Set Appliance State:

Mains Power Off
DHW Demand
CH Demand OFF
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Allow the appliance to complete its self-check.
Test 1:
Does appliance respond to a DHW demand?
(indicated by the pump starting to run again)
Test 2:
If the boiler responds monitor the operation of the DHW, is the operation satisfactory?
Notes:
1. Boiler will take approximately 45 seconds after power on before responding to the DHW demand.
2. The pump can be very quiet so it may be necessary to confirm by gently pressing on the centre screw until it makes contact with the impeller (if it is running a grinding noise will be heard).