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Adding A/C to my old Victorian house

Various options have been proposed, one is suggesting that we replace the current warm air furnace with one that will accommodate a/c input as well, using the current heating vents. The primary heating in the house is steam, the warm air vents are in some rooms, not all (my guess is that they're holdovers from the old coal system). These vents are on the floor or lower in the wall, not where I'd ideally want a/c vents (warm air rises, cool air falls), and we'd have to cut in and add some more. Thoughts?


  • Paul SPaul S Posts: 1,257Member
    where are you located....most heating only systems cannot have ac instalked with the current ductwork
    ASM Mechanical Company
    Located in Staten Island NY
    Servicing all 5 boroughs of NYC.
    [email protected]
  • HVACNUTHVACNUT Posts: 1,073Member
    1- Does the steam system adequately heat the whole house?
    2- Is the furnace in use? Steam coil?

    If the answer to 1 is yes, and the answer to 2 is no, look into a Unico or SpacePak system. They're designed to accommodate ducts in areas of difficult access.
    And have the old furnace and ductwork removed. But post some pics of the furnace first.
  • Kybeans403Kybeans403 Posts: 31Member
    Where are you located? Unico has a contractor finder page that can help you find a qualified installer, unless your in Fairfield County, CT or Westchester County, NY, where I'd be happy to help.

    Not a good idea to try and hack in a coil on top of a furnace with ducts that were designed to only carry warm air. You can add supply vents, but returns on upper floors are essential along with an ecm blower on furnace to have any hope of cooling upper floors.....don't do that. Excessive new duct work, soffitt work after the fact and a system that isn't guaranteed to work will end up wasting your money.

    Small duct high velocity systems were designed to cool houses specifically with old steam or hot water systems. A main trunk line, usually 7 to 10 inches in diameter is installed in the attic and feeds for each room can be installed in the ceiling and fished down in closets or interior walls to reach the 1st floor. Minimal, if any plaster/sheetrock repairs are needed after job is done. If sized and installed properly, a single system cooling 2 floors can maintain temperature with less than 2 degrees difference between floors.
  • ratioratio Posts: 1,380Member
    Perhaps mini splits would serve your needs. They are available in heat pump models (would be adequate during swing seasons, possibly into heating season) and cooling only models, with one or more indoor units per outdoor unit. They are available in wall tumor models that everyone is familiar with, but also in concealed ducted models and floor/wall mounted units similar to an enclosed radiator. They can be coordinated with your steam system (with lessened efficiency, as I've learned, for single-control; i.e. one thermostat for both systems), and will perform swimmingly so long as they're sized properly.
  • jumperjumper Posts: 1,153Member
    How many floors? In old homes you can put ducts in attic and at least cool the upstairs. Rest of house can depend on cold air falling through staircases. Generally a house with cool upstairs won't be too bad downstairs unless someone cooks up a storm.
  • FredFred Posts: 6,405Member
    I have steam heat in a 115 year old 5000 sq.ft. , 3 story + basement house. I kept the steam, would never give it up. Initially I put a forced air furnace and central air in a storage area on the third floor. I was able to duct the third floor with registers at the top of the walls. I managed to get ceiling ducts to each room on the second floor. As @jumper said, I depended on the air falling down an open staircase to the first floor. for the first four or five years. It was okay as long as the outside temps stayed in the low 80's or any cooking happened. I then put a second forced air furnace and central air in the basement, ducted to the first floor with floor registers. Should the steam fail, for any reason, I can heat the house with the forced air systems and the air in the summer is like dying and going to heaven.
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