Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Gain access to boiler terminal block
Observation:
Are the external controls powered via connection 1 on the boilers terminal block or are they powered from elsewhere?
OBSERVATION HOW ARE EXTERNAL CONTROLS WIRED
External controls powered from boiler
Wire fitted to terminal 1 running to external controls
External controls wired elsewhere
No wire from terminal 1 indicating external controls powered from elsewhere on system