Even a relatively small fire can fill a house with smoke in a matter of minutes. For this reason, many local building codes and home insurers now require smoke detectors in new houses and apartments.

    Smoke detectors come in two types-photoelectric and ionization. Photoelectric types bean light into a chamber containing a photocell and trigger the alarm. Slow, smoldering fires set off these more readily than fast, flaming blazes.

    Ionization units use a radioactive source that ionizes or breaks up the air inside the detector and gives it a small electrical charge. Smoke particles reduce the current flow, which sounds the warning. Ionization detectors respond more quickly than photoelectric units to fast, flaming fires.

Which works best?

   Each type has its advantages and drawbacks. Most photoelectric models run on house current, which means you get no protection in a power outage or in an electrical fire. Ionization units run on a current, batteries, or both. Besides reacting more slowly to smoldering fires, they're also more susceptible to false alarms. To increase your peace of mind, you may want to use one of each-an ionization detector in your bedroom hallway and a photocell unit in the main living area. Deluxe fire protection systems also include heat sensors wired in the tandem so that all alarms will sound if just one senses excessive heat or smoke.

Maintaining Smoke Detectors

    Test each smoke detector monthly. Most have a test button that sounds the alarm when you press it. If yours doesn't have a test button, it's at least 15 years old and you should replace it with a newer model. Most battery-powered smoke detectors require the you replace the batteries annually. Before testing the smoke detector, take a moment to clean the inside of the detector and its vents with the soft brush attachment of a vacuum cleaner.

Installing Smoke Detectors

    Most smoke detectors take only a few minutes to install and come with complete instructions. Knowing where to locate them, though, can help you decide how may you need, and may also have a bearing on the type you select.

  1. Attach each unit to a ceiling, or high on a wall 4 to 6 inches below ceiling level.
  2. Don't install smoke detectors in corners because air circulation there is poor.
  3. Don't install smoke detectors close to the kitchen, furnace, garage, or fireplace, or just outside a bathroom door.