As I promised I have created a first-cut model of weather compensation, attached.  Its based on the Mitsubishi PUZ-WM112 performance data, which is pretty comprehensive.  I have modelled the CoP with 5 different W/C schemes and none, estimating the CoP as a function of flow temperature and ambient by linear interpolation.  Weather data is average daily temperature for 2022 from the Met Office Central England database.  The average daily temperatures are collected into bins 1 degree wide, the num