air quality troubleshooting
Carbon monoxide detector is going off
What it probably is, what you can safely check yourself, and the point where it becomes our job.
Get everyone outside and call 911 now
If the alarm is sounding, leave the house with every person and pet, leave the door open behind you, and call 911 from outside. Do not hunt for the source, do not open windows and go back to bed, and do not call us first. Carbon monoxide poisoning looks like flu — headache, nausea, confusion — and it gets worse the longer you stay inside.
Once the fire department has cleared the house and told you it is safe to go back in, call us. Nobody should relight or run that appliance until a technician has found out why it did this.
Call 911 from outside before you call anyone else, including us. We come once the fire department has cleared the building.
What is most likely going on
Get everyone out of the house, including pets, and call 911 from outside. Do not go looking for the source, do not silence the alarm and wait, and do not go back in until the fire department tells you it is safe.
Likely causes, most common first
- 1
Cracked heat exchanger or a combustion fault in the furnace
A furnace heat exchanger that has cracked can let combustion products into the supply air stream, and a burner running with insufficient combustion air produces carbon monoxide directly. This is the reason a furnace with a suspected exchanger crack gets shut down and red-tagged rather than patched. Diagnosis requires combustion analysis and inspection, not a look through the burner ports.
- 2
Blocked, disconnected or backdrafting flue
A vent blocked by a nest or ice, a disconnected flue section in a crawlspace or attic, or a chimney that is backdrafting sends exhaust into the house instead of outside. Tight houses with strong exhaust fans can pull a naturally drafted appliance into backdraft. Wind-driven weather across Whatcom County makes vent termination problems a seasonal reality.
- 3
A gas water heater, range or unvented appliance
The furnace is not the only suspect. A gas water heater sharing a flue, a range used for heating, or any unvented combustion appliance can be the source, which is why the whole house gets evaluated rather than just the furnace. Include the water heater in whatever inspection follows.
- 4
A generator, vehicle or equipment running in an attached space
A generator in a garage or near an open window, a car warming up in an attached garage, or a propane heater used indoors will set a detector off quickly. During a windstorm outage this becomes a very common scenario. No amount of ventilation makes running a generator in an attached garage safe.
- 5
End-of-life or faulty detector
CO detectors have a service life and will chirp or alarm as they expire, and a false alarm is possible. It is not a possibility you get to assume from inside the building. Evacuate first, let the fire department measure, and replace an expired detector afterward.
Do these things, in this order
This is not a troubleshooting list. It is the sequence that keeps everyone safe until responders have measured the house.
- Get everyone and every pet outside into fresh air immediately, then call 911 from outside.
- Do not re-enter the building for anything until the fire department says it is clear.
- Do not restart, reset or run any gas appliance, and do not silence the alarm and go back to bed.
- If a generator, vehicle or propane heater is running in or near the building, tell the responders when they arrive.
- After you are cleared, note the detector’s manufacture date and replace it if it is past its rated service life.
What is deliberately not on that list
Nothing above involves refrigerant, gas piping, or opening a live electrical panel. Refrigerant work is federally regulated and needs recovery equipment. Gas work done wrong kills people. An energised panel turns a $300 repair into a hospital visit. Electrical work on the circuit itself is done by a licensed electrical contractor. If a step you have read elsewhere involves any of those three, stop and call instead.
When to call us
Call 911 first, from outside, every time. Call us after the fire department has cleared the building, so we can inspect the furnace and the venting before anything is put back into service. A CO event means the appliance stays off until it has been examined, and that is not a negotiable step. Emergency calls are answered 24/7 at (360) 592-3824.
Monday–Friday, 8:00 AM – 5:30 PM · Emergency calls answered 24/7
Tell us what it is doing
Describe the symptom and we will tell you what it takes to fix, what it is likely to cost, and whether it is worth fixing at all.
Monday–Friday, 8:00 AM – 5:30 PM · Emergency calls answered 24/7