The only open source implementation of OpenTherm (and EMS bus too now) that actually works (unlike commercial thermostats) and provides low load and weather compensation at the same time is:<p><a href="https://github.com/Alexwijn/SAT">https://github.com/Alexwijn/SAT</a><p>PID is used to smooth out weather compensation errors.<p>See my grafana for realtime boiler and cost data:<p><a href="https://gasboiler.grafana.net/public-dashboards/8d44381aafa94fe9bdc87839d8845ada" rel="nofollow">https://gasboiler.grafana.net/public-dashboards/8d44381aafa9...</a>