Understanding the Differences Between MERV and HEPA Filters
Your HVAC system’s air filter plays an extremely important role in the life and health of the system. Specifically, the filter works to trap airborne particles to prevent them from getting inside the system and potentially damaging its various components. There are also more highly rated filters that can help to improve indoor air quality by filtering out many airborne allergens, germs, and pollutants. With this in mind, here is everything you need to know about the differences between MERV and HEPA filters to ensure you can easily choose the best filter for your home’s HVAC system.
The MERV Rating System Explained
Most HVAC air filters are rated in terms of efficiency using the MERV (Minimum Efficiency Reporting Value) scale. This system measures how efficiently the filter can trap particles ranging in size from 10 down to 0.3 microns. Each filter is tested to determine the percentage of particles of varying sizes that it can trap and then assigned a rating based on the results.
At the lowest end of the scale are MERV 1 to MERV 4 filters, which can only trap around 20% of the largest particles between 3 and 10 microns. On the highest end of the scale are MERV 13 to MERV 16 filters, which are capable of trapping at least some particles down to 0.3 microns. These smallest particles include things like bacteria, exhaust fumes, pet dander, and tobacco smoke.
True HEPA Filters
The MERV scale technically goes up to MERV 20, and anything from MERV 17 and above is considered a true HEPA (High Efficiency Particulate Air) filter. Whereas a MERV 16 filter can trap around 95% of the typical household airborne particles, a HEPA filter is capable of capturing 99.97% of all airborne pollutants and contaminants.
The biggest difference between a higher rated MERV filter and a true HEPA filter is how effective they are at filtering out tiny airborne particles down to 0.3 microns in size or smaller. Both MERV 16 and HEPA filters should trap nearly 100% of larger airborne particles from 1 to 10 microns, but only true HEPA filters can achieve similar results for even the smallest particles. Although a MERV 16 filter can technically trap close to 95% of the airborne contaminants found in typical residential and commercial settings, this type of filter is only around 80 to 90% effective at trapping tiny particles of 0.3 microns or smaller.
HEPA filters are commonly used in things like vacuum cleaners and portable air filtration systems. They can also be used in some HVAC systems, but this isn’t all that common outside of certain laboratory, industrial, and hospital settings. In fact, even hospitals only use HEPA filters in certain areas that need to be extremely sterile, such as some specialized surgical or operating rooms. Otherwise, hospitals typically use something between MERV 14 and 16 filters for inpatient rooms and general surgery and usually around MERV 11 or 12 for all other areas.
Part of the reason that HEPA filters are so rarely used in HVAC systems is that they are extremely restrictive in terms of airflow. This means that the system needs to be extremely powerful and use additional fans in order to properly draw air through the HEPA filter and circulate it throughout the room or building.
Other Air Filter Rating Systems
Although the MERV scale is the most commonly used system for rating HVAC air filters, there are two other systems you may come across. Both 3M and the Home Depot have their own proprietary rating scales for all residential air filters they produce. 3M uses the MPR (Micro-Particle Performance Rating) scale, and Home Depot filters are rated using the FPR (Filter Performance Rating) system.
FPR is determined in basically the same way as MERV in terms of measuring how effective the filter is at trapping particles of different sizes. The FPR scale ranges from 5 to 10, with FPR 5 equaling MERV 8 and FPR 10 being the equivalent of MERV 13.
The MPR scale is slightly more complicated as this system only looks at how well the filter can remove particles smaller than 1 micron. This scale ranges from MPR 100 to 2800, with the higher numbers equaling greater efficiency. An MPR 100 to 200 filter is similar to MERV 6, whereas MPR 2800 equates to MERV 13.
At first glance, these other rating systems may be slightly confusing. Luckily, there are numerous resources and charts available online that show you exactly how FPR and MPR compare to MERV. This makes it simple to choose the right filter for your home no matter what rating system is used.
Choosing the Best Filter for Your Home’s HVAC System
Most residential HVAC air filters range between MERV 5 and MERV 13. Anything under MERV 5 is generally not sufficient to prevent potential damage to your HVAC system, and these lowest-rated filters are primarily used for things like window AC units.
On the other hand, anything above MERV 13 is usually too restrictive in terms of airflow to be used in a normal residential HVAC system. If you try to use too efficient a filter in your HVAC system, it can dramatically decrease the efficiency and effectiveness of your system. This can lead to insufficient heating or cooling as well as drastically increased energy costs. It can also potentially damage your heating and cooling equipment leading to increased repair needs and a shorter lifespan.
Choosing the best air filter for your home’s HVAC system is a matter of balancing air quality needs and cost. The higher-rated filters like MERV 12 or 13 tend to be quite a bit more expensive. However, they are still definitely recommended for anyone who suffers from respiratory issues or allergies, as they will do a much better job of eliminating most airborne allergens, pollutants, and contaminants.
On the other hand, if you don’t suffer from any breathing problems or aren’t as concerned about indoor air quality, then you can definitely get away with using a less expensive MERV 5 to 8 filter. While these filters won’t remove pollen and other contaminants from the air, they are still efficient enough to ensure that dust and other larger particles don’t damage your HVAC system.
How Often Should an Air Filter Be Replaced?
No matter what type of filter you decide to use, it is essential that you inspect it regularly to make sure it isn’t overly dirty or clogged. Under normal circumstances, you should be replacing your filter somewhere between every one to three months. Three months is typically fine during times when your heating or air conditioning doesn’t get much use. Still, you will definitely want to change the filter more often during the middle of summer or winter when your HVAC system runs much more frequently.
Expert Heating and Cooling Services
At Custom Comfort Air, we have been proudly serving customers in Rosenberg, Sugar Land and the surrounding areas for more than 50 years. We offer a full range of heating and cooling services, including preventative maintenance, repairs, and installation. If you are experiencing any issues with your home’s HVAC system or looking to replace your old heating or cooling equipment, our expert technicians will be happy to show you what makes us the area’s top-rated HVAC company. We are proud to have an A+ rating from the BBB, and our commitment to customer service is evidenced by our winning the BBB Award for Excellence 13 years in a row. No matter what type of HVAC service you need, give the pros at Custom Comfort Air a call today to see how we can help.