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  1. #1
    Join Date
    Jun 2004
    Location
    4H: Hot, Humid Houston H.O.
    Posts
    3,304

    Manual-J Pros, a question

    I have just done a room-by-room Manual J, and observe that one of the bedrooms has disproportionately more heat loss in the winter, compared with the others. Not surprisingly, this bedroom has a tendency to get cold on winter nights.

    The room in question is 206 sqft, its summer heat gain at design temperature is 2728 btuh and winter heat loss is 5214. A near-twin room with different exposure is 189 sqft and has summer heat gain 3212 and winter heat loss 4931. Note that one room is "dominant" in winter, it flips to the other in summer.

    This is apparently integral to the house design and orientation, so how to live with it is the big question. When the bedroom has adequate airflow for winter needs, it should be excessively cooled in summer. In this climate, winter occurs in short sporadic bursts, so a once-a-year airflow adjustment is not a feasible solution. I cannot think of any comfort solution that does not involve moving parts (or spending a fortune in new windows).

    When designing HVAC to make the house comfortable summer and winter, how would a pro try to make the best of this situation?

    Thanks for your wisdom -- Pstu, formerly known as P.Student

    [Edited by pstu on 01-26-2006 at 08:48 AM]

  2. #2
    Join Date
    Mar 2004
    Posts
    1,042
    No moving parts? That's no fun

    Looks like a good application for Arzel, to me. You could just have a damper and thermostat in each of those two rooms (not a central zone control) just to prevent overheating/overcooling.

  3. #3
    Join Date
    Nov 2004
    Posts
    2,927

    Re: Manual-J Pros, a question

    Originally posted by pstu
    When designing HVAC to make the house comfortable summer and winter, how would a pro try to make the best of this situation?

    I didnt recognise you with that fake moustache,P

    dsign for cooling and add electreic baseboard

  4. #4
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,002

    Re: Manual-J Pros, a question

    Originally posted by pstu


    room-by-room Manual J,
    and observe that one of the bedrooms has disproportionately more heat loss in the winter, compared with the others.

    The room in question is
    206 sqft, its summer heat gain at design temperature is 2728 btuh and winter heat loss is 5214.

    A near-twin room with different exposure is
    189 sqft and has summer heat gain 3212
    ............ and winter heat loss 4931.

    , so how to live with it is the big question.

    When designing HVAC to make the house comfortable summer and winter, how would a pro try to make the best of this situation?
    [Edited by pstu on 01-26-2006 at 08:48 AM]
    Set A/C to summer conditions & use a heat blanket
    or small (1 kW) heater to maintain bedroom >66F
    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

  5. #5
    Join Date
    Jul 2005
    Posts
    643
    Manual damper in supply. You can get fancy and istall a powered damper with controls and stuff but IMO it's more $$ and headache than it's worth.

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