You should check four things before installing a water pressure pump to a low pressure system.
First: is there enough cold water storage? If you are drawing water from a tank, you need at least 50 litres of water to supply a bathroom successfully without running out of water.
Secondly: has the pump been put in the right place to aid the correct appliance? Pumps will always prefer to push water rather than pull it.
Thirdly: Is the hot and cold water supply fed to the pump from a dedicated supply?
Finally, do you have an adequate temperature control on your system? If you have the water at excessively hot temperatures, you will damage your pump components and could create more air in the system. Salamander recommend that these temperatures do not exceed 60 degrees centigrade.