In the alphabet soup of industry terms that residential contractors discuss with homeowners — HVAC, IAQ, Btu, etc. There’s at least a couple that don’t come up as often as others: ERV and HRV.
That’s according to the makers of energy recovery ventilators (ERVs) and heat recovery ventilators (HRVs), mechanical systems that can save energy on heating and cooling loads, improve air quality and lower homeowners’ utility bills year-round.
Many air quality experts say such systems are essential in modern construction. While homes today are more energy efficient because they are built extremely “tight,” most lack the natural ventilation of homes built in decades past. Spending hours in these “tight” indoor environments can lead to comfort complaints as well as symptoms of so-called sick building syndrome.
ERVs and HRVs can solve many of those issues, manufacturers say, since they ensure that “tight” structures can remain that way while also having the airflow they need to maintain comfort and increase the air exchange rate.
And for residential HVAC contractors, they offer excellent profit potential, whether sold with a new furnace and air-conditioning system, or installed as a retrofit with an existing unit.
How they work
HRVs work by capturing much of the heat that’s retained in system air being exhausted and preheating the fresh outdoor air entering the system. The result is a boost in the energy efficiency of HVAC systems. ERVs also capture and transfer moisture as needed. That means they precool and dehumidify during summer and preheat and humidify in colder seasons.
The result is a home that is able to maintain ideal relative humidity levels of around 30% to 50%, depending on the season, and comfortable occupants.
Unfortunately, the advantages of such systems are not always conveyed to builders or homeowners, said Nick Agopian, the vice president of sales and marketing with RenewAire, a Madison, Wis.-based manufacturer of ERVs.
“Contractors should think about the point of sale for ERVs and HRVs when a contractor is in a person's home, looking for an upgrade or changing the system or even working with the builder, Agopian said. That contractor should see the opportunity to sell the ERV option at that point. … They can’t go back to the homeowner and say, ‘Oh, by the way, do you want to buy an ERV?’ It doesn’t work.”
Agopian is an expert in building systems, having studied mechanical engineering in Montreal. He’s also a board member with the Home Ventilating Institute (HVI), and a voting member for ASHRAE committees 62.1 and 62.2, which deal with indoor air quality standards.
U.S. lags other nations
He pointed out that the U.S. is behind other countries in embracing ERV and HRV technology. For example, in Canada, such equipment is often required by local or provincial building codes.
While that’s not the case in the U.S., Agopian said some states, such as Vermont, do offer rebates to homeowners who install the equipment.
“What we recommend is that contractors follow SMACNA guidelines across the board,” he said. “Length of duct, static pressure in the duct, should the duct be insulated because it’s handling outdoor air. Simply follow the SMACNA guidelines.”
And in the case of ERVs, they offer a lot of flexibility, he added. “You can install it upside down. You can install it on an angle. You can install it right-side up,” Agopian said. “You can install it in any orientation you want, because there are no drain pans.”
Agopian pointed out another reason he recommends the technology to consumers: profits. For residential HVAC contractors, few pieces of equipment are as lucrative as ERVs, he said.
“It’s extremely profitable. They can make as much mar-gin on this one component as they probably do on the entire furnace and air conditioner,” he said.
Welsch Heating & Cooling Co. has long sold ERVs from brands such as Panasonic, Trane, Lennox and Fantech. They’ve installed the units in million-dollar homes as well as in Habitat for Humanity projects that are more modest but require Energy Star certification.
However, Matt Finch, a vice president at Welsch, said the St. Louis residential contractor doesn’t recommend them to a lot of homeowners, only putting in about 25 energy recovery ventilators per year, he said.
Finch said the company finds that other means of ensuring fresh air, such as using ventilating dehumidifiers, are a better fit in the humid Missouri climate. “We do a lot of the ventilating dehumidifiers,” he said, adding that builders prefer that technology in his area.
Like an HVAC system, ERVs and HRVs must be properly sized for where they're going to be installed. Timin Musallam, a RenewAire product manager, said the formula for determining the right ERV or HRV is based on ASHRAE’s IAQ standard 62.2. However, Musallam added, those calculations might be different depending on the homeowner’s ventilation goals. “It’s important to note that the ASHRAE standards only specify the minimum rates, and that it may be prudent to look at increased ventilation rates depending on the customer’s need," Musallam said. And fighting airborne viruses such as SARS-Co-V2, the coronavirus that causes COVID-19, is one reason why many homeowners are more interested now in indoor air quality than ever before.
Pandemic has increased interest
The COVID-19 pandemic has focused attention on IAQ in home environments, Agopian said. Balanced ventilation, high-quality filters such as MERV-13 and greater emphasis on disinfection all work to reduce the risk of coronavirus and other airborne viruses. ERVs can help boost a homeowner’s defense system.
“The pandemic has been devastating for a lot of people,” he said. “But the pandemic has also shown us that the buildings we live in can be potentially susceptible to adverse situations. Building systems really need to be resilient and a protection for us. And that’s opened our eyes to what we have to do inside buildings. … If you’re looking at all cognizant authorities, they’re all recommending increased ventilation. The United States has by far one of the lowest ventilating standards of homes among most developed countries in the world.”
That’s something that the HVAC industry, with a focus on technology such as ERVs and HRVs, can help change, Agopian said.