Set Appliance State:

Set Multimeter to DC Volts Set meter to measure DC Volts
Hot water tap ON and fully open
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Allow the burner to ignite and establish.
After 10 seconds measure the DC voltage across the two wires.
Expect 8.2 vdc or greater.
Is the voltage measured as expected?