When this happenend the first time I frantically checked the house for smoke, including all the kids' rooms. Nothing, no smoke, no fire. I reset the alarm. After a week of doing this, I did a web search and found that my hard-wired alarms were too old and were indicating that they needed changing. Did you know that after 10 years you should change your smoke alarms?
Smoke alarms that are 10 years old are near the end of their service life and should be replaced. Some people think that their smoke alarm sits idle until smoke is present. But it is working every minute, constantly monitoring the air 24 hours a day. For example, an ionization smoke alarm goes through 3.5 million monitoring cycles in 10 years. In a photoelectric smoke alarm, a light operates 24 hours a day to check for smoke particles in the air.
Just like any electrical appliance, the working components of smoke alarms wear out over time. When a smoke alarm reaches 10 years of use, the potential of failing to detect a fire has increased substantially. Replacing them after 10 years reduces the likelihood of failure.
On Monday I bought two new smoke alarms for the house. Alas, having an ill infant prevented me having the time to investigate how to install them. My hero this morning was Phill. He just did it. No looking at directions or anything.
How old are your smoke alarms? More than ten years? Change them out. It's simple, really.