Backdrafting occurs when the combustion gases can't go up and out flues and chimneys because outdoor air is already flowing down them (Fig.
B BACKDRAFTING BACKDRAFTING is a condition in which air flows down a flue or chimney rather than up, and combustion fumes can't flow out.
Backdrafting is a threat to the health of your family and your house.
Backdrafting became an increasing problem after the energy crisis of 1973 when gas lines and rising fuel prices made energy conservation a high priority.
Fortunately you can easily test your furnace and water heater for backdrafting.
If the flame or smoke is not drawn to the flue, or is blown away from it, you have a backdrafting problem.