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  1. #1
    Join Date
    Nov 2007
    Posts
    5

    Confused A/C registers and returns

    1)
    What is the minimum distance between 2 A/C registers location on the ceiling? I've a scoffed ceiling, and there are recess cans near the corners. Because of that my builder moved the A/C registers closer - approx. 2 to 2 1/2 feet apart.

    I think they are too close, but builder says it is okay. This master bedroom size is 15x17 ft.

    Any suggestion is appreciated.

    2) This is a 2 story home and we have 2 zone system one for each floor. There are 2 return registers located on the 1st floor only. None on the second floor. Builder says it is okay. But, I'm not sure.

    What are the recommended number of return registers?

  2. #2
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    1.)If you mean the distance between a supply and return grille ,what you have is fine ,as long as the supply is not blowing at at the return.

    2.)You'll be better of with returns in all rooms ,except baths,kitchens .closets and utility.It's now code to do this in Florida.Without a return or return path(search jumper dict),supply air into the room,with the door closed is limited to the amount that can escape under the door.

  3. #3
    Join Date
    Nov 2007
    Posts
    5
    Thanks Dash.

    To your question:
    <quote>
    1.)If you mean the distance between a supply and return grille ,what you have is fine ,as long as the supply is not blowing at at the return.
    </quote>

    It is not the distance between the supply and return grills. It is between two supply grills.

    About the return grills, is it easy to retrofit in other rooms or one in 2nd floor? Builder says they do not have it in plan so they won't do it now.

  4. #4
    Join Date
    Jun 2006
    Posts
    96
    Tell the builder that you are paying for the house and if you want a return upstairs (and he wants to get paid) he should include one, even if there is a small additional charge.

  5. #5
    Join Date
    Jan 2007
    Location
    Minneapolis, MN
    Posts
    415
    1. It depends on the registers throw and spread, its a design thing, 2 feet sounds too close.

    2. Every floor should have at least one central return and rooms that could be
    closed with a door should have a return or jumper duct (except bathrooms).

  6. #6
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,837
    Quote Originally Posted by l0ll1 View Post
    1)
    What is the minimum distance between 2 A/C registers location on the ceiling? I've a scoffed ceiling, and there are recess cans near the corners. Because of that my builder moved the A/C registers closer - approx. 2 to 2 1/2 feet apart.

    I think they are too close, but builder says it is okay. This master bedroom size is 15x17 ft.
    The distance between two supplies is inconsequential. The amount of air you get into the room (total) makes a difference and the spread of the air (distance thrown from the diffuser out toward the walls) affects the comfort if it's too short.

    2) This is a 2 story home and we have 2 zone system one for each floor. There are 2 return registers located on the 1st floor only. None on the second floor. Builder says it is okay. But, I'm not sure.

    What are the recommended number of return registers?
    Without question, you need total return air on the 2nd floor equivalent to the supply air being introduced. In addition, I'd recommend a balanced return in every bedroom. These are just good design criteria and shouldn't be an extra expense on your part. Returns should be part of the basic installation, IMO.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  7. #7
    Join Date
    Jan 2007
    Location
    Minneapolis, MN
    Posts
    415
    The placement of registers is very important to proper design. The spread of two registers should not merge before 50% of the throw. It would be unknown what kind of air pattern will form and it could very well enter the occupied zone causing comfort complaints. If the registers are that close a single register of correct design would be preferable. These considerations are especially important in the master bedroom were noise and air velocity can cause problems while sleeping.

  8. #8
    Join Date
    Feb 2003
    Location
    Huntsville,AL
    Posts
    4,125
    probably, 2 supplies were used because of structrual limitations against larger ducts ??
    harvest rainwater,make SHADE,R75/50/30= roof/wall/floor, use HVAC mastic,caulk all wall seams!

  9. #9
    Join Date
    Sep 2007
    Location
    Shreveport, LA
    Posts
    64
    Quote Originally Posted by cem-bsee View Post
    probably, 2 supplies were used because of structrual limitations against larger ducts ??
    I'm just a student, but I'm thinking they used 2 ducts because 1 would not have given them the correct velocity to attain the correct throw?

  10. #10
    Join Date
    Nov 2007
    Posts
    5
    Thanks a lot to all of you replied! Good info for a novice.

  11. #11
    Join Date
    Nov 2007
    Location
    Chicago
    Posts
    76
    Quote Originally Posted by RandyRich View Post
    I'm just a student, but I'm thinking they used 2 ducts because 1 would not have given them the correct velocity to attain the correct throw?
    Throw is dependent on the face velocity of the supply register, not the size of the ductwork. Ductwork velocity factors into pressure loss due to friction and noise. The contractor ran two ducts for one of two reasons, structural as mentioned, or cost.

    I agree with the above posts too, just because he under bid to get the work, doesn't relieve him of installing a proper system. Make him install the returns properly, they should be in every separate room with a supply minus kitchens and baths. The builder will basically never tell you the truth, just try to do it as cheap as possible and move on to the next house.

  12. #12
    Join Date
    Dec 2002
    Location
    Houston,Tx.
    Posts
    16,071
    Well IMO 2 to 2.5' apart regardless of the effects has to look terrible cosmetically, why not just one large one?
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