Most people know it's important to replace your furnace filters, but they don't know how often they should change them. To learn more, we're in Millbrae with Joe Frediani of AWC speaking on behalf of our Diamond Certified expert contributor Ron Frediani. Your furnace filter should be replaced as often as needed. Some of them are washable, so just make sure you wash it as directed. Others are disposable. A lot of the disposable ones have a longevity of three months, so make sure you change that out after three months of running either your air conditioning or your heating. Just know when and how to replace that. If you don't know, then call an expert and get it replaced, and that will help on your indoor air quality. To learn more from local top-rated companies, visit our Diamond Certified expert reports at experts.diamondcertified.org.