PITTSBURGH (KDKA) — We all know it’s important to change the batteries in your smoke alarm, but there’s something you may not know about those alarms.

Sometimes fresh batteries aren’t enough, and your family could be at risk.

It is the definition of a tragedy. Angela and Stephen. Noah, Kayley and Hannah Lasch. The Bellevue family that perished together in a fire.

“The children were so beautiful, and it’s just so sad they are all gone,” family friend Cheryl Stephens said.

On average, seven people die every single day in house fires in the U.S.

KDKA’s Susan Koeppen: “The difference between life and death in a fire… does it come down to working smoke alarms?”
Chief Mark Stowe, Beaver Falls Fire Department: “Working smoke alarms. 100 percent is working alarms.”

KDKA’s Susan Koeppen, with the help of Chief Mark Stowe and the Beaver Falls Fire Department, wanted to show what happens in a house with a working smoke alarm. They set a chair on fire, with several cameras rolling, and it was easy to see — the flames, the smoke and the alarm going off.

“There’s no time to get out if you don’t have a working smoke alarm,” Stowe said. “You are not going to get out.”

But there’s something about smoke alarms you may not know.

Join The Conversation On The KDKA Facebook Page
Stay Up To Date, Follow KDKA On Twitter

“Just because there is a smoke alarm on the wall, doesn’t mean it’s going to go off if it’s not maintained,” Stowe said.

And he’s not talking about fresh batteries. According to a survey by the National Fire Protection Association, 9 out of 10 consumers are unaware they need to replace their smoke alarms every 10 years.

“I had no idea at all,” said homeowner Tara Dick.

KDKA asked Tara to check the alarms in her home.

Koeppen: “So there’s one up here in the dining room. Any idea how old this one is?”
Dick: “Nope.”

The first one she grabbed was 12 years old.

Koeppen: “So what are you thinking? What’s going through your head, that this is past its expiration date, basically?”
Dick: “That I could have put my family in a lot of danger.”

And they found a 20-year-old smoke alarm in the home of Patty Friedrich.

“We check it every year with fresh batteries, but I wasn’t aware that it could malfunction,” Friedrich said.

After 10 years, the sensors in the smoke alarms can start to fail. Here’s a sobering statistic: in 10 percent of home fires where smoke alarms should have gone off, they didn’t.

Koeppen: “So if you have old smoke alarms in your house?”
Stowe: “They may not work.”
Koeppen: “Crap shoot.”
Stowe: “At two o’clock in the morning, when a fire breaks out in your house, there’s no time for a crap shoot.”

You can find the age of your alarms by checking the date they were manufactured right on the back. Experts recommend replacing old alarms with new smoke alarms that come with 10-year batteries. They chirp when the entire unit needs to be replaced. Alarms that are hard-wired also need to be replaced after 10 years. And make sure you press the “test” button every week to check the sensors.

Koeppen: “There might be people who say, ‘It’s going to cost me so much money to replace my alarms.'”
Stowe: “You know what I tell everybody? This is what I use all the time: for less than the price of a pepperoni pizza, you can buy a smoke alarm that will save your family’s life.”

Many fire departments will give you a smoke detector for free if you can’t afford one and install it for you. Several states — including California, Florida and Maryland — and cities like Philadelphia and New York City have passed laws requiring 10-year battery smoke alarms in residential buildings.