GSW Signature Series Electric manual Formula for mixing hot water

Appendices

Reference Guide for Water Heating

•11 BTUs are required to raise 1 gallon of water 1o F at 70% efficiency (gas)

•3,412 BTUs equal 1 kilowatt hour (KW)

•1 KW will raise 410 gallons of water 1o F at 100% efficiency

•1 BTU x 0.293 = watts

•1 KW = 1000 watts

•2.42 watts are required to raise 1 gallon of water 1o F

1 KW will raise 10.25 gallons of water 40o F at 100% efficiency

1 KW will raise 6.8 gallons of water 60o F at 100% efficiency

1 KW will raise 5.1 gallons of water 80o F at 100% efficiency

1 KW will raise 4.1 gallons of water 100o F at 100% efficiency

Formula for mixing hot water

M-C = Percent of hot water required to produce desired mixed H-Ctemperature

Where M = mixed water temperature; C = cold water temperature; H = hot water temperature

For example: How much of a shower is hot water and how much is cold water?

My shower temperature is 105o F, my water heater thermostat is set on 120o F and the cold water inlet temperature is 50o F.

105 – 50 = 55 = 79% of the shower is 120o hot water 120 – 50 = 70

This formula for mixing hot water is important when explaining a NOT ENOUGH HOT WATER trouble call and the water heater is functioning properly.

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