The alarm
Illustrative example. Not a real job or customer.
Early on a winter morning, the carbon monoxide alarm in the hallway of a Fullerton home sounds. Two people in the house have woken with headaches. The water heater and furnace share space in the attached garage and the hall closet.
- Everyone gets outside immediately, leaving the alarm sounding.
- From the front yard, they call 911.
- Responders check the house and find elevated carbon monoxide readings near the garage door into the house.
- Gas to the water heater is shut off and the house is ventilated before anyone goes back in.
The household is safe outdoors, and the source is narrowed to the garage water heater.
What the contractor found
The vent pipe from the top of the water heater had separated at a joint above the draft hood, likely after something stored on a shelf was knocked against it. Exhaust was spilling into the garage instead of leaving through the roof. The flame itself was also slightly yellow, and the burner had some soot.
Unlike a gas leak, there was no rotten-egg smell. Carbon monoxide has no odor, which is why the alarm was the only warning.
The repair
- Vent.The separated joint was reconnected and secured, and damaged sections were replaced.
- Burner.The burner was cleaned and the flame checked until it burned blue.
- Draft check.With the heater running, the contractor checked that exhaust was drawing up the vent rather than spilling at the draft hood.
- Clearances.Storage was cleared from around the water heater and shelving moved away from the vent.
- Strapping and alarms.Seismic straps were checked, and an additional CO alarm was recommended near the bedrooms.
Gas leak vs. carbon monoxide, as this case showed
| Feature | Gas leak | Carbon monoxide |
|---|---|---|
| Smell | Rotten eggs | None |
| Warning | Your nose | CO alarm, symptoms |
| Source | Leaking pipe or connector | Poor burning or blocked or broken venting |
| First move | Leave, call 911 or SoCalGas from outside | Leave, call 911 |
Lessons
Common questions
Is this a real case?
No. It is an invented example.
Would a gas detector have caught this?
No. A natural gas detector senses unburned gas. Carbon monoxide needs a CO alarm.
Could the furnace cause the same thing?
Yes. Any fuel-burning appliance with poor combustion or broken venting can produce carbon monoxide.
General information for Fullerton, not a quote or professional advice. In an emergency, call 911.