Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Disconnect and make safe the Orange wire from the heating zone valve in the wiring centre
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Observation:
Is the system still firing with no demand while the orange wire is disconnected?
Isolate as per TOPs P4
and refit as necessary