You cannot boost the flow from an electric shower if that flow is limited by the KW output of the electric shower but you can stop the electric shower dropping out and running cold (or running hot) when the incoming mains pressure is low or fluctuates when others use a tap in your home.

For most people the pressure problem is obvious and a single SPB is all you need. If you think it might just be the electric shower is just not big enough to give you a good shower then please click this link:-

Is my electric shower big enough

Buy a SP1 Manual Pump Now
Buy a SP2B Fully Automatic Now (fit and forget – plug and play ready)

We do offer a test kit if you think the problem is more complex.