1 Update on CO2 HPWH Ken Eklund Washington State University Energy Program Showcase September 27, 2016
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3 Update on CO2 HPWH Ken Eklund Washington State University Energy Program Showcase September 27, 2016
Introduction to Technology Research Overview and Manufacturer Update Performance of Split System Heat Pump Water Heaters Demand Response Performance of 40 and 80 gallon systems Combined System Development and Findings Next Steps Update Roadmap 4
A Split System Heat Pump Water Heater Split System CO 2 Refrigerant Variable Speed Inverter Driven No Electric Element 1.5 kw Input/ 4.5 kw out From 50 to 150 F in Single Pass
Basic Function Illustration from Sanden Brochure 6
BPA Funded Research on Advanced CO 2 HPWH TIP 292 Performance as a Water Heater (2012-2016) TIP 302 Demand/Response Potential (2013 2015) TIP 326 Combined Space and Water Heating in New, High Homes (2014 2016) TIP 338 Combined Space and Water Heating in Existing Homes (2015--) 7
UL Listed and Available In July 2016 Sanden obtained UL listing on its split system heat pump water heater and began marketing it The new system has settable temperature and is 5% more efficient than the original model Finished lab test this week results will soon be available 8
Advanced Water Heater Specification Listing NEEA Listing is in process The Regional Technical Forum is in process of considering the measure for provisional UES When this is done, NEEA will proceed to place the system on its Advanced Water Heater Specification List This listing will facilitate utilities offering incentives 9
at Different Sites 10
kwh/100 gallons Comparative Performance 25 kwh per 100 gallons water delivered 20 15 10 5 0
Demand Response 40 Gallon CO 2 HPWH PNNL Lab Home 12
80 Gallon Split System 13
Extreme Oversupply Mitigation Test Water Heater Off at 1 pm To Make Room to Absorb Off-Peak Wind Energy Split System (80 Gallons) Unitary System (40 Gallons) The top of graph points are delivered water temperature bottom are between draws Electric Resistance water heater off for only 3 hours max 14
Ecotope Lab Test for Demand Response Hours Allowed to Operate 15
Impact on Load Water Heater Load Shape Total Load Shape System Off Time in Box DR Could Help Flatten the Peaks! 16
Impact of DR on 17
Genesis of Combined System Project The CO 2 System is very efficient as a dedicated water heater. Average.05 kwh per gallon Same efficiencies in climates ranging from 4,500 to 8,500 HDD System serves large loads while operating 25% of time in very cold weather Decided to try adding another load
Project Design Targeted homes with low design loads of 10,000 to 15,000 Btu per hour current WA code house design load is 20,000 to 30,000 Btu per hour. NEEA provided recruitment, technical assistance to builders, engineering and monitoring through its Next Step Home (NSH) program BPA provided program management, building code support, installation support, lab testing and data analysis and reporting Ecotope provided design assistance and a lab test CLEAResult provided NSH support and services of Mark Jerome, lead system installer WSU managed project, installed monitoring, analyzed, reported field data 10 field sites with 7 located in Heating Climate Zone 1 ( 6,000 HDD), 1 in Zone 2 (6,001 to 7499 HDD) and 2 in Zone 3 (> 7,500 HDD) 19
Combi System
Monitoring and Analysis In the field study there were more than double the number of sensors and data than in the dedicated water heating research Monitoring and analyzing the performance of two loads from the same source is challenging A follow-on lab study was designed to capture the interaction of the two loads 21
Monitoring Setup 22
Monitoring Issues Murphy works overtime in field research Installing monitoring requires many sensor installations and connections and all have to be perfect for collection of complete data Internet connections should not be relied on for continuous data collection Flow meters must be calibrated to collect accurate data Whoops! Plumber moved the sensor. Monitoring is impacted by changes in design, plumbing and wiring 23
House Characterization Site # 1 2 3 4 5 6 7 8 9 10 HDD 5,622 6,239 8,851 8,851 5,655 4,461 4,867 4,867 4,867 4,696 Design T F 19-1 -16-16 23 24 27 27 27 24 Conditional Floor Area Design Load Btu/hr 2,057 1,062 2,812 1,533 1,152 2,000 2,218 1,936 3,764 1,538 13,098 11,760 28,864 21,061 12,430 6,226 10,285 8,516 10,853 11,007 Dist. system RF RF RF RF RP RP RF RF RF RF+FC Set point 67 73 67 63 70 60 71 73 68 73 DHW T F 120 120 122 120 120 130 120 130 120 120 # Occ. 4 2 2 0 2 0 3 2 4 5
