I bought a Kidde KN-COSM-IBA to replace a 6 years old Firex i4618A detector that won't quit chirping even after battery replaced. Both the old and new detectors has the same wire quick connector that looks like below.


Since they have compatible connectors, I didn't re-wire the quick connect that comes with the new one.

Once I plug the connector into the new fire detector, the rest of the detectors in my whole house went off and won't stop.

Does anyone know what could be wrong?

  • Hello, and welcome to Home Improvement. Does Kidde say that their detectors are compatible with the (discontinued) Firex? Jul 24 '19 at 1:32
  • Not all manufacturers use the same wire protocol between detectors. Try contacting the manufacturers.
    – DaveM
    Jul 24 '19 at 1:32
  • @DanielGriscom Yes the manual specifically list my old detector as compatible.
    – KFL
    Jul 24 '19 at 2:24
  • 2
    I'd consult Kidde; they may have a FAQ which answers "why do all my other detectors trigger when I plug in a new one?". Jul 24 '19 at 2:27
  • The manual(s) for each model probably contain a initialization and pairing sequence.
    – noybman
    Jul 24 '19 at 3:53

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