The FURNACE will be usually set in a crawl space under the house, in the attic, in a utility room or in a basement. There are also PACKAGE heating and cooling systems which incorporate the FURNACE, EVAPORATOR COIL and CONDENSING UNIT into one unit which sits outdoors. We will cover PACKAGE UNITS in another article. We will only discuss the FURNACE in this article.

Furnaces can be fired using natural gas, liquefied petroleum ( propane ), or oil. There are also HEAT PUMPS which use AIR HANDLERS in the place of a fuel fired FURNACE. ELECTRIC FURNACES are actually AIR HANDLERS and will be discussed in another article.

The furnace is equipped with a number of gas burners, a gas manifold, a gas valve, and an incoming gas line from the natural gas meter or propane tank outside the home. The burners are in a HEAT EXCHANGER which is where the gas is burned. Attached to the heat exchanger is a flue ( the pipe which exits the home usually through the roof ). This flue pipe carries the burned gases which has carbon monoxide in it as well as other harmful gases. On the newer furnaces there is also an inducer motor which aids in removing these gases and increases the efficiency of the furnace. It is extremely important that the HEAT EXCHANGER, FLUE, BURNERS and all related electrical valves, and safety controls be checked at least at the beginning of the heating season for safety as well as proper operation. A crack or rust hole in the HEAT EXCHANGER can prove deadly from carbon monoxide entering the living space. In the case of an OIL FURNACE the HEAT EXCHANGER is actually a FIRE BOX but serves the same purpose for this article. The burners are replaced with an oil pump and an oil GUN which sprays a mixture of oil and air into the fire box to be burned. Click here for more important information Air Quality .

• A blower motor and blower wheel to distribute the heated or cooled air through an AIR FILTER and ductwork running to the different rooms in the building. Sometimes a belt connects the blower motor to the blower wheel.

• A high temperature limit control which will shut the furnace down should it overheat.

• A blower control which starts and stops the blower.

• A gas valve which works along with the thermostat mounted within the building.

• An inducer motor, pressure switch, flame roll out switch and other controls are used on the newer furnaces.

• Other parts are transformers, related wiring, regulators, gas shut offs, service disconnect switches and a host of others depending on the manufacturers design.

• OIL FURNACES also have different parts and controls, a few are: a much larger transformer, electrodes that fire the air/oil mixture, a flame eye, and an ignition control box, and a barometric draft regulator which is mounted in the flue pipe.

There are many different furnace efficiency ratings you can buy. The highest ratings are in the 90% and higher area.

We will discuss these efficiency ratings at length, in another article.

Some other aftermarket high efficiency air filters will go much longer between service, some have pleated paper elements which will need changing between 3 and 6 months. If you aren't sure of which kind you have, call your Heating and Air Conditioning Contractor, they are there to help you.

Seasonal Tip.
In the fall before the freezing temperatures arrive, have your swamp cooler properly drained so you don't have damaged equipment or damage to the building in the spring.