Who is an expert on Baxi Combi boilers?
 

I have a BAXI combi boiler, which is about four years old. The central heating works well, but there is no hot water. Why is that?

My advice to you is to call a qualified BAXI contractor for a one site inspection and repair.

Now to answer the question.

A bad pressure pump
A bad diaphram
A bad micro switch switch in the brass hat area.

These units are not user friendly and should have professional service for safety and longevity.