Hi. A couple of days ago I replaced the water pump and the motorised valve for the central heating. The pump is working fine but the motorised valve is not (Orkli RT-ZT) Heated water reaches the valve but not beyond, so the radiators are cold. I called the suppliers for advice and they said it was fitted the wrong way round. I changed it but still have the same problem. The wiring is correct. When I took the old Sunvic off, I removed one wire at a time and replaced with the wire of the new one. There is an extra white wire but the instructions don't say anything about it. Any suggestions would be greatly appreciated. Thanks