Field Energy Factor Field Energy Factor (FEF) is the combined space and water heating performance It accounts for all system inefficiencies including: Tank loss Pipe loss Pump energy Controls Defrost Freeze Protection The formula is FEF = (Q DHW + Q SpaceHeat ) / Q Energy In
Performance Bellingham, WA McCall, ID Olympia, WA Milwaukee, OR Seattle (Ballard), WA Tacoma, WA
The Numbers Site OAT (F) CWT (F) XRWT (F) DHW (GPD) FEF Days sampled H NH H NH H H NH H NH H NH 1 43.1 56.3 76.3 77.51 82.9 34.3 23.5 1.04 0.9 31 65 5 47.47 64.1 60.2 69.93 111.4 17.9 21.0 0.6 1.2 83 75 7 48.94 57.2 60.4 67.06 89.7 28.6 18.3 1.2 0.8 80 2 10 49.12 59.6 58.1 58.99 101.4 151.9 167.3 2.3 3.4 60 33 Lowest performance correlates with highest return water temperature (S5) FEF of Site 5 doubled in Non Heating due to increased hot water use Where DHW use drops, performance during Non Heating drops (S1 & 7) Largest hot water use correlates with highest FEF due to cold water (S10)
Design Issues Systems worked best where design load was within heat pump limits even if load was met by total capacity Standard programming for combined heat exchange, control and pump (X Block ) did not operate system properly Tank destratification occurred especially in cold climates and with high temperature heating systems which reduced efficiency Cross flow resulted in reduced operating efficiency
Matching Capacity to Load Sites 4 and 6 were both unoccupied but heated during the same period in winter 2015 At Site 4, design load is 21,061 Btu per hour at Site 6 it is 6,226 Capacity for both sites was 13 to 15 thousand Btu per hour depending on outdoor air temperature Note the large difference in FEF Site OAT XRWT (F) FEF Days sampled 4 25 80 0.13 24 6 48 106 2.05 16 The very low FEF at Site 4 indicates the system did not function properly
Tank Destratification Occurs when the heating system flow recycles the tank making the water one temperature at 3 GPM can cycle 83 gallon tank in 28 minutes Without temperature difference transcritical operation efficiency plummets To maintain tank stratification: Match load to heat pump output Use a larger tank in combined systems 120 gallon is recommended based on lab tests Return water to tank location closest to that temperature Use hot water which pulls cold water into the bottom of the tank maintaining stratification
Tempering Valve Highway to Reduced Performance Check Valves Tempering Valve Cross Flow Sanden Hot Water Storage Tank Sanden Heat Pump Water Supply
Impact of Cross Flow Cross flow is suspected at all 7 currently operating systems and confirmed at 3 sites High temperatures delivered to gas exchanger ranging from 110 to 121 have been measured Impact on system efficiency may be as high as a full FEF or COP level It applies to hydronic heat pumps used as dedicated water heaters as well as combi systems 32
Optimized Efficiencies with Split System To attain combi field efficiencies closer to those predicted in the Ecotope Lab Study of Combined Systems To attain summer water heating efficiencies for combi systems like those in field studies of the system used as a dedicated water heater Climate Annual Water Space Heating Heating Combined Boise 2.9 2.3 2.5 Kalispell 2.6 2.1 2.2 Portland 3.0 2.6 2.7 Seattle 2.9 2.6 2.7 Spokane 2.8 2.2 2.4 33
Next Steps Optimize systems and monitor for another year Field Test a Ductless Heat Pump plus DHW Test a higher capacity CO 2 Heat Pump designed specifically for space heat for colder climates and higher load homes Domestic Hot Water will be heated with a sidearm exchanger or indirect tank
The Eco Runo 11 kw Output (37,532 Btu per Hour) No freeze protection issues No cross flow issues Designed for space heat 35
Perspective on Combi Research Heated and provided hot water to 7 low load homes with a 1.5 kw heat pump through at least one heating season in climates ranging from 4,461 to 5,655 HDD Average annual efficiencies ranged from.9 to 2.85 FEF Optimization including cross flow prevention, relocation of return and reprogramming the controls may increase performance We need more time for this project to measure the impact of these optimizations
Conclusion 4x as efficient as electric resistance water heating and more efficient than currently available integrated HPWH High heating capacity means it operates only ¼ of the time in normal DHW operation CO 2 refrigerant impact on climate is minimal 37
Contact Information Ken Eklund Building Science & Standards Lead Washington State University Energy Program eklundk@energy.wsu.edu Project Principle Investigator and Manager 38
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