Last year i wrote a overly complicated weather compensation function to control our ASHP (we have no internal thermostat).
It was based on the method Worcester Bosch(Rebadged IVT) GSHP's use and matched the heat curves in their manual perfectly.
All winter i adjusted the settings, the heat curve, the ofset, the hysteresis and sometimes the house was the correct temperature. Then the weather would change and we'd be too hot again, more adjustment and a week later it'd be chilly in the house.
By march when i turned the heating off we had is sussed and the only time the system didn't cope well was after a few days with very high solar gain.
The short version, it took a whole winter of messing to get the weather compensation set correctly.
Towards the end of winter i was asked to look at a GSHP and a ASHP at 2 properties owned by a local builder, both were alarming due to incorrectly set weather compensation with the heat pumps objecting to the return temp or the water being far higher than they expected. The heat pumps were fighting the internal thermostats.
The GSHP used the system i had copied(I had commissioned the heat pump for him 2 years earlier) so i made a guess at how much to turn it down and told him to call me if it still alarmed. Nothing yet
The ASHP (by the same manufacturer) had a complete different method of setting up the weather compensation. One that doesn't involve picking a number between 1 and 10 and waiting to see what happens and even better in can be re-created in Arduino with only line of code.
For anyone that wants weather compensation and hasn't fallen asleep yet.
DesiredWaterTemp = map(osTemp, coldOS, hotOS, coldWater, hotWater);
Descriptions
DesiredWaterTemp is the return temp from your heat emitter or buffer tank.
osTemp it the current outside temp
coldOS is the outside temp on a cold day, you need to record this value and the required water return temp needed to heat your house.
coldWater is the return water temp you recorded on the above cold day
hotOS is the outside temp on a warm day (that still requires heating), you need to record this value and the required water return temp needed to heat your house.
hotWater is the return water temp you recorded on the above hot day
Hope someone finds this useful
Steve