Tried the boiler too and have been looking around the house to no avail. The wiring box with the other two only has two orange wires so it's not being wired here. Wiring box
We have a heating issue where the boiler is staying on and heating downstairs. It's a 3 zone system, upstairs, downstairs and hot water. The upstairs and water are functioning as normal, only coming on when set to on at timer. Downstairs remains on with timer turned to off its a horstmann 3zone...