Understanding the Different Types of Air Filters: A Guide for Maryland Homeowners

Presidential Heating & Air Conditioning

Gaithersburg HVAC Contractors


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Your home’s indoor air quality is important to the health and well-being of yourself and your loved ones. Regularly changing or cleaning your HVAC’s air filter is one of the simplest steps to improve it.

But with so many different types of air filters available on the market, choosing the right one for your home can be overwhelming. In this guide, Presidential Heating & Air Conditioning, HVAC technicians in Gaithersburg, MD, break down the different types of air filters and what you should know as a Maryland homeowner.

Types of Air Filters

MERV Rating

MERV stands for Minimum Efficiency Reporting Value, developed by the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE). MERV rating is a measurement system that evaluates the efficiency of air filters in removing airborne particles. It uses a scale from 1 to 20. The higher the number, the better the filtration capability.

Fiberglass Air Filters

Fiberglass air filters are the most basic air filters and have low-efficiency ratings. This type of filter has a flat-panel design and is made of layers of fibers that trap large particles such as dust, lint, and pollen. The MERV rating is between 2 and 4 because they do not trap smaller particles such as mold, bacteria, or pet dander.

Fiberglass filters need to be routinely replaced every month or two because they can quickly get clogged, reducing airflow and the efficiency of your HVAC system. They are inexpensive but do not offer the best protection for your indoor air quality and may become costly over time with the frequency of replacement.

Pleated Air Filters

Pleated air filters have a folded design that increases the surface area, which allows for improved particle capture and greater airflow. They are made of synthetic or natural fibers and offer a higher efficiency rating than fiberglass filters. Pleated filters typically have a MERV rating between 5 to 13.

The downside is that pleated air filters have the potential to reduce airflow to some extent due to their denser construction compared to flat panel filters. A pleated filter should be replaced every three months or when it becomes visually dirty.

Electrostatic Air Filters

Electrostatic air filters are washable and thus reusable. They are made of electrostatically charged synthetic fibers that trap small and large particles such as mold, pollen, dust, and pet dander. The  MERV rating depends upon the manufacturer. Electrostatic air filters should be cleaned and dried thoroughly before replacing monthly.

High-Efficiency Particulate Air (HEPA) Filters

HEPA filters are the highest-rated air filters. They are commonly used in hospitals, cleanrooms, and laboratories due to their ability to clean the air. HEPA filters trap viruses, bacteria, smoke, and fine dust. They capture 99.97% of particles as small as 0.3 microns..

Technically, HEPA air filters are not MERV rated because they exceed the ASHRAE test protocol 52.2 used to determine the MERV ratings. However, all HEPA filters would have a MERV 17 and higher.

It’s important to note that HEPA filters must be changed every 6 to 12 months for best performance and efficiency. A professional HVAC company can measure the airflow in your home and recommend the best whole-house air filter system for your indoor air quality needs.

Electronic Air Cleaners

Electronic air cleaners refer to electric ionizers or air purifiers that use an electric charge to attract and trap particles. They have a high-efficiency rating and can trap tiny particles, including smoke and bacteria. Electronic air cleaners can be installed in HVAC systems or as standalone units requiring periodic cleaning.

The iWave is one of the most popular air purifiers on the market for its ability to remove pathogens, including STAPH, MRSA, and E.COLI.

Choosing the right air filter for your Maryland home is an important decision that requires consideration of the efficiency rating, maintenance requirements, and cost. Understanding the different types of air filters and their strengths and weaknesses can help you decide what’s best for your indoor air quality needs. We suggest you consult your HVAC technician for their experience and recommendations based on your needs.

Schedule a consultation with an HVAC technician at Presidential Heating & Air Conditioning in Gaithersburg, MD, today!

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