So, all the smoke alarms in our house keep going off every so often when there is clearly no smoke in the house. We checked all the appliances, and nothing is on fire, and there’s no smoke in the highest part of the house, where you’d expect smoke to gather.
Why is this happening? How do we make it stop? It’s kind of turning our life into a living hell!
one at a time. take the alarm down, remove the battery. vacuum the alarm and its ventilation holes. check the battery (even if it’s just power backup). place a good battery in it and remount the alarm.
do this to all of them.
humidity and dust (in the alarm) can sometimes trigger the alarm.
smoke alarms have about a 10 year useful lifetime. carbon monoxide (CO) have a seven year lifetime.
replace old or malfunctioning alarms.
Steam can set mine off.
Paint fumes and some aerosols can set them off too.
Second the suggestion to replace the batteries and see if that helps.
There’s also some body of “conventional wisdom” out there that this may also mean the battery needs replacing.
That’s not how smoke alarms are supposed to work when the battery is low. They’re supposed to just make periodic chirps when the battery is low, and some of them do. But when you start getting false alarms, changing the battery often fixes it.
I say that’s an outright malfunction, because it’s not what’s supposed to happen. One of the smoke alarms in my apartment started doing this just last week. I think I’m going to ask the manager to give me a new one, on the grounds that this one is malfunctioning.
You’re sure they’re just smoke alarms, and not CO2 alarms as well, correct?
If so, I agree that replacing the battery seems like the next best step.
Time to clean the oven and or stove.
Funny thing, I just had this problem, but with interconnected hardwired alarms, not battery ones. Mine are ionization type smoke alarms + CO detectors. Vacuuming out dust seemed to be the prevalent recommendation, also that humidity can cause or aggravate it with some sensors.
In my case I narrowed it down to the one in the basement, causing all alarms in the house to go off. Vacuumed it thoroughly on both sides, reinstalled it, and now it goes off constantly! 
Oh, well, according to the label they’re past their best-by date so I’ve ordered a new one. Apparently just age is another thing that will cause them to go off. One thing I found out is that interconnected hardwired alarms aren’t generally compatible between manufacturers, or even necessarily between different models from the same mfg.
If they are CO2 alarms, that would explain why they’re always going off! 
ETA: I know don’t have CO in the basement. The false alarm was indicating smoke, and I also have a separate CO alarm.
I blame it on the cat.
Thank you all for the quick responses! We narrowed the problem down to the third floor smoke alarm. I hit it with some compressed air, and now we’ll see if it recurs. I’ll try vacuuming it after that, and replacing the battery if that doesn’t work.
It’s a fairly new detector (smoke only, photovoltaic), which I installed myself several months ago, so I doubt the battery is low or that the device is wearing out, but I suppose anything could happen.
When mine, in a pretty new house, did that, it turned out one of the base units was defective. The electrician replaced all of them, no more problems.
I blame it on the Bossa Nova.
Sorry I got here late. Wolfpup, if your smoke detectors are all ionization detectors you may want to rethink that. Ionization detectors do not detect smoke at all. They detect the non visible products of combustion. This is why home smoke detectors sound when people fry bacon.
All home smoke detectors should be combination Ionization/Photoelectric detectors. Photo detectors will pick up thick smoke from smoldering fires, while an ion detector will not.
This short video lays out the problem very well: The Aquarium Smoke Detector Test
After half an hour in an aquarium filled with thick toxic smoke, the ionization detector never sounds. The Co detector shows just how toxic the smoldering couch cushion foam is. The photo detector sounds in just a few seconds after being dropped in.
Check your smoke detectors for type. Change your batteries each time you change your clock for daylight savings time. Replace your smoke detectors every 5 years. Yeah, I know that NFPA 72 says ten years, but they are not that expensive and it is much better to err on the side of safety.
Just my humble opinion backed up by 36 years as a fire alarm technician.
We had a similar problem with our hardwired interconnected alarms. We first tried replacing all the back-up batteries. When that didn’t solve the problem we narrowed it down to the one in the guest bedroom. We disconnected it while trying to decide what to do. And left it disconnected for about 2 months because yes we are really that indecisive. Before we could make up our minds about what to do another one decided to pull the “going off for no reason” trick. Because they were 8 years old, and they have a probable lifespan of about 10 years we replaced all 8 of them. That was 2 years ago and they’ve all behaved since.
No false alarms since I gave it a few good puffs from a can of compressed air.
Thank you for the very detailed post, longhair75. If we weren’t moving in a couple months, I’d replace the alarms I have here, but I’ll remember to only get photo/ion combo alarms from now on.
having interconnected alarms is a good idea. wired interconnect is best. there are wireless interconnected that i’ve no experience with.
you should have a carbon monoxide (CO) alarm on every floor and in sleeping areas. these could be ceiling or plug-in-the-wall types (these have a disadvantage that they can be unplugged, also most types obstruct a receptacle [there are some corded types that don’t]).
there are combination ceiling mount CO and ionization smoke alarms, combination ceiling mount CO and photoelectric smoke alarms. i haven’t seen one with both smoke detection types.
so you might want to mix detectors. have combination smoke detectors in hallways. ceiling CO combo detectors in kids bedrooms can’t be deactivated by them.
When I was in college, tiny ants set off the dorm’s detectors all fall.
Thank you for the information, I appreciate it. The ionization-only (+CO) wasn’t my choice, this seems to be a popular model with builders, and was part of an original install.
Your advice comes at an opportune time. My original intent was to replace the basement ionization+CO unit with an exact replacement – which I was glad to find was still available – to minimize wiring and interoperability hassles. But I’m now thinking that what I should do is replace all three with better units, since actually all three are past their nominal replacement dates. It means I’ll have to rewire the pigtails in each fixture, since every manufacturer’s plug connectors are different (and so, apparently, are some of the interconnect protocols).
Interesting comment about ionization types going off on non-visible combustion products. The one next to the kitchen has an annoying habit of going off whenever anything fatty is in a hot oven even when there’s no apparent reason for the stupid thing to be blaring at me. That problem, plus the failure of the ionization sensor in the basement, actually tempts me to consider photoelectric-only for the new ones, much as I appreciate the value of having both. The ionization ones just seem troublesome.
Further to the above, while we’re on the subject, since I think I’m now on the path of replacing ALL of my smoke detectors, anyone have specific recommendations on the best brands and models for hardwired interconnected types? Around here, Home Depot seems to carry mostly Kidde, while Lowe’s likes First Alert, and then there’s the vast array of other brands and models carried elsewhere and orderable online.
good to have a ‘desensitization’ feature on the alarm near a cooking area. you push a button and it is less sensitive for 10 minutes or so.