I live on the third floor of a mansion block and the mains pressure is low. I have a combi boiler and want to install a shower so thought that my only option was an electric. This has proved to be virtually impossible and extremely expensive due to the wiring of my flat and the whole block (which is ancient). Can I fit a pump to the mains supply to boost the pressure into my boiler so that I can then fit a mixer shower? Alternatively, is it possible to fit a low powered pump between the boiler and the shower to boost the pressure? I have a feeling this is impossible with a combi boiler. Any advice would be very much appreciated.