Changing your HVAC air filter is one of the cheapest, easiest things you can do to keep your system running well — and one of the most commonly forgotten. A clogged filter makes your furnace and AC work harder, drives up your energy bill, and can shorten the life of your equipment. Here's exactly how often to change it and how to tell when it's time.
How often should you change your HVAC air filter?
As a general rule, replace a standard 1-inch air filter every 90 days. But that number changes based on your home and your filter type:
- Standard 1" filters: every 30–90 days
- Thicker 4" to 5" media filters: every 6–12 months
- Homes with pets: every 30–60 days
- Homes with allergy sufferers: every 30–45 days
- Vacation or lightly-used homes: every 90 days or a bit longer
If you have shedding pets, run your system constantly through an Indiana summer or winter, or anyone in the home has allergies or asthma, lean toward the shorter end of these ranges.
How do I know when my filter needs changing?
Don't rely on the calendar alone — pull the filter out and look at it. Hold it up to a light. If you can't see light through it, or the surface is coated in gray dust and debris, it's time for a new one. Other signs it's overdue:
- Your energy bill is creeping up for no clear reason
- The air coming from your vents feels weak
- You're dusting more often than usual
- The system runs longer to hit the same temperature
What happens if you don't change your air filter?
A clogged filter chokes off airflow to your system. That forces the blower motor to work harder, which raises your energy costs and puts extra strain on components. In a furnace, restricted airflow can cause the system to overheat and trip its safety switch, shutting it down entirely. Over time, running a dirty filter is one of the fastest ways to wear out an HVAC system before its time — and dirty filters let more dust and allergens circulate through your home. If air quality is a concern in your household, our indoor air quality services can help you breathe easier.
What MERV rating should you use?
MERV (Minimum Efficiency Reporting Value) measures how much a filter captures. Higher isn't always better for a home system:
- MERV 8–11: the sweet spot for most homes — good filtration without straining the system
- MERV 13: captures finer particles; good for allergy households, but confirm your system can handle it
- MERV 16+: built for hospitals and labs; too restrictive for most residential furnaces
A filter that's too dense for your equipment restricts airflow just like a clogged one. When in doubt, ask your HVAC technician what your specific system is rated for. The U.S. Department of Energy recommends regular filter changes as one of the simplest ways to keep a system running efficiently.
How to change your air filter
It takes about five minutes:
- Turn your system off at the thermostat
- Locate the filter slot — usually in the return air vent, the furnace, or the air handler
- Slide out the old filter and note the size printed on its frame
- Check the airflow arrow on the new filter and point it toward the furnace/air handler
- Slide the new filter in and turn the system back on
Write the date on the filter frame with a marker so you know when you last changed it.
Keep your system running strong in Jennings County
Regular filter changes go a long way, but they don't replace a professional tune-up. Moore Quality Heating & Air is a family-owned HVAC company serving North Vernon and the surrounding Jennings County area, offering honest, upfront pricing and 24/7 emergency service.
If your system isn't heating or cooling the way it should — even with a fresh filter — call (812) 718-1358 or schedule a visit and we'll take a look.