It is important to have your furnace checked once a year by a professional for a tune-up. However, there are a few simple things you can check yourself to make sure your family is safe and warm this winter.
Visually inspect the flue system of your furnace and water heater. The flue is the round galvanized pipe that takes the unburned gas products and the carbon monoxide outside the home. It is located on the top of your furnace, and the water heater usually ties into the furnace flue. Carefully examine the pipe for holes or rust. Squeeze the round pipe and make sure you do not have rust-outs working from the inside out. Make sure the flue is solid and strong. You should not be able to easily crush the pipe with your hand. The flue should be sloping upward at all times and should be attached to both the furnace and water heater.
Remove the top door to your furnace and, with a flashlight, carefully look for rust build-up inside the burners and the heat exchanger. The heat exchanger is the compartment that contains the burning of gas, and the burners protrude into the heat exchanger cells. Look for any rusty metal and flakes of rusted particles. Carefully examine the condition of the burners, looking for damage. If there is any rust in the heat exchanger, or on the burners, it has to be cleaned out. Check the front panel of the furnace for burned paint or hot spots. The panel should never get hot enough to burn the paint or the finish off the front or the side of the furnace. The cause of burned paint is a heat exchanger that is not containing the heat of combustion, and can be a sign of a furnace that needs service or replacement.
Have someone turn the furnace on while you observe the burners lighting. They should all light smoothly and evenly without any whooshing sound or booming. Once the burners light, they should all burn blue, with a slight yellow tip of the flame. Wait until the fan and the blower start up, and watch for movement of the flame and watch for yellow in the flame. This can be a sign of a leaky heat exchanger or a rusted out exchanger. Turn the power switch off and the blower will stop. Watch the flame. If it stops moving and dancing around, this is a problem you should have checked out. Also, observe your pilot light for movement and yellow flame when the blower is running. Turn off your furnace power switch and see if the movement and the yellow flame change.
Change your furnace filter. This is a good time of year to change your air filter, since summer is over and the furnace has run many hours. A clean filter will allow proper airflow and efficiency on your system year-round.
By Dan Jape, contributing writer and founder of Reliable Heating & Air.