You'll have to play with the vent holes and the water amount per time of year and even down to the room you want the bator in. It all changes based on the humidity outside the house, in the house, and down to the room you are in. Give at least an hour or even more for temps to stabilize, and know that once you put eggs in, give it at least half a day to get to temp and try not to touch the knob. The coolness of the eggs will make the sensor think it is too cold, thus make it "too warm" till everything is at equilibrium. The key is patience and lots of patience.