Air-to-Air Heat Recovery Units vs HRV and ERV: What is the Difference
Buyers often ask whether an air-to-air heat recovery unit is the same as an HRV or ERV. Short answer: an HRV or ERV is a type of air-to-air heat recovery unit. This article clarifies the overlap and the difference that actually changes the specification.
HRV and ERV are recovery units
Any device that transfers heat between exhaust and supply air is an air-to-air heat recovery unit. HRV (heat recovery ventilation) and ERV (energy recovery ventilation) are the ventilation-grade versions of that idea, usually packaged with fans, filters and controls for buildings.
See HRV benefits and HRV vs ERV for the ventilation view.
The real difference: sensible vs total energy
- HRV transfers only sensible heat (temperature).
- ERV (enthalpy) also transfers moisture through a membrane or wheel, controlling humidity.
This matters in humid climates — see sensible vs latent recovery.
When to spec which
- Cold, dry winters: HRV recovers heat without dumping indoor moisture outdoors.
- Hot, humid summers: ERV keeps indoor humidity down while pre-cooling incoming air.
- Process or industrial: a bare air-to-air exchanger may be enough without ventilation-grade packaging.
Our Heat Recovery Guide ties these choices together.
Frequently asked questions
Is an HRV an air-to-air heat recovery unit?
Yes. An HRV is a ventilation-grade air-to-air heat recovery unit that transfers sensible heat between exhaust and supply air.
HRV or ERV in a humid climate?
ERV is usually better in humid climates because it also transfers moisture and helps control indoor humidity.
Can a recovery unit also recover moisture?
Only enthalpy (ERV) units with a membrane or wheel recover moisture. Plain HRV and plate units move sensible heat only.
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