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Thread: return size ?

  1. #14
    Join Date
    May 2008
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    43
    thanks dash that helps alot.

  2. #15
    Join Date
    May 2008
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    43
    dash will the return size matter on the btus of the system, will it affect its performance as far as cooling. besides the noisy return, the reason i ask is because my old 3 ton system had a 14x25 return grill and it was a little noisy but did cool the house down to comfort level

  3. #16
    Join Date
    May 2008
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    43
    i quess i will have to make two return griles. two 16x25 = 800 or two
    14x 25=700. the only thing is that the other return is going to be on the other side of the wall that this unit is not cooling. the other unit is the one that is cooling this other side of the wall.

  4. #17
    Join Date
    May 2007
    Location
    Naples, Fl
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    889
    Are they open to one another or separated by doors and walls?

  5. #18
    Join Date
    May 2008
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    43
    if i understand you correctly they are separated by walls. but the wall behind the air handler is being cooled down by the other system. i have a 2600 square foot home single story with two units. hope i made sense i sometimes tend to not fully explain myself correctly

  6. #19
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
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    18,836
    You don't want the second return from system A to be in the area that is cooled by system B,unless they are totally open to each other,basd on the second return location.

  7. #20
    Join Date
    May 2008
    Posts
    43
    thanks dash for your reply. the second return from system A will be about thirteen feet away from system B return will this be considered as totally opened to each other ? i understand that system A should have its own return to be able to pull its side of the humidity. the situation im in is that i do not want to force my newly installed air handler by not giving it its required return size, this will shorten the life of my air handler in my opinion besides the noisy return.


    there are no walls between the system A second return and from system B return. basically both systems A second return and system B return would be considered as if they are in the same room facing each other with thirteen feet away from each other but in the same room with no walls dividing them apart.

  8. #21
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    68,074
    Its not if the returns of system A and B are open to each other.
    Its if system A's supply air can freely travel to the new second return for system A.
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  9. #22
    Join Date
    May 2008
    Posts
    43
    Quote Originally Posted by beenthere View Post
    Its not if the returns of system A and B are open to each other.
    Its if system A's supply air can freely travel to the new second return for system A.
    no system A's supply air can not freely travel to the system A's second return. so i assume this is not a good idea. can you educate why this is not acceptable besides it pulling systems B humidity.

  10. #23
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    68,074
    A. It puts the area served by system B into a negative pressure.
    B. It puts the area served by system A into a positive pressure.

    So B's area draws unconditioned air from outside through door seals, wall cracks, recepts, and switches.

    And A's area blows the air you just paid to condition outside.

    In order for a return to work. It has to be able to get the air from the supplies of the area its to serve.

    Its kind of like having 2 pick ups. And putting 2 gas tanks on the one for long trips.
    But then driving the truck with the single tank instead. Plenty of gas in the duel tank truck, but not enough in the one your driving. And no way for teh gas to get there.
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  11. #24
    Join Date
    Feb 2006
    Location
    Tn.
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    1,344
    It took me a few years to learn formulas for calculating face grille size.
    Nowdays hop on the internet and there you go.

  12. #25
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    Mar 2008
    Location
    Shelby Twp MI
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    820
    System A is designed for system A period. If you put the second grill in for A in B's area, it will quiet the return for system A. However, your now starving the return for system A's area. What I mean is, you will not pull the required CFM's out of system A's space, hence the system will not work efficiently or properly as designed. You'll be pumping more INTO A's space than you are taking out. Understand?
    Jim

  13. #26
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
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    Quote Originally Posted by junior1 View Post
    no system A's supply air can not freely travel to the system A's second return. so i assume this is not a good idea. can you educate why this is not acceptable besides it pulling systems B humidity.
    Closed door separating them,or what??

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