hvac system types for Dummies
GRD stands for Grille, Sign-up and Diffuser. GRD suggests a part is both a grille, a sign up or even a diffuser. It's really a generic term used to describe just about anything that’s source/return and exhaust/intake air.IU means Induction Device. IU is a secondary air conditioning device that is often Found close to the focus on cooling/heating