What is the Difference Between Ionization Smoke Detectors and Photoelectric Smoke Detectors?

When it comes to installing smoke detectors in your home there are two choices: ionization smoke detectors and photoelectric smoke detectors. When you rent or buy a home most already have ionization smoke detectors in place and this is also the most common detector you will find in hardware or discount stores.

Both the ionization and photoelectric smoke detectors are effective in protecting you and your family. The only difference is in how each senses smoke. This means that each detector can better detect certain types of smoke. While many think there is only one type of smoke, there is in fact two types.

One type of smoke is hazy and almost invisible, this is usually caused by cleaner burning fire like grease or leaky furnaces. The second type is the more common thick, noxious, cloudy smoke which happens with smoldering fires such as fireplace or burning upholstery.

The first type of smoke is easily detected by ionization smoke detectors which detect based on electrical sensitivity. The second type of smoke is more easily detected by photoelectric smoke detectors since they work by visibly detecting the smoke. Each of these smoke detectors come with their own unique advantage.

To further complicate matters there are two versions of photoelectric smoke detectors even though they both work the same. The first type activates when incoming smoke blocks light from shining on the light-sensitive sensor. The second type of photoelectric smoke detectors activates when smoke reflects the light shining past the sensor back onto the sensor.

The process of detection is a little different for ionization smoke detectors. These detectors have a small amount of radioactive material that lets out alpha and gamma radiation. The air inside the smoke detector is ionized by alpha radiation which then conducts a current through a small gap. If smoke enters the detector it will lower the conductivity level of the air and set off the alarm. However, the ionization smoke detector is very safe since the amount of radiation given off is miniscule.

If you are installing a new smoke detector in your home make sure you place it on a ceiling and at least six inches away from any wall. You should especially avoid corners or the ends of hallways since these are considered dead air spaces. For wall mounted units they should be placed one foot below the ceiling.

Smoke detectors of any kind should be located away from drafts that can be caused by vents, door and windows. The best place for smoke detectors is in hallways leading to the bedrooms or at the top of stairwells. Every level of the home should have at least one smoke detector including the basement.

To maintain your smoke detectors you should carefully vacuum them once a year and change the batteries as needed. You should included a battery powered smoke detector as a back up even if you have a wired in detector in your home. Check them at least once a month to make sure they are still functioning properly. To properly test your detector you should hold a lit candle six inches below it. If the alarm doesn't sound right away then blow out the candle. If no alarm sounds still then you need to check your smoke detector.