... 2.perfect design,construction 3.high quality, low price Ventilation Centrifugal Fan for HVAC System We are one of the biggest and ... professinal manufacturer of ventilation products including FAN, FLEXIBLE DUCT, AIR DIFFUSERS, PIPE FITTING, ETC in ... and low weight. 2. Structural characteristics housingThe housing of fan consists of air inlet cover and air outlet cover. It ...