Navien NFB-175H Installation Manual page 75

System Application #5- Cascade System with DHW Indirect Tank (for Low DHW Demand)
●
Supply
Air separator
Cold water
Backflow
preventer
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.
●
Connect zone pumps to the zone controller. Do not connect zone pumps to the main or sub units.
●
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.
●
Connect zone pumps to the zone controller. Do not connect zone pumps to the main or sub units.
●
Main
Temperature
sensors (required)
Main
Backflow preventer
Expansion tank
Sub1 Sub2
Sub2
Sub1
Cold water
Installing a Cascade System
DHW
Indirect
tank
Aquastat
Cold water
DHW
Indirect
tank
Aquastat
Cold water
75