A closeup of energy transfer coils on an ERV

Because of rising levels of dust and pollution, many homeowners prefer to keep their windows and doors closed to prevent these contaminants from entering their homes.

While this can prevent allergy flare-ups and respiratory issues, it can deteriorate air quality inside your home, which is particularly true if you have a big family or multiple pets living with you.

Fortunately, energy recovery ventilators (ERVs) offer an effective solution to this problem. They regulate moisture and humidity levels inside your home and ensure fresh and clean air circulation. 

But before you decide to purchase an energy recovery ventilator unit, let’s investigate what it means to recover energy when using an ERV. This way, you can be sure about the technology you’re investing in.

What Does It Mean to Recover Energy Using an ERV?

An ERV utilizes HVAC exhaust air to pre-cool or preheat the air entering your home or building. This process collects or ‘recovers’ some cooling or heating output that would otherwise be lost, depending on the season.

Energy recovery ventilation is based on air-to-air heat exchange, using a stationary core or a spinning wheel where airstreams exchange energy without mixing.

An energy recovery ventilator exchange component and vents on a home's exterior
  • The energy recovery ventilator system preheats the incoming air during winter by collecting the heat from the warmer exhaust air. The system even recovers some heat from cooking, washing, and the water heater to warm up the air entering your home. 
  • In summer, the system pre-cools and dehumidifies the incoming air by exchanging energy with the drier and cooler exhaust air. 
  • As a result, ERVs cut down the electricity consumption of HVAC systems while enhancing indoor air quality. 

However, as the laws of thermodynamics limit the system, an ERV cannot attain 100 percent energy recovery. 

The effectiveness of an ERV unit is certified by the Air-Conditioning, Heating, and Refrigeration Institution and it varies depending on specific environmental conditions. The performance is usually defined independently for winter conditions and summer conditions. 

Heat Recovery vs Energy Recovery 

There are two primary ways to recover energy through air exchange. 

These ways use a configuration that sends outgoing and incoming airstreams simultaneously through specialized channels. Even though the two airstreams don’t mix, either cooling or heating energy is transferred depending on the season. 

Heat recovery ventilators can recover sensible (dry) energy only. On the other hand, energy recovery ventilators use an enthalpy procedure that recovers both latent (moisture) and sensible (dry) energy. 

This additional function ultimately helps increase comfort and reduce operating costs. Nevertheless, it is essential to remember that an ERV won’t actually lower relative indoor humidity.

The key advantage of this system in a humid region is that the incoming air will have less moisture content when compared to a heat recovery ventilator.

ERVs capture humidity from the exhaust air during winter and transfer it to the incoming fresh air, which can eliminate the need to use artificial humidification methods. 

Technology Used by Energy Recovery Ventilators 

ERVs can recover up to 80% of the energy usually lost in the energy exchange process depending on the technology used. In addition, introducing pre-conditioned air into an AC system can reduce the overall capacity needed to cool your home.

According to estimates, reducing a single-zone air conditioner from 20 to 18 tons can result in savings equivalent to 23% of the ERV’s total installation cost

Here is an overview of the four principal technologies for energy recovery ventilators. 

1. Rotary Wheel 

Rotary energy recovery ventilators employ a constantly rotating wheel made from plastic or metal that passes through the inlet airstreams and the exhaust. The wheel gains energy from one side of the system and transfers it to the other side. 

ERVs with metal wheel models can transfer sensible energy only. However, systems with a plastic wheel can capture and release latent energy. The best thing about rotary wheels is that they are relatively cheap, compact, and easy to maintain. 

2. Fixed Plate

Certain HVAC contractors only install fixed-plate energy recovery ventilators as they don’t have any moving parts that can break down or wear out.

Even though they are larger than rotary wheel ERVs, these units might be the ideal solution for bigger buildings and institutions with accessibility problems. 

In a fixed-plate model, the airstreams flow through several isolated chambers. As air passes through, energy is transferred from the indoor exhaust air to the fresh air intake through the media. Manufacturing companies generally make fixed-core plates in metal and plastic. 

3. Heat Pipes

Heat pipes are a relatively rare option as they cannot recover latent energy. So instead, the unit employs a cooper piping network charged with refrigerant.

The tubes are located between the fresh air and exhaust streams. One airstream heats the refrigerant, whereas the other stream cools the pipe. As the refrigerant condenses, it transfers energy to the cooler side.

4. Runaround Coils 

These units are used in bigger facilities where a significant distance separates the outdoor and indoor airstreams.

Along with the refrigerant, these systems use separate water coils installed inside the fresh air and exhaust sides of the system. Runaround coils are only capable of transferring sensible energy. 

The Case for Energy Recovery Ventilators 

There are plenty of reasons why you should invest in an ERV, including:

1. Better Indoor Air Quality 

When an energy recovery ventilator removes stale air out of your house, it also removes the pollutants it contains.

In addition, it also filters the incoming air, capturing contaminants including dust, pollen, and other pollutants before they can make their way into your home. This leads to better indoor air quality, improving concentration, better sleep, and fewer respiratory problems. 

2. Higher HVAC System Efficiency 

When an energy recovery ventilator transfers heat energy between outgoing and incoming airstreams, it successfully preheats or precools the air entering your house.

This treatment reduces the work your HVAC system needs to do, thereby increasing its efficiency, reducing energy consumption, and reducing energy bills. 

3. Better Moisture Control 

An energy recovery ventilator helps maintain humidity levels inside your house. When the system transfers heat energy between two airstreams, it also moves the moisture it contains.

Thus, when the two airstreams enter the system, the ERV takes some moisture from the airstream with higher humidity and applies it to the one with less humidity. 

This transfer keeps humidity out of your house during warm and humid months and retains some humidity indoors during the dry, cool months. 

Nevertheless, energy recovery ventilators aren’t dehumidifiers. They just help with moisture control.

4. Reduced Odors in Your Home

By eliminating contaminants from your house and cleaning the incoming air, an energy recovery ventilator also helps reduce odors in your house. Odors from cooking ingredients, pets, and other sources are largely decreased. This way, the air inside your home smells clean, fresh, and crisp. 

Last Few Words

Knowing what it means to recover energy using an ERV can help you identify its potential advantages and make it easy to spot discrepancies. Additionally, you can ensure your ERV is working efficiently. 

ERVs are now present in almost every home, thanks to the wide range of benefits they offer. You can now say goodbye to poor air quality, foul smells, and moisture once and for all! 

Just make sure to purchase a high-quality ERV and get it installed by a professional contractor. 

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