Domestic EcoCute outdoor unit (front) and hot water storage tank (back)

The EcoCute is hot water supply system consist of two units, air source heat pump unit and large hot water storage tank unit.[1] Air source heat pump in this system is mandatory to use supercritical carbon dioxide as the refrigerant.[2][3] Hot water is produced by air source heat pump then supply to hot water storage tank for home or domestic bathing, kitchen, floor heating and others usage. The start of hot water usage had been home or domestic area then later become in general in economic activity area of manufacturing and trade. EcoCute is the registered trademark of Kansai Electric Power Company applied in January 2001 and registered in June 2002.[4][5]

Etymology timeline

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Japanese word Eko (Eco) for Ecology (ja:エコロジー) and Economy (ja:エコノミー), Cute is a near homonym to kyūtō (給湯); literally "supply hot water" and Cute is used instead of Kawaii (ja:可愛い). All these words are wasei-eigo and frequently used broadly in general.[6]

  • Denso began to develop new and more energy efficient use of CO2 heat pumps, that makes hot water from cool tap in Japanese Market in 1990.[7][8]
  • The first commercial breakthrough came under the name of "EcoCute" in Japan in 2000, announced by Belgium organization SHECCO.[7][9]
  • EcoCute is the registered trademark of Kansai Electric Power Company applied in January 2001 and registered in June 2002.[4][5]
  • The first commercial EcoCute was marketed in Japan by Corona Corporation (ja:コロナ) in 2001.[10]
  • It is literally called Natural refrigerant (CO2) heat pump hot water supply machine "EcoCute" (In Japanese: 自然冷媒(CO2)ヒートポンプ給湯機「エコキュート」) when awarded by Minister of Economy, Trade and Industry in fiscal year 2001.[11]
  • It also literally called with another term Home use heat pump hot water supply machine "EcoCute" (In Japanese: 家庭用ヒートポンプ給湯機(エコキュート)) by JRAIA standard "JRA 4050" until JIS Standard in 2011 issued.[12][13]
  • JIS issued Standard "JIS C 9220" in 2011, revised to "JIS C 9220:2018" in 2018, titled in English; "Residential heat pump water heaters", without "EcoCute", titled in Japanese; literally "Home use heat pump hot water supply machine" (ja:家庭用ヒートポンプ給湯機).[14][15]

Authentic name is "Residential heat pump water heaters" by JIS, however trademark naming simple and short term "EcoCute" is much popular and general in public and market, so that authority only use Japanese term defined or titled long Japanese by JIS C 9220 in occasion bases as necessary.

Background and demand

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Historically Japanese people love bathing in hot spring or Onsen that is everywhere in Japan as seen List of hot springs in Japan. Communal bathhouse called Sentō is popular culture and bathroom Furo is in every family house and condominium.

In September 2004, the survey conducted how many times of bathing in a week, the outcome is everyday 77.2%, 3 to 4 times 11.1%, and 5 to 6 times 5.4%.[16]

The mandatory bathroom (Furo) proportion as the essential equipment is 95.5%, of 49.598 million family houses and condominiums, rest of 4.5% family use Sentō or communal public bathing of onsen operated by local government, surveyed by Statistics Bureau (Japan) in 2008.[17]

In Japan in 1998, water heating (Kyuto (給湯, kyūtō)) accounted for 33.8% of typical domestic energy consumption, with air conditioner and kerosene heater heating accounting for another 26.9% and cooling by air conditioner another 2.3%. Most of the remaining 37% was spent on electrical home appliances, a field where 21st-century innovations in energy conservation began to make considerable energy savings.[18] This left hot water supply as the most difficult area for energy conservation, leaving a gap in the market for the EcoCute. By January 2005, Japanese companies were producing more than 450 models of EcoCute systems, and sales of domestic units increased 130–150% each year in-between 2001 and 2005.[19]

Denso first introduced the EcoCute outside Japan at the COP9 Milan, Italy in December 2003.[20]From 2007, Denso began concentrating on marketing the EcoCute in the EU.[21][22][8]

In Japan, the Japanese government incorporated the EcoCute into its CO2 reduction program under the Kyoto Protocol, mandating the installation of 5.2 million units in commercial and domestic properties by 2010.[23]Japanese Ministry of Economy, Trade and Industry prospects 14 million EcoCute system spread by fiscal year 2030 as of 2015.[24]

History

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Fusanosuke Kuhara, founder of Hitachi, Ltd., made air conditioner for his own home use using compressed CO2 as refrigerant in 1917.[25]

Thomas Midgley Jr. discovered dichlorodifluoromethane, a chlorinated fluorocarbon (CFC) known as freon in 1930. CFCs rapidly replaced traditional refrigerant substances, including CO2 (which proved hard to compress for domestic use[26]), for use in heat pumps and refrigerators.

From the 1980s, CFCs began to lose favor as refrigerant when their damaging effects on the ozone layer were discovered. Two alternative types of refrigrant, hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs), also lost favor when they were identified as greenhouse gases. HCFCs were found to be more damaging to the ozone layer than originally thought. The Vienna Convention for the Protection of the Ozone Layer, the Montreal Protocol and the Kyoto Protocol call for the complete abandonment of such refrigerant by 2030.

