My boiler has been in operation since 1983 and I have replaced various parts over the years so am fairly happy to tackle most jobs. Everything works but the hot water does not get as hot as it used to as the boiler modulates to low flame most of the time the hot water is on. Turning the flow down from the hot tap improves it a bit. I suspect the hot water heat exchanger may be getting coked up as I live in a hard water area.
Before I tackle the heat exchanger are there any other thoughts that may help resolve the issue?
Thanks in anticipation.

Roy, October 2008

my vaillant boiler has 0.0 bar pressure where is the filling loop.

bob jennings, February 2009

if its the black bacolite/plastic type exchanger then your probably right, new ones are conversion kit to metal plate exchanger.

iain, October 2008