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Chattering check valves

Simply RadSimply Rad Posts: 161Member
Good morning all. Just as of lately, my last 2 jobs, I have been experiencing chattering check valves. One of the system's sounds like the group of Magpies that live in the tree outside my window. I have them install on the return piping after the distribution system. The checks are spring style.
Jeffrey Campbell


  • STEVEusaPASTEVEusaPA Posts: 3,166Member
    edited June 7
    Kind of wondering, but do you really need one with that piping configuration?
    If your are experiencing thermosiphoning, maybe trap it with a loop/bend and forget the check valve, or put a check in the circulator (seems like a big circulator).
  • hot_rodhot_rod Posts: 11,763Member
    More info about the type of check. What is the Cv rating?

    Air in the line, turbulent flow condition, or inadequate gpm to hold the check fully open, are the main causes. It is becoming more of an issue with variable speed circulators.

    Most hydronic specific checks should work, regardless.

    They should have about 1/2 psi "pop" requirement, conical shape, small travel distance and a soft seat. These features make it seal tightly, open with minimal flow, not induce water hammer, and not cause turbulence.

    Here is a new offering from Caleffi to address all the issues with hydronic checks. They are not in the catalog but are available in 1/2- 2" with a choice of tailpieces.

    With piping vertical like that it is wise to check both S&R. Or deep drop thermal traps as Steve mentioned, it may require 3' drops to assure adequate protection.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • EYoderEYoder Posts: 57Member
    edited June 7
    I've had trouble with chattering check valves on one model that the internal part is only supported on one end. It wobbled. Switching brands stopped the issue.
  • Checks with brass seats will chatter. I always order mine with teflon seats and don't have a problem.

    I like the looks of the Caleffi checks. The unions!
    Often wrong, never in doubt.

    Click here to learn more about this contractor.
  • HVACNUTHVACNUT Posts: 2,404Member
    Your diagram is showing radiant manifolds. Is that what's there?
  • gennadygennady Posts: 758Member
    Move check valve to outlet of the pump, before manifold. Adjust flow to proper GPM.
    Gennady Tsakh

    Absolute Mechanical Co. Inc.
  • Simply RadSimply Rad Posts: 161Member
    Hello Everyone.

    Sorry late responses. The CV is 33. I spoke with Grundfos and they do not want the check valve installed on the outlet of the pump. Grundfos want the check installed on the inlet. I will look into the the tephlon seal. HR do you have a part number for the Caleffi check valve. Yes they are radiant manifolds. The main reason for the check valve is to ensure that when the DHW pump is energized it does not pull fluid backwards from the radiant floors. What type of check valves would you recommend with variable speed pumps?

    Thanks Jeffrey
    Jeffrey Campbell
  • hot_rodhot_rod Posts: 11,763Member
    Yeah, I'm not so sure about a check on the suction side of a circulator? Seems like an invitation for cavitation?

    Well pumps sometimes have suction side checks, like the foot valves down the well.

    Here is the list of what Caleffi has available. These are hydronic specific check valves not unlike the checks that ship with most circulators nowadays. I suggest the check installs 8-10 pipe distances away from the circ discharge as the best location.

    You could mix and match connections on these checks, FIP X press or pex for example. Both the crimp ring and expand pex 1960 ( Uponor, Rehau) style adapters are available.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • Jamie HallJamie Hall Posts: 10,845Member
    A thought on check valve location... more from a general practice point of view. It is generally better not to put any kind of flow disturbance within the mentioned 8 to 10 diameters of the intake of a centrifugal pump -- although some things, such as swing checks and globe valves, are much worse than others. Beyond that distance, it really doesn't matter -- provided (and potentially a big if) you have adequate NPSH at the inlet.

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • Solid_Fuel_ManSolid_Fuel_Man Posts: 1,649Member
    Could you move the check to the other end of the zone? Assuming you have the pump on the supply of the zone, then the check would go on the return.
    Serving Northern Maine HVAC, and Controls
  • Simply RadSimply Rad Posts: 161Member
    I installed the new serviceable check valves from Caleffi and problem solved and system chattering is gone. That is all I will use from now on. thanks for your help
    Jeffrey Campbell
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