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dlr98004

condo renovation.. no duct work

dlr98004
9 years ago

our 1974 San Diego condo has a 1997 heat pump. there is no metal or flex duct work...instead, they just used the dropped ceiling and soffits In hall and kitchen for the ductwork. we are renovating, bur hope to keep the heat pump. we will add insulated flex ducting to the kitchen, living room and two bedrooms. how do we properly size this? what type of manifold is required at the top of the heat pump to distribute these five runs? do we need to take down the dropped ceiling to do this or can we just snake the ductwork through the ceiling?

any suggestions most appreciated! I tried to google for answers, but must be using the wrong terminology... no good hits!

condo is 1450 sq feet, fifth floor (of 15) concrete construction, glass walls face east and south. new windows going in with thermal glass and low-e. we rarely need heat or cooling... at least currently!

thanks in advance, Diane

Comments (6)

  • klem1
    9 years ago

    Why do you think it's nessary going through with this?

  • energy_rater_la
    9 years ago

    I'd leave the fur down. or if you have to tear it out..
    run ducts inside of fur down and replace fur down.

    this is THE best way to run ducts, keeping them
    inside of conditioned space rather than in 140 degree
    attic.

    take a supply grill off and take some pics for us to see.

    best of luck.

  • dlr98004
    Original Author
    9 years ago

    there is no attic here. our ceiling is the same as the upstairs neighbors floor... 8" of poured concrete. in the entire hallway and kitchen soffits, they dropped the ceiling 13" with drywall to install some recessed can lights and to use the cavity as the ductwork. not very efficient. however, it is not used much either.

    heat pump is centrally located in hall. longest runs are fifteen feet to living room vent and fifteen feet to master bedroom vent. kitchen is about ten feet, bathroom is about six feet, and second bedroom is four feet.

    we want good flow, bur would like to keep duct height to a minimum so we can raise the ceiling in hallway.

  • klem1
    9 years ago

    This is a classic case of "if it's not broke,don't try to fix it." If you feel "something"should be done,here's my opinion. To deliver equal volume of air as present would likly require dropping the ceiling even farthur to accomidate nessary flex duct. It's possible that one or more rooms might be ducted from unit thruogh wall to adjoining room thereby allowing hall celing to be raised a little. It's also possible the area allowed to handle air origionaly is oversized but resizing is not a diy undertaking,with or without assistiance on the net. Contrary to common believe, ducting hvac systems is a sience requiring precise calculations involving several variables.

  • energy_rater_la
    9 years ago

    my fur down is 13" length by 12" wide
    serves 5 rooms with 7-8" duct (sized for room requirements) that the heating system closet
    is in the middle of the house, two ducts run to
    one side of the house, 2 ducts to the other side
    of the house, and one is a very short duct
    in top of closet directly into opposite room.

    given the width of the hallway..at least 3' wide
    there is plenty of room to run ducts.

    using the fur down as supply plenum is a good
    idea..but fur down has to be air tight.
    cutting holes for recessed lights that may not
    be ICAT (insulation contact air tight) allows
    for air to leak out of the fur down/supply plenum.
    this would affect air flow through supply grills.

    putting ducts in fur down would eliminate the need
    for making IC recessed lights air tight, and sealing
    the penetration in the fur down that the trim
    of the recessed light covers.

    13" would be the minimum depth. and actually...
    when properly sealed...without holes cut into
    it for recessed lights..is very efficient.

    with a concrete roof and walls...where else
    would ductwork be located?
    sounds like building was constructed & designed with
    fur downs originally.
    to alter it would be less efficient, and possibly be
    a hacked job.

    are you replacing hvac system at this time or just
    wanting to raise the ceiling of the hallway???

    the only other option I can think of that would
    eliminate fur down would be to go with mini split
    heat pumps.

    best of luck

  • ionized_gw
    9 years ago

    Dropped ceiling in the hall and soffits in the kitchen might be viewed as interesting architectural detail by some.

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