NIST APAR19 – Cooling coil valve command is fully open and SAT error exists (Mode 4 – Mech. Cooling w/min OA)

Applicable Systems

  • NISTAPAR: APAR19
  • Primary: AHU, RTU, MUA, ERV

Objective/Method/Outcome

  • Objective: Indicates that the heating coil valve is fully open and the SAT is less than the setpoint while the AHU is in Mode 1 (Heating)
  • Method: Check if the SAT is more than 2 degrees above set point for over 8 occupied hours per week while the unit is in Mode 4.
  • Outcome: An insight is generated when the SAT is more than 2 degrees above set point for over 8 occupied hours per week while the unit is in Mode 4.

Logic

If (SAT - SAT SP > Temperature Threshold && CCV > 2% Open) { return true; }
NIST APAR19 – Cooling coil valve command is fully open and SAT error exists (Mode 4 – Mech. Cooling w/min OA).

Inputs

  • SAT {sensor, discharge, air, temp} (Real Trend Log)
  • CCV {cmd, cool, water, valve } (Real Trend Log)
  • SAT_SP {sp, discharge, air, temp} (Real Trend Log)
  • AHU_MODE_CTL {ahu, mode} (Real Trend Log)

Parameters

Parameter Expression Block Series Number Description Default Value (Units)
Temperature Threshold 7 5 The acceptable temperature deviation from set point that is considered normal 2 (C)
CCV Error Threshold 74 The movement tolerance of the CCV. This is used to define when the valve is open -everything above the formula (100 – CCV Error Threshold) is considered saturated. 2 (%)
Acceptable Hours per Week 60 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)