OAT and MAT is not approximately equal when MAD is fully closed

Objective/ Method/Outcome

Objective: Determines if the Mixed Air Temperature and Outdoor Air Temperature sensors are accurately reading when the Mixed Air Damper is closed.

Method: Compares the Mixed Air Temperature to the Outdoor Air Temperature and the defined temperature threshold. If the Mixed Air Temperature and Outdoor Air Temperature are outside of the temperature threshold range while the Mixed Air Damper is closed, the hours of faulty operation are calculated.

Outcome: This rule generates an insight if the Daily Hours of Faulty Operation exceeds the acceptable daily threshold.

Description

Reference: ASHRAE36-5.16.14.8

OAT and MAT should be approximately equal when MAD is fully closed.

This rule is part of the CopperTree Standard rule-set. (Aliased Celsius / Aliased Fahrenheit)

Default Priority

Low

Diagnosis

1. MAT sensor error

2. OAT sensor error

3. Leaking or stuck mix air damper or actuator

Message

OAT and MAT is not approximately equal when MAD is fully closed.

Rule Template

Insight Type: Fault Detection

Trigger Type: Active High

Notes

Default Values:

Const. – Threshold – Daily Hours of Faulty Operation [Hours]: 2

Const. – Temperature Threshold[°]: 2°C/3.6°F

Const. – MAD Closed Threshold: 5%

CTLs:

OAT differs from MAT when MAD closed- Weekly Hours of Faulty Operation (KPI)

OAT differs from MAT when MAD closed – Hours of Faulty Operation (CUSUM)