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  1. #14
    Join Date
    Apr 2011
    Posts
    22
    Ladies and Gentlemen,
    Please let me know your thoughts on my last reply below.
    Thank you in advance!!

  2. #15
    Join Date
    Jun 2011
    Location
    Houston area
    Posts
    1,493
    If it's not ductless it must be setup for ducts. Do they want you to run multiple supply ducts to the same room? I say if the all the supplies and returns are balanced properly anf the coil sees the same CFM and the fan motor the same static pressure it will work. Balancing a such a simple system should be a piece of cake.
    The picture in my avatar is of the Houston Ship Channel and was taken from my backyard. I like to sit outside and slap mosquitos while watching countless supertankers, barges and cargo ships of every shape and size carry all sorts of deadly toxins to and fro. It's really beautiful at times.....just don't eat the three eyed fish....

    `. .` .>(((>

    `... `. .` .>(((>

    .` .>(((>

    LMAOSHMSFOAIDMT

  3. #16
    Join Date
    Apr 2011
    Posts
    22
    The manufacturer is saying that this unit should not be connected to multiple rooms as unbalanced air flow may occur creating positive or negative pressure in the room. But I am trying to find a way to convince them that you can connect the unit to multiple rooms as long as you have equal amount of CFM going into the room and coming back from the room to the unit from both the rooms.
    They are against it big time.

  4. #17
    Join Date
    Jun 2011
    Location
    Houston area
    Posts
    1,493
    Quote Originally Posted by Samart View Post
    The manufacturer is saying that this unit should not be connected to multiple rooms as unbalanced air flow may occur creating positive or negative pressure in the room. But I am trying to find a way to convince them that you can connect the unit to multiple rooms as long as you have equal amount of CFM going into the room and coming back from the room to the unit from both the rooms.
    They are against it big time.
    Yes, I know, I've read the whole thread. Which EXACT unit is it? Are you a homeowner or an installer/technician? Are you trying to put this in your own home?
    The picture in my avatar is of the Houston Ship Channel and was taken from my backyard. I like to sit outside and slap mosquitos while watching countless supertankers, barges and cargo ships of every shape and size carry all sorts of deadly toxins to and fro. It's really beautiful at times.....just don't eat the three eyed fish....

    `. .` .>(((>

    `... `. .` .>(((>

    .` .>(((>

    LMAOSHMSFOAIDMT

  5. #18
    Join Date
    May 2012
    Location
    San Diego, CA
    Posts
    352
    Quote Originally Posted by dlove View Post
    you cant be negative in a room that doesn't have enough air supplying it. It only becomes negative if your returning more than what your supplying.
    Isn't that what my math was showing? 267 CFM Supply minus 800 CFM Return equals -533 CFM.... therefore more return than supply equals negative pressure.

    Samart: I don't think there is enough external static pressure for your AC. 0.15 inches is pretty low and some of the take-offs from trunks can add 30+ ft to the effective length of the duct (check Manual D for exact effective lengths).

  6. #19
    Join Date
    Apr 2011
    Posts
    22
    Based on the feedback received from everyone so far, is it safe to say that there will be no problem as long as there's balanced airflow -enough CFM going in to the rooms and same cfm coming back to the unit? I mean if it is done based on the maximum external static pressure, CFM of the evaporator fan and appropriate length of the ducts.

    Please let me know how many of you agree with it and how many of you disagree with it.
    Thank you

  7. #20
    Chris_Worthington's Avatar
    Chris_Worthington is offline Controls Committee & Global Moderator
    Join Date
    Jul 2007
    Location
    Mount Airy, MD
    Posts
    7,281
    Thread relocated to "Tech to Tech"

  8. #21
    Join Date
    Aug 2008
    Location
    Burlington , Mass
    Posts
    465
    How about giving us a link to see the unit your talking about ?? You may get better feedback, otherwise the tread is useless.
    I'll be there when I get there and not a minute later

  9. #22
    Join Date
    Jul 2011
    Location
    East coast USA
    Posts
    955
    Quote Originally Posted by hcong View Post
    Isn't that what my math was showing? 267 CFM Supply minus 800 CFM Return equals -533 CFM.... therefore more return than supply equals negative pressure.

    Samart: I don't think there is enough external static pressure for your AC. 0.15 inches is pretty low and some of the take-offs from trunks can add 30+ ft to the effective length of the duct (check Manual D for exact effective lengths).
    I stand corrected

    BYW there is no such thing as negative PRESSURE. You can only have one at a time.

  10. #23
    Join Date
    Jul 2011
    Location
    East coast USA
    Posts
    955
    Quote Originally Posted by BURL-REF View Post
    How about giving us a link to see the unit your talking about ?? You may get better feedback, otherwise the tread is useless.
    10 to 1 its a Movincool

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