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Connecting a new radiator to “supply in adjacent room”?

We are trying to resolve a dispute between our architect and plumber and would love any informed advice.

We added a new small bedroom to our home as part of a renovation. We have steam heat, and added a new steam radiator in the new room.

The architect’s plans say, “connect new radiator to supply in adjacent room.” The plumber interpreted these words by connecting the new radiator to an existing radiator in the adjacent room, using a pipe above the floor. This is not working (a loud sloshing noise in the pipe feeding the new radiator is waking our daughter, as well as us in the next room). I called the radiator manufacturer, and he said it should not have been connected that way. Now we need to either correct the system, or detach it – at further cost, of course.

The architect refuses to help, saying her words were perfectly clear and a plumber should have known what to do. The plumber also refuses to accept blame, saying there was no other way to interpret her words unless we had wanted to rip up the floor and do a major, major job, which was not indicated on the plans or scope of work.

We have already soaked $1,000 into the new radiator and connection and have little budget left to work with.

Any thoughts for a tired and frustrated mama? Would esp love to hear from any licensed plumbers out there!


  • Ban
    Ban Member Posts: 79

    You need someone who understands steam. Please up-load some photographs of the situation.
    Richard Ban
    Detroit, Michigan (Dunham 2-pipe vacuum)
  • BobC
    BobC Member Posts: 5,473
    It's not easy but can be done

    To do something like that you really have to obey all the rules.

    Is the existing Riser large enough to handle both radiators?

    The existing radiator feed has to run to both radiators SEPERATELY, if you don't want to open ceilings and walls the extension pipe for the new radiator can be run above the floor. Both the existing and the new radiator feeds have to be sloped back towards the riser, that usually means putting the new radiator up on short blocks to get the needed slope (one inch in ten feet) and perhaps the old one as well. The Lost Art of Steam Heating has a picture that shows how to do it on page 96.

    It sounds like both the architect and plumber don't understand steam heat.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • Rod
    Rod Posts: 2,067
    Adding a Radiator

    Hi- I might first mention that I’m a homeowner and not a pro.  From your description it would sound to me like neither the architect  nor the plumber know much about steamheating and are just  passing the buck to each other hoping the other one will bail them out.  In most cases just  “connect new radiator to supply in adjacent room” won’t work as the supply line going to the radiator in the “adjacent room” is sized just for that radiator and adding another radiator to that line causes problems.  As for the plumber, he should have known that it probably wouldn’t have worked and said so.

       What to do now- What you need is a good steam pro. We have a lot of good steam pros on this board and if you tell us where you are located we can possibly suggest one to you. You might also try the “Find a Contractor” section at the top of this page. Scroll down until you see the States listing and see if a pro is located near you.

           It would help if you posted some pictures of the two radiators. Also let us know what is under two rooms, is it basement or crawlspace with the piping exposed or another room with a finished ceiling? What sort of access is there under the floor of the new radiator?

          How far is the new room from the boiler? I ask this as it may be more practical to run a hot water heating leg off the steam boiler and use hot water to heat the new radiator. This is quite often done to when a new addition is added. When we know some more about the situation we may be better able to help you out.

    - Rod


  • thegoodtribe
    thegoodtribe Member Posts: 3
    More info coming!

    Wow, thanks so much for trying to help me figure this out. I'll post photos tomorrow. The new radiator is on the 3rd floor, far above the boiler in the basement. Beneath the 3rd floor are joists and the finished ceiling of the 2nd floor.

    Unfortunately, the new radiator/room is to the left of the adjacent room w/ the existing radiator, while the joists beneath the floor go the opposite way, so I imagine any pipes going from the existing radiator to the new radiator beneath the floor would have to go through the joists.

    Photos to come...
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576
    what would King Solomon do?

    the architect's choice of wording of the job description puts her in the wrong, with the plummmer as accessory. she made the determination that the new radiator could be spliced somehow onto the existing 3rd floor radiator.

    if she had said "connect the new radiator to the existing steam system", she would have shifted the blame more to the plummmer. Solomon would have had them both cut in half!

    probably this existing riser will not have enough capacity for two radiators, and so an additional riser will have to be run. a competent steam pro would have seen that this was not going to work, before the job started. how did you choose the one who has done the work?

    an alternative would be to put the radiator on it's own water loop, fed from the boiler. this would have the advantage of being separately controlled by a thermostat in the new room, and the water could be run with flexible pex pipe.--nbc
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