Any heater that burns fuel can produce carbon monoxide. CPSC advises battery-operated or battery-backup CO alarms on every level of the home and outside sleeping areas, interconnected where possible. Know the symptoms (headache, dizziness, weakness, nausea, vomiting, sleepiness, confusion), get outside and call 911 if you suspect CO.
Why hearth heat and CO go together
Carbon monoxide is produced when fuel burns without enough oxygen to burn completely. CPSC calls it the 'invisible killer' because it's colourless and odourless, and reports that more than 200 people in the United States die every year from accidental non-fire CO poisoning associated with consumer products. Wood and pellet stoves, gas stoves, gas fireplaces and log sets all burn fuel, so all of them depend on good combustion and good venting to keep CO out of the room.
Electric fireplaces burn nothing, so they produce no CO; that's one reason they're used in bedrooms and apartments.
Alarms: CPSC's advice
- Install battery-operated CO alarms, or plug-in alarms with battery backup, on every level of the home.
- Put one outside each sleeping area.
- Interconnected alarms are best: when one sounds, they all sound.
- Check the batteries regularly and replace alarms at the end of the life their maker states.
A smoke alarm is not a CO alarm. Combination alarms do both; check the label.
Symptoms and what to do
CPSC lists the symptoms of CO poisoning as headache, dizziness, weakness, nausea, vomiting, sleepiness and confusion. They can be mistaken for flu, and everyone in a home can feel them at once. If a CO alarm sounds or you suspect poisoning, get outside to fresh air immediately and then call 911.
Habits by heater type
| Heater | Habits that matter |
|---|---|
| Wood stove | Doors closed except when loading (EPA); dry wood; chimney inspected and cleaned yearly (NFPA) |
| Pellet stove | Vent kept clear and inspected; follow the manual's power-outage procedure |
| Vent-free gas | Room size per manual; ODS working; never in rooms the manual or code excludes |
| Direct-vent gas | Vent termination kept clear of snow, leaves and nests |
| Vented gas logs | Chimney damper open whenever they burn |
| Electric | No CO; follow the manual on cords and circuits |
EPA's burning advice adds one more: keep the doors of a wood-burning appliance closed unless loading or stoking, because chemicals such as carbon monoxide can be released into the home.
Generators and outages
Outages bring the highest CO risk, mostly from generators. CPSC reports that more than 100 of the yearly non-fire CO deaths are linked to portable generators, and says never to use them inside homes or garages, even with doors and windows open: run them outside at least 20 feet from the home, exhaust pointed away. If your pellet stove relies on a generator in an outage, that rule applies to it too.