I mentioned the hot tub, and tracking that temperature is working well.
But there are some more options now I have them working so well...
My small environmental monitors already work with various temperature sensors including SCD30 (not very good), SCD41 (good, but slow startup adjustment), and DS18B20. Adding an option to read from a BLE sensor was really easy. This has solved a problem where the downstairs (small) toilet radiator was linked to the hall, and reportedly "hotter than the fires of hell" (actually 33℃). It was not convenient to wire up its own sensor before. Now it has one of these BLE sensors on the wall. It works really well.
For now, I am using my environmental sensors to control both radiators (winter) and aircon (summer). They way it works radiators is using a Shelly Plus flashed with tasmota and a (wax based) actuator - works well. The environmental sensor turns it on/off for the corresponding radiators (GroupTopic). They then tell a FireBrick to turn a profile on/off, and a linked set of profiles tell a Shelly driving the boiler to turn on if any of the radiators (on a floor) are on. Complicated, but works.
I suspect what I need to make is some ESP32 code for the Shelly that does this directly - the control of the radiator actuator directly from the Shelly, and using the BLE sensor for reference. This could then announce from all radiators that are on, so that some other ESP32 code in a Shelly for the heating can turn on if any radiator in its area is on. All done with no WiFi, in theory. Both bits of code will be a doddle, but actually the harder part is setting the required temperature setting for each radiator, and then the fact that I may want to control the aircon. So actually, for me, these are probably better using my environmental sensors for now (which also have a nice display). I can see how this would work for most people though.
Daikin air-con control
The other thing that could perhaps be made simpler is the Daikin wifi control modules (amazon). At present these provide simple web control and status, or they can work with my environmental sensors to manage them based on a separate temperature from that sensor (or, now, even from a BLE sensor).
What would be cool is a direct mode to work with an external BLE sensor - no need for the environmental monitor doing the control. It could be related to a status display!
This would actually be really cool for most people - whilst I have a complex system of radiators and/or aircon in various rooms, for most people with air-con the control should be simple. And being able to literally stick the temperature reference where you need it - e.g. by a bed - would be ideal. Even better if it works with no need for an MQTT broker (or even wifi, apart from set up).
So what next?
I think both are good ideas, so planning to work on them. For aircon, some simple start and stop times may make sense as well.
The real trick with all of these is setting the target temperature. I currently use a configuration file, JSON, over MQTT, which is fine for me, editing a config file. But not for most people.
I suspect I need to make an interactive graphical temperature target profile graph edit thing in HTML. That will be a pain in the arse! It should be possible though, and then apply to all there different approaches here. I may end up just making a time/temp table, sort of like old school heating controllers. I'll have to see...
Comments welcome... What do people want?