We purchased a home about a year ago that had three hard-wired smoke detectors installed. All of them were BRK Electronics Model 2002RAC. All have a 9-volt battery backup. They attach directly to three wires coming out of the ceiling using a connector plug that is on the end of the wires.
We believe they all were ionization-type detectors.

We had no problems with this system until about two months ago when the smoke detector on the top floor, where the bedrooms are located, began chirping randomly. It would chirp loudly, with the chirps spaced 10 to 15 seconds apart, for at least three to six times and then it would be silent. This often happened in the middle of the night, waking the entire household including our young child.

We replaced the battery but the problem just continued to get worse, with the random beeping starting to occur at all times of the day and night.

We decided that, perhaps, the smoke detector just needed to be replaced. We did not know how long it had been there but the house was 22 years old.

We could not find another BRK hard-wire with battery backup in our area. We had a still-in-box smoke detector/CO detector on our basement shelf that we had not installed in our old house, so we decided to use that. It is a Kitty Nighthawk KN-COSM-B. It is battery-powered only, not hard-wired, and we used a brand new battery. We believe it also is an ionization-type detector.

The random chirp began happening again within a day or so of putting in the new detector. We replaced the battery with yet another new battery. Yet, the chirp continues. Many times, the chirping happens when we have windows open, but not always.

Last night the chirping woke us all up again at 3 a.m. and my husband yanked the smoke detector off the ceiling. To our amazement, the chirping continued - apparently coming from the wires and connector dangling from the ceiling with no alarm attached to them.
We thought at first that we must be hearing things wrong and that the chirping must be coming from the smoke detector on the first floor. But we stood right under that gaping hole in the ceiling with the dangling wires and it was beeping at us.

Can someone help us? What is going on here? How do we stop this? The beeping is driving us nuts, depriving us of sleep, and forcing us to go without a smoke detector on the sleeping floor of the house in order to keep our sanity.

How can things keep beeping when no smoke alarm is there? Is it feasible for the wires and connector themselves to be emitting a beep?

Any insight, help, fix-it advice would be appreciated.

Thank you.

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