Effective cooling DAT setpoint determination - Johnson Controls - LIT-12011950 - Building automation software - Smart Equipment Controller - 5.0

Smart Equipment Controls Sequence of Operation Technical Bulletin

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

The Eff Clg DAT Sp is determined as follows.

If SZVAVEn = Yes, then it uses the same Eff Clg DAT Sp used to control the fan during cooling in a single zone VAV unit.

If DAT control is active (i.e. during multi-zone VAV control), then it uses the same Eff Clg DAT Sp used to control the compressors during normal cooling operation.

If neither of the above conditions are true, then it calculates an Eff Clg DAT Sp with the following logic.

  • If RAT is below Zone Cooling Setpoint, then use SATUp-Sp for Eff Clg DAT Sp
  • If RAT is above Zone Cooling Setpoint + 1.5°F, then use SATLo-Sp for Eff Clg DAT Sp
  • If RAT is between the values above, then interpolate between SATUp-Sp and SATLo-Sp
  • For example, Zone Cooling Setpoint = 72°F, SATUp-Sp = 60°Fand SATLo-Sp = 55°F
    • If RAT < 72°F, then Eff Clg DAT Sp = 60°F
    • If RAT > 73.5°F, then Eff Clg DAT Sp = 55°F
    • If RAT is between 72°F and 73.5°F, then interpolate between 60°F and 55°F