The pump in our cupboard next to the hot water tank comes on when we select hot water and leave the central heating off. It then gets very hot as there is no water going through it. Does this mean the wiring is wrong. We only noticed this as we bled the central heating system because we were changing radiator pipes to make them more sightly. Left it drained over night as we don't need the central heating on during the summer. Then noticed the pump was coming on when the hot water came on. Hope this makes some sense to whoever reads it. Any advice appreciated.