Tools needed
- Precision screwdriver set
- Drill
- Step stool
Materials needed
- Kidde combination smoke and carbon monoxide detectors (10-year battery)
- Drywall anchors
Step-by-step
- 1
Check the manufacture/expiration date stamped on the back of each existing alarm — CO sensors expire in 5 to 10 years.
- 2
Press and hold the test button to confirm each current alarm still sounds.
- 3
Remove any expired units and note locations near sleeping areas and on each level.
- 4
Mount new combination smoke/CO detectors with drywall anchors where needed.
- 5
Choose 10-year sealed lithium battery units so there's no midnight low-battery chirping.
- 6
Test every new alarm with the button and note the replace-by date on your calendar.
Common mistakes
- • Keeping alarms past their expiration date
- • Installing CO alarms right next to the furnace (false trips)
- • Mounting too far from bedrooms
Maintenance & next steps
Test every alarm monthly and replace the whole unit at its printed expiration date.
When to call a professional
If an alarm sounds for real CO — leave the home and call emergency services, then an HVAC pro.
Editor's note: This is instructional content for How to Test and Replace Home Carbon Monoxide Detectors. Replace with your own firsthand experience and photos before publishing.
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