I have had these more than 10 years now, and the only problem has been the thermostatic cartridge which was replaced a few years ago. I have recently found out that the pipework from the pump should be 22mm but is in fact only 15mm. Since the shower's worked perfectly well for all this time, I am guessing the only reason 22mm is recommended is to increase the flow rate. The shower is perfectly adequate, although not a monsoon by any means. The hot water cylinder is only a torpedo. If the pipework were to be changed to 22mm, say when the pump needed changing, would I get a better shower, and would this be at the price of the hot water running out? I am hoping the pump will keep going for at least another ten years!