technical feature Figure 6A Summer. Recovery with dual glycol coils/air-handling system, neutral air. Room Exhaust (75,000 cfm) HW (G) 82°F Heat Source (Off) (75°F/62.5°F) ERU (28.4 Btu/lb) 3°F Increase from H Friction & Duct Heat Gain AHU Room Supply 70°F 73°F (75,000 cfm) Neutral Air C (75°F) Typical VAV Box Supplemental Cooling CB (Provides Minimal Reheat FCU As Required) MEP Spaces 78°F Manifolded Exhaust (80°F) G C 55°F/ G G 54.5°F C 70°F/69°F 23.5 33.5 Btu/lb C Btu/lb C HW (G) 65°F C 43°F Outside Air 92°F/76°F (39.5 Btu/lb) 58°F Three-Way Diverting Valve (typ) Chiller CT HX energy recovery effectiveness 39.5 Btu/lb – 33.5 Btu/lb = 54% 39.5 Btu/lb – 28.4 Btu/lb Water Economizer for Shoulder Season Figure 6B Winter. Recovery with dual glycol coils/air-handling system, neutral air. Heat Source Provides Additional Heating Energy G/C Provides Preheat Using Energy Recovery HW (G) 35°F* HW (G) 60°F (+10°F) Heat Source Room Exhaust (75,000 cfm) 70°F ERU G HW (G) 75°F Manifoldeded Exhaust (40°F) C 3°F Increase from Friction & Duct Heat Gain AHU H Room Supply 58°F (75,000 cfm) Bypassed in Winter (Off) C (58°F – 70°F) Typical VAV Box Supplemental Cooling CB (Provides Final Heating FCU As Required) MEP Spaces energy recovery effectiveness (40°F — 0°F) (G/C) — 10°F (Heat Source)+ (55°F — 40°F) (C/C) = 64% 70°F Room — 0°F Outside Air G 55°F C C 40°F C G HW (G) 75°F C Two Recovery Devices Operating 50°F 60°F CT Outside Air (0°F) Three-Way Diverting Valve (typ) Chiller HX Modified recovery efficiency (40°F — 0°F) (G/C) — 10°F (Heat Source)+ (55°F — 40°F) (C/C) =64% 70°F Supply — 0°F Outside Air Chilled Water Coil Recovery Mode (1,200 MBH) *Minimum HW (G) temperature where indicated limited by frosting considerations. an exhaust-intensive laboratory building. Chilled-Water Coil Energy Recovery www.info.hotims.com/44636-46 28 ASHRAE JouRnAl ashrae.org All four combinations of recovery methods and air-handling systems Septem ber 2013 Water Economizer for Shoulder Season in these examples include a chilled water coil energy recovery feature, using diverting flow control valves (three-way valves) in the chilled water system. Under winter operation, the chilled-water flow leaving