Set Appliance State:

Mains Power Off
Turn Hot Water Tap On
Selector switch to DHW position
CH temperature selector to minimum
DHW temperature selector to maximum
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Allow fan to run and burner to ignite.
With a flow rate of 9.8 litres/minute at the tap is there a temperature rise of 35 degrees C and is operation satisfactory?
Notes:
1. A flow rate less than 9.8 litres/min will result in a higher temperature rise. If you wish to investigate a poor DHW flow rate click here.
2. Overheat indicated by either the manual overheat tripping or if auto resettable overheat is fitted, boiler will start sparking then go to lockout.