I had eerily similar scenario happen to me!
I also have BRK smoke detectors, and after a year of living in my current
home, they started going off randomly (always in the middle of the night of
If they are the same model as mine, and it sounds like they are at least
close if not exactly the same (mine has same wires and battery), then you
can tell the one that is going off by the red flashing light IIRC. That
said, the damn things are so loud (especially since, as you said, once one
goes off they all go off) that I couldn't stand to sit there and figure out
which one was the culprit.
I tried vacuuming them out, but then after they started going off again I
plugged my ears and looked to find the one with the light. I made the
mistake of just replacing that one. The others started going off within a
I advise you replace all three with exactly the same brand/model. If you
have a Lowe's near you, I know they carry BRK detectors. I've lived in my
current house for almost 4 years and I've had to replace all of the 3
detectors once, and then another one had to be replaced. BRK is junk IMO,
but the local big box stores only carried BRK or a few other cheesy looking
brands, and nothing but the BRK matched the plug IIRC.
Do yourself a favor and replace all three, and hope that the ones you buy
weren't returned by someone else. That's what I think happened to me for the
one of the three that I had bought originally. That's the problem with an
open return policy though : )
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