Air flow: Quite a few HVAC units are hooked up into a ductwork system to circulate dealt with air during a building. Vents and chimneys also are Portion of air flow systems.H? th?ng chiller m?ch n??c 4 Principal Secondary Stream • T?i m?ch n??c 3 và 4 thì h? th?ng s? d?ng chiller bi?n t?n ?? ch?y theo nhu c?u t?i c?a h? th?ng.?? tìm hi?u chi t