It’s a service or human engineering problem rather than a mechanical engineering or knowledge problem.

Contractors today put in over-sized equipment, set flow temps higher than needed, undersize emitters for aesthetics and cost, and run pumps at full speed to avoid callbacks for “it’s too cold”. You can’t afford the windshield time to drive over to tweak the system to extract maximum performance, because homeowners don’t want to pay for it and will go with the lower bidder enough times that your premium AI-powered service will struggle.

I’ve tweaked my reset curve 12 times the first winter and 2 more times since then (counted from my spreadsheet).

Realistically, if I gave up on the last 3% tweaking, we could have lived with it after 2 post-install tweaks, but at least one of those had to wait for seriously cold weather snap to fine-tune the low end.

My spouse would happily agree that the house is finally very comfortable and noticeably more than before. She’d also tell friends who asked that there were a few days the first winter where the house wasn’t warm enough and needed an adjustment. People who heard that story might conclude that their neighbor’s guy who never has a callback for “too cold” is a safer bet.

Over time, I think even the best mechanical contractors will start to lean towards avoiding callbacks and do that by running the system 5-10°C hotter than “correct” engineering requires. That’s still better than today, where flow is set to 80°C, pumps to max, and the thermostat cycles 4 times an hour but the house is never too cold.