Installing A Cascade System; Connecting Water Supplies - Navien NFB-175 Mode D'emploi

8. Installing a Cascade System

When installing a cascade system, carefully consider the design of the system and the features of the installation location. Follow all local
codes and regulations, as well as all guidelines for installing the boiler. The following sections describe additional considerations that are
specific to installing cascade systems. Read them carefully before designing or installing the system.

8.1 Connecting Water Supplies

Several options are available for plumbing a cascade system of boilers. The options shown here are only examples. The setup you choose will
vary based on the installation location, local building codes, and other factors. Follow all applicable regulations when installing a cascade
system.
You can connect up to 16 boilers to meet high-volume heating demands. Some possible connection options include the following:
Example of a Basic Cascade System Application
●
Supply
Cold water
Back flow preventor
Expansion tank
Return
System application drawings are intended to explain the system piping concept only.
Note
●
Install a filter in the system return to remove foreign objects from the system. Foreign objects inside the system may result in
●
abnormal system operation.
Refer to "3.3 Filling the System" on page 27 for make-up water connections and refer to the requirements of your local codes
●
to ensure compliance.
Use pumps with integral check valves or install check valves at the pump outlets.
●
Navien system supply (Included box)/return (Accessory) Temperature sensor must be installed for cascade system operation.
●
Adjust the settings at the main unit as the cascade system uses only the main unit settings. Changes made to the sub units are
●
ignored.
Refer to ""Configuring a Cascade System" on page 93 to make adjustments to the boiler staging settings. By default, boilers
●
will be added to the system when the input capacity exceeds 70%, and removed when the input capacity falls below 30%.
Air separator
12" (30 cm)
Temperature
maximum
sensors (required)
[NFB-175/200]
Sub1
Main Sub2
Installing a Cascade System 61