New Thermostat wiring

STIG83

I had to replace a non working thermostat in one of the rooms, couldn’t get the one I had, got a different one. It’s an air to water heating system I have.

I can wire it myself if I knew the correct way to do it.

I’ll attach photos to show the current wiring on the old one and the new thermostat with the connections on the back.

Live and Neutral is self explanatory but the other two I don’t know about.

Thanks.

meercat

in A1

Out A2

STIG83

thanks meercat