I have a 3rd Gen Thermostat linked to an Ideal Vogue Max system boiler using S-plan to control central heating and heating a hot water tank. From the limited information referred to in some community responses https://support.google.com/googlenest/answer/9259109?hl=en-GB#zippy=%2Chow-to-set-up-opentherm-heati... I need to replace the wiring for the HW and CH zone valves and replace with just the two Opentherm wires. I can just about understand how the Central Heating Opentherm part works, but I don't understand how NEST can control both the Central Heating and Hot Water flows using just the Opentherm wires. First NEST and the boiler have no control over where the water is flowing (to the radiators and/or the hot water tank) and second, there is no feedback to say that the tank has reached temperature.
Can you explain?
