My combi boiler works fine in central heating mode.
When in hot water mode, however, it fires intermitently so the water gets hot,cold, hot, cold and so on.
BG insisted that I need power flushing because the secondary heat exchanger is half hot, half cold, therefore it is choked by sludge.
They also said they can replace it for a cost of around £250.
I noticed that it can be easily pulled out by unscrewing two screws.
Can I clean myself?
Thanks in advance for replying.

TonyX, April 2011