Is more insulation the answer here

Discussion in 'HVAC Heating & Cooling' started by DIY, Jan 30, 2007.

  1. DIY

    DIY New Member

    Messages:
    153
    Location:
    Florida
    The building i am talking of was built in the late to mid 50's. Block exterior walls,interior walls framed.The only insulation ever given this building was modern type single hung slider windows,single glazed,and insulation blown in the attic @ 3 1/2" thick throughout the 1,200 sq. feet of attic space.(duplex each unit is @600 sq. feet) It has central heat and air (heat pump) each central heat and a/c is rated at a ton and half , and the heat pump is located in the attic with spider ducting to each room. If this helps.. the roof has two 4 foot off ridge vents. My main question is: The unit never ,or hardly ever shuts off or gets to the desired temperature that i set it for? The thermostat checks out to be working fine. My immediate thoughts were to install a few gable end fans to circulate the air in the attic? Is there a way to insulate blocks? Is there a way to at this point to insulate the interior walls?
    Would wrapping the heat pump in the attic in a insulated blanket like on a hot water heater help? Any and all help/advice would be greatly appriciated! Thanks.
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    You can retro fit foam or blown in cellulose into those interior framed walls. 3.5" of insulation isn't helping in the attic. In many locales, today's code requires upwards of R40 - you probably have in the order of R8 or so there now. The biggest bang for the buck is insulation in the attic. Then consider the walls.

    What's on the outside of the block walls? If you ever decide to put siding on it, consider putting a layer of foam insulation under the new siding.

    You might be able to fill the holes of the block walls with foam, too, but I'm not sure how much this would do. You might want to try some additional research here.

    Insulating the heat pump probably isn't a good idea!, but, if the ductwork is uninsulated, do that. The cheapest is probably to buy some fiberglass batts and lay them over the existing insulation. Buy it without a vapor barrier, since you don't want one in the middle of the stack.

    Consider replacing the single-pane windows with some better ones, but in the interim, installation of some 3M window film weather proofing is quite inexpensive and gives a good buffer to the glass.
  3. jimbo

    jimbo Plumber

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    Please elaborate on the "heat pump in the attic". Are we talking a split system with a compressor unit outside and air handler in the attic? Or a package unit of some kind.?
  4. Gary Swart

    Gary Swart In the Trades

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    Location:
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    My best advice is to contact an insulation contractor. They have the expertise and equipment to do the job right. You clearly do not have anywhere near enough insulation especially with the price of heating fuels today.
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    There are a couple of ways to get insulation into existing walls. Tear them down and insulate, put back the drywall. Or, cut some holes and either inject (foam) or blow in (cellulose or fiberglass). Both can have problems if there are fire stops part way up the vertical channel, requiring additional holes.

    Insulating the walls will help, but since heat rises, the most cost effective and easiest is probably attic insulation. For a do-it-yourselfer, it might be easiest to lay unfaced batts of fiberglass. You can rent sprayers that distribute cellulose or shreaded fiberglass, but that can be messy.

    There are two ways to approach this, pay a little, one-time upgrade so you don't lose the heat/cooling you pay for constantly with some insulation to keep in what you just did; OR, buy bigger equipment to attempt to condition what is little more than the outside. Adding insulation should quickly pay back its expense from what you've described.
    Last edited: Jan 31, 2007
  6. DIY

    DIY New Member

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    Location:
    Florida
    Clarification

    Thanks for noticeing Jimbo. Yes, the compressor is outside, and the air handler in the attic.
  7. Gary Swart

    Gary Swart In the Trades

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    Location:
    Yakima WA
    When it comes to blowing insulation into an attic, I found that our local installation company would blow the insulation in using their equipment and labor for exactly what the insulation and free blower would cost me at the big box store. Go figure.
  8. DIY

    DIY New Member

    Messages:
    153
    Location:
    Florida
    Is more insulation the answer or...

    Gary, I did just that by calling in a insulation expert with the experience and necessary tools. Infact they are a very well known insulation company and have a good reputation, for new and old construction in the building industry in this state. They suggested/reccomended that blown in insulation of @ 3.5"
    thick would be very sufficient in my case (age of building,ceiling height,size of central heat and a/c unit installed,total sq. footage,average seasonal temps. for this area, new window R values and process used to install them etc. There reccomendation suprised me to!. I was very dubious. I checked around and got the same insulation answers. (most came over and inspected the building inside and out and the attic.) I am beginning to wonder if the air handler in the attic has a profound difference on reaching the desired temperature and/or performance?However, moving the air handler to a different location is not an option. I was thinking... blow in or roll in more attic insulation,and perhaps install gable end fans to circulate the air up in the attic. If i get no results from those possible remedys I think it is time to either shake up the HVAC people who installed and reccomended this system
    and took into consideration the air handler was going in the attic, or the insulation people.
  9. PEW

    PEW DIY Senior Member

    Messages:
    487
    DIY,

    What area do you live in, seems hard to believe that 3.5 inches would be sufficient for winter and summer. Could the 3.5 possibly be blown in on top of other insulation?

    Paul
  10. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
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    Location:
    New England
    In many places, they recommend R40. Even with a high-tech foam, 3.5" won't get close (well, maybe aerogel, but that stuff would bankrupt you and if you look at it cross-wise, it disintegrates). Unless you live somewhere like maybe Hawaii, where the temp only varies maybe 10-15 degrees season to season, day to day...more is better.

