Set Appliance State:

Mains Power Off
Gas Off
Ensure that the Boiler Thermostat is set to MAX
Note:
If the appliance is used with a Fully Pumped System then this test should be carried out with a CH demand
If used with a Gravity Pumped System then a DHW only demand should be used
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Is the fan running?
Note:
1. Do not take noise or vibration as an indication of operation.
2. Ensue the selector switch is in the correct position for the type of system the appliance is fitted to.