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SR501 and powerheads

I want to wire in a taco powerhead zone valve with the Thermostat and SR501 single zone relay. Thermostat does not require power. I'm confused about how to rework the wiring. Right now the wire just comes off the TT in the SR501 to thermostat. But to power the zone valve do I now have to use the 24v com terminal next to TT?


  • STEVEusaPA
    STEVEusaPA Member Posts: 6,506
    What other controls/zones do you have? What's running the circulator? You could probably work it off of your aquastat, or you should use a zone valve control.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,816
    I'm a little confused.
    What would you be doing with one zone valve?

    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • GroundUp
    GroundUp Member Posts: 1,903
    The SR501 is a switching relay to power a 120v circulator, not a 24v zone valve. You would need a transformer to power a zone valve, but why are you wanting a zone valve in the first place? The thermostat should power the circulator on and off with heat call, no need for a ZV unless you've got some funky stuff going on
  • rockdan
    rockdan Member Posts: 1
    I have the same set up and use the zone control valve to keep the hot water from thermal siphoning from my indirect tank throughout the house when sitting idle. Ive been set up successfully this way for years, something electrical just failed (either a power head or the SR501) so now I am starting from scratch. Is there a better way and how should i wire this?
  • Zman
    Zman Member Posts: 7,569
    Flow checks that are either independent or integral to the circulators will solve the problem.
    IMO zone valves add unnecessary complexity to the system.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    EBEBRATT-Ed Member Posts: 15,510
    One heating zone and one indirect mean you have two zones. If you have two circulators you need two flow checks. If you have 1 circulator you need two zone valves