back carbon emmitting from baxi heating boiler?

your appliance has incomplete combustion ,there is a problem with (a) gas pressure/supply (b)ventilation/air supply (c)mechanical fault/injector,burner blockage or wear. This appliance requires immediate service ,this must be carried out by a CORGI registered gas engineer

MR DOUGLAS MALLEN
March 2008

Or to put it more bluntly - you have incomplete combustion which is chucking out carbon monoxide which is potentially lethal

don't use it until it's been serviced

geoff@cet
February 2008

It means that your boiler is blocking up and in dire need of a service and clean as its not combusting properly.....promptly!!

John
February 2008