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Zv valve ghost flow

kcopp Member Posts: 4,440
Anyone ever had a problem w/ ghost flow in a system w/ the Taco 571 zone valves? I have a system where this appears to be the case. I have exercised the plunger to make sure nothing is stuck and changed out the ZV head.


  • lchmb
    lchmb Member Posts: 2,997
    one or two over the years..
  • Joe Mattiello
    Joe Mattiello Member Posts: 707
    Good morning
    The 571 heat motor zone valve is a fail closed valve, so not likely to have ghost flow. However, it has a maximum shut off head of approximately 60 ft/hd, so if your system pump differential pressure is greater than shut off head, it will allow flow through?
    Try taking the head off, and see if the pipe gets hot on both sides of valve. You could have a faulty thermostat too. If it’s a perpetual demand, the valve will stay open. Not too much more that can go wrong with 571 staple valve.
    Joe Mattiello
    N. E. Regional Manger, Commercial Products
    Taco Comfort Solutions
  • hot_rod
    hot_rod Member Posts: 22,251
    with any valve it is possible to get debris stuck in the valve mechanism that could cause "leakage"
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • lchmb
    lchmb Member Posts: 2,997
    Joe I have had a couple over 20 years that have had leakage. As Hot Rod pointed out and I failed to, it's generally from either debris or mineral build up in the valve. Taco is still my go to valve...the sentry however is my new favorite preference..;)
    Dave H_2