Installing A Cascade System; Connecting Water Supplies - Navien NHB-055 Installation & Operation Manual

8. Installing a Cascade System

When installing a cascadesystem, 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
Slave2
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 24 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/return temperature sensors (#GXXX001417) must be installed for cascade system operation.
Adjust the settings at the master unit as the cascade system uses only the master unit settings. Changes made to the slave units
are ignored.
Refer to "Setting the Cascade Staging Adjustments" on page 84 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%.
Slave1 Master
Air separator
Temperature
12" (30 cm)
sensors (required)
maximum
[NHB-110/ 150]
Supply
Cold water
Back flow preventor
Expansion tank
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Installing a Cascade System 51