Shower pump pulsating.

[danplumb]

Just fitted a power shower twin impeller pump and installed new cistern for the cold water, all working well with the shower running, however when the shower is turned off the pump is pulsing every few seconds. Now I believe it's just the water pulsating in the pipes kicking the pump in, so none-return vales after the pump would cure this. Has anybody found this to be the case before?
Thanks

 

[cider]

Water doesn't pulsate alone. Most likely you have air trapped in the pipe work which will cause the water to continue to move back & forth through the flow switch.
Remove the shower spray head and let the shower run hot then cold. The pump is most likely able to deliver a higher flow rate then the outlet spray will allow thus trapping the air.