美国海淘    First Alert SA511CN2-3ST 声音定位 烟雾报警器（2件装）约￥840

alarm and then stop without explanation make me nervous. I'd replace them, but since every detector has bad reviews, I don't know what to replace them with.Updated Nov 2015: Continuing to have issues with false alarms. I wonder if any of them actually work...Updated March 2016: I had to wait on hold for 38 minutes, but once I got through, they are mailing me a replacement detector for the one that keeps going off, without charging me shipping or requiring me to ship back the old one. Much happier. I hope these really work.Updated Sept 2016: Another one failed. This one started chirping in a way that (according to the label on the alarm) indicates that the alarm has reached the end of its 10-year life. The manufacturing date on the alarm is May, 2015, so the alarm is only 18 months old.

ownstairs hallways. The units I obtained were on the California Fire Marshal's list of approved devices. These don't have the 10 year battery - a requirement that can be waived if multiple units communicate with each other and report faults and weak batteries, etc. I sent a list of devices and planned locations to my local building inspector before I bought these - he said OK and they were installed and inspected. After programming the locations for the announcements, we hung them in their respective rooms. While some other construction was going on (flooring), we put dust booties over them to keep the sensitive detectors form collecting dust. These may need vacuuming periodically - so far in 3 months no false alarms.One trick in getting all these programmed - I got a room-full of pillows and covered each one with a pillow (in the same room) when programming the cross-communication - kept the noise level down when I set up a house full of devices.

K, that was weird, but maybe just a one-time thing. Now, about a month after that, they have false-alarmed four times in three days. None of the times did talking wireless feature work. You hear one start going off and then they're all going off.I can not recommend these. Not at all. Find some with better ratings. Sure you want to be safe, but you don't want your safety devices to drive you insane, either.

n not be reactivated and must be replaced. Clearly this is a widespread problem since, as of today's date, 41% of other reviewers give it a one-star rating. Avoid this model -- and all First Alert models with sealed (non-replaceable) batteries.

They worked so well that I have since installed them in each of our homes as well as in my parents and my grown children's homes.Pros (+) and Cons (-):(+) - They very easy to install (I recommend self-tapping drywall screws and forget about drilling and the plastic toggles and screws that come with each unit - hold the base on the ceiling, insert 2 drywall screws, snap the unit onto the base and you're done - 2 minutes at most).(+) - They are really easy to program. I do it a little differently from the instructions - when I put the batteries in the unit before I put it up I push the test button when the unit initializes and then select the room location. Then when I snap the unit onto the base I open and close the battery drawer while holding the test button, the green light flashes and I go to the next nearest detector and push its test button and voila, the new detector is now on the wireless network and goes into its test mode in the room where I installed it. Very quick and easy!(+) - They are really loud, and when one goes off they all do, each one reporting the location of the originating alarm ("Fire in Child's Bedroom" for example, or "CO2 level in Kitchen is xxx parts per million - Evacuate!" when you have a combo smoke and CO2 detector).(-) - It would be nice if they provided a location recording function so you could program additional locations with your own voice because the detectors come with a finite set of locations that you can use. For example, there is no "garage" location to choose from, or "upstairs" and "downstairs" locations that might be duplicates (like hallways, bedrooms, etc.). There's only one "Child's" or "Guest" bedroom locations to choose from so it would be nice to be able to program each child's room with their name, so you could say: "Nancy's Room" or "Teddy's Room". As it is now, if you have 3 kids' bedrooms, each one would say "Fire in Child's Bedroom" and you would not know which child's or if it was upstairs or downstairs. Nonetheless, this is 100% better than just having one detector in each hallway and not knowing where the fire was concentrated at all.Bottom line... I recommend that you get one of these for every room in your house. It will be expensive, but shy of getting a complete central alarm system, it will be the best piece of mind that your dollar can buy for you and your family's home safety.