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

Parameter Expression Block Series Number Description Default Value (Units)
HCV Error Threshold 74 The 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 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)