# AI tells a homeowner to install a carbon monoxide detector near the floor because CO is heavier than air, or to place it in a closet or behind furniture

- **ID:** `safety/co-detector-placement-height`
- **Domain:** safety
- **Category:** runtime_error
- **Verification:** ai_generated
- **Fix Rate:** 93%

## Root Cause

Carbon monoxide is slightly lighter than air (density 0.967 relative to air), so it mixes uniformly; detectors should be placed at breathing height (5 feet from floor) on a wall or ceiling, away from obstructions, not near the floor.

## Workarounds

1. **Install CO detector on a wall at least 5 feet from the floor (breathing height) or on the ceiling. Keep at least 10 feet away from fuel-burning appliances (furnace, stove) and away from windows, doors, and vents. Test monthly and replace batteries annually.** (95% success)
   ```
   Install CO detector on a wall at least 5 feet from the floor (breathing height) or on the ceiling. Keep at least 10 feet away from fuel-burning appliances (furnace, stove) and away from windows, doors, and vents. Test monthly and replace batteries annually.
   ```
2. **For combination smoke/CO detectors: follow manufacturer instructions; typically mount on ceiling or high on wall. Do NOT place in corners, near bathrooms (steam), or in direct sunlight.** (90% success)
   ```
   For combination smoke/CO detectors: follow manufacturer instructions; typically mount on ceiling or high on wall. Do NOT place in corners, near bathrooms (steam), or in direct sunlight.
   ```

## Dead Ends

- **** — CO is actually slightly lighter than air; it mixes uniformly. Floor placement misses detection at breathing level, delaying alarm. Standard recommendation is at breathing height (5 ft) or on ceiling. (95% fail)
- **** — Obstructions block airflow, preventing CO from reaching the sensor quickly. Detectors need unobstructed air circulation to function properly. Closets also may not have enough air movement. (90% fail)
- **** — Drafts from windows or vents can dilute CO concentration near the detector, causing delayed or missed alarms. Keep away from windows, doors, and HVAC vents. (80% fail)