These are my experiences with Spirit. My main point: Its a good device as is, it would be even better with manual mode enabled. I hope it gets to that.
I have 6 of them now. It is a great valve for the price. For now I am using the internal temperature sensor and internal valve logic. It’s far from perfect, but it is not useless. It is opening and closing frequently (not very battery friendly), but it does keep temperature quite stable as a result. I mean, it does fluctuate ±1°C, but this is expected with radiators, when you close the valve a hot radiator will keep heating, and when you open the valve it will take some time to start heating. Also it is often just partly opened which causes water flow to be loud (whining). This depends on the pump also. In my case its annoying sometimes. Depending on the position of the valve in the room you have to figure out what is required offset of read temperature. You can set this offset to the valve, or just set a degree or two higher/lower setting because of it.
I have 60°C in my radiators.
If you want the valve fully closed or fully opened, you have to set it way below or above the current temperature. I think it is possible to open it fully with a command, and close it fully with another command. This could be used in external valve logic, but it takes some motor action (battery drain) to preform 0->100% and back. If I had manual control of the valve, I would probably also use just open/close states, but I would figure it out when it is already fully open (so no whining). So 0% for close and 20% for open on my valves for instance.
Anyway, I still think this is a good product. Batteries are cheap (2xAA) and in my case they are good for one season/year. It is very responsive. I have it set to report changes for 0.2-0.5°C difference or 5% valve change or 60 minutes (had it 10 minutes for first season even). So this is rather aggressive reporting schedule, and is good enough to compute logic to start/stop pump depending on difference between set temperature and read temperature.
For sure, I see how I could improve the logic with manual mode. I hope we some time find a way to make this happen. But even in its default state this is usable product.
Here is todays graph of set vs current temp in one of my rooms:
External thermometer shows 21°C in the afternoon, within a degree. It is quite good result.
And this is its valve % for the same time period:
It seems smart enough.
It does depend on my logic of starting the pump for hot water, I have it set to require at least 2°C of heat (sum of absolutes of differences of set and current temperature must bi at least 2°C for pump to start). But other than that, I only have cron schedule for this room (green graph), and it can be easily overwritten on the valve itself.
Maybe I add also pump run time for the same period. Other rooms had very small effect on these three graphs. Yesterday at 21:00 some other room needed heat.
I hope I shared some insight that may be useful for somebody.
I also hope that manual mode will be enabled. This is a good device and it could be even better. And they have great price in EU (I got mine from amazon.de over 2 years and the price is stable 35-40€).