Woodside Fire Protection District

There are two types of home smoke detectors available: the ion type and the photoelectric type. The ion type reacts faster to open flaming fires and is usually the least expensive. The photo electric type reacts faster to smoldering fires and is less likely to react to cooking. Both types provide adequate protection and can be used without worry. If you need more than one detector, you might get one of each depending on placement of the detector.

There are multiple ways to power smoke detectors. Most operate on a battery (usually a 9 volt), which should be replaced at least one a year. When the battery needs changing, the smoke detector will begin to "chirp" every 20 seconds or so, which will persist for a month. This is most likely to start in the middle of the night (when the temperature in the house drops) so that you have to get up and remove the battery so you can sleep. To prevent this nuisance, you should pick a special day (like your or your child's birthday) and give your detectors new batteries once a year. Some fire safety organizations also promote "change your clock, change your batteries" when the change is made back from daylight savings time each fall. Always make sure that you use the right battery - the required battery type is marked on the detector near where the battery goes.

Smoke detectors installed in a new house will be operated from the household electrical power and do not need battery replacement. These types all have a "power on" light to tell you that the detector has power. Fires do not generally affect the power until they get very large, so it rare that such detectors fail to work due to loss of power. Smoke detectors are available which run on house power but also have a battery in case the main power fails. Since the battery is not normally in use, such batteries will last about six years before they need replacing. (the detector will "chirp" like the battery-powered ones).

How should it be installed?

Smoke Detectors are normally installed on the ceiling or high on the wall, with the top of the detector not closer than 4 inches nor further than 12 inches from the ceiling. Detectors should be no closer than 3 feet from supply registers of forced air heating systems (that might blow on the detector preventing it from seeing smoke) and no closer than 3 feet from the door to a kitchen or a bathroom containing a shower (steam can set the detector off when the door is opened).

If a detector is mounted on an exterior wall or a ceiling below an unheated attic that is poorly insulated (the surface gets noticeably cold in the winter and warm in the summer), the temperature difference can prevent smoke from getting to the detector. Placing a detector in an inside wall avoids the problem. In desert climates where evaporation coolers are being used, mount smoke detectors on walls 12 inches below the ceiling because these coolers add moisture which can cause the smoke to drop.

Older adults may have difficulty reaching smoke detectors on ceilings to change batteries. If house-powered detectors are impractical, wall mounting 12 inches down should be considered.

Replacement

Smoke detectors that are more than 10 years old should replaced. Statistics show that a smoke detector that is 10 years old will have been in constant use for about 87,000 hours. Make sure that your smoke detectors are inspected often, and replace any that are broken or more than 10 years old.