We moved into a new house about 3 years ago and have been plagued by nuisance alarms ever since. They happen most often in the middle of the night, but aren't uncommon in the daytime.
I have:
Replaced all the old hardwired detectors with new battery-only ones thinking it might be caused by EMI.
Ruled out insects crawling into the detectors.
Sealed the electrical boxes thinking it might be dust from the attic.
Installed an excellent filter system in the HVAC.
Other random info:
Only the ones on the second floor go off. There are five upstairs and two downstairs.
I'm pretty sure one (and only one) of the false alarms was caused by humidity from a shower.
Seems like they're happening less often since I installed a new HVAC system, but that could be due to less dust or due to smaller temperature swings (less of a setback at night).
I think at this point I want to get some fancy multi-criteria alarms, ones that are specifically for reducing your nuisance alarm rate. Also for increased capability, though - one of my coworkers just narrowly escaped a housefire with his wife and dog. Their fire alarms failed to go off and he was only woken by the sound of the flames.
Any suggestions for multi-criteria alarms that work with hardwired 120VAC three-pin connections?