When it comes to your HVAC system, one of the most important—and often overlooked—decisions you’ll make is choosing the right air filter. That choice usually comes down to one key measurement: the MERV rating.
Whether you’re battling seasonal allergies, trying to improve energy efficiency, or just want to protect your HVAC system, understanding MERV ratings can help you make smarter choices. Let’s break it all down.
What Are MERV Ratings?
MERV stands for Minimum Efficiency Reporting Value. It’s a rating system developed by ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) to measure an air filter’s ability to capture airborne particles.
Think of MERV like a school test score. The higher the number, the better the filter is at trapping small particles like dust, pollen, pet dander, and smoke.
Why MERV Ratings Matter
Air filters play a vital role in both indoor air quality and HVAC system performance. A low-rated filter may let allergens pass through, while a high-rated one could strain your system if it’s not compatible.
HVAC and indoor air quality are directly related to one another, because filters that remove more pollutants from your home’s air can reduce respiratory irritation and dust buildup—leading to a healthier environment and less HVAC wear and tear.
Deciphering MERV Ratings: Understanding the Numbers
The MERV Rating Scale Explained
MERV ratings typically range from 1 to 20:
- MERV 1–4: Basic filtration. Captures large dust particles. Common in older systems or budget filters.
- MERV 5–8: Good for standard residential use. Captures mold spores, dust mites, and pet dander.
- MERV 9–12: Better filtration for allergy sufferers. Captures fine dust, pollen, and even some bacteria.
- MERV 13–16: Hospital-level filtration. Captures bacteria, smoke, and even viruses.
- MERV 17–20: HEPA-level. Typically used in labs and medical environments—not compatible with most home HVAC systems.
What MERV Rating is Best for Home Use?
For most St. Louis homeowners, MERV 8 to 13 hits the sweet spot. Here’s a quick guide:
- MERV 8: Good balance of performance and cost. Ideal for homes without pets or allergy concerns.
- MERV 11: Great for homes with pets or mild allergies.
- MERV 13: Excellent for allergy sufferers or homes with high air quality needs.
Going above MERV 13 in a residential system could reduce airflow and increase HVAC energy use.
What MERV Rating Should I Use?
Choosing the right MERV rating depends on your lifestyle:
- Pets: MERV 11–13 helps capture pet dander and hair.
- Allergies or asthma: MERV 11–13 provides better filtration for pollen, mold, and to reduce allergens.
- Springtime allergies: Consider air purification systems with filters in the MERV 13+ range during springtime to keep seasonal pollutants minimal
MERV Ratings: Advanced Considerations and Common Questions
What is the Highest MERV Rating?
The highest possible MERV rating is MERV 20, which is equivalent to true HEPA-level filtration. These filters can trap microscopic particles such as viruses and bacteria. However, they’re typically only used in cleanrooms and surgical suites.
What MERV Rating is Too High?
While better filtration sounds great, higher isn’t always better. Using a MERV 16 or higher in a residential HVAC system can:
- Reduce airflow
- Overwork the blower motor
- Increase your energy usage dramatically
For most homes, MERV 13 is the maximum recommended rating.
How to Determine MERV Rating for Furnace
To find the correct MERV rating for your furnace filter, always consult the manufacturer’s specifications, typically located in the user manual or sometimes noted inside the filter compartment. Using the recommended rating is crucial, because installing a filter that’s too high for your system can impede airflow, reduce efficiency, and potentially even damage your furnace. If you’re unsure after checking these sources, it’s best to ask an HVAC professional for guidance during your next maintenance visit .
What MERV Rating is HEPA?
HEPA filters typically rate at MERV 17–20 and can capture 99.97% of particles as small as 0.3 microns. While not common in most homes, some air purification systems use HEPA-level filtration to complement your HVAC system.
Is a Higher MERV Rating Better?
Only if your system can handle it. Higher MERV filters remove smaller particles but may restrict airflow if your system isn’t designed for them. It’s about balance.
Choosing the Right MERV Rating for Your Home
Assessing Your Indoor Air Quality Needs
Understanding the relationship between indoor air quality and HVAC system filtration is key to selecting the right filter for your St Louis, Mo home. To gauge your specific requirements, consider these questions:
- Do you have pets?
- Does anyone suffer from allergies or asthma?
- Do you live near highways or construction zones?
These factors will influence your ideal filter rating.
Consulting HVAC System Specifications
Check your current HVAC manual or contact your HVAC company for guidance. Systems are designed with certain airflow tolerances in mind. Exceeding them with too dense a filter can do more harm than good.
Balancing Filtration and Airflow
Here’s a general rule: Use the highest MERV rating your HVAC system allows without compromising airflow. It’s not just about air cleanliness—it’s also about energy savings and equipment longevity.
Contact Meyer Heating & Air for HVAC Maintenance
Need help choosing the right filter or improving your air quality? Meyer Heating & Air is here to help.
We can inspect your system, provide MERV-compatible filter recommendations, and install whole-home air purification solutions if needed.
Call Now: (314) 845-1929, Text Us: (314) 845-1929 or book online now to schedule your HVAC filter consultation.
Let’s keep your air cleaner, your HVAC running efficiently, and your home more comfortable year-round.