The air filter for zone 1 is in the basement and the air filter for zone 2 is near the top of the central stairwell, just as the stairway reaches the third floor. A service tech who came out to do a "tune-up" recently told me that the whole system is about 12 years old.
We use zone 1 throughout the day to cool the first floor, with the basement vents closed, and with zone 2 turned off. When we go upstairs to sleep at night, we turn on zone 2, with the third floor vents closed, and turn off zone 1.
At night, with zone 2 cooling the bedrooms, and with the bedroom doors closed, I usually leave the windows on the first and third floors open. I assume this is circulating fresh air through the house, which is getting sucked up the central staircase and vented out the open third-floor windows.
During the day, when zone 1 is cooling the first floor with zone 2 turned off, I sometimes leave the second- and third-floor windows open.
Because heat rises, this whole scheme makes good sense to me and I assume makes efficient use of our AC system. On the other hand, it would not surprise me if, like my wife, your response is "What the hell are you thinking?" Any thoughts?
Answer: Despite your wife's incredulity, it seems as if you have the situation thought out well. I note that you are a lawyer, and your thinking reflects that.
The experts - I don't include myself among them, since all I do is ask the questions of them - probably are thrashing out the plausibility of what you have done here. My thought is whatever works for you is fine, even if it doesn't do the same for the next person.
All situations are just a bit different from one another. That's the reason why the source of a leak in one ceiling may be a hole in the roof, while another might be missing mortar from a chimney. The result is the same: a wet ceiling.
