Enhanced Prioritization – Return Fan Cycling Excessively

Objective/Method/Outcome

Objective: Determines if the return fan is changing more than expected

Method: Normalizes the Binary and Analog Samples to determine if they are being cycled more than the acceptable amount of time. The Potential Savings are determined by calculating the annual cost of cycling subtracted by the cost to replace equipment.

Outcome: Triggers an insight, and calculates the potential savings.

Description

Analyzes equipment state changes using Analog or Binary trend log, triggering an insight when daily cycles exceeds a threshold.

This rule is part of the CopperTree Standard rule-set.

Default Priority

Medium 

Diagnosis

Check and revise programming and sequence of operation to prevent unnecessary equipment cycling.

Message

Return fan is cycling more often than expected.

Rule Template

Insight Type: Fault Detection

Trigger Type: Active High

Logic

Logic used to determine if the return fan is cycling excessively

Inputs

InputUnitTagsDescription
Equip Command Or Amperage Return Air Fan Status, Return Air Fan CommandThe recorded status of the fan
Threshold – PropertyImpact Weekly  The minimum weekly property impact that can trigger insight
Threshold – UrgencyScore WeeklyMax  The maximum urgency score that the rule can assign
Cost to Replace Equipment$ 
Expected Equipment LifetimeYears  
Annual Days of Operation  The yearly days the system is operational
Threshold – Analog Cycle Delta  The acceptable analog change
Threshold – Daily Cycles  The acceptable daily analog cycles

Notes

Urgency Score is a measure of how urgent the fault is and a high score denotes critical adverse impact on the equipment. Urgency Score is scaled so that if the number of cycles is equal to or less than the Daily Cycles Threshold, the score is 0. If the number of cycles per day is twice that of the Daily Cycles Threshold, the score is 100. The maximum score of the week is used to trigger the Insight.

Property Impact is calculated as the number of days during the week where the cycle count was higher than threshold (expresses in percent of total days being monitored in the week)

Default values for constants:

  • Threshold – Analog Cycle Delta: 1
  • Threshold – PropertyImpact Weekly: 14
  • Threshold – UrgencyScore WeeklyMax: 30
  • Threshold – Daily Cycles: 20