The boiler has a maximum output of 2400 watts. This means that a 13 A fuse is sufficient (with 13A, 13* 230 = 2990 watts). Theoretically and in my case also practically (I have the usual 13A fuse) there is no need for 16A.
i don't know how it was cleaned, but we always use a descaler and then rinse very well. however, the cooker is never immersed in water. cleaning should not actually have any effect on the heating element.