In 1989, international concern about the effects of chlorofluorocarbons and hydrochlorofluorocarbons on the ozone layer, scientist Gustav Lorentzen and SINTEF patented a method for using CO2 as refrigerant in heating and cooling. Further research into CO2 refrigeration was then conducted at SHECCO (Sustainable HEating and Cooling with CO2) in Brussels, Belgium, leading to increasing use of CO2 refrigerant technology in Europe.[26]

Denso in collaboration with Gustav Lorentzen, developed an automobile air conditioner using CO2 as refrigerant in 1995.[27]They demonstrated the invention at the June 1998 International Institute of Refrigeration/Gustav Lorentzen Conference.[28] After the conference, CRIEPI and TEPCO approached Denso about developing a prototype air conditioner using natural refrigerant materials instead of freon. Together they produced 30 prototype EcoCute units for a year-long experimental installation at locations throughout Japan, from the cold climate of Hokkaidō to hotter Okinawa.[29]After this successful feasibility study, Denso obtained a patent to compress CO2 refrigerant for use in a heat pump from SINTEF in September 2000.

The first commercial domestic EcoCute was marketed in Japan by Corona Corporation [ja] in May 2001, and several manufacturers sold this year as well, and nine manufacturers were awarded by Minister of Economy, Trade and Industry,[11] cumulative total 300 thousand units sold in fiscal year 2001, 1.74 million units by fiscal year 2008, and 9.01 million units by August of 2023.[30][31]

EcoCute machine basics

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An EcoCute machine or system consists of mainly air source heat pump unit which is a type of heat pump and hot water storage tank unit.

Heat pump unit

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Heat pump unit consist with components of auxiliary fan heater, two heat exchangers, gas compressor, ejector or expansion valve and refrigerant CO2 circulating piping. The following is functional sequence in heat pump unit. The sealed components of heat pump unit are serially connected with refrigerant CO2 gas in circulation. Heat pump unit is installed in outside of house or building, but in cold district unit to be installed inside.

  1. At the first stage, first heat exchanger (air to refrigerant) collects heat from the air outside then move its heat to the refrigerant as energy transfer. Air flow is usually obtained using a centrifugal fan; in cold areas with ambient temperatures around −20 to −25 °C an auxiliary fan heater is attached.
  2. At the second stage, a gas compressor is used to increase the temperature of the gaseous CO2 refrigerant to hot around 90 °C via adiabatic compression.[32] The carbon dioxide becomes a supercritical fluid by pressure up around 100 atmospheric pressure.[2] Several types of gas compressor can be used in this stage by manufacture and EcoCute model number, dual layer cylindrical compressors, scroll compressors, or dual stage rotary compressors.[33]
  3. At the third stage, second heat exchanger (refrigerant to water) transfers energy of the hot refrigerant to cool water for warming up cool water to produce hot water. Cool water from storage tank unit here is feed into heat pump unit and changed to hot water through second heat exchanger (refrigerant to water) then return to feed out to storage tank.[32][34]
  4. Finally at fourth stage, ejector or expansion valve reduces pressure of refrigerant, letting it cool down refrigerant CO2 temperature via adiabatic expansion and revert to CO2 gas from supercritical fluid, then circulation back to the first stage.

Water storage tank unit

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The following is to describe cool/hot water flow via heat exchanger component of heat pump unit and water storage tank unit. Large hot water storage tank unit with volume range from 180L[35] to 560L[36]and installed in outside, but in cold district, tank to be installed inside to keep hot water from cold air outside. The storage tank has two inputs and two outputs, these are;

  • "Cool water input" from tap water piping to water storage tank unit
  • "Cool water output” from water storage tank unit to heat pump unit
  • "Hot water input” from heat pump unit to water storage tank unit
  • "Hot water output” from water storage tank unit to supply hot water to bath, kitchen and others

Cool water input and output are placed in lower portion of tank due to cool water is heavier than hot water in relative density and Hot water input and output are placed in higher portion of tank due to hot water is lighter in relative density. Water storage tank unit is a single tank, however to avoid unnecessarily decreasing temperature of hot water with cool and hot water too much mixture, a single tank has two small dual compartment of hot water storages within single hot water tank storage.[32]

Other functions

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On upper grade EcoCute implements two cool/hot water mixing valves, one mixing valve is for bath and other mixing valve is for kitchen at the same time use with different temperature of hot water for example.[37]

One or two wired remote control, size bit smaller than tablet, is used for bath and/or kitchen or other places for example to control temperature, hot water warms up timing of daytime or nighttime concerning electric power cost difference in night and day.[34]Remote control is attached any place by family’s preference.

JIS published revised version JIS C 9220:2018, 90 pages standard document in 2018, from initial version JIS C 9220:2011, that states with title Residential heat pump water heaters and use refrigerant either CO2 or Hydrofluorocarbons (HFCs) as the single system, however EcoCute shall use refrigerant CO2 because of Hydrofluorocarbons (HFCs) is greenhouse gas.[38][15]

Refrigerant carbon dioxide (CO2) is numbered or coded as R-744 for carbon dioxide by ASHRAE standard 34.

