Check the wiring of each one. Probably a wire has come loose in one of them. How humid is your attic? How hot does it get in there? Is the one installed in the attic UL-listed for attic use (extreme temperatures)?

catbuilder - thank you for the tips! I will check on the UL listing - that sounds like it's important.

Is there a spider living on or near one of the detectors? Bugs can set them off. I would take a vacuum wand and go over each detector

Are candles burned near one? The greasy smoke(natural with candles) coats the sensors and causes false triggers. Just happened to us in wife's sewing room.

Handy - I don't burn many candles - BF hates them. When I do, they're not near a smoke detector (which now that I type that maybe seems bad!) - but that's a good thing to keep in mind.

Chispa - good call on the vacuum. I'll either do that or an air canister to clean them out.

For now, BF has replaced the attic detector with a new one, and they've been blessedly silent. Hoping that does the trick.

Thanks for the responses!

Same thing happened in our old house. They started going crazy a few years ago and the only 'fix' was to rip the cursed ones out of the ceiling. Solved the berserk problem, but we lived the last 6 years in the house without a smoke detector in the guest room and hallway.

What we found the cause was not a faulty detector, but that dust had settled inside and obscuring the sensor just enough for it to read as smoke'. The fix was to remove each cover and vacuum out each one to remove the dust.

So in this new house, I've already set a yearly reminder to vacuum the smoke detectors. It shouldn't take more than 30 minutes to do our entire house. I'm hoping it keeps the crazy away!

"I'm hoping it keeps the crazy away!" Well I have 2 fun college kids, one wacky dog named Hendrix, regularly open my doors to the basketball friends, garage bands, assorted neighbors of all ages (some 4-legged), and then there's me... lots of crazy! :)

Is it pollen season in your area? I had problems with one smoke detector that was in a screened breezeway which was often open to fresh air (and pollen). Of course, all of the connected smoke detectors would go off too.

Vacuuming might help, although I considered a sledge hammer. Covering it temporarily with a dust cap made a difference.

Claire

Skip the cheap ones from the box stores and get commercial ones. System sensor comes to mind but there are many more brands. I have false alarms all the time with the cheap ones but not once from the higher end smokes.

jk- the brand I'm replacing (and planning to replace with the same kind) are $53 at my local hardware store and more on Amazon. I'll look into commercial sensors, but buying 9 of them... yikes. It's one of those necessary-not-fun purchases!

Why would there be a smoke detector in an attic if its not a habitable space and not a "floor" of the house? Perhaps local enforcement is stricter than the IRC. Normally there would not be detectors in bathrooms, kitchens or garages (heat detectors used in garages.) I can't imagine why one would be in a breezeway. If cleaning the detectors and removing the detector in the attic doesn't work, your best option is to use an electrician who will understand the purpose and best models of these devices.

IRC requirements:

R314.3 Location.

Smoke alarms shall be installed in the following locations:

1. In each sleeping room.
2. Outside each separate sleeping area in the immediate vicinity of the bedrooms.
3. On each additional story of the dwelling, including basements and habitable attics but not including crawl spaces and uninhabitable attics. In dwellings or dwelling units with split levels and without an intervening door between the adjacent levels, a smoke alarm installed on the upper level shall suffice for the adjacent lower level provided that the lower level is less than one full story below the upper level.

When more than one smoke alarm is required to be installed within an individual dwelling unit the alarm devices shall be interconnected in such a manner that the actuation of one alarm will activate all of the alarms in the individual unit.

I will add in the past year we have had 3 homes catch fire (2 tear downs, 1 top level full replacement) in our neighborhood - different builders because air handlers were in the attic without smoke detectors. The last one the family was home and a neighbor knocked on the door to tell them their house was on fire, they had no idea because it was in the 2nd story attic and they were downstairs. Scary. I have had to do the full smoke detector replacement as well. They tried swapping a couple out and it didn't fix the problem, I had them fully swapped out with the commercial units and no problems since.

Also are they fully going off or just chirping? We had chirping issues in the past that was fixed with replacing the batteries in all of them at the same time, when ours lost it completely they started sounding like there was a fire, of course at 2am.

JDS: we have AC units in the attic. (Don't know why - they were installed before we bought the house and upgraded by us, but same location. Furnace is in a mechanical room in the basement.)

andria: they were full on siren wailing. I wore ear plugs (from spin class) to change all the batteries and then take them down. Even after taking them down and removing the batteries, they each still chirped a couple of times which kind of creeped me out. Any chirp now makes me cringe a bit. What brand and model are your commercial units if you don't mind me asking? I have a call in to First Alert to get info on latest and greatest, but of course that's just for their brand.

We have the System Sensor. Part of me wants to switch to the Nest ones just because it will notify me if anything happen while not at home. We also have some that are part of our alarm system, I don't get why they are not linked but whatever.

If HVAC equipment is located in an uninhabited attic, a heat detector should be installed rather than a smoke detector. You might be able to use a smoke detector if the attic is within the thermal envelope of the house, i.e. the insulation is in the rafters so the space does not get too hot or cold and humidity is controlled.

I like the nest protect, and will likely use them in my new build. I think I will need about 8, so its abit pricey, but when they do go off, they will give you a heads up first, and they tell you which detector senses the problem. Also tells you if it is smoke or CO. They do a self test every month to check that the speaker is working. Also functions as a night lite. And if you are away from your home, it give you a chance to call the fire department if you get the alert.

If you have a nest thermostat, they will talk with the stat to help it determine if you are home or not, and also shutdown your HVAC if smoke or CO is detected to prevent the spread or generation of it.

There's also a history logged of all the alerts, so if one of your kids was smoking weed in their bedroom while you are gone and it sets the detector off, you will know about it :-)

Let's all hope that was an example and not an actual occurrence.