How-To Guides · DIY & home
How to Change Your Furnace or AC Air Filter
A clogged air filter makes your heating and cooling work harder. ENERGY STAR says a dirty filter can raise your energy costs, and even damage your equipment. Changing it takes about two minutes.
1. Step 1: Turn The System Off
First, switch your system off at the thermostat, so the fan isn't pulling air while the filter is out.
2. Step 2: Find The Filter
Now find the filter. Most are in a slot on the side of the furnace, or behind a small door or panel. In some homes, it's behind a big return air vent, in a wall or the ceiling.
3. Step 3: Read The Size
Slide the old filter out, and look at its frame. The size is printed right on it, like sixteen by twenty-five by one. Snap a photo, so you buy the right one.
4. Step 4: Point The Arrow
Every filter has an arrow on the frame. It shows which way the air flows. At the furnace, point the arrow toward the furnace, away from the return duct. In a wall or ceiling vent, point it into the wall or ceiling.
5. Step 5: Slide It In
Slide the new filter in, so it fits snug with no gaps around the edges. Close the panel or vent, then turn your system back on.
6. How Often?
Check it once a month. Trane says to change it at least every ninety days, and more often if you have pets, or during pollen season. If it looks gray and dusty, it's time.
7. What'S Merv?
The MERV number tells you how fine the filter is. Most homes do well with eight to thirteen. Higher isn't always better for your system, so check your manual.
Tools that make this easier
Simple Google Sheets + Excel tools from WiscHaven. Buy once, no subscription.
Sources
- energystar.gov/saveathome/heating-cooling/maintenance-checklist
- trane.com/residential/en/buyers-guide/hvac-basics/filters-help-keep-your-indoor-air-clean
Checked against the official sources above. Steps can change as apps update - tell us if something looks different: wischavenindustries@gmail.com