# AI tells a homeowner to install a carbon monoxide detector near the floor because CO is heavier than air, or to place it near gas appliances only

- **ID:** `safety/co-detector-placement`
- **Domain:** safety
- **Category:** system_error
- **Error Code:** `CO-DETECTOR-ERR-006`
- **Verification:** ai_generated
- **Fix Rate:** 85%

## Root Cause

Carbon monoxide (CO) is slightly lighter than air (molecular weight 28 vs air 29) and mixes uniformly with air; it does not settle near the floor; detectors should be placed at breathing height (5 feet from floor) or on the ceiling, and not just near appliances but in sleeping areas and on every level of the home.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| UL 2034 Standard for Single and Multiple Station Carbon Monoxide Alarms | active | — | — |
| NFPA 720 Standard for the Installation of Carbon Monoxide Detection Equipment | active | — | — |
| CPSC Safety Guide for CO Detectors 2022 | active | — | — |

## Workarounds

1. **Install CO detectors at 5 feet from floor (breathing height) on each level of the home, including basements. Place one outside each sleeping area and near attached garages. Avoid corners and behind furniture.** (90% success)
   ```
   Install CO detectors at 5 feet from floor (breathing height) on each level of the home, including basements. Place one outside each sleeping area and near attached garages. Avoid corners and behind furniture.
   ```
2. **Use combination smoke/CO detectors with 10-year sealed batteries (e.g., Kidde KN-COB-B-LPM) and test monthly. Replace units every 7-10 years.** (85% success)
   ```
   Use combination smoke/CO detectors with 10-year sealed batteries (e.g., Kidde KN-COB-B-LPM) and test monthly. Replace units every 7-10 years.
   ```
3. **For maximum safety, install detectors on the ceiling at least 10 feet from fuel-burning appliances, but not in dead air spaces. Follow manufacturer instructions for specific placement.** (80% success)
   ```
   For maximum safety, install detectors on the ceiling at least 10 feet from fuel-burning appliances, but not in dead air spaces. Follow manufacturer instructions for specific placement.
   ```

## Dead Ends

- **Install detector at 5 feet from floor or on ceiling** — Placing detector near floor misses CO that rises with warm air; CO from appliances mixes with room air and is at breathing height. (70% fail)
- **Install one detector on each level and outside each sleeping area** — Only placing near gas appliances misses CO from attached garages, fireplaces, or blocked chimneys; bedrooms need detectors. (65% fail)
- **Install at breathing height (5 ft) as recommended by UL and NFPA** — Assuming CO is heavier leads to floor placement; in reality, CO diffuses evenly, so floor placement delays detection. (75% fail)