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gravity system

I've seen many of these in Baltimore. When dual (combined feeder and safety) valves came out someone got the dim-bulb idea they could handle the pressure by alternately feeding and then releasing water using the dual valve. This saved the cost of a tank. Trouble is, this wears the valves out, and if one of them gets stuck it could cause a leak or even an explosion.

Whenever I see one of these I sell the owner on a diaphragm expansion tank and a new dual valve and backflow preventer.


  • wilber
    wilber Member Posts: 4
    gravity system

    is it possible to have a gravity system without an exspansion tank a closed system
  • RoosterBoy
    RoosterBoy Member Posts: 459
    sure .

    pipe goes up the chimney does a u'ie and drops back to the basement floor any expansion runs down the drain.:)
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928

    Saw one in the St. Louis area. No circulator, no expansion tank. Was told they relied on the small amount of air trapped in the top of each radiator.
  • Ron Schroeder_3
    Ron Schroeder_3 Member Posts: 254
    I guess the gypo contractor is not a new phenomenon after all.

    I always thought that all the Dead Guys were good guys. Did you really have to disabuse me of that idea?
  • Doc Radiant
    Doc Radiant Member Posts: 57

    Yes and no. Some early gravity systems used an OPEN expansion tank in the attic, so it was an "open" system with an expansion tank.
  • yes but

    a closed system utilizing the little air pockets in the radiator tops? give me a break. The expansion tank in the attic is legitimate. Air pockets are not.
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