i have fitted a salamander shower pump to a new mixer shower on a gravity feed system. everything has been working fine then after about 2 weeks when i turned it off there was a loud banging coming from the pump. when i turned it on again the shower worked fine. the banging contiued every time i turned the shower off. i now have to turn the power off to stop the banging although the shower still works.
"the pump is under the bath on the hot and cold supply to the taps. the cylinder is next to the bath room (upstairs) and the tank is above in the loft"
Thanks - at least we don't have a positive head pump in a negative head scenario. Possible you have a duff pump but I wonder if you are asking it to share supplies with all other taps? Cold supply to pump should be direct from CWST (via new and separate connection to tank), hot supply from HW cylinder again separate from all other taps using a Surrey or Warix flange (or an E s s e x if your cylinder has a suitable tapping. If you've teed the hot directly off the vent pipe you'll be sucking air down the vent into the pump - they don't like it!