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wifi · 05-07-2009, 01:57 PM

BTU = heat required to raise one lb of water 1 degree F
Water weights about 8 lbs/gallon.

Lets guestimate we start at 50 degrees and want to get to 120 degrees. This is a 120-50=70 degree rise times 8 lbs/gallon = 560 BTUs to raise one gallon of water from 50 to 120.

So, 3 gals/min = 1680 BTUs/minute times 60 minutes = 100,800 BTUs per hour. Efficiency is ~50%?

Hmm... where am I wrong ?

05-07-2009, 01:57 PM	#4
wifi Senior Member Join Date: Jul 2007 Location: Lakes Region Posts: 1,321 Thanks: 282 Thanked 287 Times in 169 Posts	This ought to be easy to figure out BTU = heat required to raise one lb of water 1 degree F Water weights about 8 lbs/gallon. Lets guestimate we start at 50 degrees and want to get to 120 degrees. This is a 120-50=70 degree rise times 8 lbs/gallon = 560 BTUs to raise one gallon of water from 50 to 120. So, 3 gals/min = 1680 BTUs/minute times 60 minutes = 100,800 BTUs per hour. Efficiency is ~50%? Hmm... where am I wrong ?