76 Installing a Cascade System
8.2 Connecting the
Communication Cables
Up to 16 boilers can be connected with Navien
Ready-Link communication cables. Select one of the
boilers in the cascade system as the main boiler, and
then connect the other boilers to it as sub boilers.
Before making any connections, ensure that the
power is turned off to all boilers.
Connect the Ready-Link cables to the CNK1 terminal
strip:
CNK1
ZONE3
ZONE2
ZONE1
DHW
CNT1 CNT2 CNT3 CNT4
SUPPLY RETURN OUTDOOR
DHW
TANK
CNC3
LWCO
CNC4 CNC5
CNC6
CNC1
R
W
C
R
W
C
R
W
C
R
W
C
Note
When installing the cascade system,
refer to “8.1 Connecting Water Supplies”.
Also, connect zone pumps to the zone
controller. Do not connect zone pumps
to the main or sub units.
8.2.1 Configuring the Communication
Settings
After connecting the Ready-Link communication
cables, restore power to the boiler and turn on all
boilers using the Power button (
).
Refer to “11.13.4 Configuring a Cascade System” to
configure the communication settings.
8.1.1 Piping Sizes and Considerations
When plumbing a cascade system, consider the
following pipe diameters and flow rates. Note that
flow rates above 4 ft/s may cause pipe erosion
or velocity noise. These specifications may vary
depending on installation conditions.
NHB-110H
Qty
Flow Rate (GPM)
@ 20°F ΔT
Recommended
Boiler Pipe Sizes
(2-4 ft/s)
2 32.2 2"
3 48.3 2-1/2"
4 64.4 3"
5 80.5 3"
6 96.6 3-1/2"
7 112.7 3-1/2"
8 128.8 4"
9 144.9 4"
10 161 4"
11 177.1 5"
12 193.2 5”
13 209.3 5"
14 225.4 5"
15 241.5 5"
16 257.6 6"
NHB-150H
Qty
Flow Rate (GPM)
@ 20°F ΔT
Recommended
Boiler Pipe Sizes
(2-4 ft/s)
2 36.6 2"
3 54.9 2-1/2"
4 73.2 3"
5 91.5 3-1/2"
6 109.8 3-1/2"
7 128.1 4"
8 146.4 4"
9 164.7 5"
10 183 5"
11 201.3 5"
12 219.6 5"
13 237.9 5"
14 256.2 6"
15 274.5 6"
16 292.8 6"
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