I have a negative head pump in the attic bathroom which has been just completed. However it is hard to get it to kick in and start pumping the water up from the cylinder below. It takes a lot of attempts by turning on and off the taps before it reacts.
Both the shower and basin are connected to the pump which sits alongside the hot cylinder below on the ground floor. the pipe feeding the shower is 1/2 qualpex with a T for the basin.
Any suggestion? Thanks.