Hi, I have a fairly large Evohome installation with 2 controllers. It's currently on a large oil boiler, and at times eg. in the summer when few people are around, it's better to use the electric immersion heater than fire the boiler up. Does anyone know how practical it is to control the immersion heater from the second controller? Currently the immersion heater is just on a spur switch.

Considerations include:
1. It's fine for the 2nd controller to be disconnected from the boiler relay, as the rooms on it are very much secondary rooms
2. Can the HW tank thermostat be connected to both controllers? (or can it be set up without the need for a thermostat?)
3. Can the "Hot Water" zone on the controllers be renamed to "Boiler HW" and Immersion HW" to reduce the likelihood of people getting confused.
4. Should I set it up as an electric heating zone on the 2nd controller instead?
5. I assume there are no safety issues as both heating methods have their own failsafes
6. Presumably I connect a contactor to a BDR91. How can this be wired neatly? All the contactors I see are DIN rail mounted, which is quite a big change from the surface mounting of the rest of the system.

Many thanks.