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  1. #1

    ducts in concrete slab, cold and clammy 1960 house in NY

    Hi,
    I just bought a 1-story home in central NY State built in 1960 that has a poorly working heating system. Appears to be the original Lennox nat. gas forced air furnace, which still seems to be functioning fine. Ducts are simple channels (unlined/uninsulated) in the concrete slab and when heat is running the flow is very low at the registers and air is quite moist (evidenced by sweat marks and some mold spots on walls of interior of house). Previous occupant (a renter) complained of it being cold, clammy, and expensive to heat.

    I tried to run a plumbing snake through from a register to see whether running flex duct would be practical but ducts don't appear to be a straight shot and can't get any further than 6 feet in at any of the registers (~20ft to the furnace). I suspect the designer might have been trying to achieve radiant heating with this set up but I don't think they succeeded.

    My question to the forum is whether I should abandon the ducts in the floor and run new ones up through the attic instead? This option doesn't seem all that optimal either though since winters can get cold here in NY, and the attic is an unheated crawl space (granted, I will be installing R-39 insulation on the attic floors). Is there any hope in trying to salvage the in-slab ducts or was it a bad idea in the first place?

    Any wisdom about dealing with in-slab ducts (or work-around alternatives) appreciated!! Should I try to salvage this system or abandon altogether and maybe jump to wall-mounted heaters??

    Thanks very much.

  2. #2
    Join Date
    Aug 2001
    Location
    Pavilion, NY
    Posts
    2,025
    I have worked on several of these systems with similar complains from homeowners. If they insulated under the slab the units can generally be fairly comfortable and can give the benefits of Radiant heating. Based on what you describe with high utility bills, in all likelihood an attic ducted system properly installed will pay for itself in comfort and efficiency very quickly. Check out the contractor link and call someone to evaluate the system for you. There Are likely several in your area.
    ...

  3. #3
    Join Date
    Jun 2002
    Location
    Dacula, GA
    Posts
    12,039
    Why not insulate under the rafters and seal off the attic and then you can put your ducts inside the thermal barrier and be more efficient. Thank you very much
    "I could have ended the war in a month. I could have made North Vietnam look like a mud puddle."
    "I have little interest in streamlining government or in making it more efficient, for I mean to reduce its size. I do not undertake to promote welfare, for I propose to extend freedom. My aim is not to pass laws, but to repeal them."
    Barry Goldwater

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