At this home inspection I came across a hot water heater in a utility closet in which the vent flue had become disconnected at the ceiling. In addition to the exhaust and CO venting directly to the closet, you can see that the paper on the adjacent sheetrock is heavily charred from the exhaust heat.
The home owner stated that the water heater was professionally installed less than 6 months ago. Lucky for them, the door to the utility closet sealed fairly securely which slowed the flow of CO into the living area of the home. I recommended to the home owner that they contact the installer immediately for emergency repairs to the vent flue.
You cannot see or smell carbon monoxide (CO), but at high levels it can kill a person in minutes. It is the leading cause of poisoning death, with over 500 victims in the United States each year. The initial symptoms of CO poisoning are similar to the flu but without the fever. They include headache, fatigue, shortness of breath, nausea, dizziness, vomiting, disorientation, and loss of consciousness.