I have a junkers water heater (sorry not sure of model) which I have serviced regularly & have never had a problem with ,but in the last week or so there seems to be a lot of soot on the ceiling above it,is there a way I can solve this problem myself as I am currently out of work, hope someone can help thanks.
Your heater requires a full service comprising of the removal of the main burner assembly as well as the heat exchanger to remove the blockage causing incomplete combustion resulting in soot deposits ( often caused by spiders and the like dying in the burner venturi tubes ), due to the work involved in this I would suggest that you would be way better off to get a proper service agent to undertake the task for you.