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What Vapor System is This?

Harry_6 Member Posts: 128
OK, I am perplexed. I recently looked at a home from the late '20's that had a pretty standard looking Vapor or Vapor/Vacuum system in it. A small house, probably under 2,000 square ft. a steam main that splits at the boiler, with each half following its half perimeter to where they rejoin. No vent on the steam main. Return mains follow the same route and are vented with one main vent (currently Hoffman 75, for what its worth). Both are dripped into a wet return (return main through a check) which returns to the boiler. So far, as common as dirt. The thing is, the radiators have original valves marked "Michigan Lubricator Co. Patent Applied for", but there are no traps or outlet gizmos like a Mouat, Broomell, etc. There is just a standard 1/2" union 90, like it was a hot water system. And upon examination I cannot find any evidence that it's an orifice valve. It looks like a common packless valve with a rising disc against a flat seat. Both the valve and return fitting have the same insignia with a superimposed M-L-C-O. The valve handle is an unusual shape, sort of like a toy top, and made of semi-hard composition of some sort. You see the problem! I see no restriction in the valve, no sign of an orifice plate, and no trap. I don't have pictures at this moment, but will attach some asap. Anybody got a clue?


  • Steamhead
    Steamhead Member Posts: 15,348
    These may be orifice valves that regulate steam flow by changing the height of the disc above the seat, instead of using a shutter or orifice disc. I bet if you put a Vaporstat on that boiler you'd be able to find a suitable ounce pressure level that would keep steam out of the dry returns. Where are you located?
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • mattmia2
    mattmia2 Member Posts: 5,539
    If this is your valve, you have to take the whole thing apart to replace the bib washer:
  • dopey27177
    dopey27177 Member Posts: 873
    See enclosure.
    Although this a Dunham Vapor system there are piping requirements common to all Vapor systems especially where the check valves are at the lower end of the return. Often in very old systems these check valve are changed are not clean of debris. It is essential that these check valves work properly as they permit the condensate to reenter the boiler.

  • Harry_6
    Harry_6 Member Posts: 128
    If there was anything fancy like a return trap at the boiler it is long gone. The wet return goes into the Hartford loop and that's that. At the drip end, there is a check to allow the condensate in the return main into the wet return, but keep the drip from the steam main from back-feeding it. Pretty standard. Here are pictures. It had occurred to me that it might be one of those valves that limits the height it can raise above the seat, but I haven't tried to dissect it yet. I don't know what else it could be. The return fitting has no P-trap or orifice, it's just an elbow.

    The boiler piping is all new and done perfectly, right down to the cast fittings.
  • dopey27177
    dopey27177 Member Posts: 873
    Do the radiators have vent valves on them?
    If so this could be a two pipe steam system with one pipe steam rules.

    If not I cannot name this steam system as it could operate at Vapor or lower steam pressures.

    As for the check valve it separates both returns so condensate will flow in direction.

  • ethicalpaul
    ethicalpaul Member Posts: 3,739
    Harry_6 said:

    The boiler piping is all new and done perfectly, right down to the cast fittings.

    We love to see pictures of perfectly-done boiler piping, hint hint!
    1 pipe Peerless 63-03L in Cedar Grove, NJ, coal > oil > NG
  • Harry_6
    Harry_6 Member Posts: 128
    No, the radiators are unvented (except for one done recently by a screw-up contractor). And there is just one system main vent, visible in the last photo. Sadly, I don't have any boiler photos presently. It's crammed in a closet, making photos difficult. I guess all I can do is wait 'till heating season and see if the returns get hot. It might tell me if those are some kind of metering valve.