Most common causes

  • Flat or low backup battery: the number-one cause, even in mains-powered alarms.
  • A faulty alarm: chirping that survives a fresh battery means the unit itself needs replacing.
  • Dust or insects in the sensor chamber cause intermittent chirps and false alarms.
  • A loose battery: the battery isn't fitted correctly.

Chirps often start at night, when cooler temperatures drop battery voltage enough to trip the warning.

Try this first

  1. 01Identify which alarm is chirping: in an interconnected system, only the faulty unit chirps.
  2. 02If replaceable, fit a fresh battery and make sure it is fitted correctly.
  3. 03Gently vacuum around the alarm to clear dust and insects.
  4. 04Check the manufacture date on the back: near or past 10 years, it's due for replacement.

When to call an electrician

Chirping after a fresh battery, a sealed 10-year alarm, or you'd rather not chase it up a ladder: that's our cue. We'll find the real cause and fix it. Don't just pull the battery and leave it: that leaves you unprotected, and in a rental breaches the tenant's duty not to disable alarms.