Navien NHB H Series Installation And Operation Manual page 30

3.5.2 System Application - Zone System with Zone Valves (Primary/Secondary Piping)
Make-up Water
Backflow Preventer
Pressure Reducing Valve
Expansion Tank
System application drawings are intended to explain the system piping concept only.
Note
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Install a filter in the system return to remove foreign objects from the system. Foreign objects inside
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the system may result in abnormal system operation.
Refer to "3.3 Filling the System" on page 26 for make-up water connections and refer to the
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requirements of your local codes to ensure compliance.
Use a pump with an integral check valve or install a check valve at the pump outlet.
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Refer to "3.6.5 Wiring Diagram - Zone Valve System" on page 39 for wiring connections.
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30 Installing the System Piping
Zone #2
Zone #1
Zone Valve (Typical)
System Pump
Air Separator
Additional Zone
Not to exceed 4 pipe Dia or Max. 12"
Boiler Pump