Yes this might happen the first time but that's why it's called "adaptive" - the idea being to leave it for however long it takes (a few days, a week maybe) in a steady state at your chosen room temperature setting, so it can "learn" from the micro-incremental temperature changes how your room temperature reacts to your flow temperature, with reference to your target room temp. If, the first time, the flow temp climbs too fast, the next time it will choose a more gradual increase in the flow temp, and repeat this "learning" until the flow temp behaviour achieves a steady state vs. your room temp target. Then if the sun is shining through your window it will reduce the flow temp further according to the higher rate of room temp increase.