Can Electric Heaters Produce Carbon Monoxide? Explained

Carbon monoxide (CO) is a colorless, odorless, and highly toxic gas. When it accumulates in enclosed spaces, it can displace oxygen in the blood, binding to hemoglobin and preventing oxygen transport to tissues. Thus, CO is often called the “silent killer.”

Many people wonder: if I use an electric heater in a closed room, might it produce carbon monoxide and pose a poisoning risk? At first glance, electric heaters seem safer than combustion-based heaters (like gas or kerosene), but careful analysis is worthwhile.

In short: electric heaters, under normal operation, do not produce carbon monoxide. But there are caveats, misinterpretations, and edge cases that are worth understanding well. Below is a detailed breakdown of the science, misconceptions, potential indirect CO risks, and safety guidance.

Basic Physics & Chemistry: Why Pure-Electric Heaters Don’t Generate CO

To see why electric heaters do not produce CO, it’s helpful to examine how they work, and how CO is generated.

How electric heaters produce heat

• Electric heaters use resistive elements (metal wires, coils, ceramic heaters, PTC (positive-temperature coefficient) elements, etc.). The element resists the flow of electric current, and electrical energy is converted into heat (via Joule heating).
• The heat is then transferred to air (convection), surfaces (radiation or conduction), or a fluid/gas being heated. There is no combustion (no burning of fuel) involved in this process.
• Because no fuel is burned, there is no chemical reaction that produces CO or other combustion by-products.

From multiple sources: “Electric space heaters work by turning electrical energy into heat – no combustion, no fuel, and best of all, no carbon monoxide.”
Also: “Only heaters that burn a combustible fuel … can cause carbon monoxide build-up in your home.”
Electric appliances do not produce CO.

Therefore, under ideal and intended operation, an electric heater is safe from the CO generation perspective.

How carbon monoxide is generated

• CO arises when carbon-containing fuels (gas, propane, oil, wood, kerosene, charcoal, etc.) undergo incomplete combustion (i.e. when there is insufficient oxygen or flawed combustion conditions).
• If combustion is perfect (with enough oxygen, high temperature, proper mixing), the main products are CO₂ and water. But real-world combustion often is incomplete, producing CO, soot, and other by-products.
• Thus, heating systems that burn fuel (gas heaters, wood stoves, kerosene heaters, oil furnaces, grills, etc.) pose CO risks if they are poorly vented, miscalibrated, or in environments with poor air supply.

Hence, CO risk is meaningful for “fuel-burning heaters” rather than purely electric ones.

Misconceptions and Edge Cases: Why Some People Report CO with Electric Heaters

Despite the scientific baseline that electric heaters do not produce CO, reports or beliefs exist that CO measurements near electric heaters show elevated levels. Let’s examine possible explanations or exceptions.

Sensor interference, cross-sensitivity, and “false positives”

• Some CO sensors or detectors are sensitive not only to CO but also to other gases (volatile organic compounds, certain vapors, or hydrogen) under particular conditions. Heating certain materials may cause off-gassing (release of volatile compounds) which might trigger sensors.
• For example, in a Reddit discussion, a firefighter responded to a CO alarm in a house with only electric heaters in use. The commenter noted: “No – resistive heating cannot produce CO on its own.
  What you saw is a cross sensitivity false positive to something (almost certainly VOC) being heated and thus off gassing.” In other words, some sensors may respond to heated organic vapors or other chemical outgassing rather than pure CO.
• If a heating element is defective (e.g. insulation burning, wiring melting, or plastic parts charring), it might release smoke, fumes, or partial combustion of some materials (e.g. coatings, adhesives). Those fumes could produce species that confuse sensors or even generate CO in a local spot. But this is not typical of normal, intact, well-maintained electric heaters.

Heating of materials and secondary combustion

• An electric heater warms the surrounding air and surfaces. If combustible or volatile materials (plastics, paints, adhesives, solvents) are placed too close to the heater, they may heat up, degrade, or even ignite or decompose, producing smoke or CO or other gases. In such a case, the source of CO (or other toxic gases) would be those heated materials — not the heater’s resistive element directly.
• In poorly ventilated or sealed rooms, accumulation of some off-gassed chemicals might yield detectable levels of CO or similar gases, especially if detectors are sensitive or miscalibrated.
• In extreme misuse or failure, an electric heater could short-circuit or cause arcing, potentially igniting surrounding materials, leading to combustion and CO—not from the heater’s normal heating function, but from a fire event.

