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15Part No. 550-141-935/0602
Connect water boiler piping (continued)7
3. Piping for multiple boilers (see Figure 13):
A Size secondary boiler pump GPM based on
following formulas:
Calculate only secondary piping circuit resistance.
Boiler resistance will be about equal to three 90
degree elbows of secondary pipe size. Operate each
boiler and its secondary pump from a Weil-McLain
boiler control panel.
Do not maintain boiler at
predetermined water temperature.
B Primary pump GPM and head calculation should
not include secondary boiler circuits. Primary
pump can operate continuously during heating
season.
C Space 12" maximum or as close as practical.
D Check valve.
E Hand valve.
Expansion tank(s), relief valves and other accessories are
required but not shown.
Figure 13 Multiple water boiler piping
Temperature rise, °F = 230°F – Return water temperature
Gross output is in Btuh.
= GPM
Gross output
Temperature rise x 500