I NEED ADVICE PLEASE. WE ARE HOPING TO HAVE A VIESSMANN BOILER FITTED. CURRENTLY OUR OLD BOILER HAS 3 WIRES FROM BOILER TO PUMP. PLUMBER SAY WE CAN MAKE DO WITH THIS ALTHOUGH 4 OR 5 WOULD BE BETTER. THE FOURTH BEING THE PUMP OVER RIDE WIRE. VIESSMANN RECOMMEND AT LEAST 4 . PLUMBER SAYS BOILER CAN RU...
