On Thu, 30 Jul 2020 23:53:00 -0700 (PDT), Mercellus Bohren posted for all of us
to digest...


On Thursday, July 30, 2020 at 6:19:24 PM UTC-4, Fred McKenzie wrote:
In article ,
wrote:

On Thu, 30 Jul 2020 13:49:47 -0400, Fred McKenzie
wrote:

In article ,
Mercellus Bohren wrote:

do they ever need to be completely replaced?

The fire alarm people say yes. Apparently there is some radioactive
material involved, that deteriorates over several years.

Fred


That would be smoke detectors ..
Fire Alarms are the break-glass-pull-down thingies.
John-

You got me! I have smoke detectors here, but they give off an alarm.

I wonder which Mercellus meant?

Fred

I meant smoke detectors, not fire alarms. I have a couple of smoke detectors and a couple of combo carbon dioxide/smoke detectors and they both started beeping. The two carbon dioxide/smoke detectors are wired together and to power on one circuit. The started beeping and I replaced the backup batteries. Turns out, both of the CO2/smoke detectors had to be replaced, after about 7 years.

That is correct they must be replaced according to the manufacturers specs. The
sensors inside have a finite lifetime.

--
Tekkie