NIST APAR25 – Persistent supply air temperature error exists (All Occupied Modes)

Applicable Systems

  • NISTAPAR: APAR25
  • Primary: AHU, RTU, MUA, ERV

Objective/Method/Outcome

  • Objective: Indicates that the SAT is not within the desired set point (Valid for All Occupied Modes). If APAR 3, 13, or 19 are active, this rule will be suppressed.
  • Method: Check if the SAT is not within ±1.5 degrees of set point for more than 4 occupied hours per week.
  • Outcome: An insight is generated when the SAT is not within ±1.5 degrees of set point for more than 4 occupied hours per week.

Logic

If (abs(SAT - SAT SP) > Temperature Threshold)
NIST APAR25 – Persistent supply air temperature error exists (All Occupied Modes)

Inputs

  • SAT {sensor, discharge, air, temp} (Real Trend Log)
  • SAT_SP {sp, discharge, air, temp} (Real Trend Log)
  • APAR3_TRUE_CTL {apar3} (Real Trend Log)
  • APAR13_TRUE_CTL {apar13} (Real Trend Log)
  • APAR19_TRUE_CTL {apar19} (Real Trend Log)
  • AHU_MODE_CTL {ahu, mode} (Real Trend Log)

Parameters

Parameter Expression Block Series Number Description Default Value (Units)
Const- Temperature Threshold 74 The acceptable temperature deviation from set point that is considered normal. 1.5 (C)
Acceptable Hours per Week 75 The amount of time that this error is allowable for the unit per week. Anything more than that time is considered a fault. 8 (h)