What is the replacement for the SVT controller range?


The discontinuation of the SVT controller due to component obsolescence.

Product Line

Field Devices







What replacements are available for the SVT 4201 / 4251 controllers?


Important Note - The replacement controller mentioned in this Lessons Learned is no longer available, and therefore a replacement for the SVT 4201 / 4251 is not available.

The SVT controller range has been discontinued due to component obsolescence.

The SVT controller was a basic optimiser that performed the start calculation using only an internal temperature sensor. There are no exact replacements for this controller available.

What is available? The Schneider Electric DC1400 Optimiser / Compensator is the recommended replacement, but this is not a direct replacement.

Differences in the controllers.

  • The SVT controller provides only an optimum start, the DC1400 provides optimum start and stop.
  • The SVT controller uses only a room temperature sensor for the start calculation, the DC1400 uses only a room temperature sensor and an outside temperature sensor for the start/stop calculations.
  • The SVT controller has a dedicated "Boost" relay, which allows overriding of a CSC compensator, and control valve. This is an internal function with the DC1400 optimiser/compensator.
  • The DC1400 has many other built in functions.


Controller wiring - Modifications will be required.

SVT general wiring connections.

Relay R1 is the main plant relay and relay R2 is the boost relay.

To see the full controller details, please click HERE.

DC1400 general wiring details.


To see the full controller details, please click HERE

Controller Sensors

As already indicated, the SVT controller uses only a space temperature detector, and this sensor is NOT suitable to use with the DC1400.

The DC1400 controller will, as a minimum, require a room temperature sensor and an outside temperature sensor, meaning that extra wiring for the outside temperature sensor, and the sensor itself, will need to be installed.

For details on suitable sensors, please refer to Lessons Learned # 12616