An air-to-air heat exchanger transfers sensible or total energy between exhaust and supply air streams using coils, wheels, or heat pipes, recovering 50-90% of thermal energy for heating or cooling purposes. These devices are fundamental to energy recovery ventilation systems in residential, commercial, and institutional buildings. Common configurations include plate exchangers, rotary wheels, and passive heat pipe arrays achieving significant energy savings.
Technical Details
Air-to-air heat exchangers operate with face velocities of 2.0-3.5 m/s and pressure drops of 25-100 Pa depending on core design. Sensible effectiveness ratings range from 50-80% per ASHRAE 84 testing standards, while total energy effectiveness reaches 60-90% for enthalpy cores. Coil materials include aluminum, copper, and composite materials. Standard equipment sizes accommodate 500-10,000 CFM airflow rates. Operating temperature ranges span -40°C to 50°C depending on core construction and working fluids.
Applications and Practical Significance
Air-to-air heat exchangers reduce heating and cooling energy consumption by 30-50% in properly commissioned systems. They are essential in tight building envelopes complying with energy codes and high-performance standards. Maintenance requirements include quarterly filter changes and annual duct cleaning. Typical installation costs of 800-3000 dollars produce payback periods of 5-8 years in cold climates through reduced utility consumption.