Air Condtioning Contractor San Antonio TX

Upgrades to residence air-con techniques could assist struggle the coronavirus

You wear a mask, social distance and make liberal use of hand sanitizer whenever you’re out of the house, just like the experts advise.

But what about when you’re at home? What can you do to keep yourself and your family safer from COVID-19 inside the house?

One obvious place to look is in your home’s heating, ventilation and air conditioning system, because all inside air eventually passes through it. Since we know the coronavirus is mostly transmitted by air, it makes sense to focus your efforts there.

But be wary. The virus is so new — that’s why it’s called a novel coronavirus — there’s a lot even the experts don’t know yet.

Still, lots of claims are being made about products that promise to zap viruses out of the air like so many arcade ducks. Some, such as high-efficiency air filters, are relatively inexpensive. Other options, including retrofitting your HVAC system with an ultraviolet light disinfecting unit, can cost thousands, and the jury is still out on their real-world effectiveness against the coronavirus.

Even if these steps won’t make you 100 percent safe from COVID-19 at home, they all will make your indoor air cleaner and so contribute to your respiratory health, which is always a good thing.

We talked to a number of experts to find out what homeowners can — and cannot — do to keep the air in their home as free of the virus as possible.


A high efficiency air filter should be able to remove most viruses in the air, including the coronavirus. Look for one with a MERV rating of 13 or higher.

slobo /Getty Images /iStockphoto

The first place to look is your HVAC’s air filter.

Viruses are very small. A micron is a millionth of a meter, and viruses are a fraction of a micron in size. “Naked” coronaviruses are rare in the wild, though; they usually come encased in tiny liquid droplets emitted when someone coughs, sneezes or just speaks. These particles can hang in the air for minutes or hours.

“A high efficiency air filter should be able to remove most viruses in the air,” said Max Sherman, a retired senior scientist at the Lawrence Berkeley National Laboratory in California and the Residential Team leader of the American Society of Heating, Refrigerating and Air- Conditioning Engineers’ epidemic task force.

Air filters are rated according to the minimum efficiency reporting value, or MERV. Ratings range from one to 16, and the higher the number, the finer the filtration.

“We recommend filters with MERV ratings of 13 or higher,” Sherman said. “These can catch even submicronic particles.”

MERV 13 filters are available on starting at about $18 each.

But even if a filter can remove aerosolized viruses, there’s no guarantee it’s going to protect you.

“If a husband and wife are sitting next to each other and he has COVID and coughs, the filter’s not going to be able to remove the virus before it reaches her,” said Ian Cull, president of the Chicago-based indoor air quality consulting Firm Indoor Sciences. “Maybe if the filter is between them, but it’s not going to do much good in the air handling unit.”

A good filter will remove dust, allergens, air pollution and other microorganisms in the air such as bacteria, mold and yes, viruses, he adds.

But it shouldn’t be your first line of defense.

Disinfecting Ultraviolet Light

A rendering of an ultraviolet disinfecting light unit installed in a residential air handling system.

A rendering of an ultraviolet disinfecting light unit installed in a residential air handling system.

Courtesy Fresh-Aire UV

Ultraviolet light has been used as a disinfectant for decades to destroy pathogens such as viruses, bacteria and other microorganisms in high-risk settings such as hospitals and, more recently, in schools, office buildings and restaurants.

Its use in homes is still debatable.

A type of UV light called UVC is used as a disinfectant. The light can inactivate H1N1 influenza as well as the coronaviruses SARS and MERS-CoV.

(Since viruses are not considered living things, they cannot be “killed.”)

A recent Italian study that went online June 26 on medRxiv, which runs unpublished papers awaiting peer review, found that exposer to UVC also inactivates SARS-CoV-2, the virus that causes COVID-19.

A residential UVC disinfection system will generally cost between $900 and $1,600, according to Phil Wistner, HVAC manager with Aramendia Plumbing Heating & Air. They can be installed in less than an hour.

Another alternative are stand-alone ultraviolet lighting units, which are available starting at about $100.

“These are helpful especially if you have someone in the house who is at a higher risk for COVID,” Sherman said.

Outdoor Air Ventilation

Outdoor air ventilation is a fancy term for bringing more fresh air into the house. The more fresh air, the more any virus in the air is diluted.

While building codes usually call for commercial buildings to have outdoor air ventilation systems, in most cities, including San Antonio, they aren’t required in residential homes.

In nice weather, the best, and cheapest, way to ventilate is simply to open a window. But in San Antonio, with its high temperatures and higher humidity, this isn’t always reasonable. Too much heat and humidity can strain an air conditioning system, making it burn more electricity.

There are several ways to bring air in outside without overwhelming your system, but one of the best is called energy recovery ventilation.

This involves the installation of a unit containing two fans, one that draws fresh air into the home, the other that pushes stale air out. As the two air streams pass one another, air from inside the house cools (or heats) and dehumidifies air coming in from the outside, so the HVAC system doesn’t have to work as hard.

Usually it will take a two-person crew from two to four hours to install an energy recovery ventilation system which, depending on the size of the home, will cost between $5,000 and $6,000, according to Wistner.

Richard A. Marini is a features writer in the San Antonio and Bexar County area. To read more from Richard A., become a subscriber. | Twitter: @RichardMarini