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Heat pump aux heat to zone relay

I have a heat pump setup with Neat thermostat.  All works great, heating and cooling.  The air handler does not have any aux heat / emergency electric coils.

I have installed a hydronic coil to the air handler to connect as zone 3 on the hydronic heating system.  Each hydronic zone has its own pump controlled by a Taco 503-4 zone relay.

I wired the W1 (alternate heat) from the Nest to the W on Zone 3 and the C on Zone 3 to the C in the air handler.  Note that R on zone 3 of controller is not connected.  

When the thermostat calls for Aux heat I see voltage between W1 and C, but zone 3 does not activate.



    HVACNUT Member Posts: 4,876
    R and W from zone 3 in the SR503 go to Rh and W on the Nest. The Nest will recognize it. Remove the Common you added. What activates the fan with the hydro air? If you didn't install an aquastat then set the Nest to bring the fan on. 
  • skippy76
    skippy76 Member Posts: 4
    Thanks.  The Nest activates the Fan.
  • skippy76
    skippy76 Member Posts: 4
    Thanks again, this resolved my issue.  I now have hydro air for when it is more efficient / not possible to run the heat pump.