How to Replace a Forced Air Furnace Filter

The furnace filter on your forced air furnace should be changed once every three months. Regular filters air particles and debris that could harm your furnace blower and motor. Air flow reduces to the furnace when the filter becomes clogged with dirt causing the furnace to work harder. You can replace the filter with a standard filter or with a HEPA filter that will improve the air quality in your home.

Things You'll Need

• Tape measure
• Replacement filter

Instructions

1. Turn off the power supply to the furnace. Most furnaces will have a red emergency switch that resembles a regular light switch near the furnace. Flip the emergency switch to the off position. You can turn the circuit breaker off to the furnace if you cannot locate the emergency switch.

2. Locate the access to your filter area. The filter will either be behind the access door on the face of the furnace or in a slot door between the furnace and the incoming air duct. Lift and remove the access door from the furnace if your filter at the blower compartment. The access door for the slide in filters will have to turn rings that you turn counterclockwise to open the slot door.

3. Pull the old air filter out of the furnace. Some people will take this time to vacuum out the furnace blower compartment when the door is off. Measure the current filter with a tape measure. Most filters with cardboard sides will have the size written on the side.

4. Locate the arrow on the side of your replacement filter. Place the filter inside the furnace in the direction the arrow points. Close the access door to the filter and turn the power back on to the furnace.

Tips & Warnings

• Always turn the power off to the furnace before attempting repairs.

References

• Homenergy.org - About Furnace Filters
• Hss.energy.gov - HEPA Filters