Page 2 of 9 FirstFirst 123456789 LastLast
Results 14 to 26 of 116
  1. #14
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,913
    Your current return grille isn't using the wall studs. It has a large duct attached to it.

    If you put one below it. It would use the wall cavity, and that cavity isn't nearly big enough.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  2. #15
    Join Date
    Jan 2008
    Location
    BAYOU LAND
    Posts
    697
    like t527ed said,ceiling fan on low speed should help pull the heat down
    The government works for me. I do not answer to them, they answer to me.

    we need a few more sheep dogs to keep barking at the wolves,and the stupid sheep

    A well-regulated militia, being necessary to the security of a free State, the right of the people to keep and bear arms, shall not be infringed.

  3. #16
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,325
    I'm thinking the OP brought this whole subject up because he has a comfort concern with the room in the photo.

    Looking at that photo, I see some possible contributors to his possible discomfort, and they are not related to the return air intake location.

    Recessed "eyeball" "can" lights...if not sealed, they are contributing to stack effect.

    Supply registers...if not sealed where register boot meets drywall, they are contributing to stack effect.

    Return air grill...same as above.

    Stack effect is the occurrence of a house interior acting as a chimney. As another poster stated, heated air has buoyancy, and tends to rise. If a room were completely airtight, the air that is rising would hit the ceiling, travel toward the walls, where it would eventually cool and sink toward the floor. The air that rose to the ceiling has to be replaced by air elsewhere, hence the tendency for air at the ceiling to fall toward the floor as it cools. This cycle would repeat unbroken as long as a temperature difference existed in the room.

    In an actual dwelling this circulation of air naturally occurs all the time, mostly at velocities too low for human detection. However, as air warms and rises toward the ceiling, it will create a low pressure zone toward the floor. Any gap in construction on exterior walls/windows/doors will allow make-up air to enter due to this pressure difference. The air rising toward the ceiling...if it finds a way to escape through a hole in the ceiling, such as a can light or unsealed register boot, it will. This is the other half of the pressure imbalance...air escaping the dwelling into the attic has to be made up, so the higher pressure of air outside the structure pushes through the building envelope and into the house, displacing the heated or cooled air that the homeowner is paying for.

    Ceiling fan...reverse the blade rotation so air is pushed toward the ceiling during the winter. Run on low speed to avoid drafts.

  4. #17
    Join Date
    Feb 2007
    Location
    18951
    Posts
    1,593
    Quote Originally Posted by Ed Janowiak View Post
    But heat doesn’t rise. Lighter air does
    That’s an interesting statement. Can you tell me in what instance a cubic ft. of hot air would not be lighter than a cubic ft. of cold air?

  5. #18
    Join Date
    Apr 2002
    Posts
    11,808
    Return location will have next to no impact on comfort. What it can do is follow where air stagnates

    Try this http://www.price-hvac.com/content/fl... Air Diffusion

    If it does not work, then try this link and select "Space Air Diffusion" http://www.price-hvac.com/media/trai...ule.aspx#flash

  6. #19
    Join Date
    Apr 2002
    Posts
    11,808
    Quote Originally Posted by shophound View Post

    Ceiling fan...reverse the blade rotation so air is pushed toward the ceiling during the winter. Run on low speed to avoid drafts.

    Yes, in heating mode have the ceiling fan pull air up in the middle of the room, then force ceiling air towards the walls and down to work against natural convection

    In cooling have the fans blow down to cool occupants by convection.

  7. #20
    Join Date
    Nov 2004
    Location
    NJ
    Posts
    1,203
    Quote Originally Posted by bobb25 View Post
    That’s an interesting statement. Can you tell me in what instance a cubic ft. of hot air would not be lighter than a cubic ft. of cold air?
    It depends on your definition of hot and cold.

    I can make a cubic for of air that is “hotter” heavier than a cubic foot of “colder” air. The same way I can make the same pound of air contain more heat at a lower temperature. Moisture content is always a factor. But that is not really what is being discussed here.

    Hot goes to cold.

    Warmer air that has a moisture content that is “relative” to colder air will rise .

