Shipton's CleanAir Solutions Blog
HEPA Filter vs MERV Filter - Which Is Better for Your Indoor Air Quality?
Two years ago, the topic of air filtration rarely came up. And if you were talking about indoor air quality, you were probably just working in a related industry.
Today, all that has changed. Now, everyone is interested in filtering and purifying their indoor air. We realize that air quality is directly linked to health! It can even help protect us from coronavirus and many other airborne illnesses and pollutants.
But what isn't quite so clear yet is what does what. There is a whole new language to learn, complete with new acronyms and vocabulary!
In this post, we tackle one of the most common sources of indoor air quality confusion. A MERV filter vs a HEPA filter.
What does each type of air filtration system have to offer? How can you be sure which one is best for you? Let's find out!
What Is a MERV filter?
MERV stands for Minimum Efficiency Reporting Value. Air quality experts often talk about "MERVs” when they are discussing the effectiveness of various air filters to capture a certain class of airborne solid particulates.
MERV-rated air filters are designed to capture particles between 0.03 and 10 microns in diameter. To give you some perspective, 0.03 microns is about 1.181102e-6's of an inch and 10 microns is about 0.00039's of an inch.
So here, we are talking about pretty small particles.
Still, not all air filters are capable of capturing the smallest airborne solid particles.
This is where we turn to MERV ratings to help us select the air filter that is right for our indoor air quality concerns and needs.
Let's take a quick look at the ASHRAE official MERV rating chart to get a sense of how this might work.
- MERV rating 1-4: can trap pollen, dust mites, carpet fibres, dust/sawdust.
- MERV rating 5-8: all of the above plus mould spores, lint and concrete dust.
- MERV rating 9-12: all of the above plus lead dust, legionella, coal dust and humidifier/nebulizer dust.
- MERV rating 13-16: all of the above plus tobacco smoke, bacteria, car fumes, insecticide dust, cosmetic dust, sneeze particles, copier ink fumes and pet dander.
- MERV rating 17-20: all of the above plus virus particles and carrier particles, salt, carbon and radon dust, micro-allergens and combustion smoke.
What Is a HEPA Filter?
HEPA stands for High-Efficiency Particulate Air. But are there different types of HEPA filters?
Not really. All true HEPA filters must have passed the HEPA standard test for filtration efficiency.
So be careful when reviewing the marketing information about different types of air filters. For example, saying a filter is "HEPA-like" is not the same as saying a filter is a HEPA filter.
There is also such a thing as medical-grade HEPA. The difference between regular HEPA (HEPA 10-12) and medical-grade HEPA (HEPA 13-14) is a very small one, but is vital if what you are trying to trap is a tiny COVID-19 aerosol riding on an equally tiny solid airborne particulate.
At a minimum, any HEPA filter you choose should be rated as a true HEPA filter.
Can You Upgrade Your MERV Filter to Work With Your Existing HVAC?
Every day, we get calls from excited homeowners and employers who want to know if they can just take out their existing HVAC air filter and put in a higher-rated MERV filter or a HEPA filter instead.
We truly wish it were this easy.
But the truth is, there is a reason the furnace and A/C you have right now is only rated to work with a certain level of MERV filter. The reason has to do with the blower motor and fan.
The highest-rated MERV filters and all HEPA filters are made of incredibly dense material. They have to be dense to trap such incredibly tiny airborne particles.
This means the HVAC blower motor must be incredibly powerful to push air through the filter with sufficient force so that the unwelcome particles get trapped in the air filter.
If you try to retrofit an HVAC system with a higher grade of MERV filter (or HEPA equivalent) than it is rated to run with, you run a very high risk of either overheating the blower motor and starting a fire or literally burning out the blower motor.
What Can You Do to Improve Indoor Air Filtration Without a New HVAC system?
Luckily, there is another way you can improve the air filtration at your home or workplace without having to upgrade your entire HVAC system.
What we recommend here is to upgrade to a new standalone or integrated HEPA filter system.
There are two ways you can do this.
We can add on an aftermarket HEPA filtration system if you have a central HVAC system that works with an existing air duct system. This system will bypass the blower motor and filter the air after it leaves your furnace, AC and before it enters your air ducts for distribution.
If you do not have ducts, we can add one or more standalone HEPA air filtration units that are appropriately sized for the size of your space.
This is an efficient and affordable way to get all the benefits of HEPA-grade air filtration today.
Shipton's CleanAir Solutions in Hamilton, Ontario, is Your Indoor Air Filtration Expert
We are proud to have been serving our customers in Hamilton, Ontario, and surrounding areas for nearly 100 years!
Our residential and commercial HVAC and indoor air quality clients trust us to provide superior air duct cleaning, air filtration, ventilation and a wide variety of other highly effective indoor air quality aids. We even offer air purifier and whole-house humidifier solutions!