Thus, while the heater itself is not supposed to produce CO, in abnormal or misuse / failure circumstances, a secondary combustion or off-gassing process might lead to CO or sensor alarms. But these are edge cases, not the normative scenario.

Reports and anecdotes

• There are anecdotes of CO detection in rooms with electric heaters, but usually contexts are unclear (other fuel-burning appliances, sensor issues, ventilation, etc.).
• As one comment in a firefighting forum states: resistive heating cannot produce CO on its own.
• Some sources, however, caution that improper ventilation of “electrical space heaters” could lead to dangerous CO levels — but those statements are generally erroneous or overcautious, since proper electric heaters don’t burn fuel. (One such statement is found in a blog or vendor site — but it lacks credible technical backing)
• Similarly, a source about small space heaters (including combustible ones) cautions that unvented or poorly vented combustion heaters may emit CO. But that is a different class of heater, not electric ones.

In summary: reports of CO from electric heaters almost always stem from misinterpretation, sensor cross-sensitivity, or indirect combustion of other materials — not from the heater’s core design.

Comparative Risk: Electric Heaters vs. Fuel-burning Heaters

To further clarify, here is a side-by-side of CO risk by heater type:

Thus, one of the advantages often cited for electric space heaters is precisely the avoidance of CO risk (since they do not require ventilation). For example: “non-electric space heaters (propane gas, natural gas, kerosene, wood) can [produce CO] … electric space heaters do not produce CO.”

It is for this reason that electric heaters are often considered safer in enclosed environments (from a gas‐emission standpoint) — although they still have fire and electrical risks.

Safety Considerations and Best Practices for Electric Heaters

Even though electric heaters are free from CO emission risk in normal operation, they are not entirely without hazards. Below are recommended precautions and practices:

Proper Placement

• Keep the heater at least 3 feet (or about 1 meter) away from combustible materials (curtains, furniture, paper, bedding).
• Avoid placing heaters in high-traffic areas where they could be tipped over.

Do Not Use Underrated Extension Cords or Power Strips

• Electric heaters can draw significant current (often 1,000 to 1,500 W or more). Use a dedicated outlet with sufficient capacity.
• Some codes or guidelines advise against using extension cords with heaters (e.g. NFPA / ICC rules)

Automatic Shutoff / Safety Features

• Tip-over switches: heaters that automatically shut off if they fall.
• Overheat protection: internal sensors that cut power if internal temperature exceeds safe limits.
• Cool-touch housings or protective grills to minimize risk of burns.

Regular Maintenance

• Keep heating elements and grills clean from dust and debris (dust buildup can burn, lead to odor or ignition of dust).
• Check wiring, plug, and cord for damage.
• Replace any components that show signs of wear or overheating (melted insulation, discoloration, buzzing, etc.).

Avoid Blocking Airflow

• Heaters need free air circulation to properly dissipate heat. Blocking the intake or output may lead to overheating.
• Do not drape fabrics over heaters or allow curtains to contact heater surfaces.

Have Proper Detectors (CO & Smoke)

• Even if your heating is all electric, many homes have other fuel-burning appliances (gas furnace, water heater, stove, fireplace).
• It is prudent to install carbon monoxide detectors (alarms) in your living space, especially near sleeping areas.
• Smoke alarms are also essential to detect fire or overheating incidents.

Avoid Improper Use or Misuse

• Never leave heaters operating unattended for long periods, especially while sleeping.
• Do not use heaters in areas rated as “outdoor use only” inside enclosed spaces.
• Don’t place heaters near flammable liquids or vapors.

Be Alert for Odors or Unusual Behavior

• A persistent electrical burning smell, charring, smoke, or repeated alarms may indicate heating element, wiring, or insulation failure. In such cases, turn off and disconnect the heater immediately and inspect/repair it.

Summary & Direct Answer

Can electric heaters produce carbon monoxide?

• Under normal, intended operation, no: electric heaters do not burn fuel and thus do not produce carbon monoxide (CO).
• Any observed CO in proximity to an electric heater is almost certainly due to another source (fuel combustion elsewhere), sensor cross-sensitivity, or an abnormal failure or combustion of a non-heater material.

Thus, electric heaters are among the safer heating options in terms of gaseous emissions. However, they still carry risks of fire, burns, and malfunction, so proper usage and safety measures remain essential.

If you like, I can also provide a simplified infographic you can share, or a version of this article tuned for non-technical readers. Would you prefer that?