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#### chuck.donaldson

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I have a 4 in. duct moving air at 300 FPM. I know that this equals about 24 CFPM. I want to know how much energy(BTU's or watts) it takes to heat this air 10 degrees F. The air starts at 30 F, 50 Hum. and sea level.
+ or - 5% is good enough.
OR, how much energy does it take to heat X amount of air(CFPM), Y amount of degrees(F)?
Thanks,
Chuck

#### beenthere

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1.08 BTUs per CFM per 1° temp rise.

In the case of your 4" duct, at 24 CFM and 10° rise, 259.2BTU.

A 4" rouind at 300 FPM is 26CFM.
(10*1.08)*26=280.8 BTUs.

#### chuck.donaldson

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Thanks

1.08 BTUs per CFM per 1° temp rise.

In the case of your 4" duct, at 24 CFM and 10° rise, 259.2BTU.

A 4" rouind at 300 FPM is 26CFM.
(10*1.08)*26=280.8 BTUs.
Thanks Beenthere, follow-on question- the literature says that it takes one BTU to heat 1 CF of water 1 degree C. What am I missing?

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#### beenthere

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Its 1 BTU to heat 1 pound of water 1°F.

A cubic foot of water, is 7.49 gallons, and weighs 62.39 pounds at 60°F.

#### chuck.donaldson

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Thanks again

Its 1 BTU to heat 1 pound of water 1°F.

A cubic foot of water, is 7.49 gallons, and weighs 62.39 pounds at 60°F.
Damm, you the man.
Thanks,
Chuck

#### beenthere

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