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  1. #1
    Join Date
    Sep 2007
    Location
    Sarasota/Bradenton, FL
    Posts
    56

    How to deal with doors opening and closing -- letting in hot air?

    So, I'm in the process of re-thinking my A/C. I may simply be replacing a unit (one of three), or just re-designing the whole darn thing.

    Hence, I'm asking all sorts of questions.

    I'm a slightly strange homeowner -- HVAC problems actually keep me awake at night!

    In any case, and this is a question I've pondered over the years, here goes...

    How does one best deal with an area in a house that gets a lot of exposure to the outside?

    In my own house I have three such areas. This is South West Fla.

    1) A laundry room, right off the kitchen, that leads to the garage. We are going in and out constantly. At times, we go in and out so often, that the door might as well be open full time.

    2) A living room. Very large, 20' X 20', but communicates with the pool area. So, when the pool is in use, the kids are in and out non-stop.

    3) A bedroom. Right by the pool. Less use but still, the door is letting in a lot of outside air.

    In short, we live a very indoor/outdoor lifestyle.


    I've thought of two solutions:

    1) Just install an additional, large, regular A/C return over each entrance.

    2) Over each often-used entrance (inside the house, I mean), for example in the laundry room foyer, I could install an in-line fan. It would be exhausted to the outside. I would run it at low CFMs, say 20-40CFM -- but constantly.

    Negative pressure is not a problem, because we're coming and going so often. But, if each area that get open to the outside all the time, has an exhaust fan, less of the hot, not-conditioned air gets into the house. Or so I'm thinking??


    Thoughts?

    And all input is always very carefully considered, and much appreciated!! (And will keep me awake...considering...things...)


    b (Thanks!)

  2. #2
    Join Date
    Jul 2012
    Posts
    12

    Perhaps think of your home as a walk-in cooler??

    This is the Ask Our Pro's forum. In order to post a response here, you must have verified qualifications and have been approved by the AOP Committee. You may ask a question by starting a new thread.

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    Last edited by jpsmith1cm; 07-30-2012 at 09:31 PM. Reason: Non AOP Member

  3. #3
    Join Date
    Jun 2010
    Location
    Philadelphia PA
    Posts
    2,190

    You need a small chiller

    so you can get some cold water and pick coils that can handle the high latent load. Pool that communicates to living space with kids splashing around and you have AC and expect residential equipment to do the job...

    Good Luck
    You have got to learn from other people's mistakes! Because God knows you don't live long enough to make them all yourself !!!!!!!!

  4. #4
    Join Date
    Jul 2012
    Posts
    12
    This is the Ask Our Pro's forum. In order to post a response here, you must have verified qualifications and have been approved by the AOP Committee. You may ask a question by starting a new thread.

    You can find the rules for posting and qualifications here.

    Additional infractions may result in loss of posting privileges.
    Last edited by jpsmith1cm; 07-30-2012 at 09:31 PM. Reason: Non AOP Member

  5. #5
    Join Date
    Jul 2012
    Posts
    12
    This is the Ask Our Pro's forum. In order to post a response here, you must have verified qualifications and have been approved by the AOP Committee. You may ask a question by starting a new thread.

    You can find the rules for posting and qualifications here.

    Additional infractions may result in loss of posting privileges.
    Last edited by jpsmith1cm; 07-30-2012 at 09:32 PM. Reason: Non AOP Member

  6. #6
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,563
    Frank-0

    This is the Ask Our Pro's forum. In order to post a response here, you must have verified qualifications and have been approved by the AOP Committee. You may ask a question by starting a new thread.

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    Additional infractions may result in loss of posting privileges.

  7. #7
    Join Date
    Sep 2007
    Location
    Sarasota/Bradenton, FL
    Posts
    56
    Quote Originally Posted by genduct View Post
    so you can get some cold water and pick coils that can handle the high latent load. Pool that communicates to living space with kids splashing around and you have AC and expect residential equipment to do the job...

