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Why is Hot water passing into zones that are not calling for heat?

I have multiple zones (3), each with its own pump circulator (Taco 007-F5 with no IFC in it). Why is Hot water passing into zones that are not calling for heat? It is because there is no IFC in this pumps? Replacing it with a pump with IFC will solve my problem? Why this pumps let water go thru the pump when the pump is not used? Do I need to add an additional valve to stop water flowing thru the pump when is not used?

Thank you


  • CristianCristian Member Posts: 7
    Is not the IFC (Internal Flow Check ) inside of some pumps the same thing?
  • TechmanTechman Member Posts: 2,144
    edited September 2016
    A lot of times two flow checks are needed . One in the supply(circ) and one in the return line to prevent those "ghost flows". Carefully feel the copper lines going to/from the overheating zone to feel which line has the ghost flow. Or there is a "cross flow "from a running circ thru a non-running circ, due to piping problems.
  • CristianCristian Member Posts: 7
    None of the pumps have IFC and I see no other flow check in the system. And the equivalent Taco pumps with the IFC have the flanges rotated 90 degrees (why Taco, why?) and they are slightly longer. Can I have the motor not parallel to the floor but on top?
  • CristianCristian Member Posts: 7
    Because I don't want to start to cut the pipes, drain the system etc. Replacing the pumps looks easy and safe enough for me. I just hope this is the problem and not something else.
  • TechmanTechman Member Posts: 2,144
    Having a Flow Check in the supply piping has been normal for DECADES. All that you can do is try the circ w/ the IFC and see. If not, the re-piping is in your future.
  • CristianCristian Member Posts: 7
    ok..I changed the pump with one with IFC in it. I STILL get some heat passing the pump into the radiators.
    I guess the check valve stops the water flowing in one direction only (opposite the normal pump flowing), so I still have hot water creeping thru the pump into my system.

    So I guess I need an electronic valve to completely close the system when the pump is not working (or a pump with this kind of valve inside) and to open when I start the pump. There is such a thing?
  • jeffhornbyjeffhornby Member Posts: 3
    Just a zone valve will work
  • hot_rodhot_rod Member Posts: 13,205
    You really should not need a zone valve if the pump has a spring check installed. If anything a second check or flow valve on the return side of each zone. If you are getting ghost with a check equipped circ, it is usually through the return side. See if the return piping gets warm with the circ off. If so you need a check or flow control device on the return.

    It is rare to find a system the needs that much check protection unless it is mis-piped. Ghost flow is more common in primary secondary piping, not parallel loops like it seems you have.

    Make sure the pumps are in fact powering off, a stuck relay could be causing a circ to run when it should be off.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • CristianCristian Member Posts: 7
    good info..thank you
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