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Thread: New Duct-less Air Pressure?

  1. #1
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    New Duct-less Air Pressure?

    My ac company will add a duct to my bedroom. If you add a duct to your a/c unit will it pull air from the other ducts causing less pressure in those rooms? My fear is they will add the new duct and then there will be less air in the other rooms.

  2. #2
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    Yes,less cfm will be available to the other rooms.This shouldn't be a concern if the system is large enough to condition the house,and the correct cfms(airflow ) are being delivered.

  3. #3
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    I was told the heat load tests were done and I have the correct size unit. A 4ton 16seer carrier infinity heat pump in north Texas. I still have a warm bedrrom after all the adjustments were made. I was told they are going to run a duct straight from the plenum to this room. It is a large room and its the farthest from the unit. The rest of the house cools great, I just dont want this last duct to take that away.

  4. #4
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    Just got off the phone with the wife. The room we are talking about is 82 and my thermostat is set on 78. The room right next to the warm room is 78. I do have a vs 2 stage sytem. It does run on low most of the time. It just feels like the room doesnt get much air. The room is about 20x20 and has two vents in it.

  5. #5
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    What they propose should "do no harm" ,may or may not solve the temp. issue in that room.Can't tell from here,without testing,seeing what you have,etc..

    I'd let them go ahead,and see if it works.Your system will naturally run a little longer or less in low stage,when it's cooling the room in question.

  6. #6
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    How much air is this new duct intended to flow, 150 cfm? And your 4 ton AC is set to flow what total amount, maybe 1600 cfm? As a homeowner I should think you would be happy to divert less than 10% of the total air to a room where it is specially needed. I am no expert being a homeowner myself, but would wager this will not interfere with the ability of other rooms to cool. I think a pro suggested this in the first place, and other pros will tell you it is a sound idea.

    If your HVAC pro is like mine, he will make sure there is an adjustment damper to get the desired amount of airflow to your room. Surely with the right setting this can make your family comfortable.

    Best of luck -- Pstu

  7. #7
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    Quote Originally Posted by kkmcewen View Post
    My ac company will add a duct to my bedroom. If you add a duct to your a/c unit will it pull air from the other ducts causing less pressure in those rooms? My fear is they will add the new duct and then there will be less air in the other rooms.
    If the room already has two supply vents in it, and is warmer than the rest, why aren't they adding or enlarging a return instead of trying to do more of the same? Getting the hot air out is as important as getting the cold air in.

    If you manage to push the hot air out, where is it going to go? Do you close your door at night? How is three vents worth of air coming in going to get out? Where is it going to go? Do you mind if that area gets warm instead?

    -HF

  8. #8
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    My home has three large returns. One of the returns is right outside the room in question. The size of that return is 20x20. We do leave the door to this room open, so I wouldnt think the return is a issue? Im starting to notice that when my unit is on low iw when its the warmest in the room. When the unit goes to high it does cool off somewhat, but not enough to match the other rooms?

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