Hot water not working? You need the room temperature sensor

I have just set up a tado system for my elderly mother. She has only 4 radiators and a hot water tank in a Y-plan configuration. I put smart TRVs on the radiators and they were working to plan, but the hot water did not work. The wifi receiver seemed to be refusing to configure to the Y-plan, reverting constantly to a combi configuration.

Luckily I came across a forum post that suggested that the room thermostat supplied with the starter kit was essential to the system to make the hot water work. I had not used the room temperature sensor in my set-up because I thought as a sensor it was a duplication of the radiator valve, and therefore surplus to requirements, but also that this thermostat would work against the STRVs and turn off the whole heating system (like the room stats I am used to), making the independent room control impossible. It now appears this is not the case - the room sensor does not actually control the boiler but sends instructions to the radiator valve in the same room (I think).

Adding the room temperature sensor to one of the rooms immediately caused the wifi receiver to configure correctly and the hot water to heat as it should. Tado have checked my system remotely and confirmed that it is correctly set up.

Can I suggest that tado explain somewhere in their set-up instructions and publicity that a) the room temperature sensor is essential to activate the hot water system - don't leave it out - and b) that it does not act as a master override switch but only instructs the valve to which it is assigned. That would have made things clear and would have avoided my mistake. Thank you.