Set Appliance State:

Mains Power Off
Turn Hot Water Tap On
Heating temperature selector to OFF
Programmer or selector switch set to hot water only
Hot water temperature selector to maximum
Ensure heatbank is up to temperature
Gas On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

With hot tap fully open and a flow rate of approximately 18 l/min is there a temperature rise of approximately 35 degrees C and is the operation satisfactory with a constant DHW temperature maintained?
Note:
There may be a short delay, approximately 10 seconds, between demand and the burner firing.
Burner will fire as heatbank temperature falls.