Into the abyss . . .

Actually it’s our boiler, which I was seriously suspecting of being full of soot due to the ‘south winds’ we had constantly for what seemed like weeks.  If the wind is from the south it blows back down the boiler flue when the boiler stops.  Not pleasant.  With the constant very strong southerly winds I got the impression that it was reducing the air through the boiler which would cause under-combustion and soot.
 
I was so wrong, in fact there were just signs of too much air, most likely from me turning the combustion air up a bit to counteract the wind.
 
Another job out of the way, at least I won’t need to service the boiler this summer now.