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  1. #14
    Join Date
    Aug 2012
    Location
    Florida Space Coast
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    Quote Originally Posted by energy_rater_La View Post
    according to what you wrote...and please correct me if I'm wrong..the current r/a
    is on the opposite end of the house from master bedroom & general living area?

    That is correct.

    Quote Originally Posted by energy_rater_La View Post
    things like jump ducts and/or transfer grills will help to return air from master..
    how many supplies in the master area?
    Each room and each bathroom has one ceiling supply, with the exception of the family room, which has two wall supplies way up high. Open beam ceiling (only iso-board insulation between tongue & groove beams and roof sheathing) in the family room, so these supplies come into the room from the interior wall that abuts the attic space.

    Quote Originally Posted by energy_rater_La View Post
    your ahu closet would have to be pretty big to allow a return duct to be put from
    return on bottom, to besides the equipment..and back into attic to terminate at
    new location. do you have that kind of room?.
    See pix. I'm told the new return duct would be beside the ahu... through a new hole to be cut in top of stand... up through the ceiling. There's about 8.5 inches to the right of the ahu for such a duct, since the new ahu will be exactly the same footprint as the old one. Is that wide enough for a jumper duct?

    Quote Originally Posted by energy_rater_La View Post
    will top of this closet be sealed air tight to attic when new trunk/supply plenum is installed?.
    I would certainly expect that to be part of the contractor's job when installing the new ahu/new return duct!

  2. #15
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,633
    i would just cut a return in where the coat rack and shoes are , if the supply ducts are sized right and the doors are undercut enough you should be fine
    We really need change now

  3. #16
    Join Date
    Aug 2012
    Location
    Florida Space Coast
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    503
    Quote Originally Posted by catmanacman View Post
    i would just cut a return in where the coat rack and shoes are , if the supply ducts are sized right and the doors are undercut enough you should be fine
    Thanks! That's been the plan from day one until one of the contractors came up with his idea of a return in the ceiling closer to the living areas at the "far end" of the house. Just needed a sanity check to see if having the second return in the foyer was a bad idea.

    Is one 20x20 plus one 14x20 (680sq in total) enough return for a 3 ton?

  4. #17
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    6,845
    It will work better than with just one but is not optimal, I use this rule of thumb sometimes total surface area x .8 x 2 so in your case it would be 680x.8x2 =1088cfm which is just over 2.5 tons of air, you need ~1200cfm.

  5. #18
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    6,845
    It shouldn't be a problem to cut the studs and head them off carrying the load of the wall, without looking at it I can't say for sure that wall isn't load bearing but it most likely is not

  6. #19
    Join Date
    Aug 2012
    Location
    Florida Space Coast
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    503
    Quote Originally Posted by jtrammel View Post
    It will work better than with just one but is not optimal, I use this rule of thumb sometimes total surface area x .8 x 2 so in your case it would be 680x.8x2 =1088cfm which is just over 2.5 tons of air, you need ~1200cfm.
    Here's what the Florida Building Code says about sizing returns:

    SECTION M1403 HEAT PUMP EQUIPMENT

    M1403.1 Heat pumps.
    The minimum unobstructed total area of the outside and return air ducts or openings to a heat pump shall be not less than 6 square inches per 1,000 Btu/h (13 208 mm2/kW) output rating or as indicated by the conditions of the listing of the heat pump. Electric heat pumps shall conform to UL 1995.

  7. #20
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,170
    seems to me it would be rather crowded to try to add addtl return duct
    to what you have.
    it may be best to use other side of r/a wall. 20x20 same as other side so
    you only have one size filter to buy. (keep it simple)
    cut studs use 2x4 framing of r/a filter grill to carry weight of wall..
    once wall is determined not to be load bearing.

    make sure that they mastic seal all your duct takeoffs on new trunkline,
    and joints & seams of trunkline.

    oh and pro's..
    wow...anyone notice that furred down hallway??..oh to redo the
    ducts and put them ALL inside the fur down...ducts in conditioned space...
    wouldn't it be great!

    best of luck OP!
    The cure of the part should not be attempted without the cure of the whole. ~Plato

  8. #21
    Join Date
    Aug 2012
    Location
    Florida Space Coast
    Posts
    503
    Quote Originally Posted by energy_rater_La View Post
    oh and pro's..
    wow...anyone notice that furred down hallway??..oh to redo the
    ducts and put them ALL inside the fur down...ducts in conditioned space...
    wouldn't it be great!
    I'm not sure what image you're looking at that makes you think the hallway is furred down. All the hallways have 8 ft ceilings with attic directly above, just like all the other 8 ft ceilings in the house. Perhaps the image showing the entry to the family room gives the illusion that the hallway is furred down because the open beam ceiling in that room is about 14 ft high and has no attic above.

  9. #22
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,633
    aare you having a media filter installed at the unit ,if so a 20 x20 would be large enough if it does not have a filter in it
    We really need change now

  10. #23
    Join Date
    Aug 2012
    Location
    Florida Space Coast
    Posts
    503
    Quote Originally Posted by catmanacman View Post
    aare you having a media filter installed at the unit ,if so a 20 x20 would be large enough if it does not have a filter in it
    No... not enough space above the top of the ahu stand and the ceiling for a media filter. Eight foot ceilings are actually 94 inches above the floor... the top of the stand is 31 inches above the floor... the new ahu itself will be 60 inches, which allows for 3 inches of supply plenum up to ceiling level. The top of the 20x20 filter grille is 26 inches above the floor, so lowering the top of a 31 inch high ahu stand enough to accomodate an 8 inch high media filter cabinet without covering part of the filter grille would be quite a feat!

  11. #24
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    6,845
    Quote Originally Posted by Florida Joy View Post
    Here's what the Florida Building Code says about sizing returns:

    SECTION M1403 HEAT PUMP EQUIPMENT

    M1403.1 Heat pumps.
    The minimum unobstructed total area of the outside and return air ducts or openings to a heat pump shall be not less than 6 square inches per 1,000 Btu/h (13 208 mm2/kW) output rating or as indicated by the conditions of the listing of the heat pump. Electric heat pumps shall conform to UL 1995.
    I believe that code is referencing combustion air not return air for the air distribution system.

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