Is this overkill-Geothermal AND spray foam insulation
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  1. #1

    Is this overkill-Geothermal AND spray foam insulation

    Is it overkill to build a new home with Spray Foam Insulation, High End Energy Star Windows, and use Geothermal for HVAC?
    The home will be one story, with a fireplace and 2500 square feet in South Carolina.

    With such a tight house, is Geothermal overkill

  2. #2
    Join Date
    Jul 2010
    Location
    Bay Area
    Posts
    261
    Throw some solar panels on there and you might have your local utilities makin part of your house payment lol

  3. #3
    Join Date
    Jul 2005
    Location
    SE PA
    Posts
    183
    Quote Originally Posted by Foodeefish View Post
    Is it overkill to build a new home with Spray Foam Insulation, High End Energy Star Windows, and use Geothermal for HVAC?
    The home will be one story, with a fireplace and 2500 square feet in South Carolina.

    With such a tight house, is Geothermal overkill
    I think if you have the resources and plan to live there for some time, it's foolish building new and NOT doing what you're proposing.

  4. #4
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
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    6,231
    Quote Originally Posted by Foodeefish View Post
    Is it overkill to build a new home with Spray Foam Insulation, High End Energy Star Windows, and use Geothermal for HVAC?
    The home will be one story, with a fireplace and 2500 square feet in South Carolina.

    With such a tight house, is Geothermal overkill
    Tell us about your fresh air venitlation system.
    Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  5. #5
    Join Date
    Dec 2007
    Location
    USA, Midwest
    Posts
    35

    Watch your equipment sizing

    Spray foam insulation is great, but make sure your geothermal system is two speed and sized correctly. With decreased cooling load and no infiltration in the summer, the equipment may not run long enough to remove moisture, even with low-humidity settings on the geothermal system. Two-speed equipment will maintain comfort by running at reduced capacity.

    As "teddy bear" mentioned, you'll also need to address fresh-air control.

    Regards,

    Gus

  6. #6
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
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    6,231
    Quote Originally Posted by Gus_Scorchio View Post
    Spray foam insulation is great, but make sure your geothermal system is two speed and sized correctly. With decreased cooling load and no infiltration in the summer, the equipment may not run long enough to remove moisture, even with low-humidity settings on the geothermal system. Two-speed equipment will maintain comfort by running at reduced capacity.

    As "teddy bear" mentioned, you'll also need to address fresh-air control.

    Regards,

    Gus
    Thanks for the "fresh air" support. I also like proper sizing for your high load condition.
    In this kind of home you will not get enough at any speed of cooling to remove the moisture from the occupants and fresh air ventilation when the outside dew point is +65^F and the cooling load is low or non-exsistant. Take the extra cost of the two speed Hp and invest it into a whole house ventilating dehumidifier. This will provide fresh make-up air for your exhaust devices like clothers drier/kitchen hood/bathfans and most importantly purge indoor pollutants and renew oxygen when the home is occupied.
    Occupants and fresh air is a 2-4 lbs. per hour moisture load during wet warm weather. During hot weather, your a/c handles this moisture, but during evenings and rainy days no cooling load in SE PA or anyother green grass climates. If cost is not a concern get the two speed hp and WHV dehu.

    We do a lot vent dehu retrofiting of the finest of homes and heating/cooling systems. I taked to customer yesterday. After a year in a air tight foam home, it was like opening a plastic bag and breathing fresh air, was his statement.
    Good air quality is the most important part of a home. Air quality is fresh air, <50%RH, and good air filtering.
    Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  7. #7
    Join Date
    Mar 2008
    Location
    northern Indiana
    Posts
    114
    Quote Originally Posted by teddy bear View Post
    Thanks for the "fresh air" support. I also like proper sizing for your high load condition.
    In this kind of home you will not get enough at any speed of cooling to remove the moisture from the occupants and fresh air ventilation when the outside dew point is +65^F and the cooling load is low or non-exsistant. Take the extra cost of the two speed Hp and invest it into a whole house ventilating dehumidifier. This will provide fresh make-up air for your exhaust devices like clothers drier/kitchen hood/bathfans and most importantly purge indoor pollutants and renew oxygen when the home is occupied.
    Occupants and fresh air is a 2-4 lbs. per hour moisture load during wet warm weather. During hot weather, your a/c handles this moisture, but during evenings and rainy days no cooling load in SE PA or anyother green grass climates. If cost is not a concern get the two speed hp and WHV dehu.

    We do a lot vent dehu retrofiting of the finest of homes and heating/cooling systems. I taked to customer yesterday. After a year in a air tight foam home, it was like opening a plastic bag and breathing fresh air, was his statement.
    Good air quality is the most important part of a home. Air quality is fresh air, <50%RH, and good air filtering.
    This "opportunity" is missed by most contractors and provides highest efficiency and comfort levels.

  8. #8
    Join Date
    Jul 2005
    Location
    SE PA
    Posts
    183
    Quote Originally Posted by teddy bear View Post
    Thanks for the "fresh air" support. I also like proper sizing for your high load condition.
    In this kind of home you will not get enough at any speed of cooling to remove the moisture from the occupants and fresh air ventilation when the outside dew point is +65^F and the cooling load is low or non-exsistant. Take the extra cost of the two speed Hp and invest it into a whole house ventilating dehumidifier. This will provide fresh make-up air for your exhaust devices like clothers drier/kitchen hood/bathfans and most importantly purge indoor pollutants and renew oxygen when the home is occupied.
    Occupants and fresh air is a 2-4 lbs. per hour moisture load during wet warm weather. During hot weather, your a/c handles this moisture, but during evenings and rainy days no cooling load in SE PA or anyother green grass climates. If cost is not a concern get the two speed hp and WHV dehu.

    We do a lot vent dehu retrofiting of the finest of homes and heating/cooling systems. I taked to customer yesterday. After a year in a air tight foam home, it was like opening a plastic bag and breathing fresh air, was his statement.
    Good air quality is the most important part of a home. Air quality is fresh air, <50%RH, and good air filtering.
    Regards TB
    Do you have any recommended brands for whole house ventilating dehumidifiers?

  9. #9
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,231
    Quote Originally Posted by im4snow2000 View Post
    Do you have any recommended brands for whole house ventilating dehumidifiers?
    How sweet of you to ask. I work for Therma-Stor, we manufacture the Ultra-Aire/Santa Fe line and a few others. There are several outthere and more everyday.
    We started the concept 1994.
    Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  10. #10
    Join Date
    Dec 2010
    Location
    mich
    Posts
    2
    Don't know if its over kill but I have the spray foam and geothermal and I love it. I'm in mich and it doesn't have any problem heating our 1500 main floor and 1500 downstairs house.
    We have electric back up and we shut if off. Ours is water to air.

  11. #11
    Join Date
    Feb 2006
    Posts
    468
    That size house with described features should be able to be designed so as to load out to about 2 tons. Then you have to figure out the cost increment between a high end two stage air source and a similar geo system. The geo system will likely cost a bit less per year to operate, but you'll want to calculate payback.

    We routinely get 1200-1500 SF per ton with ICF block walls, closed cell sprayfoam, and decent windows

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