My mother's new townhome has an annoying problem on the bottom level. The smoke detector seems to beep at slow intervals when the room gets cold. We've tried replacing the battery, and she had someone come by to replace the detector, but it's still doing it. Do they all do this? So far I've only come across this explanation.

Normally the solution would be simple, just raise the heat in the room. But this is the basement (where the home theater is), it's the summer so the AC is on, and the thermostat is on the top of the three floors on that system. So the heat rises, the thermostat says to cool, and the bottom floor, which was already five to seven degrees cooler than the top, gets even colder. I've been in there when it was 72 on the floor with the thermostat, and 58 in the basement.

She and I always seem to get different stories depending on which HVAC person we talk to. Is it okay to close vents to force the air into different parts of the house? I, for one, close all the vents on my first floor in the summer and open the ones on the second, where it's always 10 degrees hotter.

So this is somewhat two parts: is there anything we can do about the detector, and is it okay to close a large number of vents to control the airflow?