    Any HVAC system must be sized to the dwelling's heat load. This takes into account the exposure, windows, walls and attic/roof insulation and the expected outside temps vs desired inside temp. One way to minimize the size of the HVAC unit required is to tighten up the dwelling - stop air inflitration and then to insulate it well to keep in what you want. Well, technically, you can't keep in cold since it isn't a thing, it is an effect (you can slow heat migration by adding insulation).
  11. climate you are in.

    paul is right. Knowing your climate, we can comment more intelligently.

    See http://en.wikipedia.org/wiki/Building_insulation
    and http://en.wikipedia.org/wiki/Installing_building_insulation
    and http://en.wikipedia.org/wiki/Building_insulation_materials

    Heated air rises. Leaving bypasses (air gaps) drastically reduces insulation's effectiveness. Warm air and moisture always find their way to these bypasses. Even if you close all bypasses around batts and blankets, they are poor barriers to air infiltration and are susceptible to convection loops, especially when there are large temperature differences on either side of the insulation (such as during cold weather).

    Insulation keeps the house cooler in summer too. It works both ways, equally well at blocking heat transfer (or cold transfer) in either direction.

    DAvid
  12. DIY

    DIY New Member

    Messages:
    153
    Location:
    Florida
    insulation

  13. why not mention climate right away?

    comment to all:

    1.) Climate,
    2.) where the building is, and
    3.) how it was built,
    are necessary to know.

    Do we agree? Perhaps ALL threads and ALL queries should explain as early as the first post, where they are, in terms of climate or geography.

    DAvid

    p.s. R40 sounds like a lot to me, for an attic in a Florida house, especially when I think about how the rest of house was likely to have been built.
  14. Bill Arden

    Bill Arden Computer Programmer

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    MN, USA
  15. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
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    Location:
    New England
    Note, there is also a federal tax credit for installing insulation. Keep your receipts and check out www.energystar.gov.
  16. Randyj

    Randyj Master Plumber

    Messages:
    1,047
    Location:
    Alabama
    I recalled reading the subject of insulation and moisture problems in Florida a few months ago so I'll post a link to an article on the subject here.
    http://www.rlcengineering.com/sprayfoam.htm

    Thinking about using the sprayed in foam myself...or how I can incorporate it into my design or if it is necessary for me to do so.
  17. DIY

    DIY New Member

    Messages:
    153
    Location:
    Florida
    Your thoughts on how the rest of the house was built? The insulation companys that evaluated to mentioned nothing of R40.
  18. stick-built with no wind barrier

    in climates far north of Florida, people wrap the unfinished house in a breathable sheet -- a housewrap -- which lets humidity evaporate but does not let wind or air pressure through.

    Any house built on site with 2x4's, stick built, will have hundreds of seams and (small) openings that let air push through, whenever any wind or air pressure is present. These gaps / leaks / openings all become a significant factor in calculating what to do in terms of HVAC, heating, cooling, etc.

    All heating or cooling creates air pressure, since air density changes; heated air wil push up, cooled air down. Since your house is likely to have been built to local building standards, you have a "leaky" house -- which is not a serious problem in your climate.

    However, you mentioned above that you would put R40 in the attic. (!).

    On Feb 2nd at 9:31 PM you said "Seems the next step would be to blow in or roll in an insulation value of R40 ,and go from there... Thanks for all the replys and advice again all! Much appreciated."
    -- That sounded like you were gone, done, finished, and gone off to order an installation of R40 ....

    Hope that clarifies a bit.

    Another thing you have in your climate, as in most, is a house built in direct contact with the foundation. Far north of Florida, people put a plastic bubble wrap (as a heat break / insulator), on top of the concrete walls of the foundation, and then lay the first sill plate of the entire house on top of that. See FoamSealRâ„¢ sill gasket using any search engine. I have a roll of it on my desk, 5.5" x 82" which cost me $5. It prevents air infiltration and it slows down the inevitable heat transfer from the (heated) house to the (cold) foundation. Heat-cold transfer works both ways -- cool house, hot foundation.

    So, R40 sounds like a lot for an attic when the rest of the house is what it probably is.

    New topic: Foam is far better than "batts".

    David
  19. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,949
    Location:
    New England
    My comment on R40 did not directly relate to places like Florida, but stated that some parts of the country require this. A bunch of heat is lost when it rises, so the easier place to insulate is the attic. How much, is up to a cost/benefit review. This can help for cooling loads as well, although a radiant barrier there probably helps more. I know that I have both a radiant barrier and about R40 in my attic. The radiant barrier is on the underside of the roof joists, and the batts are on the ceiling of the top floor. In the summer, prior to the radiant barrier, the ceilings were hot at the end fo the day. Now, they are "room" temperature. Traditional insulation slows the transfer of heat - a radiant barrier can redirect that energy - back into the house in the winter, and back out the roof in the summer.

    Tightening up the house has its good and bad points. A truely tight house will have moisture and pollution problems unless addressed (controlled air exchange). A really loose one will cost a bunch to condition.
  20. Well said. A radiant barrier redirects a lot of the heat radiating from the sun to earth, like what a mirror does to light waves, whereas as all other types of heat insulation do something totally different: they slow heat transfer down to a lower rate.

    -- I wonder if there is a way to make it automatic that people have to mention their climate they are in, after they describe their problem. It's critical in most situations dealt with in these forums.

    David
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