The Complete Guide to HVAC Air Filters

Understanding MERV Ratings

MERV (Minimum Efficiency Reporting Value) rates a filter's ability to capture particles. Higher MERV = finer filtration.

MERV 1-4: Basic filtration, captures large particles like dust and pollen.

MERV 5-8: Better residential filters, capture mold spores and pet dander.

MERV 9-12: Superior residential filters, capture fine dust and some bacteria.

MERV 13-16: Hospital-grade, capture smoke particles and some viruses.

Choosing the Right MERV

Higher isn't always better. Your HVAC system can only handle so much airflow restriction. Most residential systems work well with MERV 8-11. Check your system manual or consult a professional before using MERV 13+.

Filter Types

Fiberglass: Cheap but minimal filtration (MERV 1-4). Protects equipment more than air quality.

Pleated: Good balance of filtration and airflow (MERV 8-13). The sweet spot for most homes.

Electrostatic: Uses static charge to capture particles. Washable versions need regular cleaning.

HEPA: True HEPA filters are too restrictive for standard HVAC. "HEPA-like" filters are a marketing term.

When to Change

Check monthly. Hold up to light - if you can't see through it, replace it.

Replace at least quarterly. More often if you have pets, allergies, or during high pollen seasons.

After construction or renovation. Dust from work clogs filters quickly.

Don't Forget Filter Size

Write down your filter size (example: 20x25x1) and keep spares on hand. Running without a filter damages your system.

Need Filter Advice?

We can recommend the right filter for your system and install whole-home air purification if you need cleaner air.