Wiring is not my strong point. A customer with an open vented boiler has hot water but no heating. I suspect the danfoss 3 port valve. There are 4 wires: orange (switched live), grey (hot water off), brown & white (heating on) and blue (neutral). I was expecting the orange to become live once the valve had moved to the heating position but that’s not the case. It does become live and fire the boiler when hot water is selected. Am I right that the orange should become live when either is selected? The black wire on the left is the 3 port. Thanks!