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# How much electricity required to heat water?

#1
06-02-07, 05:03 AM
Member
Join Date: Feb 2005
Location: usa
Posts: 39
How much electricity required to heat water?

I have a 50 gallon electric hot water heater that was installed in January 2007. Assuming that the temperature of the cold water source is 50F and the tank is heating the water to 120F, how many watts of electricity will be required to heat one gallon of water?

#2
06-02-07, 07:48 AM
Member
Join Date: Feb 2006
Location: USA
Posts: 6,783
Heating Water

One gallon of water weighs 8.337 lb.
One BTU is required to raise the temperature of one pound of water one degree F.
From 50 deg. to 120 deg. is a 70 deg. change.
8.337 lb of water x 70 deg. F. change requires 583.59 BTU.
One kwh = 3413 BTU.
583.59 BTU required/3413 BTU per kwh = .171 kwh per gallon from 50 deg. to 120 deg.

Divide this by the efficiency of your water heater.(How well is it insulated?)

I apologize for all the details. I hope this answers your question. Have a nice day.

#3
06-02-07, 08:48 AM
Member
Join Date: Feb 2005
Location: usa
Posts: 39
Thanks Ken!!!

That is exactly the information I am seeking, and I like the detail. Thank you for taking the time to post that. The water heater is very well insulated. Feeling around the outer surface, it is cold metal. So I don't think there is any noticeable heat loss.

Henry