Navien NFB Series Installation & Operation Manual page 64

System Application #5- Cascade System with DHW Indirect Tank (for Low DHW Demand)
●
Supply
Cold water
Back flow preventor
Expansion tank
Return
In this configuration, space heating and DHW can operate simultaneously.
Note
●
The aquastat on the DHW indirect tank must be connected to a sub unit.
●
If a dedicated sub unit is used, the input capacity requirement of the indirect tank shall not exceed the capacity of the single
●
boiler.
Connect the DHW pump to the sub unit.
●
System Application 6 - Cascade System with DHW Indirect Tank (for Low DHW Demand)
●
Supply
Return
Temperature
sensors (required)
Dirt collector
Hydro/Air separator
In this configuration, space heating and DHW can operate simultaneously.
Note
●
The aquastat on the DHW indirect tank must be connected to a sub unit.
●
If a dedicated sub unit is used, the input capacity requirement of the indirect tank shall not exceed the capacity of the single
●
boiler.
Connect the DHW pump to the sub unit.
●
64 Installing a Cascade System
Air separator
Temperature
sensors (required)
Main
Back flow preventor
Expansion tank
Main
Sub1
Sub1
Sub2
Indirect
tank
Aquastat
12" 30 cm
maximum
Sub2
Indirect
tank
Aquastat
Cold water
Cold water
DHW
Cold water
DHW