Just like your air conditioner, your forced-air heating system has a filter that prevents blockages by keeping out dirt and dust to prevent blockages. If that filter—located in the furnace or at a return register—gets clogged, the unit will operate inefficiently and will cost you more money. One recent study indicated that a severely clogged filter (a filter with only 20 percent capacity remaining) reduced heating efficiency by 25 percent! And it’s so easy to avoid this problem that it’s a joke.
Check your filter once a month, and clean or change it when it gets dirty. You can tell it’s dirty by holding it up to a light. If little or no light shines through, it’s dirty.
If you’ve got the kind of filter that can be cleaned, an inexpensive hair shampoo makes a good detergent for washing it. Don’ t wring the filter after washing; just squeeze it gently and let it dry naturally.
For less than $20, you can buy and install yourself a device that indicates when your furnace filter is clogged and needs changing or washing. This will save you the bother of having to open up the furnace front or the exchange register to check your filter visually.