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Does Return Piping need a Drop

Bruce M.
Bruce M. Member Posts: 143
In a multi-zone hot water system that has 3 drain valves on the return piping, how much, if any, drop should there be in the return near boiler piping? The system has 3 circultors that pump away.


  • Al Letellier_9
    Al Letellier_9 Member Posts: 929
    retrun drop

    I'm not sure what you're asking here, but in a forced hot water system there is no need to "drop" any piping. If you're refering to a trap, not needed. The flow checks should handle any off cycle flow.
    We do trap some piping in radiant systems to prevent "ghost flow", but I see no reason to do so in a FHWE system. E-mail me if I misunderstood your question.

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  • ron v
    ron v Member Posts: 9
    you mean something like this.

  • ecrist1
    ecrist1 Member Posts: 3
    Check valves work well enough

    It's more common to see it (heat traps) on the install guides for indirect heaters, but for the most part weighted check valves will stop gravity circulation and ghost flow in FHW systems. Keep in mind the size of the primary loop pump and T placement if you are doing primary and secondary pumping because it can sometimes lead to the same issues.
  • Bruce M.
    Bruce M. Member Posts: 143
    That is exactly what I was thinking about.

    Does the drain valve piping that you use have a specific purpose? I am referring to the loops at bottom and top. I realize that the supply and return are connected that way. Am I correct in thinking that the Tacos have the built in check valves.

  • ron v
    ron v Member Posts: 9

    yes circs have built in checks. i did not want to put check on return. some say put check on return some say no need. well i figured i would try this too see what would happen. plus purge valves are below circs out of way. and easy to get too. supply and reurn on super store have checks.
  • Bruce , I've installed

    thousands of circulators ( with and without IFC ) , and weighted flowvalves , and never dropped the return down or added a check valve on the return . I can count on one hand the problems we had with ghost flow . And every problem was solved by either changing the flow valve or increasing the size of it .
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