[RayB]

I have changed the batteries several times on the Carbon Monoxide alarm. Alarm is BRK Electronics First Alert Model No. co5120BN which was installed by builder five years ago. About a few weeks after I install new batteries the CO detector starts chirping. It is not the normal alarm sequence for week battery or alarm signal as described in the manual. At first it chirps just once and not chirps again for a few hours. As the days go by the frequency of single chirps increase to once every few minutes. Just one chirp, that is all. I disconnect Co Detector, replace the battery which still tests good with a fresh one, reconnect detector to power. Everything is fine for about a week and then the single chirp starts up again. I have gone through this three times now in the last two months. The manual on this detector does not address this problem. Anyone have any advice or solution to my single chirping sound? It's driving us nuts.