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Have steam heat, building new space, what's best way to heat new

Dave Fitting
Dave Fitting Member Posts: 1
I am building a new space on my house. I currently have steam heat and do not want to remove it in the existing spaces. What is the most sensible way to heat the new space? The new space is adjacent to the existing space, so piping runs would be longer than any current runs. My current boiler is about 25 years old and oil fired. There is no natural gas in my area, so my options for the new space(about 440 square feet)are expanding my current steam system, adding a hot water loop to my steam system, electric or propane. Any suggestions would be helpful.


  • DaveGateway
    DaveGateway Member Posts: 568
    Find a Contractor

    Sounds like you want to add a HW loop from a steam boiler? Not a homeowner recommended procedure. Go to Find A Contractor and get a pro.
  • Mad Dog
    Mad Dog Member Posts: 2,595
    YEs, tOM'S RIGHT

    yOU Could also do it in steam for a bit less money, but a hw zone on seperate zone will give you more control. Mad Dog

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  • Constantin
    Constantin Member Posts: 3,796
    Here is what I would do:

    I am but a mere homeowner like yourself. I second the motion for you to get a contractor in to evaluate the current steam system and see if it has room for a hot water coil to take off heat for the addition. Furthermore, the contractor should run a Manual-J heatloss calculation to see if your current heating plant can supply the addition... many heating appliances were/are oversized by contractors to eliminate heat-related callbacks. This is particularly true if you insulated your house or otherwise reduced the heat losses since the boiler was installed.

    You could use one of many heat-loss calculators to do the calculation yourself - see the "Free Heat Loss Calcs" tab to the left as an example. It takes time, but it also rewards you with a better understanding of what your house actually needs in terms of heat. Furthermore, it's an independent way to see if the contractor actually did his/her calcs as well rather than selling you the same system they installed next door. After all, your conditions could be quite different from those of a neighbors.

    Regardless, you ought to consider planning for a heating plant replacement. I doubt that going with anything but oil heat in your case makes any sense... You would be amazed, however, how much more efficient modern oil-fired boilers can be. Some of the numbers I've seen suggest energy efficiencies for old oil equipment are in the 60% range while new appliances are 80%+ efficient by law.

    Whether you keep a hybrid steam/hot water system or convert fully to hot water is up to you at that point. However, unless the place has gotten insulated in the meantime, the steam radiators you have now may be too small to heat the place on the very coldest of days if you convert them to hot water. Once again, this is a question that only a qualified contractor can answer. However, there are plenty of them around the Wall, so happy hunting.
  • Steamhead
    Steamhead Member Posts: 16,736
    Dave, how about

    using a new, small boiler to heat the addition, and keep the existing steamer for the original house?

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  • Boilerpro_3
    Boilerpro_3 Member Posts: 1,231
    I'd just run out the steam

    and put TRv's on it if you want more control. If the formally exterior rooms are made interior, the rads from the enclosed rooms will probably heat the addition with little problem.

    The home I did a few years ago added about 800 to 1,000 sq ft to a 2500 sq ft home. Pulled out the two interior rads and ran runs out to the addition for some new "old" rads. Works great and that winter I also replaced the old boiler with one much smaller that matched the system.

  • Dale
    Dale Member Posts: 1,317

    At only 440 sq feet the heat loss must be really low unless you have a lot of glass. The least expensive way would be hot water baseboard zone off the steam boiler. Depending on the room use radiant floor is the most comfortable, if you are putting a bath in the new room I would go with a little condensing propane wall hung boiler and dhw tank. If you don't plan to use the room in the winter electric matt and baseboard is plenty for spring and fall
  • I'm with Dale, on this one

    Like he said, because of the small size. I'd pipe it like this...


This discussion has been closed.