A heating furnace is actually a very
simple concept. First, burn a fuel, natural gas, liquefied petroleum
or "propane", coal, oil, wood, butane, or anything else you could
think of to use. (And everything under the sun has, from corn to hay,
dried manure of any kind and old used tires.) The burning fuel then
heats a metal surface called a heat exchanger and the heat exchanger
in turn transfers the heat into the air in the building. The by
products of the combustion of the fuel are channeled out of the heat
exchanger into the flue pipe and out of the building. This heat
exchange system is what allows us to warm the air in the house and at
the same time keep the harmful fumes separated. You can see why this
is a very critical item in the machine.
A modern furnace contains parts and pieces such as the blower that
circulates the air with associated controls to turn it off and on,
high temperature safety devices to keep it from over heating and
controls that let the gas in or to keep the gas out if something's
wrong. Most furnaces built in the last 15 or 20 years have safeties
that shut off the furnace if the flue gas is not going out of the
flue pipe or chimney.
The important thing to remember about your furnace is that you have
no idea if these things are working as they should if you do not have
a professional check it occasionally!! During the 1999 fall service
season we found the high temperature safety device not functioning in
five furnaces in peoples homes. If the air circulation blower fails
to work for any reason and the high temperature safety (or limit
switch as we call it) does not shut the fire off it can lead to the
destruction of the furnace and eventually a fire in the house.
Especially if no one is home to smell the fact that something's
getting hot.
A furnace is one of those kind of "out of sight, out of mind" things.
If it seems to be working you don't pay much attention to it even if
you walk by it every day in the basement or on the porch by the
washer and dryer. From now on be aware of it. Change the filter once
a month and look it over a little bit.
Your furnace was designed to be safe. But in order to maintain the
level of safety the manufacturer intended it needs a little attention
from you and your furnace man.