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Hot water heating control...? What is it?

DanBee
DanBee Member Posts: 3


I came across this during a site visit to replace a boiler. Residential Open hot water gravity system
the item pictured has Honeywell stamped on it
My guess is that it contains mercury in the bottom section and operates a check valve.
When the return water gets hot enough the mercury would rise and close. When the water would cool down, the mercury would drop and open the valve.



Comments

  • Zman
    Zman Member Posts: 6,812
    That is the jist of it. Lot's of mercury, so be careful.
    Dan has a better explanation in "Classic Hydronics"
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • DanBee
    DanBee Member Posts: 3
    Thanks for the Reply Zman. i remember seeing something similar years ago, I wasn't 100% on it. thanks for confirming.
    DB
  • pecmsg
    pecmsg Member Posts: 2,229
    Zman said:

    That is the jist of it. Lot's of mercury, so be careful.
    Dan has a better explanation in "Classic Hydronics"

    and Asbestos!