Replace a Leonnox furnace filter by turning off the unit, locating the filter, determining if it is reusable, purchasing the correct size filter, and installing the new filter. Replace filters at least four times per year in air handlers that provide both heating and air conditioning.Continue Reading
Turn off the furnace at the circuit breaker before removing the filter. Do not turn the furnace back on until the new filter is in place.
In older systems, the filter is often located in the air-return duct. In newer furnaces, locate the filter inside the air handler. Open the access door or duct cover, and remove the old furnace filter.
Filters with cardboard frames are disposable. If the filter has a plastic frame, do not replace it unless it is torn or damaged. Vacuum and wash a reusable filter before replacing it. If the old filter is disposable, determine the size before discarding it.
Purchase a new filter at the hardware store. Look for a filter that balances efficiency of filtering and heating economy.
Insert the new or cleaned filter back into the unit. Close the access door, or secure the return vent cover. Mark the date for the next furnace filter change.