Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4

Observation:

Measure the temperature of the appliance by measuring at the flow pipe by the primary heat exchanger as shown by the red arrow.
Note:
This appliance incorporates built in frost protection, if the appliance temperature drops below 8 degrees it will fire to prevent freezing until a temperature of 40°C is reached. If the appliance is above 8 degrees but you suspect it has been exposed to temperatures of 8 degrees or below then choose the second outcome below.