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Trapping a mixing valve?

MikeyBMikeyB Member Posts: 696
Is it necessary to trap the Honeywell/Sparco AM101-US-1 Mixing Valve even though the literature mentions its not needed? (I'm thinking because  the Hot & Cold ports include check valves This Valve will be installed on a Super Store Indirect, thanks


  • icesailoricesailor Member Posts: 7,265

    The instructions for that valve are very contradictory. They come with the checks but tell you to heat trap it. Sort of. That one is the direct connect one (I think). If it has the checks, and it isn't heat trapped, it has never been problematic for me.

    When I find cross connections with hot and cold water, there are no checks installed. I put them in and the problem stops.
  • kcoppkcopp Member Posts: 3,596
    edited April 2012
    I have noticed....

    the last several Am- series mix valves w/ checks are very noisy.... Rattle. thoughts?
  • icesailoricesailor Member Posts: 7,265

    I haven't encountered that, YET.
  • MikeyBMikeyB Member Posts: 696

    Yes Ice, this is the valve that has the sweat union connections and the checks in the hot and cold ports
  • icesailoricesailor Member Posts: 7,265

    I have to purchase the checks separately because my supplier doesn't buy the valves with checks and no one uses them. Until I get a call for no hot water and I install them from the stock I bought.

    Calliffi mixers are nice but they don't buy then either. They stock 4 add on checks but I went to install two Calliffi's to replace two Sparco's with no checks and I was stuck without enough checks.

    Go figure.

    As far as the pounding, you may need a DHW Extrol on the system. I have a nursing home that I installed a CW check to keep it from backing out into the cold. It used to bang, even after I drilled a small hone in the clapper. I installed a big Amtrol DHW Extrol and the problem went away.
  • SWEISWEI Member Posts: 7,356
    trapping with check valves

    Is a safety thing, (hopefully) preventing a nasty scald risk.  You could say the lawyers made them do it.

    On commercial installs, I put a temp sensor in the mixed discharge line and alarm at 5-7F over the mixer setpoint.  Saves piping and a bit of friction loss, plus makes the tank easier to remove when the time comes for a replacement.
  • NYplumberNYplumber Member Posts: 503

    The mixing valves we install for dhw mixing (Honeywell), make a racket! We always use checks on those, so maybe that's where the issue begins. Other than the noise, they work well.
  • NYplumberNYplumber Member Posts: 503

    What brand / model alarm do you use?
  • SWEISWEI Member Posts: 7,356
    not a prepackaged product

    Just a temp sensor hooked to the DDC system and alarmed at setpoints.

    Dwyer and ACI and many others offer prepackaged solutions.
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