Can HVAC Handle MERV 12 Filters?

Learn about how modern HVAC systems handle high efficiency filters with a MERV 12 rating or higher and how they can improve indoor air quality (IAQ). Find out what factors play into using these filters.

Can HVAC Handle MERV 12 Filters?

If the MERV rating is too high for the oven fan motor or air handler to handle, the result will be low airflow. This can cause the AC coil inside or near your furnace or air handler to get very cold, potentially falling below 32F. Low airflow can cause the coil to freeze and become covered in ice, preventing your air conditioning system from doing its job. The goal of using a MERV 12 filter or higher is to improve indoor air quality (IAQ) by providing cleaner, more breathable air for everyone, especially those with allergies, asthma, COPD, etc.

The short answer is that it can, but it's not really a problem except in extreme circumstances. Most modern HVAC systems have no problem working with higher MERV filters, so millions of homeowners rely on them. The main risk of high-efficiency air filters comes from the fact that they are not modified for long periods of time. If you're aware of changing filters regularly, you're unlikely to experience filter-related issues with your HVAC system. Filters with a MERV rating between 1 and 3 can begin to trap particles in the 1.0-3.0 micron range.

This includes pet dander, lung-damaging dust and trapped automatic emissions. Filters in this range can trap more than 85% of particles with a size of 3.0-10.0 microns. A MERV 9 will trap less than 50% of particles with a size of 1.0-3.0 microns, the MERV 10 will stop up to 64%, the Merv 11 will get up to 79%, and the MERV 12 is capable of trapping up to 89%.In general, filters with higher MERV ratings are more effective and improve air quality, but they are also more expensive. Plus, higher doesn't always mean better for homeowners.

MERV ratings above 16 are commonly used in specialized commercial environments where air filtration is critical, such as hospitals. Typically, a filter with a higher MERV rating will reduce airflow. However, there are many other factors at play, such as the size of the filter and the type of fan motor in your HVAC system. A basic MERV 4 filter is probably the cheapest, but it won't trap certain small particles (such as dust mites and pet dander) that could be in your home. A MERV 5 filter will trap up to 34%, MERV 6 will stop between 35 and 49%, MERV 7 will prevent up to 69% and MERV 8 will trap up to 85% of particulates. The MERV scale is not linear; the difference between a MERV 6 and a MERV 8 is almost double in the percentage of particles captured.

Technology for HVAC units has progressed since then, and most modern units in recent years should be capable of at least one MERV 8 filter. It turns out that sometimes, due to the unintended consequences of high MERV filters, the cure is worse than the problem. Because higher speed filters allow less air to flow through the oven, it's a good idea to check if your system has a maximum MERV rating. What it represents in practice is a rating that informs how well the filter works to prevent contaminants from invading your HVAC system. However, if not, this information will answer “what is the MERV rating? What is the best MERV rating for my oven or air handler?” and similar introductory questions. The calculations seem to tell you that if you want to have the best air quality, you should buy a filter in the MERV 13-16 category and end the day. These filters are slightly more restrictive than MERV 1-4 filters and have the ability to trap mold spores and some pet dander along with dust and pollen. MERV 13 filters, for example, also remove bacteria, tobacco smoke, car fumes, insecticide dust, pet dander and more.

The fan draws air through the air filter and into the oven or air handler, where it heats or cools before pushing it through the ductwork into your home. Filters in this category can sometimes be called rock catchers because their job is to ensure that nothing too significant and devastating is absorbed by the HVAC unit at least. You are now equipped to monitor your air filter and change it regularly with the right MERV value for your home and family.