Second thermostat or add-on wireless receiver?

We are have a Vaillant EcoFit Pure 835 combi boiler with no hot water tank.

Downstairs we are having water based underfloor heating in a single zone.

Upstairs we are going to have a mix of Smart Radiator thermostats and standard thermostatic radiator valves set to frost protection.

I’ve ordered a V3 wireless Starter Kit which has:

‎Tado° Wireless Temperature Sensor

tado° Wireless Receiver

tado° Internet Bridge

Smart Radiator valves


I want the upstairs to just work based off the radiator thermostats. The plumber thinks we need a new thermostat because the old thermostat ran on 24 volts and they needed 230 volts to open the valve. I don’t see why we need a second one.


Would a second thermostat work or would the add on wireless receiver be best?


Thanks!

Chris