IBC SL Series Installation & Operating Manual page 55

3.11.2 System piping
Figure 34 Two pump, two load - parallel piping
Compared with the Primary-Secondary approach, the above design saves one pump. Use
check valves or thermal traps to isolate both the supply and return piping for each load. This
avoids thermal siphoning and reverse flow. In order to ensure appropriate flow of water through
the boiler in the case of high pressure drops or heating of a single zone, it may be necessary to
install a pressure-activated bypass device on any circuit where the flow rate could drop below
the minimum requirements.
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