The EcoCute can derive three or more unit ratio of COP (Coefficient Of Performance) to heated hot water energy from outdoor air of two or more units plus one unit input of electrical energy, resulting in reduced CO2 emissions compared to other type of water heating system that only use electricity heating energy or natural gas burning.[39][32][40]

The COP value changes depend on each temperature of outside air and tap water feed in.[41] To produce 90 °C hot water, an EcoCute consumes 75% less electricity than an electric water heater type, and costs 80% less than heating water by natural gas burning type in Japan.[42] Also, by reducing use of fossil fuels, the EcoCute results 50% reduction in CO2 emissions.[43]Not considering upstream losses of input source energy, as one example reference value, the EcoCute's COP is 3.8 in industrial use, while electric power water heating is 1.0, and gas boiler is 0.88 including pilot light loss.[42]

Market response

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Customer satisfaction

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The Japan Refrigeration and Air Conditioning Industry Association (JRAIA: 日本冷凍空調工業会) conducted customer satisfaction survey in January 2022 for 518 users nationwide of EcoCute owner who bought it between January 2020 and December 2021. The outcome is with pie chart, 47% satisfied, 47% somewhat satisfied, 5% somewhat dissatisfied, and rest 1% dissatisfied.[44]

Product recall

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Consumer Affairs Agency presents by product recall Web query site. Query with Japanese terminology "エコキュート" (EcoCute), product recall for EcoCute is, as of August 2024, only 2 cases since 2001 EcoCute put into market, that "Case 1" CORONA EcoCute; Inspection and repair produced entire heat pump units itself which were procured from Panasonic[45]in between 2005 to 2008. "Case 2" Panasonic EcoCute; Inspection and repair produced in between 2003 to 2013. Both cases the responsible action had been taken by each manufacture from July 2014. Recall trouble is salty environment, salt deposition, may be caused compressing part (machine element) in heat pump unit, then would damage with low probability though, heat pump unit itself to be deformed. For instance in comparison, recall for air conditioner is 84 cases, 13 out of 84 are home use, mostly air conditioner on automobile/car since December 2003, and Passenger car is 2,707 cases oldest recall since 23 July 2002.[46]

Lawsuit

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Married couple in Gunma had been felt insomnia, headache, dizziness, nausea etc. health hazards caused possible low frequency sound, operation sound and vibration of EcoCute since February 2009 by husband and May by wife. Couple claimed to Consumer Affairs Agency for inspection of cause and survey in 2012, and litigation to the house next door who own EcoCute. Conclusion of trial is reconciliation with approx. 2.7 million Japanese yen include health hazards and replacement of brand new EcoCute system, all fee covered by EcoCute manufacture and house builder who installed EcoCute to next door neighborhood house in November 2013. Consumer Affairs Agency reported technical details in December 2014.[47] Yōtaro Hatamura (ja:畑村洋太郎), chairman of the customer's safety survey committee in Consumer Affairs Agency asked every EcoCute manufacturer to make efforts to reduce the risk of health hazards from EcoCute on 19 December 2014.

Panasonic suit to court Saginomiya Seisakusho, Inc. (ja:鷺宮製作所) with approx. 1.933 billion Yen damages cost for 117,600 pieces defective parts of each EcoCute, procured from Saginomiya, replacement in March 2014. On the other hand, Saginomiya's rebuttal is wrongly generated ammonia from resin of Saginomiya produced part, but raw material resin has been procuring from Panasonic Electric Works ( "Works" merged as the subsidiary of Panasonic in 2011) that is ingredient of such defected part. Saginomiya requested approx. 2.054 billion Yen to Panasonic. Non-disclosure agreement is between them so that exact detail is unknown. Mainichi Shimbun report concluded Saginomiya pay approx. 1.3 billion Yen to Panasonic in reconciliation in September 2018.[48]

