RESIDENTIAL GAS AND ELECTRIC WATER HEATER
SERVICE HANDBOOK
STANDARD RESIDENTIAL ELECTRIC WATER HEATER SERVICE GUIDELINES
Construction
See “General Section” for features common to both gas and electric models. Miscellaneous:
Amperage (Amps) (1 phase) = Watts divided by Volts
Amperage (3 phase) = (Watts X .577) divided by Volts
KW Required = (GPH X 8.25 X Temp. Rise X 1.0) divided by (3413) Ohms = Volts divided by Amperes
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)
Heating element(s)
This style water heater will have one or two electric, heating elements immersed in the tank. One element will always be located low in the tank; a second element is commonly located
down about 1/3 of the tank height from the top of the tank. These elements will seldom be wired to operate at the same time. (If they operate at the same time, amperage draw doubles, wire gauge size increases, fuse size increases and little is gained in heat recovery.)
A.O. Smith Water Products Company | 18 | Training Department | |
©2002 | Ashland City, Tennessee | ||
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