My shower pump is installed in my airing cupboard which is next to my bath/shower. The pump is connected to the hot water cylinder via a flange at the top of the cylinder. The hot water pressure is pretty feeble at the best of times but intermitently the hot water doesn't come through at all. This is usually rectified by turning off the shower and then on again where upon the pressure is back to it's normal (week) level. If the temperature commanded from the show is cold then the pressure is fairly good but as soon as hot is demanded the pressure falls off considerably and periodically the pump doesn't deliver any hot until the shower is turned off and on again. Do I need to take a hot water feed from somewhere else on the hot water tank or is there another problem?