Ceiling-mounted Full Heat Recovery Ventilator typically refers to an air exchange unit containing a full heat exchange core. Its working principle is: during operation, the exhaust air from indoors and the fresh air flow cross each other in a perpendicular manner through the heat exchanger core. Due to the temperature difference and vapor pressure difference on both sides of the air partition plate, the two streams of air exhibit heat and mass transfer phenomena when passing through the partition plate, initiating the full heat exchange process.