    Good Luck
    Hmmm...

    Sounds a bit hopeless.

    But, at the same time, I'm thinking that I can't be the first homeowner in Fla to have this problem.

    Also, I'm not sure what a small chiller is?

    Installing an extra return in foyer, over the door to the garage that gets a lot of use was actually the suggestion of a pro who came to service my A/C.

    And the idea of continuous, low CFM exhaust was my own idea.

    I'm kind of leaning toward the continuous, low CFM (25 or so) idea.

    What I'm thinking is that exhausting at low CFMs to the outside won't affect the A/C too much. But, it will pull out the hot, humid air that rises to the ceiling.

    I mean, the door opening/closing itself dumps all sorts of air in and out.

    A return over that area would mess with the balance of the A/C more, I would guess.

    And air curtain would be nice -- or any other commercial solution. But, I don't know if that's realistic for me at this point...

    Any thoughts?

  8. #8
    Join Date
    Aug 2009
    Location
    Beatrice, NE
    Posts
    2,055
    Have you given any thought to an air curtain? Very uncommon in residential but would help slow down air transfer through the openings like they edo at freight doors.

  9. #9
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,837
    You need a good contractor who's not afraid to install one of the new modulating heat pumps. If you were my client, I'd recommend a zone control system, coupled with an over sized heat pump such that when high load demands are present, the system has the capacity to do the job. By over sizing you'll also be able to get very efficient heat at colder temperatures than a normally properly sized HP but at the same time, being able to reduce to 30% of maximum output will make sure the system isn't over sized for summer cooling and so can do a great job of dehumidifying your home. The ducts will need to be re-worked to accommodate the areas that are currently problematic due to outdoor air infiltration but a sophisticated zone system can easily handle the variable needs of each zone. We're a Bryant dealer so I am most knowledgeable about the Carrier/Bryant line. In keeping with that, I'd recommend a Bryant Extreme heat pump, Evolution zone control system and re-work of ducts as needed to accommodate the system over sizing. You'll be pleasantly surprised at the new found comfort and overall substantially reduced operating costs. You'll also be surprised at the sticker price so please be sitting down when you get the quote. It's going to cost but the results are well worth it. To get things into perspective, I'd say the costs to acquire a properly designed and installed system will be on the order of the cost of a small Lexus auto or less.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  10. #10
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    +1 on either a modulating heat pump like a Carrier Greenspeed, or replace all 3 with a single VRF system with 3 indoor air handlers such as those by Mitsubishi or Daikin.

    The 2nd option since it's a larger home that needs 3 systems and has high humidity and varyign loads, is putting in a chiller with 3 or more seperate fan coils possibly with hot water reheat as well off of a hot gas reheat system making hot water or a natural gas wall boiler. You can even use the chiller to heat the pool water as well with a seperate heat exchanger.

    FYI - a chiller is just like a air conditioner, but instead of cooling air, it cools water. All larger commerical and industrial that need cooling and are designed correctly and effciently, use chillers in warm and hot climates.

    That beign said, chillers, while prviding better year round comfort and dehumidification, and lower overall operating costs on larger systems, are not cheap. The Bryant and Carrier Inverter drive system like the Greenspeed and Extreme, might be more econimical overall.


    I wouldn;t specifically modify the ductowrk. IF anything I'd add a supply near and exterior exit, not a return. A return will increase the amoutn of air that leaks into the home when the door is open and could cause mold in the return ductowkr. A supply on a system that runs continously at low speed will help pressurize the space to keep the hot humid air out. However, you may also get some sweating on the registers too. I would use plastic registers if possible in thseo locations.

  11. #11
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,320
    Just put one of these over each door that gets heavy use:

    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  12. #12
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Hmmm commerical air curtain. Nice idea.

  13. #13
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,164
    I thought air curtain also.
    as did poster #8, 11 & 13.

    limit numbers of doors used to buy less air curtains.

    best of luck.
    The cure of the part should not be attempted without the cure of the whole. ~Plato

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