Smart valve and relay without thermostat ?

Hi,

I have several smart valves and I want to know if I can use them without thermostat,  just relay

My thermostat was draining the battery in 1,2 days, but yestarday became warm 31degree and stopped working, so now I want to see if I need to buy a new one or I can still use the existing relay.

I see the temp in app so valves seems that communicate with relay, but...

1. I still have warning in app and valves that thermostat is not available

2. seems that even if app shows that the heating should be started it is not.