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  1. #1

    variable speed systems "required" for spray foam homes???

    I received a call today from an HVAC contractor who stated a foam contractor told their customer that a variable speed HP should have been installed in their home because it has an encapsulated attic.

    The problem being experienced is quite simply NO MAKEUP AIR which is causing a fireplace to backdraft.

    The foam contractor obviously is placing blame, even with no HVAC this problem would exist; but I still would like to hear if anyone has EVER read that foam homes require variable speed systems? And where can I find any such documentation?

  2. #2
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    5,669
    It's got nothing to do with the type of blower motor, its got everything to do with adequate make up air.

  3. #3
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,064
    Quote Originally Posted by Tloganm View Post
    I received a call today from an HVAC contractor who stated a foam contractor told their customer that a variable speed HP should have been installed in their home because it has an encapsulated attic.

    The problem being experienced is quite simply NO MAKEUP AIR which is causing a fireplace to backdraft.

    The foam contractor obviously is placing blame, even with no HVAC this problem would exist; but I still would like to hear if anyone has EVER read that foam homes require variable speed systems? And where can I find any such documentation?
    Well insulated air tight homes need aggressive make-up air ventilation to purge indoor pollutants and renew oxygen. Any open combustion appliance is capable of being backdrafted by more powerful exhaust devices like a kitchen hood or clothes drier.
    Homes in green grass climates with adequate fresh air ventilation and occupants that add moisture need supplemental dehumidification to maintain <50%RH during low/no cooling loads and +55^F outdoor dew points.
    Using a whole house dehumidifier with the fresh make-up air ventilation option is ideal way to purge indoor pollutants, renew oxygen, and maintain <50%RH with a simple high efficiency a/c. Units like the site sponsor, Ultra-Aire whole house dehumidifier are designed for these situations.
    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"

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