Furnace Maintenance Checklist

Before the cold weather comes, prep and clean the furnace as part of the fall home maintenance checklist. To complete this maintenance you’ll need the replacement filter, screwdriver (flat or Phillip’s head, depending on your filter’s access panel), hand brush, soap, towel and a hand held vacuum cleaner. These items will be used to replace the filter, clean the blower assembly and clean the inside of the unit.

Filter Replacement

Start by shutting down power to the furnace for safety. Locate and remove the access panel using the screwdriver if the furnace has an in unit filter. Other systems will have the filters located at the intakes of the central air system. Write down the size of the air filter(s) that need to be replaced if you don’t have replacements readily available. Check the owner’s manual to see if a fiberglass or pleated filter is recommended. The fiber glass filters have to be changed every 1-2 months and pleated filters every 3 months, depending on pets, smoking, etc. Be sure to install the filter in the correction direction. There are little arrows on the side of the filter to indicate airflow direction.

A dirty or torn filter will not prevent the furnace from getting dirty and can shorten it’s life. Also, making sure the filter is the right type allows the right CFM (Cubic Feet per Minute) to blow through the furnace. A filter that restricts the flow too much isn’t conducive for good air circulation. On the other hand a filter that allows too high of a flow won’t give the furnace enough time to transfer heat to the air.

Clean the Blower Unit

The next step is to clean the blower assembly. It is vitally important for safety that all power sources have been removed, including battery back-ups, before working on the blower. After verifying all power sources have been cut off, remove the access panel to the blower, if you didn’t have to when replacing the filters. Slide the fan out of the unit. If the fan has cables that need to be disconnected in order to remove it, mark each cable so you know how to hook it back up. Use the soap and water to brush off the blades of the fan. Then dry off the parts with a towel. Next, using the hand vacuum, clean off the belts and pulleys of the motor housing.

Flue and Combustion

The flue is the vent that expels the exhaust gases from the house. It is easy to visually inspect for any corrosion or cracks. Foil tape can be used to seal up small leaks. However, corroded flues should be replaced. This is very important because the gases that are handled by the flue can be deadly if not vented.

These gases are a byproduct of the combustion process utilized to create the heat. The burner will ignite the incoming gas and air before entering the heat exchanger. In the heat exchanger the air will soak up energy through a metal medium. A furnace professional will first clean the burner from any buildup. Then they will use a special meter to measure the exhaust from the combustion process. From this data they will make adjustments to optimize your unit. If your unit is an oil furnace then the oil filter will be replaced, too.



Furnace maintenance should be included every year in your fall home maintenance checklist. It is not only a safety issue, but also a matter of energy efficiency and prolonging the life of your unit.

Easy Home Improvement

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