and the owner and user of the system is best placed to tune a system, as the final tweaking can take weeks I have found.
Yes it did take a long time with mother's house, but I don't have a differential thermometer. I am told it should be set so there is a temperature drop of around 15°C between supply and return with boiler running, I tried to use a thermometer
it was a failure, theory great, set to baby bottle setting and point and read, but reading not steady enough. So the method used was to turn off lock shield valve and turn it back on ¼ turn at a time until just felt supply pipe start to get warm, this was an improvement, however the TRV
has numbers on it which seem to have no relation to degrees C, and taking one out of my draw and testing where I can actually see if open or closed, I found at a setting there was around 3°C between fully open and fully closed, so to keep a room at 20°C it was some where between 2 and 3, so I have three or more controls, if boiler on/off, what temperature boiler set to, pump speed, lock shield valve, and TRV if only one needs adjusting great, but two or more, not easy.
It seems
this is a combined lock shield and TRV, never used one, maybe it does help?
But the wall thermostat does not help,
looks simple, not programmable, however it has a number of features, some good, for example it looks for a signal once every ½ hour so if the battery goes flat it fails safe, but also it has anti-hysteresis software, what this does is start switching the boiler off/on before it reaches set temperature, and it adjusts the off time, so it will not over shoot, however with a modulating gas boiler this defeats the built in software and causes the boiler to stop modulating, so may be great with the oil boiler I have today, but useless with a gas boiler. It means energy wasted out of flue every time it turns off, and turns on flat out rather than modulated.
This
TRV head produces this
computer read out, so you can adjust the lock shield so target and current match, however the anti-hysteresis software is too good, and it takes over two hours to settle at a temperature, and there is no manual override. The
does have a manual override, but only shows target temperature not current.
Clearly a linked system like evohome, wiser, or hive means no need to match wall thermostat with TRV, but I had a TRV and wall thermostat in the hall, and they need to work together, idea is open front door and hall will cool, so TRV will open and wall thermostat is on, so hall starts to warm up, then TRV starts to close, and will allow radiator to cool before the hall reaches a high enough temperature to turn off the wall thermostat, so extending the boiler run time so all other rooms also heated, but on a warm day the wall thermostat will turn off very soon after the boiler starts to cycle so boiler not running on a warm day.
But with radiators closer to door than wall thermostat and the TRV head being lower, when wall thermostat is showing 19°C the TRV is likely only showing 17°C, so not simply same temperature.
So adjusting takes a long time with a tweak here and there. And that is without including outside temperature, with sun shining through the bay windows 18°C is ample, when snow is falling more like 22°C.
But you can normally manually adjust for that, this thermostat
is a pain to adjust, it worked very well, but each time I wanted to adjust I had to read the book, however this one,
is intuitive, simple turn the dial, however it also has so many options including weather predilection, and I have turned most off as would find boiler running when not required.
It took me some time to work out, not helped by being told you don't fit a TRV in same room as wall thermostat, however it was doing just that which got it all working in a reasonable manor.
First house was hot air gas, it was expensive to run, but worked, so never really thought about it, second house was open plan, no hall, thermostat in centre of house, again it worked, so never really thought about it, then returned to parents old house, main problem was bay windows, and having internal doors, only really thought about control with that house, took around 3 years to get it working A1, then mother died and we sold it.
This house not as much of a sun light problem heating up living room, but again still a problem getting a house with internal doors so all rooms as wanted, I have 9 programmable TRV heads and 5 non programmable TRV heads, two wall thermostats, two zones, one uncontrolled bathroom, but it is an on/off oil boiler so no modulation to worry about.
Having had too easy to control homes, and two more involved, I can understand why people say do this it's easy, as with some homes it is, last house with a Myson fan assisted in living room, and standard radiator plus 4.5 kW gas fire, so 9.5 kW of heating in living room, I felt geofencing was pointless, this house however with 18 kW boiler for whole house, takes a little longer, and I can see the point of geofencing, although since retired heating not turned off, so still not really required even when one wall thermostat and four TRV heads can be set to use it.
Every home is different, my flat in Hong Kong only worried about cooling it. Daughters in Turkey the solar panels work well, father-in-law North Wales the DHW solar panels were a complete waste of time.
So we need to look at every home different, life style, time when heating required, all needs to be considered, it seemed my brother-in-law had it cracked, a larger water storage, combining solar, LPG, and solid fuel, however it only worked as fitted when built, with reinforced floor to take weight of water store, and roof facing right direction, and at right angle to catch the sun. And it seems the system cost £12k takes a lot to get that back. And if not original install more like £16k, so really only an option with a new build.
