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5.1.1 Piping Sizes and Considerations
When plumbing a cascade system, consider the
following pipe diameters and flow rates. Note that
flow rates above 6.6 ft/s may cause pipe erosion.
These specifications may vary depending on
installation conditions.
ΔT=54ºF
Water
Qty
Flow rate
Velocity
(GPM)
(ft/s)
1
6.02
4.38
2
12.04
4.92
The table above is based on model
Note
NHW700-199.
5.2 Connecting the
Communication Cables
Two water heaters can be connected with Navien
Ready-Link communication cables. Select one of
the water heaters in the cascade system as the
Main water heater, and then connect the other
water heater to it as the Sub. Before making any
connections, ensure that the power is turned off to
all water heaters.
Connect the Ready-Link cables to the J6 ports on
the right side of the front panel:
Pipe
Diameter (mm/in)
20A
/
in
3
4
25A
1 in
5.2.1 Configuring the Communication
Settings
After connecting the Ready-Link communication
cables, restore power to the water heater and turn
on all water heaters using the Power button.
To configure the communication settings:
1. On the Main water heater, press and hold the
Diagnostic and Up (+) buttons for more than
5 seconds. "MA.00" will appear on the display to
confirm that this water heater is set as the Main.
2. On the Sub water heater, press and hold the
Diagnostic and Down (-) buttons for more than
2 seconds. "SL.01" will appear on the display to
confirm that this water heater is set as the Sub.
3. On the Main water heater, press and hold the
Diagnostic and Up (+) buttons for more than
5 seconds. The display screen on the configured
water heater will return to the temperature
display.
To cancel the cascade
Note
communication setup, on the Main
water heater, press and hold the
Diagnostic and Reset buttons for
more than 5 seconds. The water
heater will revert to independent
operation. Repeat steps 1-3 to
reassign the Main water heater.
Installing a Cascade System
57
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