19. Procedure for replacing Main Controller in the System Controller
Introduction
This manual is intended to provide instruction for the replacement procedure of the Main Controller in the System
Controller (SCU-401).
Refer to the "Procedure for replacing Sub Controller in the System Controller" for Sub Controller(SCU-401).
Before replacing the System Controller, be sure to read this sheet and System Controller Installation Manual for
correct operation.
Make sure your replacement situation as following (Case 1) or (Case 2):
(Case 1) Only the System Controller is replaced.
(Case 2) Both the System Controller and Remote Controller (RC-9018M or RC-7649M) are replaced at the same
time.
(Case 1) When only the System Controller is replaced.
1) Verify if any options (e.g. Warning Light, Operation Light, Circulation Pump, Exhaust Fan) are utilized.
If in use, disconnect the electric power for all options being used.
2) Turn off the Power ON/OFF Button first, then disconnect the electrical power for SCU-401 and all water heaters.
3) Replace the Main Controller of System Controller.
1. Remove the screw (
1
in Figure 2).
2. Disconnect all wires from the Main Controller of System Controller.
3. Install the new Main Controller into the System Controller and reconnect all wires and connectors to the new Main
Controller.
4. Secure the screw (
1
in Figure 2) again.
4) Connect the electric power for SCU-401 and all water heaters, and then turn on the Power ON/OFF Button.
5) When using remote controller RC-9018M, refer to step 6) to 9) procedure below.
When using remote controller RC-7649M, follow instructions on pages 22 - 26.
Then proceed directly to step 8).
6) Wait for approximately 30 seconds, and then set the clock* of the Remote Controller.
* Refer to page 19 for setting the clock.
* If the system settings screen (Figure 3) is displayed, discontinue this procedure and refer to step 6) to 11) in the (Case
2) procedure below to complete the programming correctly.
7) If you want to set the recirculation system operation timer, refer to pages 14 - 15.
* This timer is only available for the recirculation system.
8) Reconnect any options (e.g. Warning Light, Operation Light, Circulation Pump, Exhaust Fan) disconnected from step 1).
9) The replacement is complete.
(Case 2) When System Controller and Remote Controller (RC-9018M or RC-7649M) are replaced at the same time
1) Verify if any options (e.g. Warning Light, Operation Light, Circulation Pump, Exhaust Fan) are utilized.
If in use, disconnect the electric power for all options being used.
2) Turn off the Power ON/OFF Button first, then disconnect the electrical power for SCU-401 and all water heaters.
3) Replace the Main Controller of System Controller and the Remote Controller (RC-9018M or RC-7649M).
1. Remove the screw (
1
in Figure 2).
2. Disconnect all wires from the Main Controller of System Controller.
3. Install the new Main Controller into the System Controller and reconnect all wires and connectors to the new Main
Controller.
4. Secure the screw (
1
in Figure 2) again.
5. Replace the Remote Controller.
4) Connect the electric power for SCU-401 and all water heaters, and then turn on the Power ON/OFF Button.
Press ENTER button
for system settings
Sub Controller
SCU-401-24M
Only.
Main Controller
Figure 1: SCU-401-24M
Figure 2: Main Controller and Sub Controller
Figure 3: System settings screen
1 Screw
─38─