Fault Detection and Diagnostics for RTUs

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

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  • BCAP = Building Codes Assistance Project
  • Fault Detection and Diagnostics for RTUs

    1. 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. 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 2 www.esource.com || © 2013 E Source
    3. 3. Examples 3 www.esource.com || © 2013 E Source
    4. 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 4 www.esource.com || © 2013 E Source
    5. 5. FDD is More Actionable than EMS  EMS alarms lack context and actionable recommendations  FDD features include:     5 More computing power to crunch lots of data Analyze why faults occur Calculate repair costs Prioritize faults based on number of variables www.esource.com || © 2013 E Source
    6. 6. Example Faults Detected            6 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 www.esource.com || © 2013 E Source
    7. 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 7 www.esource.com || © 2013 E Source
    8. 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 8 www.esource.com || © 2013 E Source
    9. 9. Different Approaches Quantitative Airflow 9 Statistical Refrigerant Cycle Economizer www.esource.com || © 2013 E Source
    10. 10. Minimalist Approach – Using Sound 10 www.esource.com || © 2013 E Source
    11. 11. Economizer Only Approach 11 www.esource.com || © 2013 E Source
    12. 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 12 www.esource.com || © 2013 E Source
    13. 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 13 www.esource.com || © 2013 E Source
    14. 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) 14 www.esource.com || © 2013 E Source
    15. 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 15 www.esource.com || © 2013 E Source
    16. 16. California Title 24 –Building Energy Efficiency Standards      16 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 www.esource.com || © 2013 E Source
    17. 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! 17 www.esource.com || © 2013 E Source
    18. 18. Combined Devices: FDD + VFD  For constant speed RTUs  Converts to variable speed and also adds FDD 18 www.esource.com || © 2013 E Source
    19. 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 19 www.esource.com || © 2013 E Source
    20. 20. For More Information David Podorson Senior Research Associate, E Source 303-345-9103 david_podorson@esource.com 20 www.esource.com || © 2013 E Source

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