Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to AC Volts 
DHW Demand
Identify the hot water zone valve electrical lead and terminal connections used
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Measure the voltage between the brown wire of the hot water zone valve and a suitable earth.
This wire provides power to the synchron motor that opens the zone valve.
Expect mains voltage.
Note: The colour and position of the wires will vary between systems and components.
This wire provides power to the synchron motor that opens the zone valve.
Expect mains voltage.
Note: The colour and position of the wires will vary between systems and components.
Isolate as per TOPs P4
and refit as necessary