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What am I looking at here?

AK_TK Member Posts: 1

Can anyone help identify what this is? All I have been told is that it is installed on a hydronic heating system here in Alaska.


  • bburd
    bburd Member Posts: 926
    That is a flow control valve, a weighted check valve. It stops heat from rising out of a boiler by gravity flow into a hot water radiator system after the thermostat stops calling for heat and shuts off the circulator pump.

    The normal setting is in the middle, marked “winter”. If the lever is set to  “open”, the valve will stay open and gravity flow will be allowed; this is useful if a circulator pump fails, some heat will still be provided. If it is set to “closed” heat will not circulate.

  • Steamhead
    Steamhead Member Posts: 16,950
    The lever on that one has been broken off. It used to point to where it says "Open", "Winter" and "Close".
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,157
    edited December 2022
    Steamhead said:

    The lever on that one has been broken off. It used to point to where it says "Open", "Winter" and "Close".

    If the system is operating properly, then the broken handle would be pointing to WINTER
    Here is a short description of Flow Control Valves on page 8 of this
    booklet https://www.xylem.com/siteassets/brand/bell-amp-gossett/resources/technical-brochure/fh-z100b-bg-zoning-made-easy-2.pdf

    Flo-Control Valves Control Overheating,
    Not the Flow!

    Maybe “Flo-Control” was a bad name to give to this device back in the
    old days when we were converting gravity hot-water systems to forced
    circulation. The industry needed something that would stop the
    hot water from rising up into the radiators when it wasn’t needed.
    Hot water will do that, you know. It’s lighter than cold water.
    But the name Flo-Control valve makes some guys think they can
    balance a zoned system by turning the top levers on the valves.
    That’s not what those levers are for.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?