1. Follow-ups from Classes 8 and 9

2. Waterside Economizer (“free-cooling”) – Series vs Parallel Notice the difference in the connection points

3. Types of VAV Boxes “VAV boxes are not all created equal”
VAV Box, Un-powered
Direct-acting: Motorized damper controls air flow to zone
Diverting: Motorized Diverting damper routes air to room or to return duct / plenum (does not provide back-pressure signal to slow down AHU fan)
Both of these are subject to poor room air distribution at low load
Fan-Powered Box (FPB)
Created to maintain constant volume at room diffusers at low load
Series: fan runs continuously, with damper controlling mix of Supply Air and re-circulated return or room air
Parallel: fan runs intermittently to re-circulate room air as damper throttles Supply Air