Safety
Water Heater Temperature: Why 120°F Is the Right Setting, and How to Check Yours
Why 120°F is the recommended water heater setting for safety and energy, and how to measure your tap temperature in about five minutes.
05Safety
Smoke and CO Alarms: Testing, Placement, and Replacement Dates
Smoke and carbon monoxide alarms only save lives if they work and they're in the right places. How to test them, where they belong, and when to replace them.
- Read
- 2 min
- Updated
- October 2, 2026
Home inspectors check smoke alarms in every house, and they find dead batteries, missing alarms and alarms older than the kids living there all the time. Here's how to make sure yours actually work.
01Where smoke alarms go
The National Fire Protection Association recommends smoke alarms:
- Inside every bedroom
- Outside each sleeping area (the hallway outside bedrooms)
- On every level of the home, including the basement
Mount them on the ceiling or high on a wall, following the manufacturer's instructions. Keep them away from kitchens and bathrooms, where cooking and steam cause false alarms.
02Where carbon monoxide alarms go
Any home with fuel-burning appliances (furnace, water heater, stove, fireplace) or an attached garage needs CO alarms:
- On every level of the home
- Outside sleeping areas
- Follow the manufacturer's placement instructions; CO mixes with air, so placement rules differ from smoke alarms.
Combination smoke/CO alarms cover both.
03Test monthly
Push the test button once a month. If it doesn't sound, replace the battery, and if that doesn't fix it, replace the alarm.
04Batteries
Alarms with replaceable batteries need new batteries at least once a year, or when they chirp. Many newer alarms have sealed 10-year batteries and are replaced as a whole unit.
05Replacement dates
- Smoke alarms: replace every 10 years. Look for the manufacture date on the back.
- CO alarms: replace according to the manufacturer, often every 5 to 10 years. Many sound an end-of-life signal.
06Interconnected alarms
In many newer homes, alarms are hardwired and interconnected: when one sounds, they all sound. That's the safest setup. Wireless interconnected alarms can add it to older homes.
07If an alarm goes off
- Smoke alarm: get out, stay out, call 911.
- CO alarm: get everyone into fresh air immediately and call 911 or the fire department. Don't go back in until it's cleared.
08A simple routine
Test monthly, change batteries yearly (or when the clocks change), replace by the date on the back. It's the cheapest safety job in the house.
It's on our fall home inspection checklist and chimney check too.
Sources (2)
Photo: Heimrauchmelder by No machine-readable author provided. Nordelch assumed (based on copyright claims, CC BY-SA 3.0.
Keep going
Related guides
Safety
Test Your Carbon Monoxide Alarms Before the First Cold Night: What Each Beep Means
Test your CO alarms and learn what each beep means. This guide covers testing procedures, sound patterns, when to replace units, and safety steps.
Safety
Holiday Lights and Extension Cords: A 10-Minute Safety Check
A 10-minute check for Halloween and holiday lights: safety labels, outdoor-rated cords, GFCI outlets, overloaded circuits and the warning signs of a cord about to fail.