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Are thermostatic vents necessary on two pipe system dry returns?

tlowc34
tlowc34 Member Posts: 75
edited February 2020 in Strictly Steam
Open pipe would work, right? Steam shouldn’t be in the dry return unless boiler pressure is too high and you’re flash steaming in the return. No?

With coal I can understand. But with natural gas and building insulation creating really short cycle times the thermostatic function seems unnecessary. I would almost think you want an indicator of steam escaping the dry return to know you have a bad trap. But I’m a noob, so I’d love to discuss.

Comments

  • JUGHNE
    JUGHNE Member Posts: 10,282
    On larger systems with +1 million btuh boilers, I have put tees with open riser pipe as high as possible. Those had multiple dry returns to a cond pump. If steam showed up coming out of any of these risers, the area of steam trap failure could be narrowed down. All the risers were in the boiler room so as to protect finished areas.

    On a smaller residential system that was gravity return, I did install G2 vents. The HO may not notice any steam passing if it happened.
    So if you visit your boiler room often you may see if you are passing steam.
    A goose neck fitting set up with 2 90's would have any cond dripping go back down to the return pipe rather than spitting up to the ceiling.
    tlowc34
  • Jamie Hall
    Jamie Hall Member Posts: 20,439
    Not only would open pipe work -- it frequently did in some older systems. Still, it's not a bad idea to have a vent -- like @JUGHNE , a G2 is a very good choice -- and on some vapour systems (Hoffman, for instance) a vent is actually required -- but isn't there for the reasons you might think.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    tlowc34
  • tlowc34
    tlowc34 Member Posts: 75
    Mine is a Trane system with the milk jug sized return trap still in place (but possibly leaky, sight glass is dry). Similar to Hoffman?
  • Jamie Hall
    Jamie Hall Member Posts: 20,439
    Vaguely... take a look in The Lost Art. They're both in there -- both vapour systems.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England