AHU Reset Control System - Metasys - LIT-12012070 - Field Device - VAV: Variable Air Volume Controller

Air Handling Unit Reset Application Note
Product name
VAV: Variable Air Volume Controller
Document type
Application Note
Document number
LIT-12012070
Revision date
2018-03-01

Pressure Request Logic in VAV Box Application (CCT 10.1 or Later)

  • An LCT process totalizes each network output PRESS-REQ SRC, which is then written to an AV point called PRESSREQ-O. The AHU Reset feature then uses the network output in the summer mode to reset the discharge air static pressure setpoint.
  • When the damper status is at 95% or more, the network output PRESS-REQ SRC adjusts to 1.0.
  • When the damper status is at less than 85%, the network output PRESS-REQ SRC adjusts to 0.0.
  • The default pressure differential is 10%.

Temperature Request Logic in VAV Box Application (CCT 10.1 or Later)

  • An LCT process totalizes each network output CLG-REQ SRC, which is then written to an AV point called TEMPREQ-O. The AHU Reset feature then uses the network output in the winter mode to reset the discharge air temperature setpoint.
  • When the cooling status is at 95% or more, the network output CLG-REQ SRC adjusts to 1.0.
  • When the cooling status is less than 85%, the network output CLG-REQ SRC adjusts to 0.0.
  • The default temperature differential is 10%.