ENGINEERING MANULA OF AUTOMATIC CONTROL
INDIVIDUAL ROOM CONTROL APPLICATIONS
399
Contents
Introduction ............................................................................................................ 401
Graphic Symbols ................................................................................. 402
Abbreviations....................................................................................... 403
Air Terminal Unit Control ..................................................................... 403
Variable Air Volume ATU ..................................................................... 403
Pressure-Dependent And Pressure-Independent ATU ................... 403
Single-Duct VAV ATU ...................................................................... 404
System Configuration ................................................................. 404
Throttling VAV ATU ..................................................................... 404
Variable Air Volume ATU ............................................................. 405
Variable Air Volume ATU with Electric Reheat ............................ 406
Constant Air Volume ATUs .......................................................... 406
Induction VAV ATU ...................................................................... 406
Parallel Fan ATU ......................................................................... 408
Series Fan ATU........................................................................... 408
Dual-Duct ATU ................................................................................ 410
Dual Duct Pressure Independent VAV ATU ................................ 410
Dual Duct Pressure Independent
Constant Volume ATU................................................................. 411
Unitary Equipment Control ...................................................................................................... 412
General................................................................................................ 412
Natural Convection Units..................................................................... 412
Radiant Panels .................................................................................... 413
Unit Heaters ........................................................................................ 413
General ........................................................................................... 413
Control ............................................................................................ 414
Two-Position Control................................................................... 414
Down-Blow Unit Heater................................................................... 414
Modulating Control ..................................................................... 414
Gas- Or Oil-Fired Unit Heater ......................................................... 415
Unit Ventilators .................................................................................... 415
General ........................................................................................... 415
Control ............................................................................................ 416
ASHRAE Control Cycles............................................................. 416
Standby/Warm-up Stage ........................................................ 416
Cycle I–Fixed Maximum Percentage of Outdoor Air .............. 417
Cycle II–Fixed Minimum Percentage of Outdoor Air .............. 417
Cycle III–Variable Outdoor Air ................................................ 418
Day/Night Setback Control ......................................................... 418
Digital Unit Ventilator Control ...................................................... 419
Individual Room
Control Applications