Don't use non-rechargeable batteries (Alkaline or Lithium) in the Evotouch. Definitely not when it is on the mount as it will try to charge them, and...
I'm not sure what you're planning to do with it as a "floor sensor" - do you mean a sensor to measure the water temperature of wet underfloor heating...
Welcome to the world of antiquated RF protocols which don't use acknowledgements to confirm that the target device actually received a message... ;)...