How can I fix valiant combi boiler - no hot water?

Try this:switch off the gas valve,turn off and on again the button for the central heating.you will hear the pump and the fan running do that few times(2 or 3),once this done leave this button on to CH/DHW.close the cold water inlet valve in the boiler,open the hot tap (the kitchen tap if your boiler is near there),if not choose your nearest.Once all the water drained leave the tap open,very gently open the cold water inlet valve (not fully if you have very high pressure).then close the tap,open back on your gas valve,your boiler will fire up the heating will start getting hot,open the hot tap and normally you will have hot water too.Hope this works for anyone with similar problem.some people have this problem even with new boiler .IF THE PROBLEM STILL THERE THEN YOU NEED HELP FROM THE PROFFESSIONAL .

Aquarius2010
December 2010

same problem, flexi reinforced water pipe clogged up with sediment, take out push knitting needle through to clear works a treat.

jimmy
September 2009

i have the same problem so stay in touch and we can compare notes i was told by a plumber it could be limescale but i like the other answer best

richard manning
February 2007

usaually the diaphragm has split in the hot water divertor valve, these are only about £15 to replace if it is

steve
April 2005