I have just had TRVs fitted and thought I would share my method of fine tuning their settings as it seems that just 1/4 of a graduation makes a significant difference.
- Check if you can hear water circulating through the radiator.
- If the room is at the correct temperature slowly turn down the TRV until you hear the sound drop.
- Set stops if the TRV has them. Fine tune by minimal amounts if not quite right.
Sorry if this is old hat - but I found it to be a good way of detecting the shut-off point.