Outdoor and mixed air temperature should be similar when OAD is 100% open

Objective/Method/Outcome

Objective: Determines if the OAT and MAT are similar when outdoor air is open

Method: Compares the OAT and MAT to determine if they are inconsistent. Checks the recorded Supply Fan Status and OAD position to determine if the fan is running and the damper 100% open. If the damper is open but there is difference in temperature, the hours of fault is determined.

Outcome: Triggers an insight.

Description

Indicates an inconsistency between outdoor and mixed air temperatures while the OA damper is 100% open.

This rule is part of the CopperTree Standard rule-set, and is derived from NIST APAR10.

Default Priority

Low

Diagnosis

  1. Input sensor(s) faulty or miscalibration. Verify input sensor(s) operation.
  2. Mixed air dampers stuck, leaking, or not following control signal.

Message

Outdoor and mixed air temperatures vary while outdoor air damper is fully open.

Rule Template

Insight Type: Fault Detection

Trigger Type: Active High

Logic

Logic for determining OAT and MAT are similar when OAD is 100% open

Inputs

Input Unit Tags Description
OAT Outdoor Air Temperature The recorded OAT
MAT Mixed Air Temperature The recorded MAT
OAD Outdoor Air Damper Position, Outdoor Air Damper Command The recorded Outdoor Air Damper Position
SF Status Discharge Air Fan Command, Discharge Air Fan Status The recorded Supply Fan Status
Threshold – Temperature Difference The minimum difference in temperature that can trigger an insight
Threshold – Weekly Hours of Faulty Operation The minimum hours of faulty operation per week that can trigger an insight

Notes

Default Thresholds:

  • Temperature Threshold: 2°
  • Weekly Hours of Variance: 8