I want to replace a bath with a shower. Water pressure is low so will need a negative head pump. Access to the existing hot water tank and cold water header tank is very difficult from the bathroom in question (without a major bit of work). Questions are: 1) Can I use the hot water input for the bath as the shower pump input? 2) Can I use the bath cold water input to fill a new header tank (which would only serve the shower) - positioned so the height is the same as the hedaer tank that provides the hot water (so it will be at the same pressure as the hot water)?