The Air Filter in Your HVAC System: An Easy Guide to MERV Ratings

It can be overwhelming as you stand in front of the wall of air filters at your local hardware store. They all look pretty similar. You ask the salesperson and they suggest a MERV 12, but you have no idea what that means. The following guide will help you make a smart choice when it comes to buying your next air filter and save you from making the costly mistake of choosing the wrong one.

What is MERV?

MERV stands for minimum efficiency reporting value, and it tells you how effective your air filter will be at removing airborne particles from your home. The rating scale ranges from 1 to 20. Higher ratings indicate greater filtration capabilities.

• MERV 1-4: Removes pollen, dust mites, cockroach body parts, sanding dust, textile and carpet fibers
• MERV 5-8: Removes mold spores, cat and dog dander, hair spray and dusting sprays
• MERV 9-12: Removes humidifier dust, lead dust, flour and auto emissions
• MERV 13-16: Removes bacteria, cooking oil, sneeze droplets, most smoke and dust from insecticide spray
• MERV 16-20: Removes viruses and all smoke

How much protection do you need?

Most people use a basic 1-inch, disposable, fiberglass air filter in their furnace or air conditioner because that’s what they have always used. This type of air filter will protect the HVAC systemfrom large particles that could cause mechanical failure, but that’s about it.

To improve the actual air quality in your home, choose a filter with a higher rating — a filter in the 9-12 range is a better choice. Anything with a MERV 16 or higher is known as a HEPA filter. These air filters provide the highest level of protection from airborne contaminants, but they can require expensive modifications to your existing HVAC system. All filters need to be changed according to manufacturer’s recommendations in order to provide the indicated level of filtration.

At Davis Air Conditioning and Heating, we can work with you to choose the best air filter for your home. Residents in the greater Houston area have been counting on our commitment to quality since 1971.