From our experience some customers still seem unsure about how often their boiler should be serviced. Boiler manufactures have always recommended that a domestic boiler is serviced annually, for new installations boilers must be serviced annually to maintain the manufactures warranty.
Enigneers and boiler manufactures have some responsibility here because they have the knowledge to inform customers with the correct information.
Servicing should be carried out by registered, competent engineers and an electronic flue analyser should be used to check that the boiler is burning efficiently and according to manufactures instructions, this should be recorded in the boiler benchmark paper work and left with the boiler. The benchmark paper work is supplied with the boiler, there is a section which should be completed by the engineer who installs the boiler, there is then a section for servicing which should be completed by the engineer everytime the boiler is serviced.
The high efficiency modern condensing boilers are far more complicated and sensitive than the old cast iron boilers which were often taken for granted and only serviced every few years. The modern boilers need to be kept clean and the air/ gas mixture needs to be measured and adjusted so that it is correct, if the boilers are not setup correctly it can damage them internally and repair costs can be high.
We would advise that everyone have their boiler serviced every twelve months by a Gas Safe registered engineer and that this is recorded and left with the boiler. The best time to have it serviced should be the summer, normally your boiler use will be greatly reduced during the summer months and you can ensure that everything is working correctly for when the weather starts to turn.