Had Greenstar Heatslave 18/25 oil fired condensing combi boiler (Worcester Bosch) installed 4 months ago. The hot water fairly frequently turns to dirty water then clear then dirty. Also for the majority of the time there are tiny black bits left in the bottom of the bowl/sink.
I'm told they will go in time but what are they and will they just stop appearing & will the water eventually settle?
Thanks

R Damson, January 2008

If you didn't have a combi boiler before then the plumbers could have used the pipework from your conventional boiler to your hot water cylinder to substitute for a hot outlet and cold feed to your combi boiler, in case there were no hot and cold service pipework at the boiler location.
This is the main theory which could explain your debris within the sink.

gordon ramsay, January 2008