Might I suggest that you do a search on boilers, there have been numerous questions on the same subject over the past week. I am sure the answer to your question will be found in some of the other answers.
If you have a combi boiler, there should be a dial for the temperature of the heating and another one for the water. Just check it hasn't been turned down.
I dont know a lot about it because it's a friends, I think it is a vaillant turbo.there is two controls one for radiaters and one for the hot water. I have done all the reset instructions by the book and still no luck. there is no fault codes come up and everything reads as it supposed to.
You can feel the hot water coming through to the radiators but the pipes leaving the boiler are cold.
If you' ve checked all the controls etc, sounds like you might need an engineer. I had this problem, and it turned out to be the diaphram that switches between rads/taps. It wasn't something I could have mended myself. Either way, I'd get an expert in : )
would that be the diverter valve because someone told me that there is a rod inside and when its down it operates the taps and when it's up it operates the radiators.I think I will take your advice and call in an engineer.