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1 This presentation is posted for public use. ACEEE does not endorse any product or service. ACEEE accepts no responsibility for any facts or claims this presentation may contain.

2 Water Heater Performance Degradation Due to Aging ACEEE Hot Water Forum Session 5B: Water Heater Performance in the Field May 22,2012 William Goetzler Director Navigant Consulting, Inc. Co-authors: Kevin Foley, Rahul Kar, Timothy Sutherland 0

3 Background The goal of this project was to investigate the real-world energy consumption of major household appliances.» DOE efficiency standards, utility incentive programs, and building energy modeling rely on predicted energy consumption, but do these models reflect real world operation?» Summary of initial project activities: Prioritized appliances with: o High unit energy consumption o High national energy consumption o Well-known questions regarding real-world energy consumption» Selected water heaters for further study 1

4 Approach We followed a four step approach to investigate real world energy consumption. Reviewed literature Procured used water heaters in working condition Tested and evaluated performance of used water heaters Disassembled water heaters and looked for signs of component degradation 2

5 Used Water Heater Procurement We procured 13 water heaters in working condition for testing from Ebay, Craigslist, and local plumbers. Manufacturer/ Brand Type Capacity Age (years) Unit 1 A Electric 40 gallons 2 Unit 2 B Gas 40 gallons 3 Unit 3 C Electric 40 gallons 4 Unit 4 D Gas 50 gallons 4 Unit 5 A Gas 50 gallons 5 Unit 6 E Electric 40 gallons 5 Unit 7 C Gas 50 gallons 6 Unit 8 A Electric 50 gallons 6 Unit 9 C Gas 75 gallons 7 Unit 10 F Gas 50 gallons 8 Unit 11 A Gas 40 gallons 11 Unit 12 A Gas 50 gallons 14 Unit 13 G Gas 40 gallons 14 3

6 Water Heater Test and Comparison We tested each water heater at an accredited laboratory and compared the performance (Energy Factor) with rated performance. Performance Metric The Energy Factor Defined as the amount of hot water produced per unit of fuel consumed over a typical day. DOE Tests The accredited laboratory tested each water heater according to the DOE test procedure and calculated the energy factor Rated EF Performance Variation We obtained the rated EF from the Air-Conditioning, Heating, and Refrigeration Institute (AHRI) database. Percent Change in Rated EF =(Tested EF- Rated EF)/Rated EF x 100 Considered variation over 5% to be significant Available at 4

7 Test Results Test results did not show a strong correlation between age and decline in performance. Two water heaters showed degradation of more than 5% 1 4% % Energy Factor (EF) % Change in EF 0% -2% -4% Age (in years) % 0-8% Rated EF Tested EF -10% Gas Electric 5

8 Water Heater Disassembly After testing, we dismantled each water heater to investigate if key components had degraded over time. - Used the governing equation to identify key components that directly affect the performance parameters in DOE tests - Qualitatively judged the state of the key components and scored them as shown: o Excellent: Little or no degradation/scaling/sediment accumulation o Good: Slight degradation/scaling/sediment accumulation o Poor: Significant degradation/scaling/sediment accumulation 6

9 Example Heavy sedimentation inside storage tank GOOD POOR 7

10 Example Anti-corrosion anode completely degraded GOOD POOR 8

11 Example Scaling on electric heating elements GOOD POOR 9

12 Disassembly Results Individual components degrade significantly after six years of use. Unit 1 Unit 2 Unit 3 Unit 4 Unit 5 Unit 6 Unit 7 Unit 8 Unit 9 Unit 10 Unit 11 Unit 12 Unit 13 Electric Gas Electric Gas Gas Electric Gas Electric Gas Gas Gas Gas Gas Age Percent Change from Rated EF 0% -4% 0% 3% -1% -8% -3% -4% -5% -3% -3% -1% 2% Water Heater Components Combustion Chamber (CC) NA Good NA Good Good NA Good NA Poor Poor Poor Good Poor Burner (B) NA Good NA Good Good NA Good NA Poor Poor Good Poor Poor Interface (B/CC) NA Good NA Excellent Good NA Good NA Excellent Poor Poor Poor Excellent Spiral Heat Exchanger NA Good NA Excellent Good NA Good NA Good Good Good Good Good Upper Element Good NA Excellent NA NA Poor NA Poor NA NA NA NA NA Lower Element Good NA Good NA NA Poor NA Poor NA NA NA NA NA Insulation (Top and Side) Good Excellent Good Good Excellent Good Good Good Poor Good Good Good Good Insulation(Combustion Chamber) Good Good Good Good Good Good Good Good Good Poor Poor Poor Poor Cold Water Inlet Good Good Good Good Good Poor Good Poor Good Good Good Poor Good Hot Water Outlet Good Good Good Good Good Poor Good Good Good Good Good Poor Good Anti-corrosion Anode Excellent Good Good Good Good Poor Poor Poor Good Poor Poor Poor Good Cold Water Dip Tube Excellent Excellent Excellent Excellent Good Good Good Good Good Good Good Good Good Thermocouple Good Excellent NA Good Good NA Good Poor Poor Good Poor Poor Good Middlebury, CT Kingston, RI Worcester, MA Melrose, MA Newton, MA Needham, MA Metro Boston, MA Newton, MA Battle Creek, MI Metro Boston, MA Metro Boston, MA Metro Boston, MA Springfield, MA Water Heater Installation Location 10

13 Key Observations Heavy sedimentation in the storage tank had no effect on performance. Primary heat transfer occurs through the spiral heat exchanger. Unit 1 Unit 2 Unit 3 Unit 4 Unit 5 Unit 6 Unit 7 Unit 8 Unit 9 Unit 10 Unit 11 Unit 12 Unit 13 Electric Gas Electric Gas Gas Electric Gas Electric Gas Gas Gas Gas Gas Age Percent Change from Rated EF 0% -4% 0% 3% -1% -8% -3% -4% -5% -3% -3% -1% 2% Interface (B/CC) NA Good NA Excellent Good NA Good NA Excellent Poor Poor Poor Excellent Spiral Heat Exchanger NA Good NA Excellent Good NA Good NA Good Good Good Good Good Scaling on electric heating elements may have a significant impact on the performance of electric water heaters. Unit 1 Unit 2 Unit 3 Unit 4 Unit 5 Unit 6 Unit 7 Unit 8 Unit 9 Unit 10 Unit 11 Unit 12 Unit 13 Electric Gas Electric Gas Gas Electric Gas Electric Gas Gas Gas Gas Gas Age Percent Change from Rated EF 0% -4% 0% 3% -1% -8% -3% -4% -5% -3% -3% -1% 2% Upper Element Good NA Excellent NA NA Poor NA Poor NA NA NA NA NA Lower Element Good NA Good NA NA Poor NA Poor NA NA NA NA NA 11

14 Conclusions Gas Water Heaters» Components degraded significantly after five years usage» Component degradation had no correlation with performance degradation» There is no correlation between age and performance degradation.» The spiral heat exchanger (baffles) is the primary source of heat transfer between combustion products and water. Electric Water Heaters» There may be a correlation between the age of electric water heaters and age but we cannot draw a strong conclusion with the limited sample size» Scaling on electric water heater heating elements may have a large impact on the performance. Future research could focus on understanding the impact of scaling on electric water heaters. 12