Struggling with a hard-wired, interconnected smoke detector that seems
to be chirping in response to humidity (we're having a cold summer in
Minnesota). I tried replacing the battery, blowing everything clean
with a blow dryer set on cool, and replacing the removable unit itself.
Nothing helped. And here's the really hard part which has even the
electricians (including the company that installed it) stumped. The
chirping is not coming from the removable part. It's coming from the
wiring up in the ceiling. I know this for sure because I took the
removable part out of the house and put it in the garage. The ceiling
hole kept right on chirping.

How is that possible?

I need to know because I want to pull the hard-wired system and replace
it with battery-only detectors. With battery-only, there IS NO wiring
inside a hole. If the detector starts chirping from humidity (and we
have a lot of humidity in MInnesota), you can remove it from the ceiling
or wall and stick it in the garage until things dry out and there won't
be anything left in a hole in the wall or ceiling to go right on
chirping. But the electrician I called seems to think if he just
removes the removable part and covers the hole with a plate, he'll be
done. He doesn't believe the chirping is coming from the hole, not the
removable part.

Thoughts?