About a week after my oil fired boiler was serviced the chimney was belching black smoke. Engineer asked if we'd had a new delivery of oil, which we had, and he said it had probably stirred up all the gunk in the bottom of the tank and cause the black smoke. The filter was clean but the nozzle was gunked up and he had to replace it and practically re-service it, taking 2 hours in all. Is it possible for gunk to get to the nozzle without going through the filter?

Bec, July 2009

I presume you are talking about a pressure jet burner here...the filter on these is extremely fine and will always catch any gunge coming through....the oil tank should have at least one filter / water trap anyway. The black smoke from the chimney isn't due to oil gunge.

John, July 2009