Suggestion to replace hot water solution

I have hot water cylinder in cupboard on 1st floor and cold water tank in loft. For pressure in shower the previous owner installed a twin impeller shower pump on outlet of hot and cold water tank. It works fine but have two issues; a) The motor starts when water in used anywhere in household. b) The motor is very noisy. I am looking for options to get around this problem. Want to know if I can get a nice quiet pump or should go for power/electric shower or install unvented hot ware cylinder? Need suggestions please.