Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
CH Demand
Attach temperature probes as indicated by the red arrows
(PCB housing may need to be removed from holder to gain access)
CH thermostat set to MAX
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

Allow the appliance to run for 2-3 minutes measure the temperature differential.
Expect approximately 22°C or less.
Note:
To reduce the time taken for this test some radiators can be turned off temporarily.