Does anyone know if the smoke detector goes off if the tempurature in the house get really cold? My smoke detector goes off in the middle of the night when the tempurature in the house drop down below 60 degree. I have about 8 detectors around the house, so I unplug four and the rest stop. So I figure there must be a defect in the four unit to goes off. So how do I check which one is the defective one?

Possibly just dust? If you unplugged 4, it was 1 of those 4, Smoke Detectors have a 3rd wire(interconnect) so when 1 goes off they all go off. Some will show a red light on the offending unit.