6th December 2019

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# How many BTU's do I need for my hot water heater?

A common input is 34,000 BTUs on a 40-gallon tank and 36,000 BTUs on a 50-gallon tank. The higher the BTU input and efficiency, the faster the recovery. Electric water heaters typically have one 5,500-watt or two 4,500-watt elements.

Accordingly, how many BTUs does it take to boil one pound of water?

lbs of water x temperature rise = BTUs required for one hour (1 lb of water x 1 degree Fahrenheit) = 1 BTU for 1 hour.
Water equals 8.3 lbs per gallon. To boil one gallon of water starting 70°F in 1 hour you will need 8.3 x (212-70) = 1,178.6 BTUs.

How many kilowatts does it take to heat a gallon of water?

Energy required to heat one gallon of water, and one tank of water. Heating a gallon of water by 1°F with no losses thus takes 8.33 lbs x 1 Btu/lb = 8.33 Btu's. Heating a gallon of water by 1°F with no losses thus takes 8.33 ÷ 100,000 = 0.00008.33 therms. One kWh is 3413 Btu's, so one Btu is 1/3413 = 0.000293 kWh.

How many BTU's does it take to boil a gallon of water?

A BTU (British Thermal Unit) describes the amount of energy to raise 1 lb of water 1 degree Fahrenheit in one hour. Water equals 8.3 lbs per gallon. To boil one gallon of water starting 70°F in 1 hour you will need 8.3 x (212-70) = 1,178.6 BTUs.