We have a Potterton Suprima boiler providing heating and hot water with a hot water cylinder. There is a pump providing water to the shower and bath to give a power shower. After a bath, the water pipe is hot from the boiler and through the motorised value and then cold when it reaches the cylinder. I would have thought that the pipe from the boiler would be separate from the water system and should not be affected? A heating engineer has replaced thermostats and the motorised value and this has not helped. However, if we use the immersion heater to heat the water cylinder this clears the problem and the boiler then heats up from the boiler....... till the next bath. Any advice gratefully received.