We have just installed a pump (1.5 bar, Varispeed 50) to increase the pressure of our shower. However, although the pump does increase the pressure, the change is quite small and the pressure in the shower is still low. The plumber tells us that this is because our pipes are too narrow to feed the pump at a high enough rate. Could this be the explanation? Is there anything else we can try? The pump is positioned less than 1m away from the shower, close to the hot water cylinder. The cold water tank is in the attic.