See also

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References

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  1. ^ Originator DENSO calls EcoCute as the system; Right side image; CO2 Refrigerant Heat-Pumps, DENSO offers a CO2 Heat Pump Hot Water Supply System called "EcoCute"
    Originator DENSO calls EcoCute as the system; Right side image; CO2 Refrigerant Heat-Pumps, DENSO offers a CO2 Heat Pump Hot Water Supply System called "EcoCute" at the Wayback Machine (archived 2020-09-18)
  2. ^ a b About Heat Pump water heater, About Eco Cute, HPTCJ (Heat Pump and Thermal Storage Technology Center of Japan)
    About Heat Pump water heater, About Eco Cute, HPTCJ (Heat Pump and Thermal Storage Technology Center of Japan) at the Wayback Machine (archived 2012-05-12)
  3. ^ JIS standard - JIS C 9220:2018 Titled; "Residential heat pump water heaters" (ja: 家庭用ヒートポンプ給湯機) Slide down "Scrollbar" 10% & 45% to see; Page 4 & 40 indicates two mandatory units in concatenation, "Heat pump unit" & "hot water storage tank unit" (ja: ページ4 & 40は必須の"ヒートポンプユニット" & "貯湯ユニット"の連結を図示している。)]
    JIS C 9220 : 2011, revised to JIS C 9220:2018 in 2018, Titled standard; "Residential heat pump water heaters"; Slide down "Scrollbar" 10% & 45% to see; Page 4 & 40 indicates two mandatory unit in concatenation, "Heat pump unit" & "hot water storage tank unit" (ja: 規格題;家庭用ヒートポンプ給湯機; ページ4 & 40は必須の"ヒートポンプユニット" & "貯湯ユニット"の連結を図示している。) at the Wayback Machine (archived 2023-11-28)
  4. ^ a b In English and Japanese selectable at top right corner; Register No. 4575216 (登録4575216) EcoCute (エコキュート) Kansai Electric Power Company (関西電力) applied date Jan.30,2001 (2001/01/30), registered date Jun.07,2002 (2002/06/07)
  5. ^ a b Report of Patents application trend on Heating and cooling by natural refrigerant[dead link]
    (in Japanese) Report of Patents application trend on Heating and cooling by natural refrigerant. Trademark No. 4575216 – Japan, third line 10. from bottom on page 3/24, 15 May 2003, Japan Patent Office. at the Wayback Machine (archived 2006-12-08) (ja: 10 エコキュートは関西電力株式会社の登録商標 登録番号 4575216号 平成15年5月15日)
  6. ^ "Cute (disambiguation)" listing Cute (Japanese group) and Cute (album), and Japanese language website "Cute (ja:キュート) (disambiguation)" listing several "キュート".
  7. ^ a b 4th section titled "EcoCute: The first commercial success"; The first commercial breakthrough came in the year 2000 with the introduction of Heat Pump Water Heaters in Japan, under the name of "EcoCute"./ "In 1990, the Denso Corporation...began to develop new, more energy-efficient heat pumps … the use of CO2 heat pumps" at the Wayback Machine (archived 2007-09-10) Shecco Page bottom, "Contact us"; call us at:+32 Belgium listed on List of country calling codes.
  8. ^ a b 2nd section "About the product"; DENSO first introduced CO2 refrigerant to its Air to Water Heat Pumps in 2001, in Japan. Known as 'Eco-Cute'
    2nd section "About the product"; DENSO first introduced CO2 refrigerant to its Air to Water Heat Pumps in 2001, in Japan. Known as 'Eco-Cute' at the Wayback Machine (archived 2023-10-10)
  9. ^ SHECCO; Sustainable HEating and Cooling with CO2 Website "ATMOsphere", formerly known as SHECCO: See; right bottom end.
  10. ^ (In Japanese) EcoCute with Katakana (ja:エコキュート) CORONA Corporation (株式会社 コロナ): Titled: Targeting 150% growth. Page 2. Item 2; Company’s growth strategy (2. コロナの成長戦略) succussed first home use EcoCute development in world in 2001. (2001年に世界で初めて家庭用「エコキュート」の開発に成功し) at the Wayback Machine (archived 2004-06-09).
  11. ^ a b (In Japanese) Fiscal year 2001. Awarded 5 companies having product name with EcoCute (ja:エコキュート) out of 9 companies. (平成13年度) 省エネ大賞 経済産業大臣賞 自然冷媒(CO2)ヒートポンプ給湯機「エコキュート」 at the Wayback Machine (archived 2002-10-20). ECCJ - The Energy Conservation Center, Japan nominated EcoCute nine manufactures for Energy Conservation award.
  12. ^ JRAIA, Web site of Japan Refrigeration and Air conditioning Industry Association
  13. ^ JRAIA (Japan Refrigeration and Air Conditioning Industry Association) had been called literally “Home use heat pump hot water supply machine” with Standard "JRA 4050" until Japanese Industrial Standards (JIS) C 9220 issued in 2011, so that replaced onward with JIS C 9220. - In Japanese (ja:“家庭用ヒートポンプ給湯機(エコキュート)は、カタログ等で(社)日本冷凍空調工業会規格(JRA 4050)の評価に基づいた性能表示をしていましたが、2011年にJIS C 9220が制定され、それ以降はJIS C 9220に替わります.“) at the Wayback Machine (archived 2022-06-26)
  14. ^ JIS standard - JIS C 9220:2018 Residential heat pump water heaters (ja: 家庭用ヒートポンプ給湯機)
    JIS C 9220 : 2011, revised to JIS C 9220:2018 in 2018, 90 pages in full Japanese, 4th sheet JIS C 9220:2018. Titled:"家庭用ヒートポンプ給湯機" "Residential heat pump water heaters"pace. at the Wayback Machine (archived 2023-11-28)
