Ancillary rooms and being on the 12-room cusp

[MisterBoy]

1. My house is as follows:
2. Kitchen
3. Family Room
4. Living Room
5. Conservatory
6. Dining Room
7. Office
8. (utility room/WC)
9. (downstairs hall)
10. Main bedroom
11. Ensuite to main bedroom
12. Bedroom 2,3,4
13. Family Bathroom
14. (upstairs hall)
15. Loft conversion - bedroom/living room
16. (cellar)
17. (sort of 2nd cellar under conservatory)

These are all the spaces and all but the cellar have radiators on the main system... so that is 16 spaces. While we don't need proper radiators in the cellar rooms (tube heaters would be fine) there is a cahnce to convert at least one into a proper room. Maybe they'd have radiators, maybe electric/floor heating.

But lets say those two aren't needed: 15
And that both hallways can be combined: 14
And our bedroom and ensuite can be combined: 13
I can get to the magical 12 zones if I could dump the utility room but... how? Traditional zoned systems have the boiler off by default except in certain times. But Evohome works that the boiler is effectively "always on" whenever one of the TRVs wants heat. I'm confused whether having one or two radiators with traditional TRVs breaks this. Is it safe to assume that when I want heat in one of these rooms, at least one room will be requesting heat anyway? Then even the hallway could be left non-smart.

And then what if I do convert my cellar into a proper room, or split my large loft conversion into two rooms and genuinely need 13 zones?

[Richard]

All depends how big the property is? Would you get Honeywell's RF signal around the entire property? We do have a signal test kit for this purpose...

If you end up having 2x evohome Controllers, then zones are not an issue.

[MisterBoy]

The test kit was out of stock when I looked yesterday, it might be worth checking.

I saw someone mention using multiple controllers but bound to the same boiler interface unit but I've never seen this discussed in detail. Are the controllers aware of each other? How would the phone app see this?

[Teaboy]

I've had EvoHome for 5 years. Previously we'd lived with the TRVs inherited with the house. I've only fitted EvoHome valves to the rads in bedrooms, living rooms, dining room, kitchen and stairwell. Utility rooms, loos, en-suites and other infrequently used rooms still have the old TRVs. The temperature in those rooms is less precisely controlled - but we can live with it, and the main lived-in rooms are perfectly controlled by EvoHome. To maintain temperature differentials between zones you need to instil a 'keep doors closed' mentality.