Home furnaces are typically the last thing in the house that people think about. They are located in out of the way places, and people simply expect them to work all the time. And this is generally the case, although after your unit is more than ten to twelve years old, the wise homeowner knows that his furnace will eventually need to be replaced. Just like with cars, furnaces can run without problems for a long time, but they do need periodic maintenance. If you are the type of person that ...