  15. ^ a b JIS standard - JIS C 9220 : 2011, revised to JIS C 9220:2018 in 2018. Although JIS standard mentioning to use either CO2 or HFC (Hydrofluorocarbon) as refrigerant, EcoCute use CO2 mandatory, on 4th sheet. (ja: 4枚目; 1 適用範囲; 二酸化炭素(CO2)又はハイドロフルオロカーボン(HFC)を冷媒として用いたもの...とされるが、EcoCuteは CO2を使用。)
    JIS C 9220 : 2011, revised to JIS C 9220:2018 in 2018, Although JIS standard mentioning to use either CO2 or HFC (Hydrofluorocarbon) as refrigerant, Ecocute use CO2 mandatory, on 4th sheet. (ja: 4枚目; 1 適用範囲; 二酸化炭素(CO2)又はハイドロフルオロカーボン(HFC)を冷媒として用いたもの...とされるが、EcoCuteは CO2を使用。) at the Wayback Machine (archived 2023-11-28)
  16. ^ (in Japanese) Second "Pie chart" everyday; 77.2%, 3 to 4 times 11.1%, and 5 to 6 times 5.4%. conducted, in September 2004, by Central Research Service, Inc since 1954
    (in Japanese) Second "Pie chart" everyday; 77.2%, 3 to 4 times 11.1%, and 5 to 6 times 5.4%. conducted, in September 2004, by Central Research Service, Inc since 1954 at the Wayback Machine (archived 2012-12-19)
  17. ^ Website of Statistics Bureau (Japan); Slide down “Scrollbar” 15% to see; Bathroom equipment rate; 95.5% in 2008 (ja: 平成20年) (in Japanese) Table 2-26, Top line; Total family house and condominium; 49.598 million, Bathroom equipment; 47.386 million rate 95.5%
    (in Japanese) Archive of Website of Statistics Bureau (Japan);Bathroom equipment rate; 95.5% in 2008 at the Wayback Machine (archived 2018-11-15) Table 2-26, Top line; Total family house and condominium; 49.598 million, Bathroom equipment; 47.386 million rate 95.5% (Equivalent equation; 49.598 x 0.955 ≒ 47.386) (Ja: 2-5 住宅の設備、<トイレ・浴室・洗面所の保有状況>、浴室保有率は95.5% 洗面所保有率は89.5%、表2-26> Year 2008 平成20年, 最上列 総数 実数 1,000 unit 住宅総数 49,598、うち浴室あり 47,386、うち洗面所あり 44,410、浴室割合 95.5% 洗面所割合89.5%)
  18. ^ 2.2 (2) Yearly home energy consumption by usage category[dead link]
    Slide down "Scrollbar" 50% to see; 2nd group of Bar graph: Section 2.2, (2) Energy consumption by purpose of usage per household、bottom bar, year '98. Hot Water heating and supply "kyūtō" (ja: 給湯) accounted for 33.8%, with number 15,648 above, out of 46,268 total in 1998; which is Mega-Joule single household consume /Year.(ja: 2.2 家庭部門のエネルギー消費原単位の推移 ((2) 世帯当たり用途別エネルギー消費量, MJ (世帯・年). The Energy Conservation Center, Japan (ECCJ)) at the Wayback Machine (archived 2007-06-11)
  19. ^ (in Japanese) TOKUGIKON (特許庁技術懇話会) Archived 2005-05-12 at the Wayback Machine, Organized current and retired officers, with Japan Patent Office, technical discussion association (特許庁技術懇話会) since 1934 (in Japanese). Ahead word Archived indicates: First page of page numbered 122: Context/content; Second paragraph (line 10-11). EcoCute put on market in 2001, approx. 450 types produced by 26 Mfg. as of now/today (2005.1.28. shown at bottom line, this pdf file/document issued date) and 130–150% annual increased in-between 2001 and 2005. (エコキュートは、2001年に発売されて以来年成長率130〜150%と好調な売れ行きを見せており、今では26社から約450種類の製品が販売されています)
  20. ^ Slide down “Scrollbar” 85% to see; (in Japanese) DENSO at COP9 Milan in December 2003 at the Wayback Machine (archived 2021-07-29) Section; Becoming Japan's representative of global warming prevention technology (ja: 地球温暖化防止技術の日本代表に), EcoCute introduced to world COP9 in Milan in December 2003 (ja: 2003年12月にミラノで開催された気候変動枠組条約締約国会議(COP9)で、エコキュートが……世界に紹介された)
  21. ^ EcoCute demand surges in Europe at the Wayback Machine (archived 2008-10-19), European Heat pump network
  22. ^ Heat pumps offer huge potential, Section "Industry; Mayekawa MYCOM" at the Wayback Machine (archived 2009-08-13), IEA Conference
  23. ^ Website of Kantei (in Japanese). Slide down "Scrollbar" 65% see; Page 16/24 (ja: 別16/別24), the second block from left of bottom layer frame: Promote CO2 refrigerant heat pump for hot water supply 5.2 million unit by 2010. (ja: CO2冷媒ヒートポンプ給湯器の普及台数<約520万台>)
    Website of Kantei (in Japanese). Slide down "Scrollbar" 65% see; Page 16/24 (ja: 別16/別24), the second block from left of bottom layer frame: Promote CO2 refrigerant heat pump for hot water supply 5.2 million unit by 2010. (ja: CO2冷媒ヒートポンプ給湯器の普及台数<約520万台>) at the Wayback Machine (archived 2024-03-02)
  24. ^ Prospects 14 million EcoCute systems,Page 1; Table indicates. (ja: CO2冷媒HP給湯機(エコキュート)2012年度 400万台、2030年度見通し1400万台, web site; 経済産業省 出所)資源エネルギー庁、「⻑期エネルギー需給⾒通し関連資料」(2015) from Website, Ministry of Economy, Trade and Industry
    Prospects 14 million EcoCute systems, Page 1; Table indicates. from Website, “Ministry of Economy, Trade and Industry” (ja: CO2冷媒HP給湯機(エコキュート)2012年度 400万台、2030年度見通し1400万台,web site; 経済産業省; 出所)資源エネルギー庁、「⻑期エネルギー需給⾒通し関連資料」(2015) at the Wayback Machine (archived 2023-12-17)
  25. ^ Fusanosuke Kuhara used CO2 gas compressed Cryocooler in 1917. Archived 2022-07-10 at the Wayback Machine 2nd Page numbered 28, right side first paragraph (line 3-6). Fusanosuke Kuhara attached CO2 gas compressed Cryocooler with approx. 6,400kcal/h in his home in 1917. In Japanese: 冷凍機が冷房用として使用されたのは1917年久原房之助が神戸の私邸に約6400kcal/h炭酸ガス圧縮機を取り付け、室内を冷やしたのが最初といわれています.
