Why regular servicing matters
Servicing protects the two things that matter most: safety and efficiency. A poorly maintained gas appliance can produce carbon monoxide, which is why combustion testing and flue checks are part of every service.
A boiler that is running correctly also uses less gas than one that is struggling, and small faults picked up during a service are usually far cheaper to put right than a mid-winter breakdown. Most manufacturers also require annual servicing for a warranty to remain valid.

