Navien NFB Series User Manual

62 Installing a Cascade System
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System Application #1- Cascade System with Closely Spaced Tees
12” (30 cm)
maximum
Air separator
Sub2Sub1
Main
Temperature
sensors (required)
Cold water
Supply
Return
Back flow preventor
Expansion tank
Note
●
Connect the “SH Demand (SH T/T or Zone controller)” to the main unit.
●
Connect the supply/return sensors to SUPPLY and RETURN terminals of the CNT1/2 terminal strip on the main unit PCB.
●
Connect the outdoor sensor (optional) to the main unit.
●
Install system pumps to the units (main and sub) as required by the system configuration.
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System Application #2- Cascade System with Hydro Separator
Sub2
Sub1
Main
Cold water
Supply
Return
Dirt collector
Hydro/Air separator
Back flow preventor
Expansion tank
Temperature
sensors (required)
Note
●
Connect the “SH Demand (SH T/T or Zone controller)” to the main unit.
●
Connect the supply/return sensors to SUPPLY and RETURN terminals of the CNT1 terminal strip on the main unit PCB.
●
Connect the outdoor sensor (optional) to the main unit.
●
Install system pumps to the units (main and sub) as required by the system configuration.
●
Connect zone pumps to the main unit, or to the zone controller.

Navien NFB Series Specifications

General

Type	Condensing Boiler
Fuel Type	Natural Gas or Propane
Heat Exchanger	Stainless Steel
Vent Type	Direct Vent
Vent Diameter	2" or 3"