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  1. #1
    Join Date
    Jan 2008
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    Adding basement to load calculation

    Hi we recently got a estimate on a new furnace and A/C replacement and the contractor did a load calculation on our two story house with a finished basement. The contractor did load calculation for the main level and upper level but did not do one for the finish basement. Does the finish basement need a load calculation done? It is insulated and dry walled except for the room that the furnace is in. We had a couple of qoutes already and both did load calculation but neither did basement which I said is finished. Thanks for any response and opinions. We live around the twin cities in Minnesota if that makes a difference.

  2. #2
    Join Date
    Jan 2007
    Minneapolis, MN
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    Did they come to your house? They would have seen the basement. He should have included the basement, it doesn't take any longer. If it is a walk-out it will add to the load, if not it probably wont make much difference. Did you look into any energy improvements before replacing your equipment? Many times building shell improvements will lead to smaller equipment and greater overall comfort and energy efficiency. Did they analyze your current system to determine if there are any deficiencies that should be addressed? Are there any problem areas? When replacing old equipment it is good to look at the whole house to make sure the new furnace will perform for you. Was the load calc done according to ACCA manual J or some short form? I have seen some load calcs that were fancy rules of thumb. Windows and doors need to be measured, attic insulation measured. It is best to check infiltration with a blower door but almost no one does. Infiltration can be an important factor, especially in homes older than 20 years.
    Last edited by mbarson; 03-19-2008 at 04:12 PM.

  3. #3
    Join Date
    Feb 2008
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    Some people have bedrooms in the basement, others entertain a lot, etc. Be sure those factors were considered. In general, only portion of basement above grade figures into the load calculation. Comfort and air flow should also be considered.

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