Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
1. Ensure the diverter valve actuator connector is plugged in, then position the actuator in a safe place (use isolation mat as required) with the spindle facing upwards.
2. Ensure that the switched live to the boiler is off and that all DHW taps are shut off and that the pre-heat is switched OFF.
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

1. Allow the boiler to complete its self-test.
2. Hold the mode knob in the reset position for more than 10 seconds.
3. The display will alternate between "d" and "u" and the actuator will
move into the mid-position.
Note.
The actuator will initially drive all the way out, this may cause
the spindle to spin in the body, If this occurs due to the spindle being face
upwards the actuator will then drive fully in before going to mid-position.
Isolate Mains Power to appliance as per TOP's P4

4. Refit the actuator into the diverter valve body.