Click here to Find a Contractor in your area.
In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation.
Need to contact us? Visit

steam pipe size

yooper229yooper229 Member Posts: 2
I have just bought a new ( old) building with steam heat. One of the rooms was an addition over an old porch and did not have a radiator in it. I had a plumber install a new radiator in the room and hook up the pipe in the basement . They installed 3/4 inch to the new radiator, around a 10 ft run with three 90 degree elbows. but all the other ones in the house are 1- 1/4 inch pipe. Except a base board radiator in one room with 2 pipes ( all the other radiators in the house are one pipe. The new radiator won't heat up all the way across the fins only three closest to the intake heat up and the heat won't go all the way across the radiator. I have a new Hoffman adjustable vent on it and and have tried all the different settings. Question is the 3/4 pipe to low of a volume to work with my radiator?


  • BobCBobC Member Posts: 4,409
    That 3/4" pipe

    is small for normal steam use on a one pipe radiator, make sure all the new piping is properly sloped back to the steam main. Also how big (height, number of sections, and columns per section) is this radiator - post a picture of the radiator.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • gerry gillgerry gill Member Posts: 2,663
    interesting thing about pipe sizing

    in that in my research, i've come across many different charts, and they dont agree..i bet they all worked for the engineer is the catch, if one guys chart says you can use a 1'' pipe, and another guys chart says it should be 1 1/2'', you can only follow the charts if your doing the whole system..otherwise you had better get out and look at whats already there, as you don't want to increase or decrease the path of least resistance..or you will increase or decrease the result too! Did that make sence? In an existing structure what someones chart says, means less than following suit with whats there. Also, if the other rads are 1.25'' and only have a couple elbows in the runouts and they are short, you will need to upsize that horizontal portion of the runout to compensate for the extra elbows.

    Serving Cleveland's eastern suburbs from Cleveland Heights down to Cuyahoga Falls.

  • yooper229yooper229 Member Posts: 2
    thanks for response

    I will take pics of the radiator and pipes on run today and post tonight
  • SteamheadSteamhead Member Posts: 11,337
    Gerry's right

    it has to match the rest of the system. That plumber needs to replace the pipe with one of the proper size- at his expense, not yours. 
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Baltimore, MD (USA) and consulting anywhere.
  • JStarJStar Member Posts: 2,668

    Let me was done in copper, too?
    - Joe Starosielec
    [email protected]
This discussion has been closed.


It looks like you're new here. If you want to get involved, click one of these buttons!