VAV minimum discharge air flow setpoint equals to maximum discharge air flow setpoint

Objective/ Method/Outcome

Objective: Determines if the VAV Active Airflow Setpoint modulates between minimum and maximum values.

Method: Compares the VAV Maximum Airflow Setpoint and the VAV Minimum Airflow Setpoint. If the minimum and maximum airflow setpoints are the same 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: ASHRAE36-5.6.5.1/5.6.5.3

This rule determines if heating or cooling output is mapped to active airflow minimum and maximum setpoints. In most cases, active airflow setpoint should vary between minimum and maximum setpoint to satisfy heating or cooling demand – hence the minimum and maximum airflow setpoints should not be equal. Health care facility could be an exception.

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

Default Priority

Medium

Diagnosis

1. Review heating/cooling maximum and minimum flow setpoints

2. Review maximum and minimum flow setpoint

Message

Maximum and Minimum Discharge airflow setpoint are the same.

Rule Template

Insight Type: Fault Detection

Trigger Type: Active High

Notes

Default Values:

Const. – Acceptable Daily Hours of Faulty Operation [hours]: 4

CTLs:

VAV Max and Min Flow SP Equal – Daily Hours of Faulty Operation (CUSUM)