"I have a question though, you mentioned that you use top entrances in winter. Wouldn't you want to do the opposite so the heat would stay in the hive? Since heat rises it would be trapped at the top. If you open the top wouldn't they have to work harder to keep the heat levels? I am not being critical, just looking for enlightenment."
I also had this question because I originally wanted to keep my top inner cover hole open on my honey apiary cover, for ventilation, but the forum members said that this would act like a chimney and the hot air would be sucked right out the center of the hive. So the solution is I have a 1/2" x 2-1/2" notch in the side - front of the top cover. (I have one of those honey apiaries top covers and they come with the notch already there, but I had closed this up when I received the top, but now have opened it back up)
The heat now leaves from the side and not the top. Apparently this is supposed to work for releasing the condensation, but still allow the hive to keep warm. This will be my first winter trying this so I will see how it works.