What could the problem be with my Grundfos selectronic ups 15-50 hot water circulation pump it has suddenly stopped working. Following the pipe work it is totally seperate from the central heating pipe work and only assists the flow of hot water and is right next to the hot water storage tank and a large 22mm pipe comes from the tank to the pump and the pipe on the other end of the pump disapears in to the floor.
The cable to the pump goes into the central heating /hot water control panel from which I assume it draws current. I assume that when you turn the hot taps on a pressure/flow switch in the pump recognises this and starts the pump but that's not happening. Also should that cable from the pump be permanently live ? There is a big screw on the round bit of the pump what's that for and could I open it without a flood to see what's what?
Many thanks