Electric Shower Pressure
Electric showers run off main pressure water and will require this supply to be of a minimum pressure in order for the unit to operate properly.
Most electric showers will specify the minimum and maximum pressure of the incoming mains water with many designed to operate at a working pressure of 1 bar. Check with your installer to ensure your water pressure falls within that recommended by your electric shower manufacturer.
If the mains pressure in the home is too low or if there is no mains supply the unit will not work correctly. There are special showers available that can cope with this situation. Triton and Mira both sell showers that have a small pump built into them to help boost the presure of the water before it is fed into the heating chamber and example being the Triton T90xr. Although this is sometimes referred to as a pumped electric shower it cannot be regarded as a power shower as the pump merely increases the water pressure to that of a standard electric shower.
These showers need to fed by water from a storage tank but they will still require a minimum pressure be maintained to ensure they work correctly. Pumped electric showers can also be fitted if pipework is to be kept to a minimum in a bathroom where the nearest feed is cold, tank fed water (such as that sometimes used to feed the cold tap of a bath). They must not be supplied via a hot water pipe or via a mains pressure supply. The rules regarding the electrical connection will be similar to that of a standard electric shower.