What would you put in instead- Be mindful that it is plumbed from the hot water cylinder.Because most people have a preference for non-electric showers, so the builder likely installed what they felt was best or what the original owner asked for. It’s not uncommon to have the main shower fed from the hot water tank and pumped so you can have a nice shower most days, but then have an electric shower as a backup. Personally I’d rip out an electric shower as quickly as possible in a house!