What Is a MERV Rating?

What is a MERV Rating?

Choosing the Right MERV Rating For Your Furnace Filter or Air Cleaner

MERV stands for Minimum Efficiency Reporting Value. It is simply a standard that rates the effectiveness of an air filter at removing particles from the air. A higher MERV rating number means the filter will remove finer particulate matter from the air. So, to find out how effective your air filter is at removing contaminants from the air, check out the filter's MERV rating.

Filters are tested for for their ability to trap particles such as pollen, dust mites, mold spores, dust, pet dander, bacteria and tobacco smoke. Here's a simple guide to measuring how effective the different MERV ratings are at removing various contaminants from the air in your home.
  • 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 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? However, 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 surface opening for air to pass through. This can make it harder for the HVAC system to force 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're better off having a whole home air filtration system. A furnace air filter is really only designed to keep your HVAC equipment clean to prevent wear and tear. A whole house air filtration system is specifically designed to clean the air inside the home.

Have questions about air filters? Call Superior Plumbing and Hearing. We can help answer all your filtration and air quality questions.
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