Replacing a Furnace Filter
One disadvantage of forced-air heating and cooling systems is that blowing air stirs up dust and dirt. The key to clean forced air is that, as the air flows up through the furnace, the filter catches these particles.
Filters are easy to replace, so check them monthly during the heating and cooling seasons. Just pull out the old one, and hold it up to a light; if you can see light through the filter, it's still usable.
Most filters consist of oil-treated fiberglass framed in cardboard. Install these so air strikes the oiled side first; you'll usually find an arrow on the filter indicating the direction of the airflow. Cleanable dry-foam filters can be vacuumed or washed. Standard filters trap only larger particles. To remove fine dust and pollen, consider an electrostatic air cleaner.
