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zone control valve by-passing

Joe Mattiello
Joe Mattiello Member Posts: 703
I'm very surprised to hear you are having problems with bypass using a taco flow control valve. Perhaps there is a piping practice where the pressure drop is so high, that may be contributing to the bypass? Why don't you give me a call to discuss it?
Taco, Inc.
Joe Mattiello
Technical Service Technician
[email protected]
401-942-8000 X 484
Joe Mattiello
N. E. Regional Manger, Commercial Products
Taco Comfort Solutions


  • Nick_18
    Nick_18 Member Posts: 1
    flow control valve by-passing

    i need help i have a 2 zone sytem with 2 circ pumps controlled by t-stats one on the first floor one on the second...the upper zone is constantly by-passing...i have removed air from the upper zone several times through the vent. the system psi is 12 so i am not introducing water/air through the tankless coil. the system is acting like a steam boiler on the second floor. the first floor is fine...the flow control valve was replaced...not the culprit...the circulator pump is not running...could this be an expansion tank issue..tank lost its charge?
  • R Stone
    R Stone Member Posts: 12
    Flo- checks

    Is thie just a regular swet-chek? We have had trouble with a lot of zones overheating with the Taco 219. Some times a cast check will help.
  • Bill Nye_2
    Bill Nye_2 Member Posts: 538

    What is the water temp. ° ? Natural convection, gravity flow. thermo dynamics, call it what you want.......... heated air or water rises, cooler air or water falls.

    Check the high limit setting, or low limit , and maybe you could lower it. Sometimes you just need to add a second flow control to the return side of the loop also.

    Make sure the nut on top is closed all the way, make sure the flow control is straight up and down or plumb and level. The weight can bind on the shaft and hang open.

    On some brands you can just change the "guts". Real hard to say w/o looking at it

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