We bought a 3 bed, 2 bathroom + a guest toilet flat which has a Winchester 24i boiler (unknown age). When we run the water in the shower or kitchen sink, the water temperature through the mixer fluctuates considerable, even when there is just one of us home. Does anyone know if this is a boiler fault or a plumbing issue. In winter the one bathroom shower (closer to the boiler) never gets hot enough, but the en-suite (further from the boiler) does get hot enough which does not seem to make sense to me. Both will then fluctuate in temperature. Any help would be much appreciated.