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Steam Heat output Restriction

You need to know the size of the boiler, the size of the load, and the size and pitch direction of the existing pipes in the system.

Then you use this easy to read book


to see how much steam is available, and what size pipe you would run to the additional radiator. You can use 3/4 of the number you come up with, the rest is pickup load to heat the new piping that you install. If that's enough, you can do it.

Don't even THINK about cheating on this test. Remember Mother Nature from the Parkay margerine commercials?



  • Ralph Trentacosta
    Ralph Trentacosta Member Posts: 13
    Steam Heat output restriction

    I have a Utica boiler in my house. Currently, I have 6 steam lines going to different rooms. I currently have 1 valve shut off (thats in the kitchen). I have one room that does not have a line going to it. The previous owners used an electric heater for that room. I would like to run get another line ran to that room. Is there a restriction on Steam Heat that would prohibit that, or on the boiler or neither?

    Ralph Trentacosta
  • Dale
    Dale Member Posts: 1,317
    Reasonable question

    Better than this answer probably. Well, to be really accurate we need to know if it's 1 pipe or 2 pipe steam. I'll guess one pipe since that what most homes are. Only one valve currently? This surprises me since most old rads had a valve on them. Can you add a rad? Depends on how big the boiler is compared to how many square feet of rad you have. Should you add a steam rad or a hot water rad off the steam boiler condensate? Depends on what's more doable and how deep is your wallet. I will guess the extra rad can be added, whether this is true and if hot water or steam, will depend on an analysis by a pro. A pro in my opinion being someone who does this kind of work alot and has lived with old systems and now has few problems. Like someone on this site in your area.
  • Christian Egli
    Christian Egli Member Posts: 277
    Beautiful steam

    You're smart to want to replace the electric heat, that stuff is expensive to operate.

    Expanding the steam heat is a good idea and it should be simple.

    The restriction to consider is to keep the size of the radiator load in line with the boiler output. Assuming the kitchen load is about the same as the extra room load, you should be fine since you don't use the kitchen. It is possible your current boiler is already oversized in which case there would be nothing to worry about. And if it is undersized, you still have the electric heater you can plug in on the coldest day on the year.

    Make sure the installation is done correctly, follow pipe size and slope rules. Trap and/or vent the addition the same way it is done for the other rooms.
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