Who to call · HVAC Technician
Carbon monoxide alarm going off? Here's Who to Call
A carbon monoxide (CO) alarm going off is a life-safety emergency that should never be ignored. Carbon monoxide is an odorless, colorless gas produced by incomplete combustion in furnaces, water heaters, gas stoves, fireplaces, and attached-garage vehicles. At low concentrations it causes headaches, dizziness, and nausea; at high levels it is fatal within minutes. If your CO detector sounds, evacuate everyone — including pets — immediately, call 911 from outside, and do not re-enter until the fire department clears the home. Common sources include a cracked heat exchanger in the furnace, a blocked or disconnected flue pipe, a malfunctioning gas water heater, or backdrafting caused by negative house pressure. After the immediate danger is resolved, an HVAC technician should perform a combustion safety inspection of every gas appliance. A heat-exchanger inspection runs $80–$150; if the exchanger is cracked, replacement costs $600–$1,500 or a full furnace replacement may be recommended ($3,000–$7,000). Flue pipe repair or reconnection typically costs $150–$400. Annual furnace maintenance ($80–$150 per visit) is the best prevention — the technician checks for CO at every burner and verifies proper venting. Install CO detectors on every level and near sleeping areas; replace units every 5–7 years.
What's going on
How to fix carbon monoxide alarm going off
Some "carbon monoxide alarm going off" cases look simple, but getting it wrong almost always costs more than calling a pro: hidden leaks, fire risk, code violations, and insurance headaches. A licensed hvac technician will diagnose the exact cause, use the right professional tools, and stand behind the repair. Most local pros offer free quotes and can visit the same day or the next.
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HVAC Technician
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Symptoms to look for
- 01
Carbon monoxide detector beeping or displaying high CO reading
- 02
Headaches, dizziness, or nausea that improve when leaving the house
- 03
Yellow or flickering pilot light on furnace or water heater instead of steady blue
- 04
Soot or scorch marks around the furnace, water heater, or fireplace
- 05
Stale or stuffy air even with the heating system running
- 06
Excessive condensation on windows near gas appliances
FAQ
Frequently asked questions
Who should I call for: Carbon monoxide alarm going off?
A carbon monoxide (CO) alarm going off is a life-safety emergency that should never be ignored. Carbon monoxide is an odorless, colorless gas produced by incomplete combustion in furnaces, water heaters, gas stoves, fireplaces, and attached-garage vehicles. At low concentrations it causes headaches, dizziness, and nausea; at high levels it is fatal within minutes. If your CO detector sounds, evacuate everyone — including pets — immediately, call 911 from outside, and do not re-enter until the fire department clears the home. Common sources include a cracked heat exchanger in the furnace, a blocked or disconnected flue pipe, a malfunctioning gas water heater, or backdrafting caused by negative house pressure. After the immediate danger is resolved, an HVAC technician should perform a combustion safety inspection of every gas appliance. A heat-exchanger inspection runs $80–$150; if the exchanger is cracked, replacement costs $600–$1,500 or a full furnace replacement may be recommended ($3,000–$7,000). Flue pipe repair or reconnection typically costs $150–$400. Annual furnace maintenance ($80–$150 per visit) is the best prevention — the technician checks for CO at every burner and verifies proper venting. Install CO detectors on every level and near sleeping areas; replace units every 5–7 years.
Can I fix this myself?
Some minor cases can be handled DIY, but most require a licensed hvac technician to avoid costly rework and safety risks. A free quote takes under a minute.
How fast can a pro come out?
Most hvac technicians offer same-day or next-day visits for non-emergency issues. True emergencies (burst pipes, gas smell, no heat in winter) are typically handled within 1–4 hours.
How much does it cost to fix?
Costs vary by severity and your location. Submit a free quote request to get real pricing from verified local pros in your area.
What are the signs of: Carbon monoxide alarm going off?
Carbon monoxide detector beeping or displaying high CO reading. Headaches, dizziness, or nausea that improve when leaving the house. Yellow or flickering pilot light on furnace or water heater instead of steady blue. Soot or scorch marks around the furnace, water heater, or fireplace. Stale or stuffy air even with the heating system running. Excessive condensation on windows near gas appliances.