Carbon Monoxide (CO) Part 2
Gas or oil fired furnaces cause more carbon monoxide poisoning in homes than all other heating sources combined. Cracked heat exchangers, clogged chimneys and back-drafting are the primary causes.
The heat exchanger is made of thin metal and is the only barrier between the air you breathe and the combustion gasses. If this metal gets too hot, tiny cracks form breaching the barrier. A very dirty furnace filter will cause the furnace to over-fire and crack the heat exchanger. This is because of the repeated expansion and contraction as the unit cycles.
The combustion process takes a lot of air. All newer systems have a special duct bringing outdoor air in, but older systems need air too. Be sure to provide some fresh air to the furnace, either by installing a duct or simply by keeping a nearby window open and inch or so.
Quarterly filter changes (use good pleated ones), annual inspections, and a good furnace and duct system cleaning every few years will keep your furnace running great and protect you and your family from deadly Carbon Monoxide gas.