Carbon Monoxide is a deadly gas that can kill you and your family. It is produced as a product of combustion, a faulty or malfunctioning gas heating appliance can cause carbon monoxide to enter the living areas within your house. High levels of carbon monoxide can affect your health, initially giving you headaches and flu like symptoms, but can quickly lead to death if you or your family are exposed to high levels.
The only way to ensure your appliances are safe is to have them regularly check and serviced by a licensed gas plumber, at least every 2 years.