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Hydronic boiler controls

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Hey guys I wanted to know what this component is on this Weil-McClain 140000btu hydronic boiler. This piece is where I believe an air separator should have been because the system doesn’t have one. Instead this is about 20”


downstream of the expansion tank on the supply piping. I’ll also add a few pics of the boiler/piping itself.

Comments

  • hot_rod
    hot_rod Member Posts: 22,468
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    That is a swing check valve. A flapper inside slides down when the circulator stops tom prevent unwanted flow
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,829
    edited December 2021
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    Flow check valve

    And if you only have one zone and no domestic hot water from the boiler you don't need it
  • neilc
    neilc Member Posts: 2,715
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    is that expansion tank supported?
    or just dangling at the top of the 1/2 inch copper?
    please support me
    known to beat dead horses
    HVACNUT
  • GeoKnight
    GeoKnight Member Posts: 6
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    neilc said:

    is that expansion tank supported?
    or just dangling at the top of the 1/2 inch copper?
    please support me

    You cant see it but the horizontal pipe it’s connected to it clamped to the floor joist.
  • GeoKnight
    GeoKnight Member Posts: 6
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    Flow check valve

    And if you only have one zone and no domestic hot water from the boiler you don't need it

    So it has about 5 baseboards with no zoning they all branch from the main poorly insulated pipe you see with no domestic water zoning. So I suppose I can put an air separator in place of that?

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,829
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    Maybe they had domestic hot water off the original boiler but with only one zone and no DHW off the boiler you don't need it