Will a HEPA filter on my HVAC Furnace System Trap Airborne COVID Type Particles?

May 13, 2021

HEPA filters are primarily known to those of us with sensitive lungs and allergies. However, the term HEPA filter is being googled and texted now almost as much as the word vaccination. When an idea of a thing has zeitgeist awareness, it is hard to stop thinking about it.

Compare new air-filtration possibilities to water-filtration: reverse osmosis, ultraviolet systems, and charcoal filters are a few common types of home water filtration systems of varying efficiency. A HEPA filter, just like a water filter system, can be a high-end solution or adequately designed for more minor concerns. Since COVID 19, HVAC systems capable of handling high-efficiency HEPA filters are becoming popular.


Can we just switch out our existing furnace or HVAC system filters for HEPA filters?

The quick answer to whether you can add a HEPA filter to an HVAC system or a current furnace is ‘it depends’.

A high efficiency filter added to your HVAC or furnace system is a competent solution to filtering all the air throughout each room of your home.

Most residential furnaces do not have a strong enough fan or motor to push the air through the thicker and tight weave of a higher efficiency MERV rated (read below to understand this important term) HEPA filter. Installing one would probably involve professional modifications to your HVAC system to introduce a high-efficiency HEPA filter. The system may need a more powerful fan installed to overcome the high pressure drop, says Mel Mossman, Chief Engineer at RS Means. Alternatively, a secondary blower can be installed in a newly introduced bypass system.


However, a lower MERV-rated HEPA filter or one deemed HEPA-type may be a possibility. Check with the manufacturer to ensure the blower and fan system will accept a slightly higher rated air filter, one with a MERV rating of 8-12.

An air filtration system with a MERV rating of 8-12 is enough to capture most regular airborne contaminates. The Coronavirus in theory should be stopped by a filter system with a MERV rating higher than 12 or 13. This information is taken from recommendations made by ASHRAE Epidemic Task Force in January of 2021.

Choosing an HVAC system with a higher rated HEPA filter is an aspect you should consider when changing your HVAC or furnace system.


Do HEPA filters stop the microscopic airborne Coronavirus particles? Yes, the higher MERV rating of the higher efficiency type HEPA filters, do stop them.

The Coronavirus has been proven to spread in several ways including through airborne particles (those that remain in the air after air is expelled through speaking, coughing or sneezing). Read this April 2021 CBC article that talks about the growing understanding of how the virus remains airborne. Therefore, it is one more particle to add to a list of air particulates we want to be removed using air filters. However, it has serious effects on our health, so arguably is the most important to fight:

  • Coronavirus particles
  • Pollens
  • Pet dander
  • Mould spores
  • Bacteria
  • Textile fibres
  • Tobacco smoke
  • Dust mites
  • Dust


Understanding MERV, the air-purifying rating system, determines the HEPA filter needed. The higher the number, the fewer particles that can pass through the filter. The higher the MERV number, the more you must replace the filter.

MERV, an acronym for Minimum Efficiency Reporting Value, is a rating system that measures the effectiveness of air purification in air purifiers, furnaces and air conditioners. It rates the filter’s performance in capturing airborne particulates from .3 to 10 microns in size.


  • Low-efficiency filters are rated as having a MERV rating less than 7-8.
  • An air filtration system with a MERV rating between 8-12 is enough to capture most airborne contaminants and is the rating used for efficient residential filter systems.
  • The Coronavirus airborne particles, in theory, will be captured in an air filtration system with a MERV rating 13 and higher.
  • An air filtration system with a MERV rating between 13-16 is used for hospitals.
  • An air filtration system with a MERV rating between 17-20 is only used in laboratory applications.


Portable Air Purifiers:

Last winter, one of those Canadian investigative-journalist television programs conducted scientific effectiveness tests on well known portable air purifiers. Can you guess what they found? It was determined that cost had little to do with performance, and their overall usefulness was, surprisingly, sometimes negligible. They looked specifically at the worthiness of UV lights and found they were almost always too small to do anything more than make the unit glow prettily.

You should keep a mental image of a Do-it-Yourself portable air filter that a scientist through together on the show. It was revealed to have the highest efficiency of all the portable air purifiers, using duct tape, a pleated HEPA furnace filter and a square portable floor fan. Just saying.


Ventilate your home.

Opening two opposing windows to create a cross breeze within the room you share with people will significantly clean the air in that room. Avoid standing in air currents that would direct airborne particles from one person to another person. It is healthy for us to have outdoor air moving otherwise motionless air and crucial to offsetting accumulated CO2 given off by our furnaces in the winter months.


What can we do Right Now with the Furnace System we Have Currently?

  • Change whatever furnace filter you have every three months to keep it functioning at whatever its peak efficiency is, and remember, the higher the MERV rated filter, the more frequent its required replacement.
  • Medium-efficiency filters for your home (MERV 8-12), often called ‘HEPA-type’ filters, can be less expensive than genuine HEPA filters and have less airflow resistance (so won’t impede your fan and blower requirements). Pleated 1-2” thick, they can often be installed without modifying your HVAC system or having to replace it. Always, always, always check the manufacturer’s information before purchasing filters.

Choosing an HVAC system with a higher rated HEPA filter is an aspect you should consider when changing your HVAC or furnace system. Plumbhouse Plumbing, serving London ON and the surrounding areas, offers several HVAC systems to suit your air filtration needs.

Call with any questions: 519 453 4650. We are here to help you.


Published by
May 13, 2021 2:09 pm

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