Set Appliance State:

Mains Power Off
Set Multimeter to DC Volts Set meter to measure DC Volts
CH Demand
DHW Selector in Minimum (-) position
CH Selector in Maximum (+) position
ON/OFF Switch in ON position
Remove control box cover
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

NOTE: If no time controls are fitted there must be a link fitted between the two "Room Stat" terminals of M5.
Measure DC voltage across the terminals of M5 marked Room Stat on the PCB.
Expect approx. 0Vdc across the terminals.