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Is this an auto fill?

tjdumez Member Posts: 10

The part on top is my pressure reducing valve, I know that much. Is the device on the bottom an auto-fill device? It has to be, as the only wire coming out of it goes to my LWCO. It makes a buzzing noise and was hot so I disconnected the wire, but it wasn't adding any water or doing anything at all. I test the LWCO and drain a little water every 3-4 weeks so I don't really care to have auto fill, I just want to know if that's what that is and maybe an explanation of how it works

This caught my attention. That copper pipe is my water supply and presumably how I add makeup water to the boiler. Is there a purpose to that valve at the end? I haven't opened that in the four years I've lived here.

Here are some more pictures. The corrosion around the unions is annoying, anybody see anything worth noting?


  • GGross
    GGross Member Posts: 1,050
    the pressure reducing valve is the autofill
  • hot_rod
    hot_rod Member Posts: 22,158
    a solenoid valve below it
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Jamie Hall
    Jamie Hall Member Posts: 23,324
    Actually the solenoid valve which was buzzing is the autofill -- the pressure reducing valve takes the stress off it (it would be regarded as an autofill on a hot water system, @GGross , but this is steam).

    The odd valve mentioned at the bottom of the fill line can be used to drain the boiler. If it works, which it probably doesn't.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,852
    edited February 20
    I see only one black wire from the Solenoid valve ?!?!? How was this valve Wired? I hope the original installer didn't just send a 120 VAC hot wire from the LWCO alarm switch, and connect the Neutral (usually white Wire) to ground to complete the circuit. That would be a real Dunce move. Is there a way to get a picture of where that black wire goes inside the junction box cover on the valve.

    Edward Young Retired

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