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  1. #1
    Join Date
    Jul 2008
    Location
    New Jersey
    Posts
    4

    New residential install

    Hello all- I'm a homeowner and have had central air in my previous two homes. I moved last fall to a house with no A/C. We had an installation done this month, Carrier Performance series. My previous two homes had, probably 2.5 or 3 ton systems. Each home had two returns. This new install is a 4 ton system (2050 sq ft living space) but I'm surprised that they only put 1 return. It is all flexduct, that they used- an attic installation. The return duct is an 18 inch round flex duct, which feeds to a filter grill 24x30 inches. Does this sound right to you guys in the industry? is this okay? It is like a wind tunnel when you go down the corridor by the return. My instinct tells me that one return may not be enough, considering that my other two homes had two. Each one had one large return and 1 smaller one.

  2. #2
    Join Date
    Jul 2008
    Location
    RTP North Carolina
    Posts
    81
    When I use the generic friction rate of .05 for 18inch flexiduct I'm getting less than 1000 cfm which is well below the recommended 400cfm per ton. The sound your return is making is your system yelling "help me, send somebody that understands duct design!"

  3. #3
    Join Date
    Dec 2007
    Location
    Afton, VA / Khorat, Thailand
    Posts
    2,469
    Adding returns in bedrooms is always a good idea, and code around here for new construction, and will quiet that noise down alot. It may be sized for that system, as far as what it needs, I doubt it, but I know we'd add return.
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  4. #4
    Join Date
    May 2007
    Location
    DC Metro Area (MD)
    Posts
    3,371
    Return is low... 5 sq. ft. for 4 tons. More return should be added for a 4-ton system. Is there any open area (preferably on other side of home) where one can be added? What's the static pressure of the system (ask for it to be tested)?

  5. #5
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,837
    You're asking questions through the open door of the barn the escaped horse used to get out. Sounds to me like you didn't do your homework before having the installation done. Read the attached and see if you did it right or not. If yes, then ask for the calcs. If no, well.....
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  6. #6
    Join Date
    Jul 2008
    Location
    New Jersey
    Posts
    4
    Quote Originally Posted by skippedover View Post
    You're asking questions through the open door of the barn the escaped horse used to get out. Sounds to me like you didn't do your homework before having the installation done. Read the attached and see if you did it right or not. If yes, then ask for the calcs. If no, well.....

    you are correct- I didn't do my homework and I do regret it. I wish I'd seen that document before.

  7. #7
    Join Date
    Dec 2002
    Location
    Rochester, MN
    Posts
    5,304
    Quote Originally Posted by stevef67 View Post
    This new install is a 4 ton system (2050 sq ft living space)
    Wow. how old is this home?? To me, that seems like a LOT of A/C for a home in the norther part of the states...

  8. #8
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,095
    I missed the part where he said its making noise.
    I've been in the return chaise of 120 ton units, its like a wind tunel, but not loud.

    A 3' x 8' hall way with 1600 CFM moving through it, have a FPM velocity of 67.

    Request your contractor to install returns in each of the bedrooms.
    It was not included in the original price, so he will want extra to do it. Which he should get.
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  9. #9
    Join Date
    May 2007
    Location
    DC Metro Area (MD)
    Posts
    3,371
    I've been in the return chaise of 120 ton units, its like a wind tunel, but not loud.
    And you didn't get sucked in?

  10. #10
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,095
    Quote Originally Posted by RyanHughes View Post
    And you didn't get sucked in?
    BIG chaise.

    And a protective barrier to prevent from going onto the blowers.

    Some times being over weight has advantages
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  11. #11
    Join Date
    Jul 2008
    Location
    New Jersey
    Posts
    4
    Quote Originally Posted by mayguy View Post
    Wow. how old is this home?? To me, that seems like a LOT of A/C for a home in the norther part of the states...
    first he said I'd need a 5 ton system but I objected to that and I told him he measured wrong. the home was built 40 years ago and is not well insulated. We do have very humid weather in the summertime, for what that's worth. It seems okay, although 3.5 tons may have been enough.

  12. #12
    Join Date
    Jul 2008
    Location
    New Jersey
    Posts
    4
    Quote Originally Posted by RyanHughes View Post
    Return is low... 5 sq. ft. for 4 tons. More return should be added for a 4-ton system. Is there any open area (preferably on other side of home) where one can be added? What's the static pressure of the system (ask for it to be tested)?
    I was wondering about static pressure. It is rated at .5 according to Carrier. If the flow is restricted and it is above .5, what does that mean? does that mean the blower motor would be working harder? especially if I close some dampers off, does that make it even worse?

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