Take a Few Minutes to Replace Furnace Filter


How long has it been since you last replaced your heating or air-conditioning filter?

Experts recommend cleaning or replacing the filter at least twice a year, and more often if the filter looks noticeably dirty.

A dirty filter can lead to clogged heat exchangers, air intakes and ductwork, which not only increases operating costs but can damage expensive equipment.

Additionally, dust buildup in the ducts and at the registers from improperly filtered air can aggravate respiratory problems and allergies, and increase dust mite and bacteria growth.

Spring and fall are the best times of the year to service filters on a regular basis, but they should be inspected at three-month intervals.

Replacing a furnace filter is a relatively easy job that takes only a few minutes, once you locate and remove it.

Most homes are equipped with a central forced heating/air-conditioning unit of an upright design, located in a closet or basement. The filter is normally found inside, at or near the bottom, behind the lower panel.

To reach the filter, raise the lower panel about half an inch, then pull it out from the bottom. On some models, the upper panel must be taken out first before the lower panel can be lifted.

After the panel(s) are out of the way, the filter will usually be visible lying either flat at the bottom of the inside of the unit or sitting vertically at the side.

The filter will likely be held in place by a metal retaining bracket. Release the bracket to slide the old filter out.

To obtain a new disposable filter (disposables have a cardboard frame surrounding a fiberglass mat), simply take the old one into your local hardware store, plumbing supplier or home center.

Reinstall the new one just as the old one came out, but be sure that the arrows on the filter point in the direction of the airflow (normally toward the center of the system).

Make certain that the retaining bracket is holding the filter securely. Also, be careful to replace the access panels tightly because most newer forced-air units have a safety switch that disables the unit if the panels are not properly seated.

If your furnace has a washable filter (it looks like a thick green or blue straw mat with no frame), take it outside and shake off as much dirt as possible. Then spray it with a high-pressure nozzle on your garden hose. Hit it from both sides until all the dust and dirt is gone. Dry it in the sun before reinstalling.

Filters for many forced-air units are not located inside the unit's housing and can be a little tricky to find. Some filters will be located behind a slide-up panel on the incoming sheet-metal air duct near the forced-air unit.

Look carefully at the sheet-metal ductwork near the unit for a panel about three to six inches wide that will slide upward. The filter may be behind it, perpendicular to the duct line.

If you do not see such a panel on your unit, the filter may be located behind a return-air grill somewhere in the house. Look at walls and ceilings for a white-metal grill with one or two large screws or small knobs.

Open the grill by turning these fasteners. The filter should be right behind it. Again, the arrows on the new filter point in the direction of the airflow, in this case away from you.

To help you remember to make the next filter change on time. post the date of the filter change somewhere near the furnace.

If any member of your family is particularly prone to respiratory problems or dust allergies, you may want to consider replacing your filter with an electrostatic filter to increase filtration. These are available in a variety of sizes to fit most furnaces and are sold by heating/air-conditioning parts suppliers. Check your local phone directory.

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