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  1. #14
    Join Date
    Dec 2008
    Location
    Buffalo NY
    Posts
    3,107

    Cool

    Great reply Energy rater La. I did not go into that much detail in my answer but that is what I meant by saying you need to insulate. Your new system will not work well with out it. I also forgot to mention air sealing.
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  2. #15
    Join Date
    May 2008
    Location
    Missouri
    Posts
    3,537

    Smile 2nd floor hot?

    This is a VERY common complaint in new 2 story homes in our area. As previously mentioned, you can either zone your home, or add another unit to handle the 2nd floor cooling. One thing you might try, is to close all of the basement air outlets, and then close 1/2 of the main floor outlets, and make sure ALL of the 2nd floor outlets are wide open. This should improve the air flow to the upper floor, and after all this is done, make sure and keep the air filter clean. Don't ever use the 1" pleated filters that look like they are made of "coffee" filter paper. They'll create a bunch of problems with your air flow. Remember, cold air falls, and hot air rises, so if your thermostat is on the lower Main floor, the upper floor air will gradually drift back down there. Just reverse this "register" closing arrangement in the winter, because warm air will natuarally find itself in the upstairs. This may improve your situation, but the real remedy would be the previous answers. Lots of luck!!

  3. #16
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,347
    Quote Originally Posted by energy_rater_La View Post
    just to offer a different perspective....
    I look at houses from an efficiency standpoint, thus the different perspective of adding more hvac.
    sometimes the house is the problem.
    it is much easier and much much more affordable to condition
    a tight box (house) than a leaky one.
    in my hot humid climate, adding more a/c is not always necessary
    if sealing of the house is done.
    if second story is not the same size as first story, and the second story of the house has attic that shares walls with the second story rooms then insulating these walls is not enough.
    if it is 90 degrees outside, then it is 120 degrees in the attic.
    however builders do not think of this when building, and seldom
    insulate these shared walls well. usually batts of insulation, not well attached are the common installs.
    so these walls are exposed to higher temps than first story exterior walls. what we do is to insulate them well..even installing batts
    works when batts fit well and are installed properly. then sealing the walls for air infiltration and heat gain is the next step and by far the most important one.
    we use a foil faced foam sheathing board to go from top plate of wall to bottom plate of wall from the attic side. these boards are nailed in place with button cap nails and seams taped. not only does this keep attic temps from transfering into the conditioned areas, but also the foil facing into the attic space reflects the bulk of the heat back into the attic.
    sole plates (or bottom plates) of second story walls are not treated as exterior walls, these plates should also be caulked or sealed with sill seal. too often it does not happen.
    if the hot air is on all six sides of these rooms..top, bottom (between floors) and all sides it is next to impossible to condition them as air movement and heat transfer would only be offset by oversizing of hvac system. (here oversizing caused high RH & tons of problems along with high utility costs)
    making these rooms as air tight as possible is the key. sealing walls shared with attic with foam/foil sheathing boards, sealing leakages in ceiling of second story..recessed lights, oversized cuts at bath fans, and sealing hvac supply boxes will improve the air barrier in this area. floors are always a problem, first is the insulation between floors in contact with first story ceiling and second story floors? if not then it needs to be, adding insulation batts never works after the fact, because there are always voids.
    pumping in more insulation works better. then with the same foil foam sheating board you continue the sealing of the walls to the
    ceiling of the first story. cutting the foam boards to go inbetween floor joists, caulking them in place and again taping all seams.
    if you improve the air barrier then the thermal barrier (insulation) will perform as designed. otherwise air flows across, through and around insulation and allows heat to transfer in to these rooms.

    sometimes we throw a whole bunch of money at problems when less money is often the solution.

    tighten up the leakage, stop the transfer of attic temps...less a/c needed to condition these rooms.
    indoor air quality is improved because you are not longer filtering air leakage through insulation, comfort is achieved, and utility costs are reduced.
    my pov is more of a whole house or house as a system way of thinking. it is very expensive to try and cool a room to 80 degrees when it is surrounded by temps in excess of 100 degrees.
    reflective products such as radiant barriers perform well when correctly installed. it is much harder (read...expensive) to retrofit into an existing house. all of roof area has to be covered, ( with foil facing into attic space) if garage attaches to main roofline, it will have to be seperated from main roofline or RB installed in garage also. any area left uninstalled with RB will allow heat into attic
    and value of RB will be none.
    florida solar energy center has good unbiased info on RB's & installs.
    best of luck..

    EXCELLENT POST!!
    • 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.

  4. #17
    Join Date
    May 2009
    Posts
    12

    Talking

    Thanks for all the insight. I assume the AC unit is ok for the house. The house was built only 5 years ago and I looked to see how much insulation was present. Looks like 15-20 inches of blown in stuff. Can anyone tell me about what it would cost to have a zone done? I have flexible ducts too. Can it be done with the Unit I have(more importantly)? I really don't have the money to install a second unit. I will also look into insulating better. I appreciate all your help. If there is anyone in Indy on here; I might have a job for you as well


    Quote Originally Posted by shophound View Post
    EXCELLENT POST!!

  5. #18
    Join Date
    Dec 2002
    Location
    Arizona
    Posts
    4,412
    Quote Originally Posted by Brent Ridley View Post
    l but I have experienced a lot of motor damper failure.
    I've been installing zoning since 1988 and have experienced very, very few motor damper failures. You mite want to change brand.
    Make your expertise uniquely valuable.

    Make your influence uniquely far-reaching.

  6. #19
    Join Date
    Apr 2009
    Location
    R.O.T.
    Posts
    301
    Quote Originally Posted by efelkey View Post
    I am not a HVAC professional, but would love some advice on what I can do about my upstairs of my home being too warm. I have a 5 year old home with soffit and ridge vents. I have an AC unit that does a great job on the main floor. I can not get my second story comfortable without "cracking up the AC" which costs a lot of money and makes the main floor too cold. I have spoken to some people about attic fans, whole house fans, second AC units, and "reflective" products.

