Air Filter Types for Residential HVAC Systems

Types of Air Filters

There are many types of air filters used in HVAC systems for your home or business. From more basic fiberglass and pleated filters to HEPA, Carbon, Washable and Electrostatic. The main purpose of an air filter is to protect your equipment from clogging up with dust as well as improve indoor air quality by trapping air born particles like dust, pollen, etc.

Air Filter MERV Rating

The industry standard for Air filter ratings is the Minimum Efficiency Reporting Value. The MERV scale is from 1 to 20 and is calculated using the air filters efficiency and captured particle size. For a residential home a MERV rating between 8 and 12 is typically used to help protect equipment and to maintain air quality. Going higher on the MERV rating will result in a more efficient filter that can trap smaller particles but at the cost of a higher air restriction to the system. Air filters with a Higher MERV rating will cause higher air flow restrictions. This can cause issues for HVAC systems that are already running at their Blower motor Static pressure limit. Staying within a MERV rating between 8 and 12 for a residential system will typically offer very good filtration without causing the blower motor to struggle pulling air through the air filter.

There are other types of Air filter rating scales like FPR. All air filter scales can be compared to the standard MERV rating using a cross reference chart.

Fiberglass Air Filters

Fiberglass air filters are on the least expensive type of filter. They are typically made from spun glass threads with the lowest MERV ratings. These filters will only be able to trap larger particles but have almost no effect on air flow. For systems with undersized air duct systems and blower motors that are working past their pressure limits, these filters are a good basic option. These are typically rated between MERV1 and 4.

PLEATED Air Filters

Pleated air filters are made from Cloth that is pleated into a series of folds to help increase filtration surface areas. These are the most often used air filter for residential HVAC systems in our Gresham and Portland area. These filters offer a great balance between particle filtration and air flow restriction making them an ideal choice for a home heating & cooling system. These filters are also capable of capturing allergens like pollen and pet dander. Pleated air filters typically have a MERV rating between 7and 13.

HEPA Filters

HEPA stands for High Efficiency Particulate Air. These filters are typically made from tightly woven fiberglass or synthetic fibers. These filters are typically used for specific applications like hospitals and clean rooms. HEPA filters are very efficient at trapping very small particles that are 0.3 microns in size. Before installing a HEPA filter in your home it is highly recommend to consult an HVAC service company to confirm static pressure readings. This will help determine if your system will be capable of running a HEPA filter or if system/ filter upgrades are required. HEPA filers have a MERV rating of 17 or higher.

CARBON FILTERS

Carbon filters are made from active carbon and are used to trap odors and VOCs (Volatile Organic Compounds). These filters trap air born particles as well as odors/ gases, offering an all in one filter for particles and odors. These filters are recommend for home renovation or when using strong cleaning products to help remove VOCs that are left in the air inside of your home.

Washable Air Filters

Washable filters for HVAC residential systems are typically made from a synthetic durable fiber. These filters are designed to be washed or vacuumed and re used. This eliminates the need to purchase replacement air filters. Washable air filters have a typical MERV rating of 8.

Electrostatic Air Filters

Electronic air filters typically use an electrostatic charge to ionize air particles, causing them to stick to oppositely charged collection plates. These are typically a 2 part filter system that is washable and reusable. These filters have an estimated service life.

Air Filter Recommend Replacement Schedule

Every air filter will have a recommended replacement schedule on the filter or packaging. Based on our Gresham area we have also our own professional opinion for air filter replacement. We recommend replacing 1" thick air filters once a month to help maintain proper air flow and filtration for your system. 4" thick air filters we recommend replacing every 3 months. If you are using washable air filters we recommend washing them once a month or the interval set by the manufacturer. Washable air filters used on ductless mini split systems are recommended to be washed every 2 weeks by some manufacturers.

CONCLUSION

Air Filters are a critical part of a residential HVAC system. They are designed to protect your system equipment from failure as well as improve indoor air quality. For typical HVAC systems here in the Gresham area, pleated air filters with a MERV rating from 8-12 are used.

If you are considering upgrading your air filter or improving your home indoor air quality. Give us a call or book us online to set up an appointment.

This Blog is written by Anton Bocharov (Owner) of A&B Air Solutions LLC.