I don’t think my room temperature is much lower than yours.
My sensor is upstairs.
It is generally 19c to 20c in the bedrooms.
Downstairs is generally 22c to 24c.
I don’t think you go warmer than that?
My heat pump goes down to about 450W normally.
My dT is set at 10c, but I don’t get there very often. Its a Daikin thing, it’s the only way I can keep the flow rate steady, set a dT it can’t get to.
It will go lower but efficiency is worse and heat pump isn’t happy below 30c flow.
I don’t want my bedrooms at 17c either, I don’t like it.
But if I am in a hotel and it’s cold, well it’s cold.
And if I have to sleep in a truck, or a coach, and it’s cold, well it is, still need to sleep.
I guess my point is, it’s difficult with a heat pump if you want efficiency too.
You could do it, run like a gas boiler, shut down rooms and increase flow temperature until other rooms shut off.
Heat pump stops, then one room gets cold and needs high flow temperature to keep heat pump running.
A mess.
Best just to get emitter sizes and heat pump correct in the first place.
Anything else with a heat pump is a compromise and compromises cost efficiency.