What is a MERV Rating?

A MERV rating is something that helps comparing the performance of different home air filters. This number tells you how well the filter is able to remove particles from the air. The test to generate these numbers was developed by American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE). 

MERV Rating Chart

Below you will find the MERV rating chart. I fond the EPA website chart difficult to understand, so I made it easier for you. 

MERV Rating3.0 - 10.0 Microns1.0 - 3.0 Microns0.3 - 1.0 MicronsIs It HEPA?
1-4less than 20%--No
620% - 49.9%--No
850% - 84.9%--No
1085% +50% - 64.9%-No
1290% +80% - 89.9%-No
14-90% +75% - 84%No
16--75% +No
17+ (Not technically MERV tested)---Yes

What MERV rating is HEPA?

Technically, MERV filters are less than the minimum for HEPA. HEPA filters are high efficiency particulate air filters that remove 99.97% of all particles .3 nanometers in size. MERV Filters use different tests than the HEPA filters, but typically MERV filters will not be HEPA filters as shown in the chart above.

You can shop our selection of trusted HEPA filters here. 

What is a good MERV Rating?

The higher the MERC rating, the more (and also smaller) particles the filter removes from the air. The higher the MERV Rating, the cleaner your air will be. 

The downside of this is that your HVAC system will need to work harder as you increase your MERV Rating. In order for your HVAC to cool your home, it will need to exert more energy to do that, resulting in an increased energy bill.  

Our current recommendation is to use a filter with a Minimum Efficiency Reporting Value (MERV) of 13, but a MERV 14 (or better) filter Is preferred. Of course, the ultimate choice needs to take the capabilities of the HVAC systems into consideration. Generally, increasing filter efficiency leads to increased pressure drop which can lead to reduced air flow through the HVAC system, more energy use for the fan to compensate for the increased resistance, or both. If a MERV 13 filter cannot be accommodated in the system, then use the highest MERV rating you can.

ASHRAE

Is MERV 13 too High?

According to ASHRAE (The American Society of Heating, Refrigerating and Air-Conditioning Engineers) recommends MERV 13 for residential HVAC units and higher if possible. However, if you are looking reduce your energy bill, you could consider using a lower MERV rated filter. 

Will a MERV 13 hurt my furnace?

MERV 13 filters should not hurt your furnace, however they will require your HVAC unit to work harder as there is less air flow when compared to lower rated filters. This will require your HVAC unit to work harder and this could cause excessive wear and tear on your unit. 

Is MERV 8 good enough?

ASHRAE recommends MERV 13 for residential HVAC units and higher if possible, but many units will be fine with lower MERV ratings if you are not terribly concerned with the air quality. MERV 8 filters will remove a majority of the tiny particles that are floating around in the air. It will not remove the smallest particles like the highest rated filters, but will still do a good job. 

What MERV rating is best for Covid-19?

To better protect yourself from COVID in your home, use MERV 13 filters or higher according to ASHRAE. This will help to filter out unwanted particles in the air. 

ASHRAE is recommending that MERV 13 filters be used where possible, with MERV-A 13-A or MERV 14 preferred. This is pushing the use of higher efficiency filters in many buildings. For locations that can’t upgrade the HVAC filter or increase outdoor air during winter, in-room units are recommended to add cleaning capability. These units should include high MERV or better filters to remove most of these virus-laden particles.

ASHRAE

Do HEPA air purifiers work for coronavirus?

HEPA air filters are a classification of air filters that are “High Efficiency” meaning they collect viruses that are very small, including the Coronavirus. However, the HVAC unit needs to be turned on in order for the filter to collect the virus. Also, the filter would not prevent the virus from being transmitted before the air gets moved through the filter.

Example: You come home from work after being exposed to the virus and you hug your kids as you walk through the door. This would not prevent you from transmitting the virus as the filter was not able to process the air in time. 

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