee thermostats, I have to add a common wire to all zones.
    The thermostat relay (an Argo AR821-T) has a 24V transformer, and measuring between T and P (red wire and the closest P terminal) I get ~30V. When I hook up a wire and feed it to the C terminal on my thermostat however, nothing happens. I tried attaching it to the other P terminal as well, which makes no difference. What am I missing?

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  2. Stuff

    Stuff Well-Known Member

    Joined:
    Mar 7, 2013
    Location:
    Pennsylvania
    You likely need to swap the red and white wires.
    For that unit R is on the left, W is next to it, then another R, then C on the far right.
     
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  4. Frederick

    Frederick New Member

    Joined:
    Dec 1, 2019
    Location:
    MA
    That was dead on Stuff! Thank you so much, everything works now!
     
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