EcoCute

The EcoCute is hot water supply system consist of two units, air source heat pump unit and large hot water storage tank unit. Air source heat pump in this system is mandatory to use supercritical carbon dioxide as the refrigerant.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.

Etymology timeline

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 |給湯|kyūtō; 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.

• 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. Shecco Page bottom, "Contact us"; call us at:+32 Belgium listed on List of country calling codes.
• The first commercial breakthrough came under the name of "EcoCute" in Japan in 2000, announced by Belgium organization SHECCO.
• EcoCute is the registered trademark of Kansai Electric Power Company applied in January 2001 and registered in June 2002.
• The first commercial EcoCute was marketed in Japan by Corona Corporation|ja:コロナ in 2001.(In Japanese) EcoCute with Katakana (ja:エコキュート)
• It is literally called|In Japanese: 自然冷媒（CO2）ヒートポンプ給湯機「エコキュート」|Natural refrigerant (CO₂) heat pump hot water supply machine "EcoCute" when awarded by Minister of Economy, Trade and Industry in fiscal year 2001.
• It also literally called with another term In Japanese: 家庭用ヒートポンプ給湯機（エコキュート)|Home use heat pump hot water supply machine "EcoCute" by JRAIA standard "JRA 4050" until JIS Standard in 2011 issued.
• 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).

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。)

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

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%.

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.

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

Denso first introduced the EcoCute outside Japan at the COP9 Milan, Italy in December 2003.From 2007, Denso began concentrating on marketing the EcoCute in the EU.

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.Japanese Ministry of Economy, Trade and Industry prospects 14 million EcoCute system spread by fiscal year 2030 as of 2015.

History

Air source heat pump#History

Fusanosuke Kuhara, founder of Hitachi, Ltd., made air conditioner for his own home use using compressed CO as refrigerant in 1917.They demonstrated the invention at the June 1998 International Institute of Refrigeration/Gustav Lorentzen Conference. CiNii 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.ja 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), 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,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.

EcoCute machine basics

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

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. The carbon dioxide becomes a supercritical fluid by pressure up around 100 atmospheric pressure. 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.
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.
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

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, to 560L Kakaku.com Japanese site: 560L Tank capacity (ja:タンク容量),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.

Cold region specification

A number of EcoCute manufactures produce with the cold region specification models for the region or area of outdoor lowest temperature down to minus 25 °C. Most Japanese manufacture put EcoCute in Japanese market with cold region specification as of October 2024. To install the air source heat pump unit at outdoor is the same as none-clod region specification type installed. The cold region specification model is capable to boil up hot water to 80 °C even in outdoor temperature is below down to minus 25 °C with minor difference by manufactures and models.

Panasonic, for example, the electric heater is implemented in hot water storage tank unit to prevent freezing the inside of water storage tank unit, and user or family pick up and purchase the indoor type of hot water storage unit should be installed at indoor where outdoor temperature below minus 20 °C. Water in Hot water storage tank unit to be boiled up to approximately maximum 80 °C, however it may be possible not applied to entire volume of hot water in tank, that is lower part of hot water tank is not reached to 80 °C. Counter measure for fallen snow, do not place Heat pump unit on the ground, put on rigid stand for heavy heat pump unit to avoid fallen snow and fallen icicle, avoid direct seasonal winds that may freeze heat pump unit and avoid or be aware defrosted water.

Daikin's cold region specification models for cold region, Hokkaido and, the high elevation part or mountain area within Gifu Prefecture to Aomori Prefecture each, controlling fan to prevent snow adhesion when outdoor temperature around heat pump unit below 0 °C and heat pump is not in operation, the fan works to prevent snow adhesion with defrost in advance.

The standard of cold region specification for EcoCute system seems to be targeting to set in fiscal year 2025; (April 2025 – March 2026) by JRAIA (Japan Refrigeration and Air Conditioning Industry Association).Targeting COP value are 2.7 to 2.9 in cold region, and none-cold region are 3.0 to 3.5.

Other functions

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.

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.

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.

The COP value changes depend on each temperature of outside air and tap water feed in.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. Also, by reducing use of fossil fuels, the EcoCute results 50% reduction in CO2 emissions.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.

Market response

Customer satisfaction

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.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.

Lawsuit

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. 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.

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