NIST APAR14 – Cooling coil valve command is frequently fully open (Mode 3 – Mech. Cooling w/100%OA)

Applicable Systems

  • NISTAPAR: APAR14
  • Primary: AHU, RTU, MUA, ERV

Objective/Method/Outcome

  • Objective: Indicates that the cooling coil valve is frequently fully open while the unit is in Mode 3 (Mech. Cooling w/100%OA). This rule is a warning and indicates that the system may be out of control. If APAR13 is active, this rule is suppressed.
  • Method: Check if the CCV is fully open for over 8 occupied hours per week while the unit is in Mode 3.
  • Outcome: An insight is generated when the CCV is fully open for over 8 occupied hours per week while the unit is in Mode 3.

Logic

If (APAR13 true && CCV Open) { return true; }
NIST APAR14 – Cooling coil valve command is frequently fully open (Mode 3 – Mech. Cooling w/100%OA)

Inputs

  • CCV {cmd, cool, water, valve } (Real Trend Log)
  • AHU_MODE_CTL {ahu, mode} (Real Trend Log)
  • APAR13_TRUE_CTL {apar13} (Real Trend Log)

Parameters

ParameterExpression Block Series NumberDescriptionDefault Value (Units)
Const- 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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