Hulk abhor smoke detector false positive. Hulk smash. SMASH! Very cathartic for Hulk.
March 15, 2012 5:16 AM   Subscribe

Smoke detectors: do products exist which aren't subject to "false positives," i.e. activating due to dust, dirt or other reasons when there isn't a fire or smoke nearby?

All smoke detectors that I've owned have been the el-cheapo variety from the big box home center, and every one has gone off at random times, usually a year or more into the life cycle. As you can guess, this is really irritating, no matter how cathartic it is to destroy the offending equipment with a hammer when it won't shut up.

Why do most smoke detectors behave this way? Is it due to dust, dirt, wind, etc? What's the fundamental design problem here?

Has anybody marketed a smoke detector that doesn't give false positives--not ever? I'd be willing to shell out extra money for a reliable device that doesn't wake me up at night . . .
posted by Gordion Knott to Home & Garden (12 answers total) 3 users marked this as a favorite
 
After one year? You're not talking about a periodic chirp, are you? That's the "low battery" indicator.
posted by Doofus Magoo at 5:51 AM on March 15, 2012 [1 favorite]


All smoke detectors that I've owned have been the el-cheapo variety from the big box home center, and every one has gone off at random times, usually a year or more into the life cycle.

Is it going off because it needs a replacement battery?

Has anybody marketed a smoke detector that doesn't give false positives--not ever? I'd be willing to shell out extra money for a reliable device that doesn't wake me up at night . . .

I don't think I've ever had a smoke detector that's given off non-obvious false positives, and most of my smoke detectors have been purchased at big box home stores. You might want to look into what's causing the false positives before looking for a different detector.
posted by RonButNotStupid at 5:53 AM on March 15, 2012


That's a little weird to me, as I've had various brands of cheap smoke alarms that I've bought here in the UK, and have never had a false positive. The only times they ever go off are when I've been frying a little too aggressively in the kitchen.

There's probably some combination of environmental factors and detector placement that's causing the problem. High humidity from a bathroom or boiling water, maybe?
posted by le morte de bea arthur at 5:54 AM on March 15, 2012


I'm guessing they're designed to fail so they give false positives.

Imagine if they were silent when they failed. You'd never know it and you'd never replace it and when a real fire came along it wouldn't work and you'd die.

A failure mode that irritates you is GOOD in this case.
posted by Confess, Fletch at 5:58 AM on March 15, 2012 [1 favorite]


A failure mode that irritates you is GOOD in this case.

There's a balancing act there. Smoke detectors have to be reliable enough such that they don't have to give irritating false positives lest people just throw the detectors out and not bother with them and then die in a fire. For that reason, smoke detectors are designed to be as unobtrusive and reliable as possible.

If a single smoke detector is giving out false positives, it's malfunctioning. If two smoke detectors are giving out false positives, it's because of the environment around them.
posted by RonButNotStupid at 6:16 AM on March 15, 2012 [1 favorite]


humidity can cause smoke detectors to go off. We've had at least a couple go off in the middle of a high-heat/humidity wave, The low battery "chirp" is usually disorienting on the cheaper ones but can't be mistaken for a false positive. It can take a long time to figure out which stupid white disk that might save your life is complaining (beeping once every couple minutes).
posted by ghostiger at 6:32 AM on March 15, 2012


I have several in my house, smoke, heat, and carbon monoxide, and they've all gone off at random times. They're all wired together so when one goes off they all do. Within the first year of moving in I had to replace one and when I took down the offending one there was some pretty obvious construction dust in the sensor.

During a power outage in October we had our fireplace cranked and a carbon monoxide detector went off. I swapped it with another one and the next morning the one I swapped in went off. I called the fire dept. to check it out, they detected no danger, and then they told me that this sort of thing happens all the time. They suggested replacing all the detectors every few years because over time they become less and less reliable.

A failure mode that irritates you is GOOD in this case.

I disagree. It's gotten so when they go off I have to force myself to do a walk through of the house. Usually I just want to turn it off and go back to bed but I always remind myself "What if THIS time it's real?"

They seem to go off less and less now that the construction dust has settled. I've also permanently disabled a couple that were in stupid locations, according to the fire dept, such as directly above my fireplace.
posted by bondcliff at 6:34 AM on March 15, 2012


Is it due to dust, dirt, wind, etc?

Is your house exceptionally dusty or dirty? It's not the wind (although technically it could be wind-borne dust). It may be possible to get someone from your local fire brigade/department/whatever to come out and have a look to see if there's something specific about where you are locating your smoke detectors, or something wrong with your detectors, or something else that the layman may not know about, which is causing them to go off 'randomly'.

For whatever it's worth, the ones I've lived and worked with (as in, working in a place with a fire alarm system, not working for a fire brigade) have only ever gone off for reasons - smoke from open fires or unsuccessful cooking, aerosols and steam being the most common. A really fun one was when water leaked through the upstairs floor and set off the fire alarm on the downstairs ceiling. Fortunately that one was at work, and someone knew about the overzealous cleaning that had been going on upstairs several hours earlier and all was resolved quietly.

It's possible to get heat detectors for places where smoke detectors aren't suitable, and maybe that would work better for you? You don't want to rely on them completely in case you die of smoke inhalation before it gets hot enough for the alarm to go off, but it's better than e.g. having a smoke detector in the kitchen.
posted by Lebannen at 6:42 AM on March 15, 2012


You have to keep in mind that the difference between smoke and dust/humidity is often just particle density. To get around that, you might consider a "rate of rise heat detector", which only alarms on a sufficiently quick rise in temperature. But they aren't intended to fully replace smoke detectors, but do well as substitutes in areas where dust or moisture cause issues with smoke detectors.
posted by tommasz at 8:08 AM on March 15, 2012


When I had a security system installed, I had the alarm company put in new smoke/CM detectors on all three floors. It's been nearly a year and no false positives yet. I'm not sure if they are hardwired or whether they use a battery (no "chirps" yet either). And I live in a dusty old house to boot.

They also gave me a little orange cap to block the detector nearest the kitchen when I'm cooking something smoky - works like a charm. To be used with caution, of course.
posted by Currer Belfry at 9:29 AM on March 15, 2012


Could the folks who are claiming theirs never have false positives post brands and model numbers? Just curious if there's any kind of pattern here. I had the very cheapest Kidde model in my house when I bought it and they've almost all had false positives at this point, to the point where when the smoke alarm goes off my reaction is not "fire!! fire!!" but rather "argh, stupid flaky smoke detectors!!" It's almost always in the middle of the night, the dogs go nuts - yes I prefer it to never going off at all, but not by much.
posted by troublesome at 9:36 AM on March 15, 2012


I also just have the cheap Kidde (or FirstAlert or whateever) alarms and I rarely if ever get false alarms, depending on whether you count detection of kitchen smoke as a false or true alarm :) I do tend to get the ionization-chamber type rather than the photocell type — maybe they're less susceptible to false alarms?
posted by hattifattener at 12:55 PM on March 16, 2012


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