In article ,
Tekkie® wrote:

Teresa posted for all of us...



replying to Tekkie®, Teresa wrote:
Hi Tekkie, mine is a fireangel st620. I didn¤?t install it, it was here
when
I bought my house. It flashes red normally but occasionally flashes green
and
chirps occasionally, usually when I¤?m trying to get to sleep. Shall I
replace it as the batteries are built into the unit.

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I don't remember seeing your post and not familiar with your unit but I'll
give it a whirl. I presume the green light means the batteries are okay.
Replace the battery when the time changes so you have a landmark. This
detector MAY be connected to others, so be forewarned. You could also call
the local firehouse nonemergency number and ask them. They usually have
detectors for free and will install it if asked.

The battery can probably be changed by a technician. The cost of
changing it is probably higher than the price of a new smoke detector.

The chirping indicates a problem. In addition to trouble with the smoke
detector, it might be warning you that there is a nearby source of smoke.

Reference https://www.fireangel.co.uk/products/st-620.

Fred