What kind of smoke alarm is in your house? Odds are is that your current alarm is an ionization type. How old is your alarm? If your house is over 10 years old it's likely that your alarm is past the recommended replacement date. This post shows you how to check what type and how old your smoke alarm is.
Step 1: Find a smoke alarm. There should be one on every floor of your home and inside every bedroom.
Step 2: Remove the working part of the alarm from the base plate. Generally this is accomplished by twisting the alarm body counterclockwise until it releases. If you have a hardwired system (all the alarms are interconnected) be careful of the wire connections inside the junction box.
Step 3: Look at the information plate on the rear of the alarm body. You are looking for a date of manufacture and a statement warning of the presence of Americium 241. The date of manufacture will tell you how old the alarm is. If over 10 years old, it is recommended to replace it. If the alarm contains Americium 241 it has an ionization sensor and is best at detecting flaming type of fires. It is possible that it is a dual unit but likely that it is a single sensor system. Dual type units usually have that information printed on the front.
Step 4: Replace the alarm body in the baseplate with a clockwise motion.
Step 5: If your alarm is over 10 years old, plan on heading to the local big box store to look at replacements. It is helpful to note the brand and model of your current smoke alarm to aid in finding the correct replacement model.
Photoelectric smoke alarms are not as common in modern construction. They work on a different principle than the more common ionization alarms (see infographic below). Photoelectric alarms are better suited to detecting smoldering type of fires in a home.
Just like the post last week on ionization alarms, the takeaway for a homeowner is to consider a dual type of alarm instead of relying on just one method to detect fires in the home. You don't get to choose the type of fire that may affect your home. Dual type smoke alarms that combine both ionization and photoelectric sensors are the best choice for any alarms you are considering replacing or upgrading.
Ionization smoke alarms are very common in the US. It's likely that the current smoke alarms in your house fall in to this category. These type of alarms rely on a tiny amount of a radioactive substance called Americium 241 to help detect smoke particles in the air (see the infographic below for details).
Ionization smoke alarms are best at detecting a flaming type of fire. They do not work as well as detecting a smoldering fire in the house. An ionization smoke alarm does provide a warning for fires it can detect it may not be the best choice to cover all potential types of house fires. A better option is a dual function smoke alarm - one that has both ionization and photoelectric sensors. Look for a post next week that explores photoelectric type alarms.
Good video embedded below about the basics of home smoke alarms. Great information from the National Fire Protection Agency. If you are planning on upgrading your smoke alarms keep the recommendation of a combo unit that includes both photoelectric and ionization detection of fires in the home.
Smoke alarms - out of sight and out of mind until the battery goes bad. The only time most people think about them are when you are trying to figure out which alarm is chirping incessantly.
Do you have the right number in your house and in the correct locations? Smoke alarms are required on every floor of a home, outside each separate sleeping area and inside every bedroom. Interconnected alarms are the best - they can alert you to a problem in a different part of the home.
Batteries in smoke alarms need to be replaced yearly. Smoke alarms should be tested monthly to ensure proper operation. Smoke alarms have a useful life of about 10 years before they need replacement. This may seem like a daunting task but most are designed to be easy swapped out. Look for a post in the next few weeks about inspecting and replacing a common type of smoke alarm in houses built in the early 2000's.
Brian Jovag, owner of Jovag Home Inspection.