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Recessed steam radiators

My town's plumbing/building inspector (Bob, of Glen Ridge, NJ) suggested I write to this site and ask for advice about recessed steam radiators in my 100-year-old Dutch colonial home. I added a powder room that's 4 X 5 feet with a 10-foot ceiling and for that my plumber and the folks at the plumbing supply store recommended I install a recessed Sun Radiator with 4 sections or segments (2,000 BTUs; the smallest available). For my kitchen, which also has 10-foot ceilings and is 10 X 18 feet, we removed the free-standing radiator to make room for new cabinets and are now planning to use a recessed Sun Radiator with 12 sections or segments (7000 BTUs)--again as recommended by my plumber and the plumbing supply store. Does this sound right to you? And do you have any other suggestions or advice?


  • Jamie HallJamie Hall Member Posts: 6,653
    Depends on so many things...

    the basic one being what is the heat loss of the room at the design outside temperature and inside temperature?  But in turn, that depends on... how is it insulated?  How much outside wall is there?  Are there windows?  What kind?  Are they tight?  And so on.

    Have to admit that the figures don't look out of line, but there is really a lot more to it to make any kind of definite statement.

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  • jpf321jpf321 Member Posts: 1,558
    you can always...

    you can always (well usually always) slow a radiator down .. but you can never ask one for more than it can give .. when in doubt air on the larger size to start with .. you don't want to try to fit a larger one into a small recessed hole next year if you bet wrong ..

    yes it's all based on heat loss for the room. all rooms are constructed differently and are in different relative geographies. it would help to understand the sizes of your rads in other similarly constructed rooms (in EDR sq ft units) .. do you find the other rooms comfortable with the rads you currently have installed? then work from their sizes and adjust accordingly for the new rads. but you need to kow the EDR sq ft for both the current and new units .. Recessed Sunrads are 1sq ft EDR for each inch wide .. 30" wide rad = 30sq ft EDR .. this just happens to be the case with these types of rads .. other rads are very different in the way you determine EDR.
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  • MaritaMarita Member Posts: 2
    Good questions!

    The bathroom has one Home Depot-installed vinyl Simonton replacement window (about 2 feet wide by 3 feet high) and has two interior walls and two R-17 insulated exterior walls (stucco outside). The kitchen has 4 Home Depot-installed Sequel wood replacement windows (about 2.5 feet wide by 4 feet high) and has two interior walls and one R-17-insulated exterior wall and one half-insulated R-17 exterior wall (stucco outside). I hope that answers all of your questions!

    Does that help? And thank you for taking the time to reply!
  • haaljohaaljo Member Posts: 112
    I built an addition with recessed radiators -big mistake

    Much less insulation behind the radiator. I put 2" of foam board inside the finished wall but I can still feel a lot of heat on the exterior wall. I added more board on the outside after the fact in  an attemp to reduce the heat loss. Also, brought the pipe to the new second floor (bedroom) inside the wall. Have a lot of heat loss from that idea as well. But the recessed radiators do look good.
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