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Kit Components

MSB-C2 (Pack C)

(For wiring MSB units) 

Parts List

Part

               Qty 

MSB Communication cable  

Terminal connector

                 2 

Instruction Sheet

                 1 

Connecting Multiple MSB-M Units 

1) On the  master MSB, one connector 
is connected to the terminal connector 
 and the other one is connected to the
MSB Communication cable.

2) When 2 MSB boards are used a 
MSB Communication cable will be 
installed between the master MSB 
board and the second MSB. The open 
connector will have the Terminal 
connector installed on both MSB 
boards. 

A maximum of 5 MSB boards can
be connected to each other.  
The terminal connector is 
connected on the terminal MSB 
which has an open connector.

1

3) Set No 3 switch on the master MSB 
to ON.  The LED light 6 should turn ON
confirming the connection.

Communication Cables B

Water Heater 
Control 

Communication Cable A

Control Board

MSB Communication cable (MSB-C2)

(13.1 ft,  4 m)

U306-1032(00)

5) Set No 3 and No 4 switches on the 
third MSB board to ON. 
The LED light 6 should turn ON 
confirming the connection. 

6) Set the No 5 switch on the fourth
MSB board to ON.

7) Set No 3 and No 5 switches on the 
on the fifth MSB board to ON.

MSB-C2

Note:

• 

Up to 5 water heaters can be connected together using 

the MSB-M and MSB-C1 kits. 

United States & Canada:  For use with Rinnai Tankless Water 
Heaters (except for models V53e, V53i and R63LSe which must 
use pressure activation valves, PVA).  

• 

Disconnect all water heaters from their power source before carrying out 
the following installation procedures.

NOTE:  The front cover panels of each water heater must be removed prior 
to completing the following installation procedures.

WARNING

Please contact Rinnai if you have further questions on the 
applicable water heater models.   

• 

• 

When over 5 water heaters are connected together,

MSB-M units are connected using MSB-C2 kits. 

• 

If multiple MSB-M are used, then at least three water heaters
should be connected to each MSB-M.
Ex: With 7 water heaters, one MSB-M should control 4 water 
heaters and the other MSB-M should control 3 water heaters. 

070 00012 32069 4

Master MSB board

2nd MSB board

5th MSB board (Terminal MSB)

2nd to 4th MSB board 

LED6

LED 1 ~ 5
(See MSB-C1 instruction)

Stand alone

Solid

Off

EXPLANATION

Working with multiple MSB boards 

LED 6

Indicator light (LED 6) on the Control Board indicates the status as 

follows:

4) Set No 4 switch on the second MSB 
to ON.  The LED light 6 should turn ON
confirming the connection.

The LED light 6 should turn ON 
confirming the connection. 

The LED light 6 should turn ON 
confirming the connection. 

Master

2nd

3rd

4th

5th

Manifold Electronic Control System

Installation Instructions 

Communication cable connectors

NOTE:
When viewing the installed MSB board, the dip switch will be as 
shown below (upside down).

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