  26. ^ a b Second section; The rediscovery of CO2[dead link] Second section; The rediscovery of CO2 at the Wayback Machine (archived 2007-10-07); Web site - Shecco
  27. ^ (in Japanese) Denso site for patent Slide down "Scrollbar" 35% to see; EcoCute Development Story; It was like creating another organism; Yamanaka and other members borrowed basic patent and experimental device from Dr. Gustav Lorentzen in 1995. (ja: エコキュート開発物語; それは、まったく別の生物を作り出すようなものだった; 1995年山中たちはローレンツェン教授から自然冷媒に関する基本特許や実験装置を借り受け)
    Slide down "Scrollbar" 35% to see; (in Japanese) Denso site for patent of CO2 at the Wayback Machine (archived 2021-07-29) EcoCute Development Story; It was like creating another organism; Yamanaka and other members borrowed basic patent and experimental device from Dr. Gustav Lorentzen in 1995. (ja: エコキュート開発物語; それは、まったく別の生物を作り出すようなものだった; 1995年山中たちはローレンツェン教授から自然冷媒に関する基本特許や実験装置を借り受け)
  28. ^ Natural Working Fluids '98, IIR – Gustav Lorentzen Conference: CiNii Archived 2024-02-27 at the Wayback Machine
  29. ^ (in Japanese) Slide down “Scrollbar” 70% to see; Second Paragraph, section: Repeating improvements after improvements、then commercialization at last (ja: 改良につぐ改良、そして商品化へ), Line 9 or Second paragraph; 30 experimental monitoring EcoCute systems installed in home/housing from Hokkaidō to Okinawa. (ja: 北海道から沖縄まで約30のモニタ一家庭に試験機を設置し) at the Wayback Machine (archived 2021-07-29)
  30. ^ (in Japanese) Corona Corporation: Titled "Targeting 150% growth, succussed to develop home use EcoCute for world market in 2001". 2nd page section 2. Corona Growth strategy (ja:2.コロナの成長戦略) World first household use EcoCute developed, shipment and on sale in 2001(ja:エコキュート年率150%の成長を目指して, 2. コロナの成長戦略 - 2001年に世界で初めて家庭用「エコキュート」の開発に成功し..発売以来) at the Wayback Machine (archived 2004-06-09)
  31. ^ (in Japanese) Web site of Heat Pump & Thermal Storage Technology Center of Japan; Bar graph indicates; EcoCute: number of units , cumulative transition, shipments, 9.01 million by August 2023
    (in Japanese) Archived 2024-02-28 at the Wayback Machine Archived: Bar graph indicates; EcoCute: number of units , cumulative transition, shipments, 9.01 million by August 2023.
  32. ^ a b c d (in Japanese) EcoCute (TOKUGIKON (特許庁技術懇話会)Archived 2005-11-07 at the Wayback Machine, Japan Patent Office Society (in Japanese).
    Ahead word Archived indicates: 4th sheet Page 6/12; Page 127 & 5th sheet Page 7/12; Page 128, 2005.1.28. no.236 tokugikon (TOKUGIKON (特許庁技術懇話会),
    • Slide down "Scrollbar" 50% to see; page 6/12 numbered 127;
    Fig 7. Heat pump configuration illustration (citation from TEPCO home page): At top right, Output of hot water is possible to rise up to 90 °C from tap water (plus) 5 °C (5 °C water inlet at bottom right). Under the condition of outside air temperature (minus) -10 °C, EcoCute can produce practical hot water that could not obtain by chlorofluorocarbon refrigerant. (ja:90℃の高温沸き上げ, CO2冷媒は高温度差加熱が可能です。従来のフロン系冷媒では実現できなかった、9 0℃高温沸き上げを可能にしました。外気マイナス1 0℃の条件下でも高温沸き上げが可能です); Website is organized current and retired officers from Japan Patent Office technical discussion association (ja:特許庁技術懇話会) since 1934. Accessed on 2024-02-06.
    • Slide down "Scrollbar" 60% to see; page 7/12 numbered 128;
    Fig 8. diagram/illustration (citation from TEPCO home page) shows cool water branches two ways, from tap water piping, one way is pushing cool water into heat pump unit via storage tank bottom (ja:ポンプ) and other way is cool water push up to mixing valve, at top right (ja:温調弁), to mix cool (tap water) and hot water from heat pump for adjustment of suitable or required temperature to family use.
    • Slide down "Scrollbar" 60% to see; page 7/12 numbered 128;
    Fig 8. also indicates COP (Coefficient of performance) value 3, additive formula 1+2=3, that is "1" (Electric energy supplied to Compressor) + "2" (Energy obtained from out side air) = "3" (Obtained energy to change cool water to hot water)
    • Fig 8. also indicates; small dual compartment of hot water storages within single hot water tank storage.
  33. ^ Cooling System Composed with Rolling Piston Type 2-Stage CO2 Compressor, SANYO TECHNICAL REVIEW VOL. 37 NO.1 JUN. 2005[dead link]
    Cooling System Composed with Rolling Piston Type 2-Stage CO2 Compressor at the Wayback Machine (archived 2006-02-19), SANYO TECHNICAL REVIEW VOL. 37 NO.1 JUN. 2005
  34. ^ a b Referenced web site (in Japanese) of Sakaguchi Boiler Service, "Remote control pad" image shown at top area;
