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

ParameterExpression Block Series NumberDescriptionDefault Value (Units)
Temperature Threshold7 5The acceptable temperature deviation from set point that is considered normal2 (C)
CCV Error Threshold74The 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 Week60The amount of time that this error is allowable for the unit per week. Anything more than that time is considered a fault.8 (h)
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