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Gravity System

TomE Member Posts: 5
My Technician ran into a gravity system not circulating. Sent me a picture of one of the radiators and this is going into one side of the radiator. One side is supply and the other is return. Any thoughts on how this works? I thought maybe he has a plugged vent on the highest radiator which he is going to check today. System has been working and we are not trying to reinvent it just trying to fix and understand.


  • Jamie Hall
    Jamie Hall Member Posts: 23,656
    Two of these things in a month? That looks like a Honeywell Unique. Delightful contraption. There is a lance attached which goes inside the radiator, and the water coming in goes through the lance to the far end of the radiator and then goes through the radiator and the goes out the outlet. Works fine. Works the other way around, too.

    The valve part controls the flow...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • TomE
    TomE Member Posts: 5
    Awesome! Thanks for the info.
  • Erin Holohan Haskell
    Erin Holohan Haskell Member, Moderator, Administrator Posts: 2,346
    Here's a video on Honeywell's Unique Valve and how it works: https://youtu.be/yMezi-cnVKs?si=TmR_U3r-xpPwhIsA

    Mark Honeywell invented the Unique Valve in the early 1900s. It gave him a way of connecting a hot-water radiator at just one side instead of two sides. The Unique valve opened with a quarter turn and used a baffle to direct the water into the radiator. The cooler water flowed by the hot water and entered the Unique valve on the other side of the baffle.


    Mad Dog_2
  • Mad Dog_2
    Mad Dog_2 Member Posts: 7,250
    Ingenious!  These men were.  Mad Dog 🐕 
  • TCon
    TCon Member Posts: 1
    Will that honeywell unique valve work if we are to convert to a forced circulation