the grills around the pipe (where the fumes pass through to the Flu) were caked in carbon buildup but the flu itself from the inside at least appeared to be clear. I guess the build up on the heating grills could have ultimately caused it to become blocked. The other thing I noticed was that the carbon build up was wet but only at the front next to where the pipe enters and that the board on the inside front of the boiler was damp at the top same side.
Could it be that there is small hole in the pipe where it passes through the boiler? If thats the case, i figured maybe it expands with the heat and is dripping onto the burners causing them to burn poorly thus causing the carbon build up? My cousin who is CORGI had a quick look at it but he was visiting from Scotland and it was XMAS day so he had no real kit on him and couldnt check it properly. I want to get a pro in but previous experience means I want to be armed with as many facts as possible before I get someone in, that way they dont try and charge me for work that doesnt need doing. cheers
JP Balbi
February 2009