Filters in a Forced Air System
Filter should be clean to keep your system running as efficiently as possible. There are three types of filters:
Disposable: These have a cardboard frame and a spun fiber filter. Throw them out when they are dirty and replace. These can be bought at hardware stores or online.
Washable: These are usually made with a plastic frame and have a mesh filter. Remove the filter and handwash in a tub with household detergent.
Electrostatic: This type of filter is installed near the furnace or air handler. It has a metal frame with a metal mesh filter. These should be cleaned per the manufacturer’s instructions.
**Source - Peco.com**