Understanding The Many Types Of AC Filters

Posted on: 3 May 2019

Think that all air conditioning filters are the same? Think again! You are hopefully aware that your HVAC system needs to have its filter changed on a regular basis, but you may not be aware that the filter that you choose can have a number of effects on your home's air quality and even the efficiency of your entire HVAC system. Leaving old, dirty filters in place can cause your system to run inefficiently and cost you money over the long run, but choosing the wrong filter can have negative effects on your home's climate as well.

Choosing the right filter isn't always easy, but this guide will help give you an overview of the basic types that are available.

MERV Rating

HVAC filters are always given a MERV rating. This value, which stands for Minimum Efficiency Reporting Value, provides you with an at-a-glance view of a filter's efficiency. The higher a filter's MERV value, the more efficient that filter is at trapping debris. Filters with a MERV value of 4 or less can effectively trap pollen, dust, and other larger particles, while filters with MERV values of 13 and higher can potentially even trap bacteria.

Washable vs. Disposable

Filters are broadly divided into washable and disposable categories. As you might expect, disposable filters need to be replaced on a regular basis. Washable filters, on the other hand, can be gently cleaned with water and soap. Some people choose to vacuum off their regular disposable filters, but these filters are not designed for reuse, and it is nearly impossible to clean them thoroughly enough to avoid problems down the line.

Choosing to use washable filters is largely a matter of cost. These filters are generally more expensive, but they may save you a few bucks down the line as they need to be replaced less often. On the flip side, disposable filters are generally cheap and reusable filters will often not save a large amount of money.

Fiberglass vs. Pleated Filters

Fiberglass and pleated filters are the two most common types available for most home HVAC systems. Fiberglass filters are the traditional, disposable filter that most homeowners are familiar with. These are basic mechanical filters that work by capturing large particles and preventing them from entering into your home through your ducts. Fiberglass filters are cheap and effective at preventing larger material from flowing throughout the house. They also tend to be fairly good at allowing unrestricted airflow.

Pleated filters are more expensive, but they are also more effective at trapping smaller particles. This makes pleated filters a better choice if indoor allergies are a concern, as most pleated filters will be capable of catching larger allergens. The downside to pleated filters is that their much higher MERV value means that they have the potential to restrict airflow, reducing the overall efficiency of your HVAC system.

What About HEPA Filters?

HEPA stands for High-Efficiency Particulate Air, and it is an alternative to the MERV rating that many filters. HEPA filters are at the extreme high-end of the scale and would generally carry a MERV rating of 17 or greater, much higher than the majority of fiberglass and pleated filters available on the market. HEPA filters are extremely efficient, but they have the same potential downsides as higher MERV pleated filter. This means that they are both costly and they will potentially restrict your system's airflow, forcing your air conditioner to run less efficiently.

Ultimately, choosing the right filter for your needs is more complex than simply selecting the cheapest filter or the filter with the highest MERV rating. The filter that is right for you will depend on the overall design of your system as well as which types of air contaminants you are interested in filtering out. If in doubt, consulting with an air conditioning service technician is a great way to create a maintenance plan that is right for your home.