    The first link worked Carnak, good stuff .
    Ed J

  8. #21
    Join Date
    Jul 2006
    Location
    Southern Ca, Elkton Md
    Posts
    7,570
    My first question looking at that picture, would be what size duct is connected to it.

    Most of the time when I see one return, it is undersized!
    "Correct Installation is the Key"

    .1 has killed more HX then Rush Limbaugh

    What is your TESP?

  9. #22
    Join Date
    Oct 2006
    Location
    Baltimore
    Posts
    374
    if physically possible i ALWAYS use high and low returns.

  10. #23
    Join Date
    Feb 2007
    Location
    SW Virginia (Roanoke)
    Posts
    48
    Quote Originally Posted by beenthere View Post
    Your current return grille isn't using the wall studs. It has a large duct attached to it.

    If you put one below it. It would use the wall cavity, and that cavity isn't nearly big enough.
    The other side of the wall is my garage, whose walls are finished. I would surface-mount the duct to the new return, then build a soffit to hide it.

    ..
    Joe

  11. #24
    Join Date
    Jun 2004
    Location
    4H: Hot, Humid Houston H.O.
    Posts
    3,304
    Quote Originally Posted by tigerdriver View Post
    Greetings folks,

    I have a large great room with a high peaked ceiling. The air handler is installed in the attic of the adjacent garage. (The emergency overflow is well designed--I tested it with a garden hose.)

    There are eight output registers on the pitched ceiling a a foot or so from the wall.

    There is a single return at the ceiling peak, adjacent to the garage. (Photo attached.)

    I got to thinking (always dangerous )...shouldn't there be two returns: the (existing) high one for summer to intake the warmed cooling air; and a second one nearer the floor for winter, to take in cooled hearing air? I would open/close them appropriately when I switched between heating to cooling. A second return could easily be installed below the first (on the wall behind the TV).

    Comments?

    Thanks in advance,

    Joe
    I am a homeowner too, therefore an amateur. I hate to believe you cannot find some issue more significant than this! So many duct systems have too-small returns in the first place, in such a case adding another would be helpful but not for the reasons you are thinking.

    In simplistic terms as I understand it yes hot air rises when air is still, but... because of your supply vents blowing air into the room the air is supposed to be mixed already. This has been said already by a couple of professionals and I cannot find any fault in what they say. I also believe the ACCA manuals address this issue and disprove the usefulness of summer/winter return switching.

    Lots of AC systems have things wrong about them, such as leaky ductwork in unconditioned space (e.g. attics). Or poor match between coil and condensor leading to lousy efficiency and/or poor humidity removal. Or returns which are too small and restrict airflow. Or even fan speed set wrong which also results in poor airflow. All of these are from my own experience, I am not complaining as these have been problems found and fixed. But to worry about a 2nd set of returns just for seasonal use, in my best opinion that is dwelling on trivia.

    Hope this helps -- Pstu

  12. #25
    Join Date
    Feb 2007
    Location
    SW Virginia (Roanoke)
    Posts
    48
    Quote Originally Posted by weber View Post
    My first question looking at that picture, would be what size duct is connected to it.

    Most of the time when I see one return, it is undersized!
    The intake (return) is a 18" OD flexible duct approximately 10 feet in length. Assuming 1" of insulation, the cross-section area is ~200 sq/in. The output is 14"x16" OD insulated rigid duct. Assuming 1" insulation, the cross section is ~ 195" sq/in. So the cross-section area of the intake and output ducts are closely matched.

    After a 3-foot run from the handler toward the wall, the rigid output duct T's out about 6' per side. The T is an output manifold, feeding smaller flexible ducts that run to eight registers in the ceiling of the Great Room.

    ..
    Joe

  13. #26
    Join Date
    Feb 2007
    Location
    SW Virginia (Roanoke)
    Posts
    48
    Quote Originally Posted by pstu View Post
    I hate to believe you cannot find some issue more significant than this! ....to worry about a 2nd set of returns just for seasonal use, in my best opinion that is dwelling on trivia.
    I'll be sure to consult you when I need assistance prioritizing my life.



    ..
    Joe

Page 2 of 9 FirstFirst 123456789 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event