I have a glow worm swift flow combi boiler about 10 years old, i have had different parts replaced over the years, the latest being a new fan fitted, but i am having an intermittent fault, which is that sometimes the hot water does not come on, on other times it comes on for a few minutes then runs cold, and then at other times it is fine, the ch works fine, any ideas ?

mr john milligan, February 2011

thanks for that, your were right about the age of the boiler, checking with my wife, it turns out it is 18 years old. regards

john milligan, February 2011

Replacement of domestic flow switch will cure what ails your boiler.
As for 10 years old, try more near 20 years old. Time flies eh?

Carefree, February 2011