(Итоговый перевод для русскоязычных будет в конце темы. Если справимся с подключением, конечно же).
Let's make this topic in English if you don't mind, ok? Machine translation is bad. Nothing becomes clear.
We may start with your Baxi product's label. Like this one:

You can find it at the backside of the front cover. Or somewhere else of boiler's chassis. This one will help us to identify your boiler's model (we haven't such model in Russia).
Next - would you please write down some links to external controller's documentation (Drayton). I don't remember such Brand. Seems we haven't got it in Russia. It is useful to read it for best understanding.
Then, make some photos of electrical connections beetween boiler and controller. It must be not larger than 2Mbytes (or 1 Mbyte. I forgot

Sorry for my english. There is not much practice last years.
Ilya (Elijah) Bakhtalin.
Отправлено спустя 16 минут 20 секунд:
Electrical connection Baxi - Drayton. Электрическое подключение
https://www.draytoncontrols.co.uk/
Which one?