    If anyone can help me enjoy both stories of my home I would be greatly appreciative.

    Thanks

    Eric


    You need a second unit upstairs, the upstairs and the downstairs should be on separate units.

  7. #20
    Join Date
    May 2009
    Posts
    12
    I spoke to a neighbor two doors down (same type of layout) and he told me that he can get the upstairs comfortable by blocking the return on the main floor (that is directly above the thermostat) and keeping the fan on all the time. My home only has two returns for some reason and the second one is on the ceiling in my hottest hallway on second floor.

    Can this work? Will it damage my HVAC equipment?

    Once again I thank you all for your help.

  8. #21
    Join Date
    Nov 2008
    Location
    S.C.
    Posts
    931
    Zone the house! It will pay for itself in about 2 to 3 years.

  9. #22
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,347
    Quote Originally Posted by efelkey View Post
    I spoke to a neighbor two doors down (same type of layout) and he told me that he can get the upstairs comfortable by blocking the return on the main floor (that is directly above the thermostat) and keeping the fan on all the time. My home only has two returns for some reason and the second one is on the ceiling in my hottest hallway on second floor.

    Can this work? Will it damage my HVAC equipment?

    Once again I thank you all for your help.
    It's not a solution, it's a band-aid. Your neighbor may need a band-aid for slapping his forehead should he someday face a bill for compressor replacement.
    • 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.

  10. #23
    Join Date
    May 2006
    Location
    Raleigh,NC.
    Posts
    357
    Blocking a return is not the answer, shophound is right. laymans terms- it's like breathing, you can't exhale any more than you inhale. he's killing that system, and paying for additional energy while doing it.
    remember, with electronics; when its brown,its cooking and when its black, its done!!!

  11. #24
    Join Date
    Feb 2007
    Posts
    999

    Attic wall sharing

    In one of the posts, there was a statement that it's hard to cool a room that shares a wall with an attic.

    I have a bedroom which is warmer than the rest, and has a (north to northwestern) wall shared with an attic over a garage/laundry room. The peak of the attic runs about half way up the BR wall. It is insulated with fiberglass and the attic floor is insulated over the 1st floor laundry room, only (not the garage).

    The portion of attic floor which is over the garage does not have standard joists, but rather 2 x 4's, so creeping around is a little tenuous.

    It was suggested here that a radiant barrier (on wall portion) would help to reflect heat away from the BR. Is it possible (or proper) to staple foil barrier or reflectix insulation on the studs over the fiberglass. Would this create moisture problems.

    Thanks.

    Amp
    Last edited by ampulman; 05-20-2009 at 07:19 AM. Reason: minor edit

  12. #25
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,347
    I think energy_rater_la was specifying insulating foam boards for the exposed wall stud faces in the attic. At that, the manufacturer of the foam board material I've used requires that the product cannot be left exposed. Therefore, to comply with the manufacturer's spec, any foam board used in an attic would imply it should be covered with drywall or sheathing. This requirement is likely in place for fire safety.

    With this in mind, it might serve well to compare covering the attic side wall face with radiant barrier foil sheets vs. installing foam board with one reflective side, and then covered with sheathing. The latter will cost more, and is more labor intensive. The former offers radiant heat reflectivity but no net gain in R value of the wall. A 2 x 4 stud wall, with fiberglass insulation in the cavities between studs, and sheathed on both sides, might net an assembly R value of 11 - 13 (net assembly R value would include the insulation, stud and stud faces, top and sole plates, and headers, not including window/door openings). Add foam board and exterior sheathing to the mix, and the assembly R value can increase to 16 or better, and reduce "thermal bridging" of the stud faces where they touch the exterior sheathing. Studs have a lower R value than insulation, so where the stud faces touch a hotter or colder exterior sheathing, they will conduct heat into or out of your house faster than through the insulation.

    One additional benefit of this method is that, in the case of the wall exposed to the attic, enclosing the attic side encapsulates the fiberglass batts already in place. Fiberglass insulation performs by creating thousands of tiny air pockets that are poor conductors of heat. Air movement counteracts this effect. Encapsulating the fiberglass reduces air movement through the fiberglass, increasing its performance.

    If it were my home and my attic, I would opt for the foam board covered with OSB. The reflective side won't have a lot of say since it would have OSB right on top of it (radiant barriers need an air gap), but the overall increased R value of the wall would be a gain on my upstairs comfort levels.
    • 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.

  13. #26
    Join Date
    Feb 2007
    Posts
    999
    Thanks, Shophound, but need a few points clarified:



    TT
    Quote Originally Posted by shophound View Post
    I think energy_rater_la was specifying insulating foam boards for the exposed wall stud faces in the attic. At that, the manufacturer of the foam board material I've used requires that the product cannot be left exposed. Therefore, to comply with the manufacturer's spec, any foam board used in an attic would imply it should be covered with drywall or sheathing. This requirement is likely in place for fire safety.
    What hazard are you adding by putting foam board in place? Is the board itself, flammable?


    If it were my home and my attic, I would opt for the foam board covered with OSB. The reflective side won't have a lot of say since it would have OSB right on top of it (radiant barriers need an air gap), but the overall increased R value of the wall would be a gain on my upstairs comfort levels.
    Since the above would negate the reflective effect of the foil-coated board, is it absolutely necessary? How would the foil interact with the kraft paper lining against the interior wall board? Are we looking at a 'sandwich' from attic inward:

    OSB (outer-most) > foil covered board > existing fiberglass insulation ....and the board is installed flush with the studs, not between them.

    Thanks.

    Amp

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