Negative Head Shower Pump 1.5 or 2.0 bar?

[JRB Novice DIYer]

I currently have a Wickes positive head pump fitted but when trying to use shower have to run basin cold tap to keep pump running rather than on/off/on/off etc.

So I'm going to fit a negative head pump ideally looking at a Grundfos Amazon/Watermill as these have inlet & outlet facing upwards and push fit so minimal pipework would be required; however what bar pressure would be best its only needed for the shower and basin as there is sufficient pressure when bath being filled.

Appreciate your comments; Richard B

 

[king of pipes]

Stuart Turner universal would be my choice 2 - 3 bar . Kop

 

[townfanjon]

Dont just bung a pump in , are you neg head or poss , wheres the CWSC in relation to the spray on the riser rail ?