Carbon Monoxide and Gas Water Heaters
Why a fuel-burning water heater belongs in the same conversation as CO alarms, and what federal guidance asks of homeowners.
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What Makes Carbon Monoxide Different From a Gas Leak?
Carbon monoxide has no smell at all, while the natural gas supplied to a home carries an added odorant. The CDC describes carbon monoxide as “an odorless, colorless gas that kills without warning.”
That single difference decides how each is detected. A gas leak announces itself through the odorant; carbon monoxide does not announce itself at all, which is why detection depends on an alarm rather than on a person noticing something. Source: CDC, Carbon Monoxide Poisoning Basics, accessed 2026-09-23.
If what you smell is gas rather than a suspicion of carbon monoxide, the response is different and immediate: see Gas Smell Near a Water Heater: What to Do First.
What Are the Symptoms of Carbon Monoxide Poisoning?
The CDC lists headache, dizziness, weakness, upset stomach, vomiting, chest pain and confusion as the most common symptoms of CO poisoning.
The CPSC’s instruction is direct: “If you suspect CO poisoning, get outside to fresh air immediately, and then call 911.” Source: U.S. Consumer Product Safety Commission, Carbon Monoxide Information Center, accessed 2026-09-23.
Treat an alarm as real every time. Do not open windows and wait to see whether anyone feels better.
Where Should Carbon Monoxide Alarms Go in a Home?
The CPSC advises installing battery-operated CO alarms, or CO alarms with battery backup, on every level of the home and outside sleeping areas.
| Guidance | Source |
|---|---|
| Install CO alarms on every level of the home and outside sleeping areas | CPSC |
| Install battery-operated or battery back-up CO detectors near every sleeping area | CDC |
| Check detector batteries when clocks change each spring and fall | CDC |
| Replace the detector per the manufacturer instructions, or every 5 years | CDC |
| Have the heating system, water heater and other gas, oil or coal burning appliances serviced by a qualified technician every year | CDC |
| Make sure gas appliances are vented properly | CDC |
The servicing interval above is the CDC’s own guidance for carbon monoxide prevention. The maintenance schedule for your specific unit is the one in its manufacturer manual; what a scheduled visit covers is on Water Heater Maintenance in Harrisburg, PA.
Where Does a Gas Water Heater Fit Into This?
A gas water heater burns fuel and vents its combustion products outside, so it belongs on the CDC’s list of appliances to have serviced annually and vented properly.
The venting path is the part that matters. On a conventional gas tank, combustion gases rise through a draft hood and a flue; anything that interferes with that path is a service issue rather than a homeowner adjustment. Our repair scope for gas units, including venting and combustion air, is on Gas Water Heater Repair in Harrisburg, PA, and replacement venting arrangements are covered on Gas Water Heater Installation in Harrisburg, PA.
Homeowner scope here stays visual: look at the flue connection and the space around the unit, and keep stored items away from it. Do not dismantle a vent connector, adjust a burner, or run a fuel-burning appliance you believe is venting poorly. For other water heater topics, see our water heater guides.
Frequently Asked Questions About Carbon Monoxide and Water Heaters
Can a gas water heater produce carbon monoxide?
A gas water heater burns fuel, so it produces combustion gases that must vent outside. The CDC lists water heaters among the gas, oil and coal burning appliances to have serviced by a qualified technician every year and to keep properly vented.
Where should I put a carbon monoxide alarm?
The CPSC advises installing battery-operated CO alarms or alarms with battery backup on every level of the home and outside sleeping areas. The CDC advises placing detectors near every sleeping area.
What should I do if the carbon monoxide alarm goes off?
The CPSC states that if you suspect CO poisoning, get outside to fresh air immediately, and then call 911. Treat every alarm as real rather than waiting to see how people feel.
What are the symptoms of carbon monoxide poisoning?
The CDC lists headache, dizziness, weakness, upset stomach, vomiting, chest pain and confusion as the most common symptoms of carbon monoxide poisoning.
How often should a carbon monoxide detector be replaced?
The CDC advises replacing a CO detector following the manufacturer instructions, or every 5 years, and checking the batteries when clocks change each spring and fall.
Does carbon monoxide smell like gas?
No. Carbon monoxide is odorless, which is why an alarm is the only reliable detection. The natural gas supplied to a home carries an added odorant, so a gas leak can be smelled while carbon monoxide cannot.
Book a Gas Water Heater Check
If an alarm has sounded, get outside first and call 911. Once the property is cleared, we inspect the appliance and its venting.
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