Sirens gone wild, inside and out
What a week it was, let me tell you. On Sunday, November 24 around 10:00 AM, the fire alarm in my house sounded. It's a hard wired system with one battery-backed-up smoke/CO2 detector on each floor and several others (no battery) scattered around the rooms. Yet, there was no fire and no smoke to be seen nor smelled. What to do?
Having no idea how to reset the system, I called the fire department. I explained that there was no fire, but I just needed some help with the alarm system. (This is the first house where I've had a hard-wired system.)
Three firefighters and one police officer showed up. One firefighter went with me to the electrical panel and asked if I know which circuit powered the system. The electrician didn't mark it—course—but the firefighter said alarm systems are usually connected to the kitchen lights. Not knowing for sure, I turned off all possible circuits, leaving on the refrigerator and the heating system. The firefighter told me to change the batteries in all the backed-up detectors. The alarm silenced and the firefighters left.
A few minutes later, the alarm sounded again. I started replacing all the detector batteries. Fortunately, I had enough on hand and didn’t have to run to the store. I started removing batteries and of course, the sirens didn’t stop unitl I reached the last one. The culprit turned out to be the detector outside the bedrooms. I replaced the battery and all is well. A quick check with a voltmeter revealed that the batter voltage was around 6.5V while all the others were close to 9V.
Problem solved. I don’t understand why the low battery caused the system to announce "Fire," but it did. Even so, you really should change those fire alarm batteries or at least test them with a voltmeter.
Next came a problem that was harder to diagnose.