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In this video, This Old House plumbing and heating expert Richard Trethewey reviews air-filter options.


  1. To ensure you're purchasing the correct-size filters, remove the old air filter from the furnace and check its dimensions, which are indicated by thickness, width and length.
  2. When buying new air filters, disregard any that you can easily see through.
  3. Pleated filters have larger surface areas to trap more dirt.
  4. A pleated filter that has an electrostatic charge offers superior filtration.
  5. As an alternative to disposable filters, upgrade to a reusable electrostatic-charge filter, which can be rinsed clean with a hose.
  6. For even higher levels of filtration, consider a professionally installed filter with an oversized pleated filter that catches more dirt and must be changed less often.
  7. A professionally installed electronic air cleaner sends an electric charge through a series of metal plates that attract and trap dirt particles. And when the filter is dirty, simply put it in the dishwasher to rinse it clean.