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Thread: Is more insulation the answer here

  1. #1
    DIY Senior Member DIY's Avatar
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    Default Is more insulation the answer here

    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. #2
    Retired Defense Industry Engineer jadnashua's Avatar
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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.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    Plumber jimbo's Avatar
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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.?

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    In the Trades Gary Swart's Avatar
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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. #5
    Retired Defense Industry Engineer jadnashua's Avatar
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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 by jadnashua; 01-31-2007 at 09:43 AM.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    DIY Senior Member DIY's Avatar
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    Default Clarification

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

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    In the Trades Gary Swart's Avatar
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    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. #8
    DIY Senior Member DIY's Avatar
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    Default 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. #9

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    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. #10
    Retired Defense Industry Engineer jadnashua's Avatar
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    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).
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  11. #11
    Homeowner geniescience's Avatar
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    Default 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/Install...ing_insulation
    and http://en.wikipedia.org/wiki/Buildin...tion_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. #12
    DIY Senior Member DIY's Avatar
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    Default insulation

    [QUOTE=PEW]DIY,

    What area do you live in,Florida. 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? No. the attic had no insulation to begin with. Considerations i posted in "is more insulation the answer or..." all insulation companys factored into how much and what kind of insulation would be best.
    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.

    Paul[/QUOTE

  13. #13
    Homeowner geniescience's Avatar
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    Default 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. #14
    Computer Programmer Bill Arden's Avatar
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    I found a neat web page that calculates your savings.

    http://www.builditsolar.com/Referenc...sulUpgrade.htm
    Important note Ė I donít know man made laws, just laws of physics
    Disclaimer: I'm a big fan of Darwin awards.

  15. #15
    Retired Defense Industry Engineer jadnashua's Avatar
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    Note, there is also a federal tax credit for installing insulation. Keep your receipts and check out www.energystar.gov.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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