I intended to fit a new wall thermostat in my mothers house, but she died before I had got around to doing it, her central heating when my dad died was in a mess, before his death I never looked at it, considered that was his job, unless he asked for help.
When I came to look at it, it seemed it had been fitted by cowboys, every lock shield wide open, and a wireless thermostat one of these
fitted which was really not suitable for a gas modulating boiler, although would have been very good with oil, the reason is it had anti-hysteresis software, which as it approached the target temperature, started to use a mark/space ratio (turning on/off) to stop it over shooting, which defeated the boilers built in system which would modulate the output (turn it down) as the return water gets hotter.
The return water will get hotter as the TRV's close and the by-pass valve opens, so the boiler auto adjusts output to match demand, but each time turned off, then back on, the boiler reverts to full output. So the two systems were in conflict.
However that wireless thermostat did have a safety device, and if no signal in ½ hour it auto closed down, I tried this thermostat
which did not have the fail safe, and found the living room far too hot. After the thermostat failed did not want to just fit another one, so I tried fitting electronic TRV heads,
they were claimed to work with Nest, so I had intended to then fit Nest, however they worked very well, at first not so good, but they reported both current and target temperature
so it current exceeded target I closed the lock shield a little, and once set, they worked A1, in fact that good I never bothered with Nest.
On selling the house the new owners did not want the electronic heads, so swapped back, and found now the lock shields set, the old heads also worked A1.
On moving to this house I brought the 4 electronic heads with me, and added 5 eQ-3 heads, far cheaper (£15 in 2019) where other heads cost nearly £40 each, central heating was in a mess, so also got Nest Gen 3, the 4 electronic heads did connect to Nest, but did not follow Nest as it was claimed, and I had to disconnect them from Nest, in fact Nest has been rather a disappointment.
All the special features have now been turned off, so it is now rather a dumb thermostat. Although not helped being an oil boiler.
I have tried geofencing, both with the TRV heads and the Nest thermostat, the latter only has Eco and Comfort setting that the user can set, you could not set distance, and it tended to over shoot, and when the EE mast went down, it kept going to Eco mode while we were in the house, so it got turned off, never to be used again.
However very pleased with these heads
they are in some ways better than the more expensive ones, also look at the Terrier i30
they are very similar to each other, if more than one radiator in a room then want the bluetooth version, but although bluetooth makes it easier to program, it will only work with one phone, and it needs to be close.
