Installing the extension kit on a Vaillant EcoTech Plus 831
How do I wire up the extension kit to a Vaillant EcoTech Plus 831 so that it can use the OpenTherm protocol?
There are no room thermostats connected nor does it have the built in programmer on the boiler.
Have a good Google around and nothing seems to be clear. My boiler has terminals 3 and 4 bridged so that the call to heating is always on, and assume that this is what the extension kit needs to be connected to to switch the heating on and off?
Or should it be wired up to the eBus?
Any help gratefully received 😀