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Zone Valve location question:

Please forgive my ignorance, but I have a question regarding zone valves.

First, there seem to be several opinions on how to stop ghost/gravity flow when a zone isn't calling for heat. Some people belive a swing check should be installed on the return side of each zone, others say to create a thermal trap. It is my understanding that swing checks tend to chatter.

My question is this:

Can I install the zone valves on the RETURN side of a secondary loop and use a TACO 007 with integral flow check on the supply side? Why/Why not?

Thanks and sorry if there is an obvious answer to this question.


  • hr
    hr Member Posts: 6,106
    Sure you can

    but a soft seat spring check would also work, be less expensive, and would not require power to operate. Yes, swing checks, even on a vertical line, tend to be noise makers in hydronic systems.

    Flow check, the weighted type, are another non electric option.

    hot rod

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  • I'd choose either method

    Using IFC circs on the supply and zone valves on the return is overkill , in my opinion . We are new to using IFC circs so I'll reserve my opinion about them bypassing . But before them we used either regular Tacos with weighted flowchecks , or zone valves above the system circ on the supply . No check on the return , ever . Never had a problem with heat bypassing , except for crud getting stuck on the flowcheck . And that was one in thousands of zones installed .
  • paul sr
    paul sr Member Posts: 39

    Just curious, why no flow check on the return? Paul sr.
  • Never needed one there

    The weight in the flowvalve holds the hot water down on the supply side . It's also a flowcheck , stopping flow going in reverse . I've personally seen less than a handful of heat bypass problems , we changed the flowvalve on the supply and stopped the problem right there . I would guess you could get heat up from the return if some radiation is close and higher than the boiler , but I've not seen that happen yet .
  • hr
    hr Member Posts: 6,106
    Primary secondary

    piping adds some different flow dynamics than a basic pumped series piped boiler. Those generally work, without ghost interference :) with only one side protected.

    In primary secondary there are a number of forces trying to rob BTUs from the primary loop. Often unbeknownst to the operator. I would highly recommend protecting both supply and returns on all secondaries piped from a primary loop.

    In this link are some methods shown with pictured examples.


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