The Combustion Chamber Outer Cover has to be in position for the Air Pressure Switch to prove and the Pilot Ignition and Burner Ignition to take place.
There is an anticycling time delay for the CH demand this operates when the demand for central heating is interrupted.
The delay period is between 1 and 3 minutes, therefore it may shorten test times for tests requiring CH demand if the demand is not removed between tests.