Set Appliance State:

Mains Power Off
On/Off Switch OFF
CH Demand
Gas On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Appliance On/Off switch On.
Reset lockout as necessary.
Allow appliance to ignite and run.
Does the CH system heat satisfactorily?
Note:
Monitor system pressure during CH operation.