Grundfoss Alpha 2 always on

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Le John
Le John Posts: 250
in THE MAIN WALL

Happy Holidays all,

I have a Grundfoss Alpha 2 wired into a Taco 4 Zone Value controller. This morning, I noticed the pump was running with no call for heat. I turned the thermostat zone on and the boiler fired and then back off the boiler stopped running and the pump shut off normally. I've never seen this happen before. The pump is about 4 years old.

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  • hot_rod
    hot_rod Posts: 28,705

    Somehow the relay in the Taco box is sending 120V to the circ.

    Does the relay box have an exercise function enabled? That allows the pump to run occasionally without a heat call.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream

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