You should have a set of directions / instructions that came with the detector, if you don't have that, then first thing I would do is replace the battery, if that doesn't help, take the detector down and clean it.
First Alert smoke alarm owner's manuals are available online for download at no cost. We will, for a small shipping fee, gladly send you a replacement owner's manual or equivalent instructions. Please have your smoke alarm model number handy when requesting a replacement owner's manual. For a replacement owners manual, please contact Consumer Affairs, 3901 Liberty Street Road Aurora, IL 60504 or 800-323-9005 7:30AM-5:00PM CST.
It is likely that the reason your smoke alarm keeps chirping and beeping is that the battery is low. Whenever your smoke alarm keeps chirping, replace the battery immediately.
• A different device or appliance such as a security system, monitor, carbon monoxide alarm, or other device which has a similar low battery or alert signal.
• Some of the same factors that cause unwanted alarms can cause intermittent alarms: dust and insects in the alarm or power interruptions in hardwired alarms.
• Improper wiring on AC or AC/DC smoke alarms. AC alarms will chirp every 5 seconds if the interconnect wire is grounded. The orange interconnect wire should NEVER be grounded; it should only be used to interconnect other smoke alarms or compatible devices.
There are a number of possible causes for your smoke alarm to keep chirping even with a new battery.
• It is possible that your smoke alarm "silence" button was pushed by mistake. The alarm will now "chirp" once a minute for up to 15 minutes before resetting.
• Are you sure it's the smoke alarm? Funny to ask, but other devices have similar low battery chirps or warning tones.
• Your "new" batteries may not be fresh. If batteries are stored, especially in cold areas like refrigerators, they lose their charge more quickly. Always check the freshness date on the package when buying new batteries. Keep plenty of replacement batteries on hand so that you are sure to always be protected by your smoke alarms.
If none of this helps go to their web site (http://www.firstalert.com/) and contact them.