Most thermostats are boolean to my limited knowledge. They call for cooling/heat or they don’t. So it sounds like you want a thermostat AND a power monitor to disrupt it. The problem is, if the delta is high, I would expect 100% power usage to be called for.
Most thermostats do work in simple ON\OFF mode(dry contact is another term used at least in my country, not sure how well it translates though). That is because this is a mode that is universally supported by every heater\boiler and is relatively simple to achieve.
However many heaters\boilers do have more granular APIs\protocols to control them. (and I may be confusing the name, the model we have specifically is a Buderus Logamax U072, easily searchable in google (funny, just tried googling for it myself to make sure, and they still use frames from a promo video I made for them about 10 years ago as a gig while I was still a student)
For example Buderus (and Bosh too I think) heaters use OpenTherm protocol. It allows you to get all sorts of readings from internal sensors of the boiler, as well as directly set desired water and fluid temperatures as you would do it on the physical control panel. And there are thermostats available that utilize this protocol, for example here in Russia we have a company called ZONT that makes them. But it’s cloud based, and I’m sure that core automation happens on the device, I still would prefer something where I directly control the code that runs on the device.
Not sure what you mean by power monitor and disrupting something. As I said, in the case of this gas heater it itself does gas burner modulation, and you can set the desired fluid temperature. So all I need to do from my end is to tell it which temperature of the fluid I want, through opentherm. This part is already solved (not tested yet though, waiting for warmer weather, because atm it’s dangerous to mess with heater, if it stops working everything can freeze within a day and pipes will break).
Sounds like PID autotuning to me…
Possibly. Though that means that it would be running in autotuning 24\7, basically. And it should have protections against going too crazy, like I would NEVER want it to turn boiler fluid temperature to 100% and NEVER to make it change temperature too drastically too quickly. It should be nice and smooth. Except for maybe emergency situations, where there is a risk of freezing, then it could crank things up, but even then not to 100%. Or maybe only allow that through a confirmation with a notification. Like sending notification “Hey, house is freezing, should I crank it all up to 100% or do you think it’s a sensor fluke or something? [Heat up] [Ignore]”.
Use an automation to turn off the thermostat/PID if > 90% power ? But again, if it needs 100% before the disuption, unclear why it wouldn’t just need 100% after the disruption. Am all ears on this one.
As I said, it should never need 100%. If you have a fluid at say 10C, and you want to heat it up to 30C. You can either burn the heater at 100% for a few minutes to quickly bring the fluid up to 30C, at the cost of deforming the pipes (not permanently, mind you, but any material will expand and contract with change in temperature). And in case of a simple ON\OFF thermostat that’s how they operate, and it means it will then turn heater off, and the fluid will cool down back to 10C within a few minute… then ON again… then OFF… ON… OFF… A cycle repeating every few minutes, with pipes going crazy.
Or you could set the heater to like 50%. It will take longer to heat up the fluid but it will be a smooth change, pipes will be happier. And instead of turning it off entirely you could just turn it down to like 25%, so that fluid temperature will start dropping, but it will take hours for it to drop to 10C. And like that you could potentially even find the correct % for the heater to keep both the fluid and room temperatures constant. Just enough slow burning to keep it.
I think the term for some of this is thermal hysteresis