Change a furnace filter

Changing your furnace filter is the simplest way to keep a heating system healthy. The videos here cover the points people get wrong: the arrow on the filter frame points toward the furnace, in the direction the air flows, and the MERV rating balances filtering and airflow. A filter that is too restrictive can strain the blower.

Read the size printed on the old filter and buy the same one. Check it monthly at first and change it when it looks dirty; how often depends on pets, dust and the season. A clogged filter is one cause of a furnace that won’t start. More jobs like this are listed under HVAC, and in our winter maintenance checklist.