Where to Put Carbon Monoxide Detectors When You Have a Fireplace

Illinois has one of the strictest CO detector laws in the nation. In 2005, Illinois enacted Liam's Law (named after a boy who died from CO poisoning) requiring:

• All dwellings with fuel-burning appliances (furnaces, water heaters, fireplaces, stoves) must have CO detectors
• CO detectors must be installed on every level of the home
• Detectors must be within 15 feet of each sleeping area
• For multi-story homes, detectors are required on all levels, including basements

Not complying with Liam's Law can result in fines, and it significantly increases your liability if someone is harmed by CO poisoning in your home.

Proper Placement Near Your Fireplace

If you have a fireplace, smart CO detector placement near it is crucial:

Distance Matters

CO disperses slowly through a home. A detector placed too close to the fireplace will trigger false alarms from normal combustion byproducts. A detector placed too far away won't detect small leaks from a cracked liner or draft problems early enough. The 5–20 foot range balances these concerns perfectly.

Illinois law says "every level" but what does that mean in practice? Here's a practical guide for typical Chicago homes:

One-Story Home

• Minimum: 2 detectors (one in/near bedroom, one near fireplace/fuel-burning appliance)
• Better: 3 detectors (add one near the main living area)

Two-Story Home

• Minimum: 3 detectors (one upstairs near bedrooms, one downstairs near fireplace, one upstairs near bedroom on second floor)
• Better: 4–5 detectors (add one in basement if there's a furnace)

Three-Story Home or Basement

• Minimum: 4–5 detectors (one on each level, at least one in sleeping area)
• Better: 5–6 detectors (ensure all fuel-burning appliances have nearby detection)

Rule of thumb: One CO detector per bedroom + one per level with a fuel-burning appliance = peace of mind.

Battery-Operated Detectors

Cost: $15–$30 each | Best for: Renters, flexibility

Simple, affordable, and require no professional installation. Downside: you must remember to replace batteries annually. A detector with a dead battery offers zero protection.

Hardwired Detectors with Battery Backup

Cost: $30–$60 + installation | Best for: Permanent protection

Plugged directly into home electrical outlets with a backup battery. They don't require battery replacement and often include a loud alarm. Ideal for homeowners who want set-it-and-forget-it protection.

Smart/Connected Detectors

Cost: $60–$150 each | Best for: Remote monitoring

Send alerts to your phone if CO is detected, even when you're away. Some integrate with home automation systems. Premium option but excellent for families who want real-time alerts.

Combo Smoke/CO Detectors

Cost: $40–$80 | Best for: Maximum protection

Two detectors in one unit—detects both smoke and carbon monoxide. Saves space and ensures compliance with both smoke and CO laws.

If your fireplace has a cracked or deteriorating chimney liner, CO can seep back into your home instead of venting outside. Signs of this problem include:

• Subtle headaches or dizziness while the fireplace is burning
• Smoke backing up into the home instead of venting up the chimney
• A musty or unusual smell near the fireplace
• Visible cracks in the chimney liner (seen during professional inspection)

A properly placed CO detector catches these problems before they become medical emergencies. This is why having one within 5–20 feet of your fireplace—not in a distant hallway—is so important.

After you purchase your detectors, follow this checklist:

1. Read the manual for your specific detector model
2. Choose locations based on sleeping areas and fuel-burning appliances
3. Mount at proper height: typically 4–6 feet (mid-wall) or on the ceiling
4. Avoid obstacles: don't place behind furniture or curtains where air can't reach the sensor
5. Test after installation to make sure it's working
6. Mark your calendar for battery replacement (if applicable) every spring/fall
7. Keep a log of detector locations and battery replacement dates

Detectors save lives only if they're maintained:

• Test monthly: Press the test button; the alarm should sound
• Replace batteries annually: Change batteries when you reset your clocks for daylight saving time (a helpful reminder)
• Replace detectors every 5–7 years: Sensors degrade over time and become less sensitive
• Keep them clean: Gently vacuum around detectors to prevent dust from clogging sensors
• Don't ignore alarms: If your detector alarms, evacuate immediately, call 911, and get fresh air