About which part? The co's having a life of 7 years? Or smokes at 10?
Either way, you want to explain it to me, as well as the manufacturer?
I will add a caveat - 7/10 years, or as per the manufacturer's instructions; whichever comes first...
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Edit - supporting links:
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www.usfa.fema.gov/downlo ··· arm.htmlHow Long Should Your Smoke Alarm Last?
Smoke alarms have a useful life of about ten years. At that age they should be replaced, even if they seem to be working. This will assure that the alarm will be working when you need it.
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www.kiddecanada.com/utcf ··· ,00.htmlSmoke Alarms
Kidde offers a wide range of smoke alarms to suit your needs. Two different technologies exist to detect smoke: ionization and photoelectric.
Own both types for complete protection. Dual sensor alarms are also available. Smoke alarms do wear out, replace your alarm every 10 years.
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www.firstalert.com/DID YOU KNOW?
Carbon Monoxide Alarms should be replaced every 5-7 years.
Smoke Alarms should be replaced every 10 years.
The National Fire Protection Association (NFPA) recommends replacement to ensure the most effective protection and prevent nuissance alarms.