    "Remote control pad" image shown at top area; Archived 2023-06-06 at the Wayback Machine, sakabo.com (in Japanese) Referenced web site of Sakaguchi Boiler Service in Kumamoto, Japan (坂口ボイラーサービス). Recommending temperature setting is boiling the hot water tank to be 65 to 80 °C, hot water supply is recommended to 50 to 60 °C then mixed with cool water suitable for human body. Avoid growth range of legionella in 20 to 45 °C, also under 40 °C tend to make the trouble on thermostatic mixing valve with hot and cool water. Temperature more than 90 °C is wasting heat energy and cost of electric cost. Hot water temperature setting to 50 °C is most low cost of electric fee and energy conservation.(in Japanese) (ja: エコキュートの給湯温度おすすめ設定は50〜60度!45度以下は危険?40度は故障のリスクも!タンク内沸きあげ温度設定で電気代節約 2023年8月31日)
  35. ^ Kakaku.com Japanese site: 180L Tank capacity (ja:タンク容量), 180L Tank capacity (ja:タンク容量) at the Wayback Machine (archived 2024-05-17)
  36. ^ Kakaku.com Japanese site: 560L Tank capacity (ja:タンク容量), 560L Tank capacity (ja:タンク容量) at the Wayback Machine (archived 2024-05-17)
  37. ^ Referenced web site (in Japanese) of Sakaguchi Boiler Service; Functional Diagram EcoCute shows at the Wayback Machine (archived 2023-06-06) Referenced web site (in Japanese) of Sakaguchi Boiler Service; Functional Diagram EcoCute shows two hot/cool water mixing valves (ja: 混合弁), one is mixing valve to both "Tap (valve)" (ja: じゃ口) and "Shower", and other mixing valve is for "bathroom".
    Each mixing valve, one mixing valve accepts Hot water from storage tank and tap water then feed out to "Tap (valve)" (ja: じゃ口) and "Shower", and other mixing valve does the same mixing of hot and cool water to "bathroom".(ja:坂口ボイラーサービス; 図右上の2個の混合弁、じゃ口 Tap (valve) (ja:蛇口)とシャワー、もう一方は bathroom (ja:浴室)へ出力、弁の入力はタンクと水道水から
  38. ^ JIS C 9220 2018 revised JIS std. (written in Japanese language) for JIS C 9220:2018 in 2018, from C9220 : 2011, Archived 2023-11-28 at the Wayback Machine, titled Residential heat pump water heaters (家庭用ヒートポンプ給湯機), next page of (3), covering range (1 適用範囲), apply to machine use Refrigerant (CO2) or Hydrofluorocarbons (HFCs) (二酸化炭素(CO2)又はハイドロフルオロカーボン(HFC)を冷媒として用いたもの), this JIS C 9220 2018 states required heat pump, water heater and hot water storage tank within as single machine system. As the standard does not mention wording trademark of EcoCute in English nor Japanese.
    Before JIS C 9220:2011, JARAIA (The Japan Refrigeration and Air Conditioning Industry Association) site JARAIA , Archived 2022-06-26 at the Wayback Machine, statement from JARAIA is: Home use heat pump and hot water supply machine (家庭用ヒートポンプ給湯機(エコキュート)had been standards JRA 4050 based indication to be starting with JIS C 9220 of 2011 (Heisei 23) (In Japanese: 家庭用ヒートポンプ給湯機(エコキュート)…JRA 4050…Year 2011 Feb. 平成23年2月…JIS C 9220制定されJIS C 9220の表示が始まります).
  39. ^ About Heat Pump water heater, About Eco Cute, HPTCJ (Heat Pump and Thermal Storage Technology Center of Japan)
    About Heat Pump water heater, About Eco Cute, HPTCJ (Heat Pump and Thermal Storage Technology Center of Japan) at the Wayback Machine (archived 2012-05-12)
  40. ^ Japan Atomic Energy Relations Organization JAERO (ja:日本原子力文化財団)
    Archived 2023-10-05 at the Wayback Machine (in Japanese) Energy Encyclopedia (エネ百科), website supported by JAERO, describing: CO2 refrigerant heat pump, titled EcoCute (エコキュート) (ja:【3-1-07】CO₂冷媒ヒートポンプ給湯器のしくみ), for hot water supply, Electric energy (1) (ja:電気エネルギー1) + Outdoor air energy (2 or more) (ja:大気熱2以上) = Obtained hot water energy (3 or more) (ja:得られる給湯エネルギー3以上). Top right is the temperature adjustment valve (温調弁) to maintain suitable temperature of storage hot water and to supply for household use for kitchen (キッチン), washroom (洗面所), bath (お風呂), underfloor heating (床暖房). Cool tap water feed into Hot water storage unit at bottom right.
  41. ^ Website for example; EcoCute consideration of relation on electric cost and outside air temperature (エコキュート: 電気代と気温の関係に関する考察) COP value changes depend on temperature of outside air and tap water; Fig. 1 line chart indicates COP versus water temp. at the Wayback Machine (archived 2021-04-12) (in Japanese) Table and Fig.1 shows line chart COP (Coefficient Of Performance) value (Y axis 0-6) of four manufactures product EcoCute product and these COP against outside air temperature (X axis 0 °C to 30 °C), feed in tap water temp., COP value of Mitsubishi Blue line (三菱), CORONA Pink line (コロナ), Daikin Green line (ダイキン), Panasonic Red line (former 松下). Three conditions are @ Air temp. 7 °C (気温) & Water temp. 9 °C (水温) in warmer/high temp., winter-alike (冬季高温), @ Air 16 °C & Water 17 °C rating (定格), and @ Air 25 °C & Water 24 °C Summer-alike (夏季). Fig. 1 line chart indicates COP versus water temp. COP is 3.32 of average (ja: 平均) of four manufactures product EcoCute at Air temp. 7 °C, COP is 4.79 of average at Air temp. 7 °C, COP is 4.96 of average at Air 25 °C. Every manufactures product shows it is deemed not big difference of COP value.
