How often to change a furnace filter
Check the filter every month, and replace or clean it whenever it looks dusty or clogged. ENERGY STAR advises inspecting, cleaning or changing the air filter once a month in a central air conditioner, furnace or heat pump.
How to do it
- Find the filter at the furnace or air handler, or behind a return air grille.
- Slide it out and look at it. If it is grey with dust, it is due.
- Put in a new filter of the same type and size, or clean a washable filter and let it dry before it goes back.
Why it matters
A clogged filter chokes airflow, raises energy bills and wears out the blower and the coil. A clean filter is the cheapest piece of heating and cooling upkeep there is.
Source: ENERGY STAR, the US Environmental Protection Agency program, in its heating and cooling maintenance checklist.