Setting 4 on all mine certainly would,t shut off the TRV at 19C, setting 2.5/2.8 will maintain ~ 20/21C. Here is a setting index I found somewhere which isn't too far out.
I would say when I used old type liquid heads I got same results. When I first started to read the thread I thought may as well fit an electronic head, but is seems uncertain if head or valve.
The valve is rather simple
so faults tend to be leaking or pin sized, not much else to go wrong. The heads I paid £15 for these eQ-3
in 2019, and they auto measure the pin travel and show F1, F2, F3 is shown if travel tight (sluggish), too much travel, or too little travel, and they exercise the valve at midday Saturday so should never stick, batteries last about 2 years, but I change every year to be sure. The Terrier i30 is I think similar, they do not link to wall thermostat, but do show temperature in °C and can be set as pairs where two radiators in the same room, and have the window open detect built in so can be set to switch off if there is a sudden drop in temperature. It says window open detect, but clearly does the same when door is opened, so turns off kitchen radiator while we unload the car.
At £70 odd per pair I was not so keen to get more of the expensive Energenie TRV's just as well as it seems they don't any longer work with Nest, but at £15 each for the Bluetooth version it seemed better to use electronic heads.
However the Energenie heads which were far more expensive did not show if pin not moving, the cheaper heads seem to do more, OK cheap heads do not have geofencing, but I never used that anyway. The more expensive claimed to have two thermocouples one for air and one for water to compensate for heat direct from radiator, however have not noticed any difference in performance. Only advantage of the more expensive is I can monitor room temperature when away from home, and in the summer switch on AC before starting to drive home if room too hot. The Energenie have the option of changing spacers, which is rather pointless, as no way to knowing if pin has not opened or closed fully.
When I first fitted electronic TRV's I realised how important the setting of the lock shield was, but being able to direct the hot water to different rooms through the day as we move around the house clearly saves money.
