If the right size control system for you is the EZ4, then the Pentair part number that comes with and IC20 (yes, the transformer is in the cabinet) is 520542. It also comes with 2 valve actuators.
The spa side controller is the iS4, PN 520092. It has a 100' control cable that goes to the EZ4 cabinet.
The indoor wireless wall mounted controller is 520546.
The wired indoor unit is 520548.
Neither is required but having one is very convenient so you don't have to go to the main panel to turn on the spa, lights, change programming, etc...
The only benefit I know of for ordering an over sized cell is that may take some strain off the controller's electronics. Since these are on the cell with Intellichlor, when the cell does finally reach it's end of life due to water friction, temperature changes and chemistry, the electronics will be swapped except for the transformer and a fairly benign interface board so the EZ's controller can talk to the Intellichlor and to transfer power from the transformer.
Scott
The spa side controller is the iS4, PN 520092. It has a 100' control cable that goes to the EZ4 cabinet.
The indoor wireless wall mounted controller is 520546.
The wired indoor unit is 520548.
Neither is required but having one is very convenient so you don't have to go to the main panel to turn on the spa, lights, change programming, etc...
The only benefit I know of for ordering an over sized cell is that may take some strain off the controller's electronics. Since these are on the cell with Intellichlor, when the cell does finally reach it's end of life due to water friction, temperature changes and chemistry, the electronics will be swapped except for the transformer and a fairly benign interface board so the EZ's controller can talk to the Intellichlor and to transfer power from the transformer.
Scott