My smoke detectors have been chirping for a while. I checked the 9v battery with the multimeter to see if they died. Nope, still good I checked the detector’s sticker on the back and saw it was made in 2003. They’re 20 years old now and I guess no longer good. So, I ordered a new pack of hardwired interconnect detectors.
If you’re buying now, make sure to get UL 217 8th edition standard in whatever brand you get.
Not only are they much less likely to give false alarms, they are better at alarming earlier at detection of real fires. source
Warning for the USA: while the new UL 217 8th edition standard are on sale, the law allows retailers to sell through their stock of the old ones. You’ll still get a working smoke detector, but you’ll be missing out on this new better technology/standard.
Thank you for this. I appreciate the info.