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Cast Iron Radiators

I am looking to replace an 80 year old steam radiator with 1 1/4" bottom tap with a new Classic Burnham Radiator which only comes with a 1" bottom taping. Will this be a problem. I am sizing the Burnham to meet the equlivelent amount of sqft of steam. It is a 1 pipe steam system.

My worry is condensate drain with the 1"


  • moneypitfeeder
    moneypitfeeder Member Posts: 249

    Hi, question, whats the size of the pipe going to your supply valve? What I'm wondering is even though your current rad has a 1-1/4" tapping, was it reduced before it met the valve, or is the valve and valve nut that large? B.t.w. I looked up the Burnham, great choice!
    steam newbie
  • Bob Daros
    Bob Daros Member Posts: 11
    cast iron rad

    The old radiator riser and valve is 1 1/4"

    My fear is this. Was the riser sized for a pre-determined amont of steam and will this cause a issue at the newly installed rad at the 1" inlet/outlet. I may be over thinking this, but, I dont want to spend all this money on the new radiator and then have issues. I realize that only so much steam will make it's way into the 1" pipe but dont want a condensate jam on the way out.
  • Jamie Hall
    Jamie Hall Member Posts: 22,912
    The radiator inlet

    may be one inch, but that's not the whole story.  My inclination would be to keep the inch and a quarter valve and rest of the piping, and reduce down to the one inch after the valve.  If that's what was there before.  If you have the Lost Art, there are tables for the valve and pipe sizes for various EDR ratings.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
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