What is an ERV?

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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) prior to entering 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 the hot entering air in the summer is allowed to dissipate heat to the outgoing air in the summer

Latent recovery

By using a desiccant wheel or other desiccant media the ERV is able to 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 a lot of 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 and / or core.

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

— Daniel


  1. Avatar Dean West says:

    Excellent article!

      1. Avatar Ryan Kerr says:

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

  2. Avatar Jerry Cantrell says:

    Photo or illustration?

  3. Avatar Eric Torfason says:

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

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