What is an ERV?

This quick tip was written by Daniel Andersen in the HVAC School Group. Daniel was one of my early encouragements to make the podcast, even though he refuses to come on himself. Thanks, Daniel!

ERV – What is it? 
An energy recovery ventilator allows fresh air from outside to be introduced into the conditioned space and conditions it (recovers energy) before that air enters the space.

This is especially important on a structure that has a nice, tight envelope where you are required a certain amount of air exchange.

“How does it work?” you might ask. 

Sensible Recovery

The core in the ERV allows the incoming air to be tempered by the outgoing air, either absorbing heat from the conditioned air in the winter or dissipating heat from the hot entering air to the outgoing air in the summer.

Latent recovery

Using a desiccant wheel or other desiccant media, the ERV can pre-condition the air by removing moisture from the incoming fresh air and transferring it to the air exiting the space. This “latent” moisture energy transfer is what makes an ERV different than an HRV (heat recovery ventilator).

What will affect its operation?

CLEANLINESS! (Like most things in HVAC/R)

Keep the prefilters clean. Entering air can bring in many contaminants that can QUICKLY clog the pre-filter or inlet bug screen.

I commonly see leaves and airborne debris in the filter area. Cleaning is usually just a matter of using water on the wheel or core.

If it is belt-driven, make sure the sheave and belt are in good shape and properly aligned and adjusted.



Dean West
Dean West
7/12/17 at 08:29 PM

Excellent article!

    Bryan Orr
    Bryan Orr
    9/15/17 at 01:10 PM

    Thanks Dean!

      Ryan Kerr
      Ryan Kerr
      2/14/18 at 09:58 PM

      Have him right one on ERV vs HRV 🙂 I still dont have a true grasp of them! THANKS for all you do!

Jerry Cantrell
Jerry Cantrell
2/15/18 at 09:41 AM

Photo or illustration?

Eric Torfason
Eric Torfason
2/15/18 at 10:18 AM

dean great description but a couple of pic would have been a nice add. maybe do a post on hrv vs erv.

How to Control Humidity in Humid Climates Part 2: Myths and Misconceptions – timdestasiohvac
How to Control Humidity in Humid Climates Part 2: Myths and Misconceptions – timdestasiohvac
8/15/22 at 04:14 AM

[…] ERV stands for Energy Recovery Ventilation. They’ve been around for many years, starting in the commercial sector, then appearing in houses when codes started requiring more ventilation. You can learn more about how an ERV works here. […]


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