Photo of a Nortek enthalpy wheel.

Air-to-air energy recovery is the process of recovering heat and/or moisture between two airstreams at different enthalpies.

When designing energy recovery systems, varying enthalpies, dry-bulb temperatures, and moisture contents are important to consider, since energy composition can be recovered  depending on the application.  An optimal system not only transfers the heat with the least loss of efficiency with the least amount of cross-contamination, but does so with AHRI certification or performance guarantees.  Dedicated outdoor air systems and other HVAC systems can use energy recovery technology to bring in as much outdoor air as required while minimizing the associated energy consumption.

The various types of air-to-air heat recovery technologies for HVAC include:

  • fixed-plate heat exchangers
  • heat pipes
  • coil runaround loops
  • rotary wheels

Examples of ideal HVAC applications for air-to-air heat recovery:

  • Laboratory exhaust
  • Natatoriums
  • Healthcare
  • Classrooms

Other examples of energy recovery commonly used in the HVAC industry include:

  • refrigerant heat recovery chillers
  • desuperheaters
  • closed-loop heat pump systems
  • heat transfer variable refrigerant flow (VRF) systems
  • boiler flue stack heat recovery