I just installed a new brk 660 mbx mains powered smoke alarm with 9v battery. The green light is on and the red light flashes every 45 sec. But it also beeps while the red light flashes. Why would it beep as it  a new alarm?

thanks 

Have you read the manual that comes with the smoke alarm, it appears to explain it in the troubleshooting section and if it is hard to understand check with the manufacturer.

Hi

If the alarm beeos every 45 seconds try this

1.    Check the fuse for the power circuit for that alarm

2.    Gently vacuum around the alarm

3.    Replace the battery

4.    Have a qualified electrician inspect the wiring for the alarm

5.    Contact the manufacturer for further advice or return to the retailer if within warranty period

In case you have to replace here a link to the BRK 660MBX.

Harry