There are two basic types of ignition system on a modern combination boiler:
The permanent pilot is slowly but surely being replaced by electronic ignition systems. The electronic system removes the need for a permanent pilot and eliminates the age old problem of pilot outage in windy weather conditions.
This problem often lead to customers struggling or not being able to relight the pilot light. The knock on effect was wasted time and effort of the heating engineer having to visit site to relight the pilot light. All to often costing the heating engineer to loose valuable working time and not being practical to charge the customer to light the pilot light.
The intermittent electronic ignition of the combination boiler is now very common placed and on the majority of boilers taking the form of flame rectification.
The ignition cycle forms a vital part of the boiler cycle, (see operational flow chart), as should any part of the ignition system fail or not be detected then the boiler will `fail to safe'.
The electronic ignition or spark is generated on demand via the printed circuit board (pcb). The spark electrode is positioned to allow the spark to ignite the pilot burner or directly onto the main burner. When igniting the main burner directly, initially the burner is fed with a low rate/ignition rate gas supply. Once this has been detected then a higher gas rate is fed to the main burner to satisfy demand.