Installing A Cascading System; Connecting Water Supplies - Navien NCB-150E Installation & Operation Manual

4. Installing a Cascading System

When installing a cascading 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 combination boiler and water heaters. The following sections describe
additional considerations that are specific to installing cascading systems. Read them carefully before designing or installing the system.

4.1 Connecting Water Supplies

Several options are available for plumbing a cascading system. The setup you choose will vary based on the installation location, local building
codes, and other factors. Follow all applicable regulations when installing a cascading system.
You can install one NCB-E boiler with multiple NPE / NR / NP series water heaters to configure a cascade system. In the system, the boiler must
be configured as the master unit. You can connect up to 15 water heaters to one NCB-E boiler to meet high-volume hot water demands by
using Navien Ready-Link communication cables and following the set-up procedures in this section; additional controllers are not necessary.
The following is one of the possible connection options:
Expansion Tank
Install a 120V AC (max 1.5A) normally closed solenoid valve on the NCB-E boiler's hot water supply, and then connect the valve wires to
the external power port(Extern. Power) on the main PCB (refer to the wiring diagram). A slow-closing solenoid is recommended to prevent
water hammer from occurring.
When linking multiple water heaters to NCB-E series boiler, only the master unit can provide space heating and slave units must be
configured for DHW only (You can set only the NCB-E boiler as the master unit in the cascade system, and the master unit controls the
power on/off status of all the slave units in the system).
Once turned on by the master unit, the water heaters will operate in stages to satisfy the DHW demands.
After completing the cascade settings and saving the changes, the boiler and water heater units must be turned off then turned back on for
the changes to take effect.
If errors occur while operating a cascade system, the relevant errors are displayed in the display of the failing unit (with the exception of NR/
NP units).
Power supply to the units must be OFF during the system piping.
The recommended recirculation flow rate for each water heater is 2-4 GPM. Depending on the number of water heaters and
Note
the diameter of the recirculation line, it may not be necessary to connect all the NPE / NR / NP "A" series water heaters to the
recirculation line. If this is the case, set any unconnected "A" model water heaters to internal recirculation mode.
32 Installing a Cascading System
<NCB-E Series>
Pressure relief valve
Air Separator
Solenoid valve
<NPE Series, NR/NP Series> <NPE Series, NR/NP Series>
Ball valve
Faucet
Check valve