ERV Vs. HRV: Which Is Right For My Climate?

If your home smells like yesterday's fish dinner, then you know how easily odors can linger. Stale air can contain more than just unwanted smells. It can store excess carbon dioxide and pollutants that can harm your family's health. Heat recovery ventilators and energy recovery ventilators can expel these unwanted issues while preventing spikes in your utility costs.

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What Is an HRV Unit?

A heat recovery ventilator features two pipes, one for exhausting interior air and another for drawing fresh air into your home. The system core recovers the heat from the indoor air and then transfers it into the incoming outdoor air. The two airstreams never mix, ensuring the unit expels unwanted pollutants. Meanwhile, the heat exchange helps maintain your home's temperature without forcing your HVAC to work overtime.

An HRV doesn't alter the moisture in the air. It focuses solely on heat recovery. If used in a humid climate, it pulls in the excess water vapor along with the fresh air. Thus, it benefits homeowners in cold, dry climates where humidity won't negatively affect the indoor air. Sometimes, you can use it to pre-cool air in the summer in desert-style locations where outdoor humidity isn't an issue.

Unlike opening a window for fresh air, a ventilator filters and modifies the air to be more comfortable as it enters your home. Neither HRV nor ERV systems can recover 100% of the energy spent conditioning the expelled air. However, models can rate as high as 80% energy efficiency.

What Is an ERV Unit?

An energy recovery system works in the same fashion as an HRV by removing stale air and bringing in fresh. The difference in the ventilators lies in the core. An ERV core features a special membrane that permits a small amount of water vapor to pass between the fresh and exhausting air without allowing the air itself to mix.

Homeowners in humid climates and fluctuating outdoor temperatures can use this design to avoid overloading their homes with moisture. In the winter, an ERV will add water vapor to help keep indoor air from becoming too dry. During the summer, it does the opposite and helps prevent excess humidity from entering your home.

It's important to note that an ERV isn't a dehumidifier. It helps remove incoming humidity but doesn't eliminate it entirely. If your home experiences moisture problems, you'll still need to continue using air conditioners and dehumidifiers to prevent moisture damage in your home.

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• What Is Heat Recovery Ventilation?

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• What Is ERV Core Cleaning?

• How to Clean Your ERV

• HVAC Terms Every Homeowner Should Know

What Is the Difference? HRV Vs. ERV

To understand the difference between HRV vs. ERV, you need to understand sensible heat and latent heat. In home heating and cooling systems, sensible heat is simply heat that a thermostat can measure. You can see it in action when you turn on your furnace and the temperature rises a few degrees.

On the other hand, you mostly feel latent heat, which involves the amount of humidity in the air. Excess humidity in the summer can feel hot and sticky. In the winter, dampness can make your skin feel cool and clammy. To keep your home feeling comfortable, your HVAC and ventilation systems must achieve a balance of sensible and latent heat.

Since the HRV doesn't exchange moisture, it only affects sensible heat. It's typically used to help raise the temperature of incoming outdoor air in the winter. An ERV will influence both sensible heat and latent heat, enabling its use all year.

Humidity Control

Humidity control is vital to your home's indoor air quality. High levels of moisture cause increased odors, mold and dust mites. Whether you need an HRV or an ERV is mostly determined by your humidity control needs. If you live in the desert or a cold climate, a heat recovery ventilator may be the best solution for your needs. In areas with high humidity and fluctuating temperatures, an ERV typically offers a better alternative.

Your HVAC and HRV or ERV systems need to be customized to suit your home and climate. A wide range of factors can have an impact on how much latent heat affects your home. For example, a damp basement or large south-facing windows can heavily affect moisture levels. A professional inspection can reveal hidden needs in your home's ventilation. Then you can build a clear plan of action that enhances your home's comfort and indoor air quality levels.