Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
CH Demand
Selector Switch to Hot Water and Heating
CH Thermostat to Max
Put FGA temperature clamps on the flow and return
pipes close to the combustion chamber in the boiler
Gas On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:


Run CH and allow boiler to reach a reasonable operating temperature.
Expected differential approx. between 11°C and 20°C.