Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to DC Volts 
Remove 4 wire cable from fan assembly
Ensure NO demands
Ensure NO demands
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Reset the boiler as necessary.
(Control knob to off position then back to DHW & CH position)
Wait at least 20 seconds from when mains power is reinstated then measure the DC voltage between the pink wire at X4 on the PCB and a suitable earth.
Expect approximately 0 VDC.
Notes:
1. Fan may be running during test due to signal control connector being disconnected.
2. Boiler may enter lockout during test, reset boiler as required until test complete
3. Test at PCB connector can be carried out on either the small holes or the larger silver soldered points.
(Control knob to off position then back to DHW & CH position)
Wait at least 20 seconds from when mains power is reinstated then measure the DC voltage between the pink wire at X4 on the PCB and a suitable earth.
Expect approximately 0 VDC.
Notes:
1. Fan may be running during test due to signal control connector being disconnected.
2. Boiler may enter lockout during test, reset boiler as required until test complete
3. Test at PCB connector can be carried out on either the small holes or the larger silver soldered points.
Isolate as per TOPs P4
and refit as necessary