Rapid start - Johnson Controls - LIT-12011950 - Building automation software - Smart Equipment Controller - 5.0

Smart Equipment Controls Sequence of Operation Technical Bulletin

Brand
Johnson Controls
Product name
Smart Equipment Controller
Document type
Technical Bulletin
Document number
LIT-12011950
Version
5.0
Revision date
2024-06-06
Product status
Active
Language
English

The Optimum Stage Up Algorithm is used to shorten the start up time for the compressors. It estimates the number of compressor steps required to meet the initial cooling demand and quickly starts the appropriate number of compressors.

Anytime a request is made for cooling, if there are no compressors running and the economizer is not suitable, Rapid Start is used. During Rapid Start, the inter-stage delay time between the compressors is reduced to 15 seconds.

  • Added Rapid Start functionality for cooling and heating
  • Cooling Rapid Start Enable /ClgRapidStartEn added to Details > Cooling > Setup menu and to BACnet/Modbus/N2
  • Heating Rapid Start Enable / HtgRapidStartEn added to Details > Heating > Setup menu and to BACnet/Modbus/N2

Rapid Start turns on the first stage of heating or cooling more quickly, but in order to give the temperature more time to stabilize after the first stage, it also may add a delay to the start up time of other stages.

Set points and related data

The set points and related data include the following items:

  • Cooling Rapid Start Enable (ClgRapidStartEn)
  • Cooling Rapid Start Time (ClgRapidStartTime)
  • Staged Cooling Command (StgClgCmd)
  • Heating Rapid Start Enable (HtgRapidStartEn)
  • Heating Rapid Start Time (HtgRapidStartTime)
  • Staged Heating Command (StgHtgCmd)

Cooling operation

When cooling rapid start is enabled and the unit enters cooling mode, it ramps up the staged cooling command at a rate of 1% per second until the first compressor turns on. The staged cooling command stays constant with the one compressor active for the Cooling Rapid Start Time or until the temperature has reached the setpoint. It then switches over to the normal PID control.

Heating operation

When heating rapid start is enabled and the unit enters a staged heating mode, it ramps up the staged heating command at a rate of 1% per second until the first heat stage turns on. The staged heating command stays constant with the one heat stage active for the Heating Rapid Start Time or until the temperature has reached the setpoint. It then switches over to the normal PID control.