Set Appliance State:
Mains Power Off
Set Multimeter to DC Volts 
CH Demand
CH temperature control to maximum
DHW temperature control to minimum
CH temperature control to maximum
DHW temperature control to minimum
Remove control box cover
ON/OFF switch in the ON position
ON/OFF switch in the ON position
| WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure |
Measurement:
Measure DC voltage across the terminals 3 and 5 on the Timer.
Expect approx. 0Vdc across the terminals.
Expect approx. 0Vdc across the terminals.
Isolate as per TOPs P4
and refit as necessary