Set Appliance State:

Mains Power Off
CH Demand
Turn Hot Water Tap On
Selector switch to Heating & Water
Gas On
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

Allow boiler to fire under DHW demand, turn off hot water tap.
Is there a delay of approximately 2-3 minutes before boiler re-fires under CH demand?