Nuisance alarms are a serious problem. If a smoke alarm repeatedly sounds when there is no fire, the owner is likely to disable it. But then it cannot respond to a real fire. How serious is this problem? When surveyors from the Consumer Product Safety Commission (CPSC) visited homes, they found that one third of the smoke alarms were inoperable. Some fire department surveys have found 40 percent of smoke alarms disabled. The biggest reason for disabling them was nuisance alarms.
Here are the reasons given for disabling smoke alarms, ranked from the most frequent to the least:
- Alarm sounds continuously when powered
- Alarm sounds intermittently
- Steam or humidity
- Cigarette smoke
- Loose battery connection
Most nuisance alarms from cooking involve smoke alarms with ionization-type sensors (see Smoke Alarm Facts & Questions). That is because this type of sensor is sensitive to very small smoke particles, even particles that are invisible to the naked eye. The high heat from cooking generates small, "invisible" smoke particles.
There are two basic solutions:
- Either move the unit
- Replace it with another type of smoke alarm that is less sensitive to cooking.
Moving the smoke alarm farther away from the cooking area can allow the cooking vapors to thin out before reaching the alarm unit. But this does not always work, especially if the air current through the kitchen goes toward the smoke alarm. An example is an apartment where the air current flows from the kitchen down the hall to the bathroom and passes out through the bathroom vent. In this case, placing the smoke alarm farther down the hall from the kitchen may still leave it in the path of cooking vapors.
Replacing the smoke alarm gives you three options.
- Buy a new ionization-type smoke alarm that has a "Hush" button. Pressing the hush button silences the unit for about 15 minutes, hopefully enough time for the cooking vapors to dissipate.
- Buy a photoelectric smoke alarm. The cost of these battery-operated units starts at under $20.00. Photoelectric units are less sensitive to small smoke particles so they are more resistant to cooking vapors. Although this makes them slower than ionization-type units to respond to flaming fires (they give off more of the smaller smoke particles), the time difference is fairly short.
Buy a unit that contains both the ionization and photoelectric sensors. This might sound strange at first because we have said that ionization sensors are more sensitive to cooking. But, when they are combined with a photoelectric sensor, the manufacturer can make the ionization sensor more resistant to the small smoke particles that come from cooking vapors. Thus the owner can have the advantage of both sensors and reduce nuisance alarms from cooking. To learn more about ionization and photoelectric smoke sensors, see How Smoke AlarmsWork.
If a smoke alarm sounds continuously, it is either too dirty, too old or faulty. The sensor in a smoke alarm can become more sensitive as it gets older. As time goes by, it will need fewer smoke particles to make it respond and it may start to sound continuously. All residential type smoke alarms should be replaced when they are ten years old. And although it is rare, even new smoke alarms can fail. If a fairly new smoke alarm sounds continuously, then it should be returned for a new one.
What about intermittent alarms when there is no fire? Like the problem with a continuous alarm, the reasons could be an older unit that is getting more sensitive, or a dirty or faulty unit. In addition, people often mistake the low-battery signal for a nuisance alarm. When the battery is getting low, smoke alarms are designed to "chirp" every minute or so while the battery still has enough power to warn you that it is about to stop working.
The "chirp" is distinctive because it is a single, very short sound that occurs every minute or so. If your smoke alarm does this intermittently, first replace the battery to see if that solves the problem. If not, then the unit needs replacement due to old age or needs cleaning. To clean the unit, place the end of a vacuum cleaner hose next to it and sweep around all of the openings. This should dislodge any dust that has accumulated on the screening. If the dirt is visible and cannot be dislodged, the only practical answer is to replace it.
Steam or humid air can condense on the sensor and circuit board, and enough condensation will cause it to operate. Moving the unit farther away from sources of steam and humidity, e. g. bathroom doorways, can solve the problem. However, if the smoke alarm did fine in its location but is now reacting to steam or humidity, the problem can be age-related due to increased sensitivity. Older smoke alarms that become more sensitive are more likely to respond to steam and humidity than new units. The nuisance alarms may be a sign that the unit is over 10 years old and needs to be replaced.
Normally, a smoke alarm will not respond to cigarette smoke unless it is very concentrated, e. g, a large group of smokers in the same room. Standing close to the unit and blowing into it can cause it to respond, but this is not a normal situation, either. Older smoke alarms that have become more sensitive may begin to respond to lower smoke concentrations. Again, if the unit was fine in a normal smoking environment but is now beginning to respond, it is probably a sign of old age.
There is no practical way to repair a loose battery connection. This is more likely to happen as the unit gets older and has had several batteries replaced. It too, is a sign that it is time to replace the unit.