Table F: Boiler Temperatures and Minimum Pipe Size at Varying Return Temperatures
System
Return Temp
Supply Temp
1
Supply Temp
1
Supply Temp
1
(°F)
(°F)
<80' equiv. 80-200' equiv.
(°F)
<80' equiv. 80-200' equiv.
(°F)
<80' equiv. 80-200' equiv.
60
138
2"NPT
2 1/2"NPT
147
2"NPT
2 1/2"NPT
154
2"NPT
2 1/2"NPT
80
138
2"NPT
2 1/2"NPT
147
2"NPT
2 1/2"NPT
154
2 1/2"NPT
3"NPT
100
138
2 1/2"NPT
3"NPT
147
2 1/2"NPT
3"NPT
154
2 1/2"NPT
3"NPT
120
145
2 1/2"NPT
3"NPT
158
2 1/2"NPT
3"NPT
170
2 1/2"NPT
3"NPT
140
165
2 1/2"NPT
3"NPT
178
2 1/2"NPT
3"NPT
190
2 1/2"NPT
3"NPT
160
185
2 1/2"NPT
3"NPT
198
2 1/2"NPT
3"NPT
210
2 1/2"NPT
3"NPT
1
-Approximate high fire heater outlet temperature based on the standard heater pump and the recommended connecting pipe size.
Model 1005
Minimum Pipe Size
2
Model 1505
Minimum Pipe Size
2
Model 2005
Minimum Pipe Size
2
2
-Minimum pipe size based on total equivalent feet of supply and return piping between the system loop and heater.
Fig. 14: Single Heater with Primary/Secondary Piping
Fig. 15: Dual Heaters (Reverse/Return)
with Primary/Secondary Piping
Fig. 16: Single Domestic Hot Water Heater and Storage
Tank
Domestic Hot Water
When designing the hot water piping system for
domestic hot water applications, water hardness
should be considered. See Table H on page 18 for the
required tubing sizes and expected supply tempera-
tures for different operating conditions. Water
hardness is expressed in grains per gallon.
Fitting Type
Equivalent Length (ft)
2-1/2” NPT
3” NPT
90° Elbow (Std.)
8.5
9.4
90° Elbow (Long rad.)
3.5
3.6
45° Elbow
3.0
3.4
Gate Valve (Full open)
1.6
1.6
Swing Check Valve
22
25
Table G: Equivalent Lengths of Pipe for Typical Fittings
Note: Equivalent lengths are calculated based on typical operating
conditions with typical Schedule 40 pipe fittings and valves.
Equivalent lengths are approximate and may vary greatly.
*Maximum 4 times the pipe diameter or 12”, whichever is less.
*Maximum 4 times the pipe diameter or 12”, whichever is less.
California Hot Water Supply, Inc.
(800) 249-7244
16
