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Connecting taco sr501 and hydrostat 3150

benmoussa3 Member Posts: 2
edited January 2022 in Thermostats and Controls
Hi I have a tankless and circulator 1 on Hydrostat 3150 and another zone on Taco SR501, zone 1 works perfectly, however Zone 2 turns on the Circulator 2 but it doesn't fire the boiler... whoever made this install used the Typical Wiring (Cold Start) and didn't connect 6 (N/O) and 5 (COM)... what should I do in this case? I would like Zone 2 to fire the boiler if thermostat is calling for heat. Thanks

Note: TT on boiler is already used by Zone 1 Thermostat


  • Jamie Hall
    Jamie Hall Member Posts: 23,276
    I wonder if this is the whole of the wiring? But if it is, there's no reason you can't connect 5 and 6 on your zone relay to T-T on the boiler in parallel with any other thermostat or relay (not, however, in parallel with the one already controlling the same relay...)
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Robert O'Brien
    Robert O'Brien Member Posts: 3,541
    If you want the reverse function of 3150 to operate with both zones, wire per middle diagram, if you just want zone 2 to bring on burner, run power from #4 terminal of 501 to ZR on 3150
    To learn more about this professional, click here to visit their ad in Find A Contractor.
    HVACNUT Member Posts: 5,829
    Use this one.
  • benmoussa3
    benmoussa3 Member Posts: 2
    Thank you all
  • jennis
    jennis Member Posts: 1
    Hey did you ever get this working on your existing equipment? I have the exact same thing that I’m trying to do. Thanks!