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; }
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) |
