Nope it's not a ninja, cancer or some type of super virus. The silent killer which lurks in thousands of homes goes by the name "heat exchanger". All kidding aside, we are finding more and more dangerous furnaces which need to be condemned.
A heat exchanger is a device within your homes forced hot air furnace which transfers heat to the air in your duct work. A gas or oil burner super heats the air inside the heat exchanger as air passes over the tubing and is heated up.
The real problems begin when homeowners ignore maintenance for years, filters clog and air flow becomes restricted. The air which once cooled the metal heat exchanger is slowly choked. As the the burner continues to fire every time your thermostat calls for heat the metal becomes overheated, weak and brittle. Eventually holes begin to form. From these holes leaks a odorless killer known as carbon monoxide. Unfortunately, many furnaces will run without any signs of heat exchanger failure. LeBlanc Heating has no intent to scare people into getting their system serviced we just recommend regular maintenance as carbon monoxide poisoning is not a force to mess with. We also suggest buying a carbon monoxide detector and testing it regularly. The picture was taken from a service change out we performed on 3/26/13 in Bedford, NH