  42. ^ a b See archived site as reference;Feature; High efficiency boil up to 90 °C (ja: 特長; 高効率な90℃沸かし上げ) at the Wayback Machine (archived 2008-06-10), www.itomic.co.jp (in Japanese) Archived indicates: Information from Nihon Itomic Co., Ltd. Archived 2024-02-18 at the Wayback Machine for their EcoCute: EcoCute effectively heat up water to 90 °C. First bar chart shows comparison of COP of, from top, Itomic industrial EcoCute COP:4.0, electric heather COP:1.0, gas boiler COP:0.88. Itomic industrial EcoCute having marginal tolerance from COP 4.0 to 3.8 as specification value on delivery from factory. Chart also implicates four COP:1 machines (Electric heat type) brings the same thermal energy of hot water in volume of single COP:4 machine (EcoCute) does. Ratio is (COP:4 – COP:1) / COP:4=0.75 so that EcoCute consume 75% less than COP:1 electric kW. Second bar chart shows CO2 emission comparison: EcoCute:50% is half compared to town gas or city gas burning boiler type 100%.
  43. ^ Research and development of EcoCute [dead link] Archived 2005-09-24 at the Wayback Machine CRIEPI (in Japanese) Archived indicates: Titled – Development of home appliance hot water supply by refrigerant CO2. In 2 page, sentence in bottom area inside the bold line frame: EcoCute reduce primary energy 30% and CO2 emission 50% compared to water heating by town gas or city gas burning boiler type. (ja:エコキュートは、ガス給湯器に比べて3割も一次エネルギーを削減でき、5割のCO2排出量削減が可能です。) This point was well evaluated and awarded with prizes, on Energy Conservation Award (省エネルギー大賞) by Minister of Economy, Trade and Industry, and from other organizations in 2001–2002. ECCJ - The Energy Conservation Center, Japan nominated the award.
  44. ^ JRAIA English site Satisfaction survey outcome Survey outcome at the Wayback Machine (archived 2022-10-06) Pie chart shows outcome. Following another reference of pdf file indicate survey outcome is second pie chart numbered (8) on page 5.(ja: ⑧ エコキュート購入に対して、満足していますか) Survey outcome Survey outcome; Second pie chart numbered (8) on page 5.(ja: ⑧ エコキュート購入に対して、満足していますか) at the Wayback Machine (archived 2024-05-24) Survey Conducted timing is indicated in pdf file first page (1), in January 2022 for 518 users nationwide, conducted to families bought EcoCute between January 2020 and December 2021.(ja: 2.調査方法 2020年1月-2021年12月 & 518人 3.実施時期 2022年1月)
  45. ^ Japanse site: product recall information of MITI for Panasonic.
  46. ^ As of August 2024, with Japanese site, Consumer Affairs Agency has Web query site. Just like search on every Wikipedia page at top, put word/term and click 検索 (search) with Japanese word "エコキュート" (EcoCute), 乗用車 (Passenger car) or "エアコン" (air conditioner) which include air conditioner mounted in passenger car, excluding water supply type EcoCute. For Passenger car of 15 cases per page, 181 pages of total 2,707 cases, the oldest 23 July 2002 on last page 181, and air conditioner total 84 cases on 6 pages with oldest dated 27 December 2003.
  47. ^ Referring Japanese site, Yomiuri Shimbun (in Japanese) Archived 2014-12-19 at the Wayback Machine 19 December 2014: Possible reason of health hazards with low frequency of EcoCute is claimed to Consumer Affairs Agency by married couple in Gunma Pref.(エコキュートの音、健康被害原因の可能性) and chairman, customer's safety survey committee (消費者安全調査委員会), 畑村洋太郎 asked.
    (in Japanese) Consumer Affairs Agency report: Married couple in Gunma pref. had been felt insomnia, headache, dizziness, nausea etc. since February 2009 by husband and May by wife. Couple claimed, in October 2012(平成24年10月), to Consumer Affairs Agency for inspection and survey. The report issued in 19 December 2014 (平成26年12月19日), that health hazards caused possible low frequency sound, operation sound and vibration of heat pump hot water supply machine, (家庭用 ヒートポンプ給湯機) (not use trade term EcoCute on government documents), that heat pump hot water supply machine is installed in the house next door, 2 Metre distance from couple's house as high residential density. 17 June 2016 (平成 28) Erratum (Errata sheets)
    (in Japanese) Nikkei site 18 November 2013 Nikkei, Inc. site Archived 2013-11-21 at the Wayback Machine report it resulted that settlement in litigation between couple and EcoCute owner EcoCute suspension of operation, and litigation with approx. 2.7 million Japanese yen, and reached to reconciliation include health hazards, and replacement of EcoCute system by mfg. and owners house builder on 18 November 2013. EcoCute should stop in that year and replacement by other mfg.'s EcoCute. All fee to be covered by EcoCute mfg. and owners house builder (who seems recommended EcoCute).
    Note for yearly sequence: In 2009: Couple felt health hazards, in 2012 Couple claimed to Agency, in 2013 settlement in litigation, in 2014 Yomiuri and Agency reported.
  48. ^ (in Japanese) Panasonic's receive reconciliation with 1.3 billion Yen
    (in Japanese) Archived 2018-09-07 at the Wayback Machine Panasonic's receive reconciliation with 1.3 billion Yen from Saginomiya: Hot water supply machine litigation (給湯器訴訟, パナソニック和解 鷺宮が解決金13億円)
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