Set Appliance State:

Mains Power Off
CH Demand
ON/OFF Switch in ON Position
CH Temp Selector in Maximum position
DHW Temp Selector in Minimum position
Mode Selector Switch in Heat and Hot water position
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

If required reset boiler, turn CH / DHW control to reset position.
Observe the Differential Pressure Switch Spindle.
As the Pump starts to run, does the Spindle rise to operate the Microswitch?