David Podorson, Senior Research Associate, E Source Rocky Mountain Association of Energy Engineers, 14th Annual Energy Forum presentation

1. Fault Detection and Diagnostics
for RTUs
David Podorson
Senior Research Associate, E Source
Rocky Mountain Association of Energy Engineers
14th Annual Energy Forum
www.esource.com
Thursday, October 17, 2013

2. What is Fault Detection & Diagnosis
(FDD)?
 Add-on, embedded, or SaaS solution
 Identify a building’s mechanical system faults and
determine the causes behind those faults
 Attempts to provide persistent commissioning-like
savings
 Provide three fundamental tasks:
 Collect data
 Analyze data
 Report actionable conclusions
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3. Examples
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4. How They Work
 Collects data points
 Temperature
 Airflow
 Economizer runtime
 Use proprietary algorithms to diagnose problems
 Strong differentiator in different products
 Some products rely on human experts
 Some products rely on software algorithms
 Report results
 Generally prioritize faults based on energy-use impacts
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5. FDD is More Actionable than EMS
 EMS alarms lack context and actionable
recommendations
 FDD features include:
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More computing power to crunch lots of data
Analyze why faults occur
Calculate repair costs
Prioritize faults based on number of variables
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6. Example Faults Detected
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Air temperature sensor failure/fault
High/low refrigerant charge
Compressor short cycling
Refrigerant line restrictions/TXV problems
Refrigerant line non-condensables
High/low side HX problem
Capacity degradation
Efficiency degradation
Not economizing when it should
Damper not modulating
Excess outdoor air
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7. OEM Alarm Codes
Alarm
T110
T111
T126
T127
T133
T134
T140
T141
T142
T408
Description
Circuit A Loss of Charge
Circuit B Loss of Charge
Circuit A High Refrigerant Pressure
Circuit B High Refrigerant Pressure
Circuit A Low Refrigerant Pressure
Circuit B Low Refrigerant Pressure
Circuit C Loss of Charge
Circuit C Low Refrigerant Pressure
Circuit C High Refrigerant Pressure
Dirty Filter
Economizer Damper Actuator Out of Calibration
Economizer Damper Actuator Torque Above Load Limit Alert
T414
Economizer Damper Actuator Hunting Excessively
Economizer Damper Stuck or Jammed
Economizer Damper Actuator Mechanical Failure
Economizer Damper Actuator Direction Switch Wrong
Kristen Heinemeir 2011
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8. Economizers and Thermostats are the
Most Common Problems
100%
90%
80%
70%
64%
58%
60%
50%
46%
42%
40%
27%
30%
20%
10%
0%
Refrigerant Economizer
Circuit
Air flow
Thermostat
Sensors
New Buildings Institute 2004
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9. Different Approaches
Quantitative
Airflow
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Statistical
Refrigerant Cycle
Economizer
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10. Minimalist Approach – Using Sound
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11. Economizer Only Approach
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12. Intensive Approach – Using Data
 Collects data from the EMS
 Human analysts look over the data at some point
but software truly does the heavy lifting
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13. FDD Can Pay for Itself
Western Cooling Efficiency Center:
 Average kWh savings on the order of 12%
 Benefit/Cost Ratio 1.7
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15 year analysis period
Probability that fault will occur
Probability that fault will be detected with FDD
Probability that fault will be detected without FDD
Kristen Heinemeier 2011
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14. Standards will Allow Code Integration
and Consistency of Products
 ASHRAE Standard
207
 California Title 24 –
Building Energy
Efficiency Standards
 IECC (International
Energy Conservation
Code)
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15. ASHRAE Standard 207
 Defines an FDD tool's function
 Defines an FDD performance test
 Timeline:
 Internal draft by January 2014
 Public review by January 2015
 Expected to be published around January 2016
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16. California Title 24 –Building Energy
Efficiency Standards
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Requires all units ≥ 4.5 tons be equipped with FDD
Mandatory requirement – not a compliance option
Economizer controls only!
Releases January 2014
California leads the way – other states to follow
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17. International Energy Conservation
Code (IECC) Following CA’s Lead
 IECC is implementing same requirement
 Many states rely on IECC for their compliance –
potential for much more widespread adoption!
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18. Combined Devices: FDD + VFD
 For constant speed RTUs
 Converts to variable speed and also adds FDD
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19. Combined Devices: How Much Energy
do They Save?
 PNNL case study of 66
RTUs
 Average savings of 57%
 Basically all savings are
from the VFD
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20. For More Information
David Podorson
Senior Research Associate, E Source
303-345-9103 david_podorson@esource.com
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