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Although no one wants to think about winter during the beautiful days of autumn, that's the time to think about the air filters on your furnace. The first thing you will want to do is stroll over to your breaker panel and make sure the breaker marked "Furnace" is ON. If your A/C was on recently, you can feel reasonably confident that the breaker is okay. Now head back to the furnace and look for the switch that controls the electricity to the unit. Most furnaces have a switch that looks like a light switch controlling the electrical supply. In a newer house, the switch is often on a wall or a support about 6 feet above the floor, near the furnace. In an older house, the switch is often on the basement ceiling, or high on a wall near the bottom of the basement stairs. Once you locate your switch, check to see if it is ON. If not, the heat will not come on no matter how cold it is or how high you set the thermostat. It is embarrassing and costly to write a check for a technician who came to your house just to flip a switch.

WHAT DOES AN AIR FILTER DO? When the outside air makes its way inside, pollutants like dust, dander and spores are added to the air which has already been exposed to urban car exhaust, smog, and dirt. Many people are sensitive to these airborne particulates, and everyone is affected if the levels becomes excessive. To remove many of the larger particles from the air, your furnace is equipped with a filter. Regular cleaning of the air filter is important for your furnace and your lungs.

WHERE IS IT? The furnace filter is typically a one- to two-inch wide slot (for conventional

filters) or a six- to eight-inch wide slot (for electronic filters) in the duct-work immediately

beside the furnace air return duct. If you don't see such a slot, your furnace's air filter might be accessed only by removing the furnace and/or fan compartment cover. Turn the switch to the furnace to the OFF position before removing any covers.

WHAT DO I DO? If you have a regular mesh filter, pull it out to have a look. If the mesh looks dirty and/or the filter is more than 6 months old, throw it out (paper media or fiberglass) or clean it (metal or plastic media). Typically, there is some sort of filter support on the blower side of the filter. The filter must be installed with the "air flow" arrow pointed toward the filter not you. This ensures the filter material doesn't get sucked into the filter. If you have an electronic air filter, make sure you turn off the power switch before attempting to open. There will be two washable metal screens called pre-filters, and two electronic cells that look like layers of metal plates. These can all be soaked and washed every one to three months. Be careful of the fine wires running down one side of each cell as these are easy to lose or break.

Richard D. Malin & Associates: Technical Library

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