Combustion devices, also called burners below, of the type specified above are known in different designs in the prior art. A great problem for traditional pellet burners is the sinter formation inside the actual burner. The sintering obstructs the openings in the grate, why this normally must be taken out for cleaning at least once a week, occasionally a lot more often, which of course is a serious disadvantage.
In the prior art there is known a combustion device that substantially reduces the well known problem mentioned above, i.e. of accretion of ashes, unburned residues of fuel and other slag products as sinter by means of a movable ash feeder. However, also in connection with this new kind of burner device there are some problems. Firstly it may happen that malfunction occurs in connection with activation of the moveable ash feeder possibly leading to mechanical breakdown. Moreover it has been discovered that it may be difficult to achieve optimised ignition timing and combustion timing during start up of a burner of this kind due to different flow patterns within the combustion chamber depending on varying parameters, e.g. amount of clogging of perforations, amount of a moisture, temperature of the pellets, etc.