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Help identify a steam trap

deoreo Member Posts: 1

First post. Just turned on the steam heat in our "new" old home. Had a local steam heat contractor clean, service, and check over the system. Everything is in great shape, and working wonderfully- quick heat, and crazy silent operation- no knocking, banging, etc.


All of the radiators are heating, except for one. The contractor said it is the thermostat in the trap of that radiator, and to replace it would require a complete new trap- housing, cap and thermostat. I believe there has to be a replacement thermostatic cage avaliable for the existing housing.

It is a two pipe system, with all Trane supply valves and traps. How do I identify my traps? Two pics. attached.


  • Steamhead
    Steamhead Member Posts: 16,832
    That's probably a Trane B1 trap

    you might find the B1 cast into the body on the side facing the wall.

    You can still get parts for these, but you'd need to know if the bellows was removable from the cap or not, and whether the seat (at the bottom of the body) is integral or removable.

    Both Tunstall and Barnes & Jones make replacement kits for all these B1 variations. It's better to rebuild rather than replace if you can, since you avoid breaking anything by trying to remove the trap body from the pipe and radiator. But if you must replace, a Barnes & Jones #122 trap will fit the B1's tailpiece (part that screws into the radiator) so you won't have to try to get that out.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
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