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can i reduce a 1 1/2" steam valve to smaller TRV?

I am replacing the shutoff valves for several radiators that are 1 1/2 inches. It's a 2-pipe system, Weil McLain LGB-11

I was thinking of going with a TRV, but I can't even find anything that is 1 1/2 size. I do see a 1 1/4 size.
Would this be okay to do?

Could i even just reduce it down to 1"? Is there a rule that I can use to understand what I can do in terms of reducing steam coming in?



Comments

  • Steamhead
    Steamhead Member Posts: 15,760
    What type of system is this? Post some pics of the radiators in question...................
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • Danny Scully
    Danny Scully Member Posts: 1,396
    1-1/2” for a 2-pipe system? Could be 2-pipe air vent?
    JohnNY
  • mikeg2015
    mikeg2015 Member Posts: 1,187
    Might have been a vapor system. You need oversized pipe for vapor... whether 1 or 2 pipe. Condensate in 1 pipe really is a minimal amount of volume. It’s just a trickle of water. A 250k BTU boiler is making less than 0.5 GPM of condensate spread over a dozen radiators.
  • rhodebump
    rhodebump Member Posts: 149
    Here is a picture of the radiator and a picture of each side.

    2 pipe, shutoff valve on the intake, a steam trap on the tail end.





  • rhodebump
    rhodebump Member Posts: 149
    here is a pic of valve before i took it off

  • Jamie Hall
    Jamie Hall Member Posts: 20,462
    Problem. That valve you removed is matched to the spud in the radiator; you can't replace the one without replacing the other. The new valve -- of any size -- will come with a matching spud. What you have to do is somehow get the existing spud out of the radiator -- which is much easier said than done -- and install the new spud. You may need bushings to reduce the radiator thread size to the new spud.

    Yes you can go down to 1 inch. I wouldn't go smaller. Not sure if TRVs come with the necessary matching spuds...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • SuperJ
    SuperJ Member Posts: 605
    I thought you put TRVs on the vent of a steam radiator, not the steam pipe. But I'm not a steam guy.
  • ChicagoCooperator
    ChicagoCooperator Member Posts: 327
    SuperJ said:

    I thought you put TRVs on the vent of a steam radiator, not the steam pipe. But I'm not a steam guy.

    That's for one pipe steam - this is a two pipe system where you put it on the inlet (in other words, there is no vent on the radiator in this circumstance).
    ethicalpaulSuperJ
  • Jamie Hall
    Jamie Hall Member Posts: 20,462
    I might add to my previous comment -- you will find that adding TRVs causes the boiler to see less radiation when they are closed. This may lead to some short cycling on the boiler. Further, a TRV on a steam system can reduce the heat output of a radiator -- by turning off the steam -- but it can't increase it.

    Is this a balance problem? Because if so, and it is desired to have these radiators simply produce less heat, the solution is simple: partly close the inlet valve. That works just fine on two pipe steam.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 13,136
    Find the EDR of all radiators you want to put TRVs on. Find the steam pressure you will run at. Then size the TRVs with the MFG help if need be.

    The right size will work a lot better. I would suggest Tunstall Associates in Chicopee, MA. Google them