Change Your Furnace Filter Regularly

Perhaps the most frequent heating and cooling system maintenance problem home inspectors see is dirty furnace filters.  It’s easy to understand why people neglect this important maintenance task.  The system appears to work regardless of the condition of the filter.  So if it isn’t broken, why fix it?  Fix it because dirty filters cost you money by:

  • Making the system work longer to cool and heat your home,
  • Allowing dust and other contaminants into the ducts and furnace,
  • Contaminating parts and restricting air flow within the system,
  • Reducing the system’s service life.

In homes where the furnace is in the attic or crawlspace, the filter is often in the main return duct, which is usually located in a central hallway.  In homes where the furnace is in an accessible location such as the garage or a basement, the filter is usually located in the furnace cabinet.  If you have more than one system, you should have at least as many filters as you have systems.  Some homes have return ducts and filters in additional locations, such as the owner’s bedroom.

Here are some general rules about selecting and changing heating and cooling system filters.

  • Change disposable filters and clean washable filters at least once per month on the same day (so you won’t forget).
  • Locate and change every filter.
  • Use the correct size filters for your system (the size is printed on the filter).
  • Avoid using a filter with a high MERV rating (greater than about 8)  unless your system is designed to use a high MERV filter (most aren’t) because high MERV filters can restrict air flow.
  • Avoid installing washable filters when they are wet.
  • Look at your filter while the system is running; if it looks as if it is being pulled into the return duct or furnace then it is either too dirty or too restrictive or you may need more return ducts.
  • Buy filters in quantity so you will have them ready when you need them (they’re usually less expensive that way).

The Bottom Line

Changing your heating and cooling system filters when they don’t appear dirty may seem like a waste of money.  In fact, the opposite is true.  Changing the inexpensive disposable filters or cleaning a washable filter regularly will save you money and help the environment as well.

Information courtesy of the

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