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Thread: bedroom returns

  1. #1
    Join Date
    Sep 2005
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    We recently moved into a 12 year-old two-story house, and the master bedroom gets uncomfortablly stuffy at night whe we sleep with the door closed. It doesn't matter if we are running the furnace or the A/C. I noticed that the master suite has 4 equal-sized inlets but only a single return register, about the same size as one of the inlet registers. Should the area of the return equal the area of the inlets? Each of the additional smaller bedrooms in the house has a single inlet and single similar-sized return, and they do not get stuffy at night.
    Thanks in advance,

  2. #2
    Join Date
    Nov 2004
    SW FL
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    Exclamation R > S

    Originally posted by ivan2002
    Should the area of the return equal the area of the inlets?
    RETURN > Supply ___ Max dP = 0.01"

    FL Building Code - Mechanical

    601.4 Balanced return air.

    Restricted return air occurs in buildings when returns are located in central zones and closed interior doors impede air flow to the return grill or when ceiling spaces are used as return plenums and fire walls restrict air movement from one portion of the return plenum to another.

    Provisions shall be made in both residential and commercial buildings to avoid unbalanced air flows and pressure differentials caused by restricted return air.

    Pressure differentials across closed doors where returns are centrally located shall be limited to 0.01 inch WC (2.5 pascals) or less.

    Pressure differentials across fire walls in ceiling space plenums shall be limited to 0.01 inch WC (2.5 pascals) by providing air duct pathways or air transfer pathways from the high pressure zone to the low zone.

    [Edited by dan sw fl on 09-03-2005 at 01:11 PM]
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  3. #3
    Join Date
    Aug 2003
    Central Kentucky
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    The amount of return airflow should be +/- 10% of the airflow being supplied into the room.

    Just having the proper return grille area does not insure proper return airflow.

    Try closing your master bedroom door till there is about a 1/2" gap open.

    When your fan is running in the equipment you will probably feel air rushing out due to the lack of return.

    When you shut the door off you also limit the amount of air that can be supplied to that room.

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  4. #4
    Join Date
    Dec 2004
    Derby City
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    simple answer: yes, you're short on return air.

    solution: call in qualified contractor to visibly look at the system and air distribution system to make best possible recommendations, based on YOUR particular system.

    Remember, one size DOESN'T fit all.
    Everyone has a purpose in life..........even if it's to be a bad example.

    Seek first to understand, before seeking to be understood.

  5. #5
    Join Date
    Feb 2003
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    if that part of the system is screwed- up, then the rest probably is --
    so get or do a load calculation to determine what air is really needed for each room -- program available at this site is excellent -- just measure doors & windows & room size, amount of insulation -- know the orientation of the house with respect to North of the compass.
    harvest rainwater,make SHADE,R75/50/30= roof/wall/floor, use HVAC mastic,caulk all wall seams!

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