Whirlpool Residential Electric water heater Specifications download pdf (Page 4)

RESIDENTIAL ELECTRIC WATER HEATER

SERVICE HANDBOOK

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Technical Training Department 3 of 36 Residential Electric Svc Handbook

GENERAL SECTION – cont’d.

TERMS, DEFINITIONS, AND FORMULAS:

Water Expands when it is heated. Volume increases about 2% from 40° to 140° F.

Minerals and gases will separate from water as temperature increases

Amperage (Amps) (1 phase) = Watts divided by Volts (Ohm’s Law)

KW Required = (GPH X 8.25 X Temp. Rise X 1.0) divided by (3413)

Ohms = Volts divided by Amperes (Ohm’s Law)

One kilowatt is equal to 1000 watts

One kilowatt is equal to 3,413 BTU

Recovery Rate = (KW X 3413) divided by (Temp. Rise X 8.25)

Rise (F°) = (KW X 3413) divided by (GPH X 8.25)

Supply electrical fusing or breakers should be sized at least 125% of expected heater

amperage.

Water weighs 8.25 pounds per gallon at 120°F (49°C).

% of Hot water = (Mixed temp. – Cold) divided by (Hot temp. – Cold). This formula

gives the number of gallons drawn from the water heater for each gallon delivered at a

shower head or faucet. If the shower head flow rate (gallons per minute) is known, the

draw efficiency and gallon capacity of the water heater may be used to calculate the

length of the showering period in minutes.

Watt Density

= the density of the wattage output of the element compared to the surface area

of the element (i.e. “High Watt Density Element” will have the most wattage per square inch of

element surface

Energy Factor:

Formula: The minimum EF allowed = .97 - .0019 x V (volume of storage)

Example: Volume (50 gal.) x .0019 = .095 gal.x.97 - .095 = .875 (minimum energy factor).

Note: Since the formula varies by volume, each tank size will have a different minimum

energy factor requirement.

The formula for gas water heaters

is different than the above example.

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Whirlpool Residential Electric water heater Specifications Page 4