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7 Connect water boiler piping (continued)

3. Piping for multiple boilers (see Figure 13):

Figure 13 Multiple water boiler piping

ASize secondary boiler pump GPM based on following formulas:

Gross output

= GPM

Temperature rise x 500

Temperature rise, °F = 230°F – Return water temperature

Gross output is in Btuh.

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.

BPrimary pump GPM and head calculation should not include secondary boiler circuits. Primary pump can operate continuously during heating season.

CSpace 12" maximum or as close as practical.

DCheck valve.

EHand valve.

Expansion tank(s), relief valves and other accessories are required but not shown.

Part No. 550-141-935/0602

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Weil-McLain 80 manual Piping for multiple boilers see Figure, Size secondary boiler pump GPM based on following formulas