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What kind of purge/valve is this? Connected to return pipe.

On my boiler return pipe(which is giving me problems). There's this valve it looks like something to help purge air/dirt out of the system. Do you just hook up a host to this and open it up while turning on manual water intake?

Any help appreciated.


  • ChasMan
    ChasMan Member Posts: 459
    That looks more like a drain than a purge.. Generaly purging involves forcing fresh water through the system and out through a drain until there is no air. Then you close off the drain and let the air separator deal with the remaining air. If that is your only drain valve then it is likely a purge. Would be better if you showed more of your piping.
  • Gordy
    Gordy Member Posts: 9,530
    That looks like a Flow/balance valve. However in that position it would be open if it were. Was there a return line from an emitter in the system that may have tied into that at one time?
  • Michael60622
    Michael60622 Member Posts: 9
    It's just a real old system. This is the return pipe from the radiators in the basement to the boiler. So it goes maybe 10 feet out into the basement to a 90 degree bend then 30 feet to the opposite edge of the building then about 15 feet to the boiler. So it's kinda long uninterrupted run. I think this was a coal system before hot water.

    As far as I know it was never hooked up to anything else. At least not since 1979.

  • Michael60622
    Michael60622 Member Posts: 9
    Wait a second. If cold water goes down and it hot water floats could this be some purge because of how low these pipes are? These are like the lowest pipes so the water has to fight it's way past the hotter water to get back to the boiler.
  • Gordy
    Gordy Member Posts: 9,530
    edited December 2017
    What problems are you having?

    Purging has little to do with the buoyancy of water at different temps.

    You purge to flush dirt out system. Usually done only when a new boiler is installed.
    You purge to get air out of the system. Usually after a drain down of system to perform work if necessary.
  • unclejohn
    unclejohn Member Posts: 1,700
    Thats a balancing cock.
  • Michael60622
    Michael60622 Member Posts: 9
    This return pipe has to go up then to a T where it meets with another return pipe that's hot. So I'm thinking this was something you had to adjust to get the return(s) to all balance together and go back to the boiler.

    If hot water floats on top of cold how is the cold going to compete against the hot water in the other return pipe to ever make it to the boiler again?
  • Michael60622
    Michael60622 Member Posts: 9
    Bleh I just has to turn off the radiators on the top floor wait for the heat to go thru the bottom floors, about 30 minutes. Then slowly turn on each top floor radiator one at a time and that fixed it. So as far as the valve goes if it ain't broke don't fix it.
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