Residential Gas Water Heaters Guidelines - State Water Heaters Standard Residential Gas Water Heater Service Handbook

RESIDENTIAL GAS, NON POWER VENTED, WATER HEATER
Water Hammer – is a concussion of moving water against the sides of a containing pipe or
vessel on a sudden stoppage of flow.
EX: 1/2 "copper pipe, 5GPM flow (7.2ft/sec.) – stop. Pressure rise of approximately 412 PSI.
3/4" copper pipe, 5GPM flow (3.3ft/sec) – stop. Pressure rise of approximately 188 PSI
Minerals and gases
Formulas:
Btu (British Thermal Unit)
1 BTU = 252 cal = 0.252 kcal
BTU divided by 3,413 = Kilowatts
To convert
from Fahrenheit to Centigrade: (° F – 32) times 5/9, or .556, equals degrees C.
One gallon
of (120° F, 49°C) water weighs approximately 8.25 pounds.
% of Hot
= (Mixed Temp. – Cold) divided by (Hot Temp. – Cold)
% Thermal Efficiency
Btu Output
= GPH X 8.25 X Temp. Rise X 1.0
GPH
= (BTU/H Input X % Eff.) divided by (Temp. Rise X 8.25)
One cubic foot
of Natural Gas contains about 1000 BTU of heat.
One "therm"
is equal to 100,000 BTU
One cubic foot
of Propane Gas contains about 2500 BTU of heat.
One gallon
of Propane gas contains about 91,250 BTU of heat.
One pound
of Propane gas contains about 21,600 BTU of heat.
gas pressure
One pound of
Inches of Water Column X .036091 = PSI
Inches of Water Column X .073483 = Inches of Mercury (Hg.)
State Water Heater
© 2004
SERVICE HANDBOOK
will separate from water as temperature increases.
is the heat required to raise 1 pound of water 1°F
1 cal = 4.187 Joules
BTU X 1.055 = Kilo Joules
Pounds X .45359 = Kilogram
Gallons X 3.7854 = Liters
= (GPH X 8.25 X Temp. Rise X 1.0) divided by BTU/H Input
is equal to 27.7 inches water column pressure
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Technical Training Department
Ashland city, TN