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What happens when you add gfa to a remodel where the existing sy

Boilerpro_3 Member Posts: 1,231
A few years back I recieved a call to see if an existing one pipe steam system could be extended into a 1,000 sq ft addition. Took a look at it and ran some heat loads. Since an addition often covers a large portion of an existing older structure, the reduced heat loss of the original structure often is greater than the heat loss of the new addition, so the equipment is often plenty big. Ended up removing a radiator from a now interior room and reducing the size of the radiator in another room partially enclosed by the addition and put a couple rads out in the addition. Worked great.

The owners did not want to part with their steam system since they had lived in several homes over the years and never were so comfortable as with the steam.... despite the fact that it banged due to a boiler incorrectly installed. Replaced the boiler a short while later with one properly sized and installed and the system now is silent and comfortable.



  • Richard_2
    Richard_2 Member Posts: 1
    recommendations on preferred system for new addition

    I am in the process of adding about 600 square feet of space to my home. I
    > have a steam system with a new boiler in 2002 (one pipe system). I have had
    > differing recommendations on the best way to heat the new system. One person
    > recommends that we convert the one pipe system (using some sort of conversion
    > system) and then go from radiators to baseboard in the renovated kitchen, new
    > family room and bonus room. The rest of the house would remain unchanged. I
    > would also like air conditioning and that would mean a separate unit.
    > Another person recommends that I put a new forced air furnace in to heat and
    > cool the remodeled and new spaces.
    > My concerns are efficiency, heating ability and cost.
    > Please help me with this. I need some practical advice. Thank you.
  • Justin Gavin
    Justin Gavin Member Posts: 129
    Just a thought

    If you are only adding 600 sq feet and you are truly looking for comfort you may consider adding underfloor radiant. The cost wouldn't be too bad and it would be more efficient.

    You have to consider if the existing boiler you have has the capacity to heat the addition.

    You could do underfloor under the joists, or on the new floor if it hasn't been laid down yet. If it has been laid most PEX companies make a subfloor material made out of plywood with grooves you can use but it gets quite expensive. But for only 600 sq feet it wouldn't be that bad. And for the underfloor you could use a standard water heater(if your local code permits)

    For Air Conditioning (if wanted) you can consider a mini-split system that is quite affordable and works great. With a mini split you won't have to add any ductwork for the AC.

    Good Luck!
  • Steamhead
    Steamhead Member Posts: 16,723
    Keep the Steam

    You already have a good system in the existing house, no need to remove or convert it. If the existing boiler has enough capacity, I'd heat the addition with steam. If it does not, I'd use a small hot-water boiler to heat the addition and feed an indirect heater for your hot faucet water.

    A/C is best done with a separate system. This way, everything is optimized for a specific job instead of trying to do two things with a single duct system, which never works as it should.

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