Carbon Monoxide is odorless and colorless. It causes flu-like symptoms, disorientation, confusion, and even death. It is highly recommended that you have your furnace cleaned and checked every year. The older the furnace, the more important this service is. Newer gas furnaces are equipped with many features that shut the furnace off when a problem is detected.
Older furnaces have no such devices.
Over time, furnaces can develop small cracks in the combustion chamber. These cracks may not be visible to the naked eye. It is through these cracks that Carbon Monoxide can leak into your home. It is also important to change your furnace filter regularly. The filter usually is found just inside the front cover of the furnace.