MERV ratings- All you need to know

MERV or Minimum Efficiency Reporting Value is a system that evaluates the efficiency of an air filter based on its effectiveness in capturing dust and other contaminants of various sizes. MERV ratings help in analyzing and choosing the best air filter for your HVAC system or furnace so that you get clean and healthy air to breathe.

The common particles that these air filters captures are:

  1. Dust mites
  2. Pollen
  3. Mould spores
  4. Dust
  5. Pet dander
  6. Textile and carpet fibres
  7. Bacteria
  8. Tobacco smoke

The MERV ratings range from 1 to 20. The higher the MERV rating, the higher is the air filtration capability of the air filter. The residential filters are rated between 5 to 13 and the filters with MERV rating above that are mostly used in hospitals, hi-tech industries, clean rooms, and nuclear power plants. The ratings from 1 to 4 are not very efficient and filter out very few particles, therefore are very rarely used.   

Is a higher rating better?

It is common thinking that the higher the rating, the better it is. But the same thing doesn’t apply to the MERV rating. Though the filters with higher MERV ratings are more capable of capturing the smaller particles, it has some negative side as well. The highly-rated filters have smaller pores for airflow. This in turn creates more resistance on the system than it is designed to manage, leading to a negative impact on the efficiency of the system. The restricted airflow also makes the air quality in your home worse.

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Changing the air filters

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The air filters with a higher MERV rating have smaller pores that clog up easily. Therefore, such filters are required to be replaced at least after every three months. It prevents your system from any damage and/or inefficiency by avoiding any airflow restriction. It is important to keep the air filters always clean to improve the efficiency and lifespan of your HVAC or furnace system. 

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What are the best filters as per MERV ratings?

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There are different types of HVAC air filters available for you to choose from. Proper research and understanding about the air filters and your HVAC system are very important. While selecting the right filter for your HVAC unit, consider all your options and requirements, and also the MERV rating for various filters. 

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Let us see what ratings are provided to the different types of air filters, to understand which air filter will be best for your home.

  1. Fibreglass filters– These types of filters have thin and flat surfaces, which have the capability of capturing larger particles only. The smaller particles are out of their reach. They are cheaper and less effective in cleaning the indoor air. The fibreglass filters are required to be replaced at least once every month. They have a MERV rating ranging between 1 to 6. 
  2. Electrostatic filters– These filters use electrostatic charges created by airflow through the static-prone fibres maze, to capture the particles in the air. They are able to capture the smaller particles and are good for homes having children, pets, and/or smokers. The electrostatic or reusable filters are affordable and are required to be replaced at least once every three months. They have a MERV rating between 6 to 8.
  3. Pleated filters– In comparison to the fibreglass filters or the electrostatic filters, pleated filters capture more and finer particles from the air you breathe. Its pleats provide greater coverage of the pollutants. These filters are required to be replaced once every three months and are also very affordable. Their MERV rating score comes between 8 to 15. 
  4. HEPA filters– These filters have the highest MERV rating that ranges between 16 to 20, but they are not usually preferred for home usage due to their cost and complexity. These are mostly used in hospitals, hi-tech industries, and also nuclear plants. The HEPA filters have the capability to filter out the smallest particles, including the microparticles. Thus they provide the cleanest air for you to breathe. 

MERV rating is a standard fixed to help in choosing the best and right filter for your HVAC system and furnace. So, keeping these ratings in mind while choosing the air filter for your home is a good and highly advised thing to do. Keep an understanding of all the important and basic factors before buying anything and then make an informed decision.

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  1. 1

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    Thank you for mentioning that the highest MERV rating is not always the best option. A pleated filter with a MERV rating in the 7 to 12 range would be enough for residential buildings, including homes with allergy or asthma sufferers.

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