How Often to Change Your Furnace Filter (Oregon Guide)
The filter is the cheapest, easiest part of your heating system to maintain and the one most often forgotten. Here is how often to change it for your home.
The Short Answer: Every 1 to 3 Months for Standard Filters
Change a standard 1-inch filter every 90 days in a typical home, every 60 days with a pet, and every 30 to 45 days with multiple pets, allergies or during wildfire smoke. Thicker 4 to 5 inch media filters last 6 to 12 months.
Filter Schedule by Household
| Your Home | 1-Inch Filter | 4 to 5 Inch Media Filter |
|---|---|---|
| Single occupant, no pets | Every 90 days | Every 12 months |
| Family, no pets | Every 60 to 90 days | Every 6 to 12 months |
| One dog or cat | Every 60 days | Every 6 months |
| Multiple pets or allergies | Every 30 to 45 days | Every 3 to 6 months |
| During wildfire smoke | Check weekly, change when gray | Check monthly |
Heat pumps run in both summer and winter, so they move more air through the filter than a furnace that only runs in the cold months. Check a heat pump filter monthly.
Signs Your Filter Needs Changing Now
- The filter looks gray or you can't see light through it
- More dust settling on furniture than usual
- Weak airflow from the vents
- The system runs longer to reach the set temperature
- Allergy symptoms get worse indoors
Which MERV Rating Should You Use?
MERV ratings run from 1 to 16 for home filters. Higher numbers catch smaller particles, but they also restrict more airflow.
- MERV 8 to 11: the right choice for most homes. Catches dust, pollen and pet dander without choking airflow.
- MERV 13: traps fine particles like wildfire smoke. Use it only if your system is designed for it, or with a thicker media filter cabinet.
- Avoid very restrictive filters in older systems. Starving the blower of air can overheat a furnace or freeze a heat pump coil.
Wildfire Smoke Season in Oregon
Change It After Every Smoke Event
Late summer smoke loads a filter fast. Check it weekly while the air quality is poor and replace it once the smoke clears, so you start fall with a clean filter. For homes with smoke or allergy concerns, see our indoor air quality services.
How to Change a Filter in 2 Minutes
- 1Turn the system off at the thermostat.
- 2Find the filter slot at the furnace or air handler, or behind a return air grille in a wall or ceiling.
- 3Note the size printed on the frame, such as 16x25x1.
- 4Slide in the new filter with the airflow arrow pointing toward the furnace or air handler.
- 5Write the date on the frame so you know when it went in, then turn the system back on.
Want someone to keep track of it for you? Filter checks are part of every HVAC maintenance visit. If your system is running but not heating right, see our 9 fixes for a furnace blowing cold air.
FAQs
How often should I change my furnace filter?
Every 90 days for a standard 1-inch filter in a typical home, every 60 days with a pet, and every 30 to 45 days with multiple pets, allergies or wildfire smoke. Thicker media filters last 6 to 12 months.
What happens if I don't change my furnace filter?
Airflow drops, the system runs longer, dust builds up inside the equipment, and the furnace can overheat and shut off on its safety switch. On a heat pump, a clogged filter can freeze the indoor coil.
Which way does the furnace filter arrow go?
The arrow points in the direction of airflow, toward the furnace or air handler and away from the return duct.
Let Us Keep Your System Running Clean
Valley Flow tune-ups include a filter check, coil inspection and full safety test for homes across Silverton, Salem, Keizer, Woodburn, Stayton and Mt. Angel.