How to Change Your Furnace Filter

Filters are the unsung heroes of your home comfort system, quietly trapping dust, dander, and pollen before they circulate through your rooms. When a filter becomes clogged, your furnace has to work significantly harder to pull air through the system, which not only degrades your air quality but can also shorten the lifespan of your blower motor and drive up your monthly energy bills. Changing a filter is perhaps the single most important maintenance task you can perform to keep your HVAC system humming. It is a five-minute job that yields immediate results in air cleanliness and system efficiency. When done well, the housing seal is tight, the filter is seated perfectly in the slot, and your unit is ready for another three months of reliable operation.

  1. Kill the Power First. Switch your thermostat to 'Off' and toggle the power switch on the side of the furnace unit to the 'Off' position. This prevents the blower from turning on while you have the compartment door open.
  2. Find Your Filter Slot. Find the slot where the filter enters the ductwork, usually located between the return air duct and the main furnace cabinet. Remove any metal access door or decorative cover if necessary.
  3. Slide Out Carefully. Gently slide the dirty filter out of the housing, being careful not to spill collected dust into the blower area. Inspect the filter to see if it is pleated or fiberglass and note its dimensions printed on the frame.
  4. Clear the Track. Use a vacuum with a hose attachment to clear out any debris or loose dust that has accumulated in the filter track. Ensure the area is clear so the new filter can seat properly without gaps.
  5. Arrow Points to Blower. Slide the new filter into the slot, paying close attention to the arrow printed on the edge of the cardboard frame. The arrow must point in the direction of the airflow, which is toward the furnace blower motor.
  6. Seal and Restart System. Replace the access cover or door, ensuring it is snapped or screwed shut to prevent air leaks. Toggle the power switch back to 'On' and set your thermostat to your desired temperature.