Installing A Cascade System; Connecting Water Supplies - Navien NFC-250/175H Installation Manual

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 combi-boiler and water
heaters. 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 applying a cascade system of combi-boilers and water heaters. 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 1 combi-boiler and 15 Navien water heaters (NPE-A2 or NPE-S2 model) to meet high-
volume heating demands. Some possible connection options include the following:
Example of a Basic Cascade System Application
Pressure
Relief Valve
Heating
Supply
Pump
Air Separator
with Expansion
Tank
Optional System
Temperature Sensor
Heating Return
System application drawings are intended to explain the system piping concept only.
Note
●
Install a NaviClean Filter in the system heating return to remove foreign objects from the system.
●
Foreign objects inside the system may result in abnormal system operation.
Refer to "3.4 Filling the System" on page 32 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.
●
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.
Each unit must be configured for cascade operation.
●
82 Installing a Cascade System
<NPE-A2 Series>
Sub1
Main
NaviClean
[NFC-H]
<NPE-A2 Series>
Sub2
Ball Valve
Faucet
Ball Valve
Check Valve