NIST APAR10 – Outdoor and mixed air temp should be nearly the same (Mode 3 – Mech. Cooling w/100% OA)

Applicable Systems

  • NISTAPAR: APAR10
  • Primary: AHU, RTU, MUA, ERV

Objective/Method/Outcome

  • Objective: Indicates an inconsistency between outdoor and mixed air temperatures while the unit is in Mode 3 (Mech. Cooling w/100% OA)
  • Method: Check if the MAT is more than +/-2 degrees from the OAT for over 8 occupied hours per week while the unit is in Mode 3 (Mech. Cooling w/100% OA).
  • Outcome: An insight is generated when the MAT is more than +/-2 degrees from the OAT for over 8 occupied hours per week while the unit is in Mode 3.

Logic

If (absolute(MAT-OAT) > Temperature Threshold) { return true; }
NIST APAR10 – Outdoor and mixed air temp should be nearly the same (Mode 3 – Mech. Cooling w/100% OA)

Inputs

  • OAT {sensor, outdoor, air, temp} (Real Trend Log)
  • AHU_MODE_CTL {ahu, mode} (Real Trend Log)
  • MAT {sensor, mixed, air, temp} (Real Trend Log)

Parameters

Parameter Expression Block Series Number Description Default Value (Units)
Temperature Threshold 30 This is the minimum temperature difference between OAT and MAT needed to enable the rule 2 (C)
Acceptable Hours per Week 33 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)