The pump is installed on the 2nd floor bathroom backing onto the shower, so there is a short feed from the pump outlets to the shower thermostatic mixer taps. The inlets to the pump are from the hot water cylinder, located on the 1st floor and from the cold water tank located on the 2nd floor. The pump was installed about 5 years ago and was working fine i.e. only comes on when shower water is turned on and switches off when water is turned off and remains switched off until the shower is used again. About 2 years ago, it developed a fault whereby the pump switches off when the water is turned off, but after about 30 secs the pump turns on again and the motor runs for about 30 secs, stops and thens starts again after about 30 secs. This cycle continues for ever. I've to switch the pump off at the mains when it's not being used. I have checked the plumbing for leaks in the system, but there are none.
A second issue that also came up at around the same time is that every few months (3-4), the pump stops working i.e. the pump motor does run but it doesn't pump out water from the outlets. When I switch the thermostat to minimum temperature, it pumps out the cold water, so the cold feed (inlet and outlet) seems fine, but stops pumping out water when I change to maximum temperature at the thermostat. I have to call out a plumber, who usually disconnects and reconnects the inlets and the outlets and gets the pump working again.
I am not sure if the 2 issues are connected, but any suggestions on their possible causes would be greatly appreciated.
Thanks