I recently removed a smoke detector to patch a hole and paint the
small area that needed painting. When I reinstalled the detector (120
VAC, battery backup) it started chirping. I opened the battery
compartment to find no battery. I have been in this house since March
and this detector has never made a sound before this.

I then checked the AC connections (advice from a friend) and found the
detector's wires needed more insulation stripped, which I did, and
reconnected. Still the chirping. I put a battery in and the chirping
stopped.

Question: Why would the detector suddenly start chirping (assuming the
cause was no battery) after I removed and replaced it when it didn't
do that before, when it had no battery?

On Dec 3, 9:09 pm, nr wrote:
I recently removed a smoke detector to patch a hole and paint the
small area that needed painting. When I reinstalled the detector (120
VAC, battery backup) it started chirping. I opened the battery
compartment to find no battery. I have been in this house since March
and this detector has never made a sound before this.

I then checked the AC connections (advice from a friend) and found the
detector's wires needed more insulation stripped, which I did, and
reconnected. Still the chirping. I put a battery in and the chirping
stopped.

Question: Why would the detector suddenly start chirping (assuming the
cause was no battery) after I removed and replaced it when it didn't
do that before, when it had no battery?

I would not mess with it. Toss it out and get a new one.

"nr" wrote in message
...

I recently removed a smoke detector to patch a hole and paint the
small area that needed painting. When I reinstalled the detector (120
VAC, battery backup) it started chirping. I opened the battery
compartment to find no battery. I have been in this house since March
and this detector has never made a sound before this.

Only the manufacturer can tell you. Since this is a mains
SD with battery backup, that feature may have been designed
to cope with power outages: so if there was no power outage
there was no occasion for it to send the Dead Battery signal.

I then checked the AC connections (advice from a friend) and found the
detector's wires needed more insulation stripped, which I did, and
reconnected. Still the chirping. I put a battery in and the chirping
stopped.

The manufacturer can also tell you the probable service life
of the unit. This is determined by the radioactive elements
it uses, which last for 3 to 10 years. In Canadian units,
SDs chirp when the radioactive detectors become weak
as well as when batteries are about to expire.

--
Don Phillipson
Carlsbad Springs
(Ottawa, Canada)

wrote in message
...
On Dec 3, 9:09 pm, nr wrote:
I recently removed a smoke detector to patch a hole and paint the
small area that needed painting. When I reinstalled the detector (120
VAC, battery backup) it started chirping. I opened the battery
compartment to find no battery. I have been in this house since March
and this detector has never made a sound before this.

I then checked the AC connections (advice from a friend) and found the
detector's wires needed more insulation stripped, which I did, and
reconnected. Still the chirping. I put a battery in and the chirping
stopped.

Question: Why would the detector suddenly start chirping (assuming the
cause was no battery) after I removed and replaced it when it didn't
do that before, when it had no battery?

I would not mess with it. Toss it out and get a new one.

Ditto. It's not working right.

Dave

nr wrote:
I recently removed a smoke detector to patch a hole and paint the
small area that needed painting. When I reinstalled the detector (120
VAC, battery backup) it started chirping. I opened the battery
compartment to find no battery. I have been in this house since March
and this detector has never made a sound before this.

I then checked the AC connections (advice from a friend) and found the
detector's wires needed more insulation stripped, which I did, and
reconnected. Still the chirping. I put a battery in and the chirping
stopped.

Question: Why would the detector suddenly start chirping (assuming the
cause was no battery) after I removed and replaced it when it didn't
do that before, when it had no battery?

Hmm. Just a guess:

It needed a new battery (obviously). The AC connections didn't provide power
to drive the chirper, but you fixed that.

Further guess:
Sometime in the remote past, it began complaining that its food was running
low. The then-current resident removed the battery. More plaintive wails
from the detector. The resident, thinking "Die, motherfarker" yanked on the
ac power enough to quiet the noise.