Hello:

This is really crazy, but I thought someone might have some information or
thoughts on the following.

Live in a typical colonial in New England.

Have a Kidde ionization smoke fire alarm on the ceiling upstairs, and a
First Alert one on the ceiling downstairs.

Both have new batteries, and both units are fairly new.

Carbon Monoxide detectors in house read zero.

Every day, or at times every two days or so, each unit will give 4 chirps,
and that's all until another day or so passes.

Not the normal alarm mode as if it would be sensing a fire, or the low
battery indicator signal.

Just 4 chirps, then nothing again for 24-48 hours.

Called both manufacturers, and both don't have any thoughts on.

Both are doing it, so it's hard to believe both units from different mfg's
are defective. But, perhaps ?
Also, nothing in instruction manuals, or by talking with customer reps at
mfg's that knows anything about a 4-chirp signal.

No correlation with anything that I can determine: kitchen not in use,
sometimes AM, sometimes PM.
Gas furnace may be on, or may be off.
Can't imagine what might be doing this.

Any thoughts on would be most appreciated.

Thanks,
Bob