Choosing the Right MERV Rating for Your HVAC System

If you want to find out how effective your air filter is at removing contaminants from the air, check the filter’s MERV rating. MERV stands for Minimum Efficiency Reporting Value. MERV is a standard that rates the effectiveness of air filters. A higher numeric rating means the filter will remove finer particulate matter from the air.

Filters are tested for for their ability to trap pollen, dust mites, mold spores, dust, pet dander, bacteria and tobacco smoke. Here are how effective the different MERV ratings are at removing various contaminants from the air.

1-4 : Filters out pollen and dust mites.

5-8 : Removes mold and dust.

9-12 : Traps lead dust and most bacteria

12+ : Filters out all bacteria and tobacco smoke

When choosing an air filter for your HVAC system it may seem like a good idea to buy the filter with the highest MERV rating, since you want to have the cleanest air possible, right? In most cases, you should use a filter in the 5-8 range. The reason is that filters with a high MERV rating will have the smallest pores for air to pass through. This can make it harder for the HVAC system to push air through the filter, reducing system performance. To avoid restricting the air flow, filters with a higher MERV rating should be changed more frequently (at least every three months) to prevent damage to the HVAC system.

Ultimately, if your home’s air is dirty enough to require a higher MERV rating, or you’re changing air filters more than once a month, you may be better served by having a whole home air filtration system. A furnace air filter is really just designed to keep your HVAC equipment clean to prevent wear and tear. A whole house air filtration system is designed to actually clean the air inside the home.

Have questions about air filters? Call ABC Southwest Plumbing & Air Conditioning. We can help answer all your questions.