NIST APAR4 – Heating coil valve command is frequently fully open (Mode 1 – Heating)

Applicable Systems

  • NISTAPAR: APAR4
  • Primary: AHU, RTU, MUA, ERV

Objective/Method/Outcome

  • Objective: Indicates that the heating coil valve is frequently fully open while the unit is in Mode 1 (Heating). This rule is a warning and indicates that the system may be out of control. If APAR3 is active, this rule is suppressed.
  • Method: Check if the HCV is fully open for over 8 occupied hours per week while the unit is in Mode 1 (Heating) and if APAR3 is active.
  • Outcome: An insight is generated when the HCV is fully open for over 8 occupied hours per week while the unit is in Mode 1 (Heating).

Logic

If (APAR3_TRUE_CTL && HCV > 2% Open) { return true; }
NIST APAR4 – Heating coil valve command is frequently fully open (Mode 1 – Heating)

Inputs

  • HCV {cmd, heat, water, valve } (Real Trend Log)
  • AHU_MODE_CTL {ahu, mode} (Real Trend Log)
  • APAR3_TRUE_CTL {apar3} (Real Trend Log)

Parameters

ParameterExpression Block Series NumberDescriptionDefault Value (Units)
HCV Error Threshold74The movement tolerance of the HCV. This is used to define when the valve is open – everything above the formula (100 – HCV 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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