Mais conteúdo relacionado Semelhante a Fault Detection and Diagnostics for RTUs (20) Mais de E Source Companies, LLC (20) Fault Detection and Diagnostics for RTUs1. 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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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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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
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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Notas do Editor BCAP = Building Codes Assistance Project