ducted heater

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Permalink Reply by Timothy Fisher on May 3, 2011 at 6:06am

Duct leakage is leakage. I always apply the 6 cfm per 100 sqft energy star leakage standard for the ducts that I work with. The main difference in heating and cooling is in expected air flow of the two system types which vary.

Permalink Reply by Rick Powell on May 3, 2011 at 10:27am

21.7 times the OUTPUT btu= cfm for heat  Example: 100,000 btu furnace input   80,000 btu furnace output. 80% efficient.

21.7 X 80=1736 cfm supply for heat. You have to go outside BPI for these formula's. Try national comfort institute. The 80 comes from dropping the zero's  from 80,000 btu

Permalink Reply by Judi Lyall on May 4, 2011 at 6:39am

thank you both, ahhh I forgot my HERS stuff. Yes, when I saw 21.7 I remembered HERS. See somtimes a little nudge is all we need. I guess I couldn't think of putting HERS and BPI together. Thanks much appreciated.

Judi