Yes. Colorado law requires carbon monoxide detectors in all residential dwellings that contain a fuel-burning appliance, have an attached garage, or have a wood-burning fireplace or stove. This requirement applies to single-family homes, condominiums, and rental properties. Detectors must be installed on each level of the home and within fifteen feet of each sleeping area. If you own or rent a home in Colorado with a gas furnace, water heater, range, or attached garage, a CO detector is legally required — and more importantly, it is a potentially life-saving device that is inexpensive and easy to maintain.

Why Carbon Monoxide Is Especially Relevant in Colorado

Colorado’s altitude creates conditions that increase CO risk from combustion appliances. At 5,280 feet, the lower oxygen density means gas-burning appliances must be properly adjusted for altitude to burn efficiently and completely. An appliance calibrated for sea-level operation running at Denver’s altitude can produce more carbon monoxide due to incomplete combustion — particularly if it’s also overdue for maintenance. Furnaces, water heaters, and boilers are the most common sources of CO in Colorado homes.

Colorado also sees cold winters that mean heating systems run for long, continuous stretches. A furnace with a cracked heat exchanger — one of the most serious residential CO risks — can introduce combustion gases directly into the air being circulated through the ductwork and distributed throughout the home. This is why annual furnace maintenance, which includes a heat exchanger inspection, is critical safety practice in addition to CO detector installation.

Where CO Detectors Should Be Installed

  • On every level of the home, including the basement and any finished attic space with sleeping areas
  • Within fifteen feet of each bedroom door — the goal is for the alarm to wake sleeping occupants before CO levels become incapacitating
  • Near (but not directly on top of) fuel-burning appliances — a few feet away from the appliance rather than immediately adjacent, since very brief CO spikes during startup are normal
  • In or near any attached garage, since vehicle exhaust contains significant CO and can migrate into living spaces

How Long Do CO Detectors Last?

Carbon monoxide detectors have a limited lifespan because the electrochemical sensing cell that detects CO degrades over time. Most manufacturers rate their detectors for five to seven years. After that point, the sensor may not respond accurately to CO — it might not alarm at dangerous levels, or it might false-alarm at normal levels. Check the manufacture date stamped on the back of each unit. If any detector in your home is past its rated lifespan, replace it regardless of whether it still chirps when tested. The test button confirms the alarm circuit works, not that the sensor is still accurate.

What to Do When a CO Alarm Sounds

If a CO detector sounds, treat it as a real emergency every time — do not assume it is a false alarm. Evacuate everyone, including pets, immediately. As you leave, open any doors you pass through to ventilate the home. Do not stop to investigate, do not take time to gather belongings, and do not re-enter the home. Call 911 from outside or from a neighbor’s phone. Emergency responders have meters to confirm CO levels and can identify the source. Do not return home until authorities have cleared the building and the source has been addressed.

After any CO event, have every combustion appliance in the home inspected by a licensed professional before it is operated again. The most common sources — a cracked furnace heat exchanger, a blocked flue, or a malfunctioning water heater — need to be identified and repaired, not just reset.

Hardwired vs. Plug-In CO Detectors

Plug-in CO detectors with battery backup are code-compliant and widely used. Hardwired units with battery backup are more reliable because they continue operating through both power outages and dead batteries without any gap in coverage. Interconnected detectors — whether hardwired or wirelessly linked — are the safest configuration because when one alarms, all units in the home sound simultaneously. An electrician can install hardwired, interconnected units as part of a broader home safety upgrade.

For help installing or upgrading CO detectors, or to schedule a furnace inspection that includes a heat exchanger check, Done can help. Learn about our smart home and safety services for hardwired detector installation, or schedule a furnace maintenance visit to ensure your heating equipment is not a CO source. Our Done guarantee backs every job we do.