Determine if sensor is at fault/out of calibration

Applicable Systems

  • NIST: APAR26, APAR27
  • Primary: AHU, RTU, MUA, ERV

Objective/Method/Outcome

  • Objective: Determine if a sensor is in fault condition or requires possible calibration. Based on NIST APAR 26 and 27.
  • Method: Check if the MAT is greater than or less than both the RAT and the OAT during occupied hours.
  • Outcome: An insight is generated if the MAT is outside of range of the OAT and RAT for more than 8 hours per week.

Logic

If(MAT > RAT && MAT > OAT) { return true; } else If(MAT < RAT && MAT < OAT) { return true; }
Determine if sensor is at fault/out of calibration

Inputs

  • MAT {sensor, mixed, air, temp} (Real Trend Log)
  • RAT {sensor, return, air, temp} (Real Trend Log)
  • OAT {sensor, outside, air, temp} (Real Trend Log)

Notes

The temperature threshold is set to 2 degrees, as per NIST recommendations.

Parameters

Parameter Expression Block Series Number Description Default Value (Units)
Temperature Threshold 9 The acceptable temperature deviation from set point that is considered normal 2 (C)
Acceptable Hours per Week 22 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)