The only thing I can see is that the water will have already heated the radiator so they may not be as effective/accurate unless I’m mistaken
Thoughts ?
I found when setting up mother's system, with the TRV on the return the lock shield needs to be restricted more, so there is enough time for the TRV to work. I read all the things about setting up, using a differential thermometer
one should set the in and out with around 15°C but could I find the tool when I wanted it, no, even now found the meter, but not the plugs and sensors. So had to use another methods, lucky my TRV heads are connected to my PC so
I can see the target and the current temperature, so my method was to close the lock shield a bit at a time, until the current did not on start up (in first hour) exceed the target, and it worked, OK found the anti hysteresis software was a bit OTT, so 7 am set to 22°C and 8 am set to 20°C this worked fine. And it did take some time with a tweak here and there to get the rooms spot on, the meter method would have been faster to set up.
But the rooms with feed to TRV heated up faster than those with return to TRV, as with return to TRV the lock shield had to be set lower, as to how it would work with more expensive heads I don't know, the Wiser head is claimed to have algorithms so you set time you want the room to temperature, and it works out when to turn on.
My Kasa TRV shows me a graph,
so I know how it has preformed during the day, my boiler is simple on/off oil, so will always be a hysteresis.
There seems to be many ways to use TRV's, old house downstairs controlled by wall thermostat, and the TRV stopped bedrooms over heating. Mother's the hall wall thermostat set slightly higher than TRV, so only on a warm day would the boiler turn off, it just modulated with the return water temperature, worked well, radiators rarely hot or cold, just warm enough to maintain the room. And room temperatures, unless sun shining in bay-window, were within ½°C of setting.
Today it seems the idea is only heat rooms in use, and only just warm enough, theory is great, but if the boiler's minium output is 7 kW and only one room used with a 6 kW radiators, the only way for it to work is for the boiler to use a mark/space ratio, turning on/off all the time. With my non modulating oil boiler at 20 kW output, no way can I sink 20 kW in the living room radiators, so the boiler is switching on/off all the time.
Clearly, the kW output of radiators needs to be far greater as that of the boiler, but there is a limit, and I have to arrange the start times, kitchen turns on first, then dinning room, then living room all within ½ hour of each other, so radiators get hot in sequence, but boiler has not switched off due to return being too hot. It is a balancing act. And I have also found the three houses lived in during last 10 years, all were different, there is no one system suits all.
One has to sit back and think, how will it likely work with my house, unless you can afford to fit linked TRV's in every room, you have to use some thought, and not follow blindly what anyone says, use your own brain. I was told that many times, do not fit a wall thermostat and a TRV in the same room, in the end I decided to try it, and it cured most of my problems.
Let's face it, we are told to fit the wall thermostat in a room with no alternative heating, no outside doors, on the lower floor, in a room kept cool, but always used, in my homes, there was no such room. So need to compromise.
