Yes I thought it may be the zone adjustment factor used by the optimiser /load scaler, the bit that foxed me was that it could be manually adjusted !
Before the days of evohome I was seriously in to optimiser based thermostat controllers (we're talking the early 90s now) and one of them had an optimiser adjuster value that could be viewed. Problem was basically it set a start number and then missed the target temp and simply adjusted the number. The next day rinse and repeat. All fine if the temp gradually changes outside but when there were big o/s temp jumps the system couldn't cater. I am hoping that the "fuzzy logic" in evotouch will be smarter but am concerned that all zones show the same temp rise value of 3c and I could manually set the values better as I know from experience that there are serious variations between zones. This is one of the primary reasons why I first invested in evotouch MK I due to its zone based capability rather than a blanket central based thermostat (My hall is always lovely and toasty whilst my north facing ensuite freezes !!)