An air-to-air heat recovery unit is a device that transfers heat (and sometimes moisture) between two separate air streams—typically incoming fresh air and outgoing exhaust air—without mixing them. It improves energy efficiency by recovering heat from the exhaust air to precondition the incoming air, reducing the energy needed for heating or cooling in HVAC systems or industrial processes.

Key Features:

• Operation: Uses a heat exchanger (e.g., counterflow, cross-flow, or rotary) to transfer heat. In counterflow units, air streams flow in opposite directions for maximum efficiency (70-90%).
• Types:
  • Plate Heat Exchangers: Fixed plates separate air streams, transferring sensible heat (temperature only).
  • Rotary Heat Exchangers: Rotating wheels transfer both sensible and latent heat (moisture).
  • Heat Pipes: Use phase-change technology for efficient heat transfer.
• Applications: Ventilation systems in buildings, industrial processes, data centers, and energy recovery systems.
• Benefits: Lowers energy costs, reduces carbon footprint, and maintains indoor air quality by preventing cross-contamination.
• Example: In winter, a unit might transfer heat from warm exhaust air (e.g., 20°C) to cold incoming air (e.g., 0°C), raising the fresh air temperature to reduce heating demands.