As with, for example, central heating boilers, gas fires, stoves and wall heaters are consumable products that slowly but surely become dirty as air-borne particles are sucked in during combustion. These small particulates hinder fire or stove ignition over time. Components may also over time become subjected to wear and tear, which is why we strongly recommend you have your fire or stove serviced annually. Your dealer or installer can advise you and cares for the maintanance.
Indeed, the same applies to wood-fired stoves. It must be ensured that the air supply doesn't become blocked by ash, but this is easy enough for the owners to do themselves. What the user often can't do is clean the flue duct. Your chimney will require regular sweeping; the frequency will depend on the amount burnt and the wood type used.