The use of high-tech nanometer film technology, horizontal-reversed convection technology, antistatic maintenance-free and noise damping technology makes Hengda air to air heat exchanger ventilation unit achieve a breakthrough in heat energy recovery efficiency by more 72%. The significant energy recovery will not only reduce investments on air conditioner capacity and also will reduce the huge running costs of entire air-conditioning system. Humanized product design: 1. Super low noise: Hengda air-to-air heat exchanger ventilator unit adopts super low noise ventilator, and takes the hign efficiency noise-damping technology. 2. Maintenance-free: The special designed air passage make the air flow easily pass through it, and can be used continuously for long time, realizing the heat exchanger corpus without maintenance need. 3. Compact super thin design for easier installation and construction space saving. 4. Precision making in every processes: Using high quality steel sheets, environment-protective materials and alloyed aluminum frames. Treating the surface with static electricity painting to get elegant appearance. 5. Air filtering design: The products are equipped inside with specialized air filter to ensure the air coming into house is fresh.