Set Appliance State:
Mains Power Off
Set Multimeter to DC Volts 
Turn Hot Water Tap On
Selector switch to Water
Run DHW boiler until the secondary heat exchanger is cold before turning mains power on
Run DHW boiler until the secondary heat exchanger is cold before turning mains power on
| WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure |
Measurement:
Allow boiler to ignite.
Measure voltage between the two connections on the diverter valve.
Is there approximately 12 volts present for the first 20 seconds?
Note:
The voltage to the diverter valve will switch off when the primary heat exchanger is up to temperature.
Measure voltage between the two connections on the diverter valve.
Is there approximately 12 volts present for the first 20 seconds?
Note:
The voltage to the diverter valve will switch off when the primary heat exchanger is up to temperature.
Isolate as per TOPs P4
and refit as necessary