Hi Guys, I am new here but I seem to have the same problem on sooting up ,the boiler is 2 years old its never been brilliant but recently I have been having trouble with it running I cannot get it to run continuously, it keeps locking out and following advice on here as to moving the photocell out 20mm and reducing the air to 5.3 it fired up and ran for about an hour but then severe black smoke before locking out, the pressure is set at 100 and am running an 80eh nozzle, what is doing my head in is that it will run perfectly for sometimes over an hour but then thick smoke starts to appear then lock out, I have replaced the photocell, new nozzle and new ignitor and a new pump is on its way is there anything left? any help will be gratefully accepted Thanks Bigal1066