Interesting @stephen - I am tempted to tinker with the system settings. Our installer left them open for me because he gauged that I knew what I was doing. I’ve actually left them alone because I don’t want anyone to question my warranty - I’m on a seven year contract with the installer and the UK government for this system and it would be very expensive for me to fall off that contract. They normally leave the systems with the base user settings open in the UK.
I don’t have a buffer tank like you. My air source heat pump is connected directly to the radiators. As a result, it’s load is very much correlated with the room air temp.
I like the sound of what you’ve done with your system to get it behaving nicely. It’s always nice when a small tweak makes things work properly.