On Saturday, January 17, 2015 at 6:22:11 PM UTC-5, wrote:
On Sat, 17 Jan 2015 18:00:22 -0500, micky
wrote:

On Sat, 17 Jan 2015 14:01:23 -0800 (PST), wrote:

I have a condo and it has the original smoke detectors, FireX. Probably about 20 years old. they don't take batteries, that's probably why they have not received much attention. The are hardwired to AC with a signal wire to the other 2 detectors. Don't believe they are on a separate circuit, should they be ?

Should they be replaced ?

tHAT's what they say.

You could light a fire under one of them and see if the alarm goes off.
You wouldn't need a big fire, even a wooden match would do I think even
a wooden match that had been extinguished would make enough smoke.

The problem is that you woudn't know if it was as sensitive as it should
be. I guess you should have done this when you first moved in, so
you'd have a standard to compare with.

Recommendations !?

Thanks
Should be replaced every 8 to 10 years.

Getting direct replacements for your line powered interconnected units
may not be as simple as adding battery operated independent units.

I don't see why it would be any problem getting replacements for
AC interconnected ones. Standard install is normal AC wiring with
one additional wire that runs between units. Independent ones don't
provide the same safety. If you have a large house, are a sound sleeper,
one going off in the basement at the far end of the house may not be
enough to wake you up in the second floor bedroom, etc.