Smoke Detector Repair

Smoke detectors save lives if they are in good working condition. This Fix-It Guide on smoke detector repair tells how a smoke detector works, what often goes wrong, how to identify a smoke detector problem, and what parts and tools you will need to fix it. It then gives simple step-by-step instructions for how to test a smoke detector and how to replace a smoke detector battery. Test all smoke detectors monthly and routinely replace batteries yearly, perhaps during fire prevention month.

How Does a Smoke Detector Work?

Smoke Detector Repair

First, carefully remove the smoke detector’s cover.

A smoke detector is a small device that sounds an alarm when it senses smoke or fire. There are two kinds of smoke detectors–photoelectric and ionization. Photoelectric units throw out a beam of light that, if broken by smoke will trigger an audible alarm. Ionization units give nearby air an electrical charge and measure whether the charge stays constant; if not there probably is a fire present eating up the oxygen in the air, so the alarm goes off. Photoelectric detectors are better where smoldering fires might be, such as electrical fires in walls, making them a good choice for bedrooms and kitchens. Ionization units are better in areas where a controlled fire might get out of control such as in a furnace room. Some models combine both types of detectors. Smoke detectors are either powered by an internal battery or household current backed up by an internal battery. Some smoke detectors are part of a home Security System.

Fix-It Tip

How many smoke detectors should you have in your house? At a minimum, every home needs one smoke detector on each floor. A better idea is to add a smoke detector in or near each bedroom or bedroom group. If you are building a new home or are handy with electrical things, you can wire sensors and alarms together so that any one of them sets off the entire alarm system.

What Can Go Wrong with a Smoke Detector?

A properly working smoke detector doubles the odds of surviving a home fire. The most common reason for a smoke detector not working is also the easiest to solve: a battery that needs to be replaced. Connections can loosen and sensors can be blocked. The alarm and sensors can malfunction.

How Can I Identify a Smoke Detector Problem?

  • If you hear a chirping sound from the unit, test and replace the battery or tighten any loose connections on an alarm powered by the house current. You also can vacuum in and around the alarm to eliminate dust or dead insects clogging the sensors.
  • If the detector fails to sound after cleaning (see above), replace the unit.
  • If the alarm fails to sound when there is smoke, test and replace a bad battery.
  • If the alarm sounds when there is no smoke, relocate the alarm if it is within 20 feet of an oven or furnace or 10 feet of a bathroom or utility room. Also replace the battery. If these steps fail, check the owner’s manual. If all else fails, replace the unit.

Fix-It Tip

Is someone in your house a sound sleeper or hard of hearing? Consider buying a smoke detector that has a loud alarm and flashing lights, then making sure the alarm is near enough to that person to do some good. Alternately, make sure that someone in your house, when hearing the alarm, is responsible for awakening those who may not hear the alarm.

What Do I Need for Smoke Detector Repair?

Replacement batteries and replacement smoke detectors are available from many local outlets. The tools you will need to test and fix a smoke detector include these:

  • Screwdrivers
  • Candle

What Are the Steps to Smoke Detector Repair?

Smoke Detector Repair

Remove the sensor to access the battery and other components.

Test a smoke detector:

  1. Press the battery-test button on the unit to make sure the battery is properly connected.
  2. If the unit has a battery that’s more than a year old, replace the battery (see below).
  3. Light a candle and hold it approximately 6 inches below the detector so that heated air will rise into the unit.
  4. If the alarm doesn’t sound within 20 seconds, blow out the candle and let the smoke rise into the unit.
  5. If the alarm still doesn’t sound, open the unit up and make sure it is clean and that all electrical connections are solid.
  6. If, again, the alarm doesn’t sound, replace the smoke detector.
Smoke Detector Repair

You can test the battery in place or remove the smoke detector to remove the battery.

Replace a smoke detector battery:

  1. Remove the smoke detector cover, typically by carefully pulling down on the case’s perimeter or by twisting the case counterclockwise.
  2. Locate and remove the battery. Use a multimeter to test battery voltage. As needed, replace it with a new one.
  3. Close the case and test the smoke detector (see above).
  4. Read the owner’s manual for additional troubleshooting tips and possible adjustments.

Fix-It Tip

Buying a replacement smoke detector? Read the packages and check the price. By shopping around you often can get a quality unit for the price of a cheapie.