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:
Measure the DC voltage between the red wire at X4 on the PCB and a suitable earth.
Expect approximately 40 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.
4. There is no need to wait for the purge cycle to complete or to reset lockout before carrying out this test.
Expect approximately 40 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.
4. There is no need to wait for the purge cycle to complete or to reset lockout before carrying out this test.
Isolate as per TOPs P4
and refit as necessary