A.O. Smith TC-092 User Manual
SERVICE
INFORMATION
GUIDE
FORMULAS & FACTS
BTU (British Thermal Unit) is the heat required to raise 1 pound of water 1°F
1 BTU = 252 cal = 0.252 kcal
1 cal = 4.187 Joules
BTU X 1.055 = Kilo Joules
BTU divided by 3,413 = Kilowatt (1 KW)
FAHRENHEIT CENTIGRADE
32 0
41 5
To convert from Fahrenheit to Celsius:
(°F – 32) x 5/9 or .556 = °C.
60.8 16
120.2 49
140 60
180 82
212 100
One gallon of 120°F (49°C) water
weighs approximately 8.25 pounds.
Pounds x .45359 = Kilogram
Gallons x 3.7854 = Liters
% of hot water =
(Mixed Water Temp. – Cold Water
Temp.) divided by (Hot Water Temp.
– Cold Water Temp.)
% thermal efficiency =
(GPH recovery X 8.25 X temp. rise X
1.0) divided by BTU/H Input
BTU output (Gas) =
GPH recovery x 8.25 x temp. rise x 1.0
Linear expansion of pipe
– in inches per 100 Ft.
– 1 grain per gallon = 17.1 Parts Per million
Grain
(measurement of water hardness)
BTU output (Electric) =
BTU Input (Not exactly true due
to minimal flange heat loss.)
Capacity of a
cylindrical tank
– 1 ⁄2 diameter (in inches)
x 3.146 x length. (in inches)
Divide by 231 for gallons.
Doubling the diameter
of a pipe will increase its flow
capacity (approximately)
5.3 times.
TEMP °F RISE STEEL COPPER
0.38˝ 0.57˝
°
50
1.14˝
.076˝
°
00
1
125° .092˝ 1.40˝
1.75˝
1.15˝
°
150
FORMULAS & FACTS
TC-092
FORMULAS & FACTS
GPH (Gas) =
(BTU/H Input X % Eff.) divided by
(temp. rise x 8.25)
GPH (Electric) =
(KW x 3413) divided by
(temp. rise x 8.25) or (KW x 414)
divided by (temp rise.)
KW required =
(GPH X 8.25 X temp. rise)
divided by 3413 or
(GPH x Temp. rise) divided by 414
1 KW =
3413 BTH = 4.1 GPH @ 100° temp.
rise or 4.6 GPH @ 80° temp. rise
Meters = Inches x .0254
Centimeters = Inches X 2.54
mm (millimeters) = Inches x 25.4
One boiler horsepower (BHP) =
33,475 BTU
One cubic foot of Natural Gas
contains about 1000 BTU of heat.
One “therm” is equal to
100,000 BTU (100 CU. FT.)
One gallon of Propane gas contains
about 91,250 BTU of heat.
One pound of Propane gas contains
about 21,600 BTU of heat.
One pound of
gas pressure
is equal to 27.7 inches water
column pressure
Inches of Water Column
x .036091 = PSI
Inches of Water Column
x .073483 = Inches of
Mercury (Hg.)
One pound per sq. in.
= 16 oz per sq. in.
Water expands
approximately 2% in volume
for a 100°F temperature rise
(from 40°F to 140°F)
Water confined
to a storage tank or piping
system, when subjected
to a temperature rise of 10°F
(increasing from 75° to 85°),
increases pressure from
50 psi to 250 psi.
One cubic foot of Propane Gas
contains about 2500 BTU of heat.
Water capacity of copper tubing per foot
1
TUBING SIZE
3
⁄2
⁄4 111⁄2 23
g/ft type L .012 .025 .044 0.92 .161 .354
TC-092
FORMULAS & FACTS
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