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European guidelines for the preparation of domestic hot water Janusz R óż alski,

Euroheat & Power XXXI I . Congress, Berlin , "CHP/DHC: The Whole Picture" Tuesday, 7 June 2005 - Parallel sessions TECHNICAL ISSUES. European guidelines for the preparation of domestic hot water Janusz R óż alski, OPEC Gdynia, Poland EHP TF.

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European guidelines for the preparation of domestic hot water Janusz R óż alski,

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  1. Euroheat & Power XXXII. Congress, Berlin, "CHP/DHC: The Whole Picture" Tuesday, 7 June 2005 - Parallel sessionsTECHNICAL ISSUES European guidelines for the preparation of domestic hot water Janusz Różalski, OPEC Gdynia, Poland EHP TF

  2. Process of production of domestic hot water is a dynamic process carried out in different network water temperature conditions appearing during a year. Volume of hot water installation serviced by heat substation is different and balances between several kW (when refers to one family house) to several MW ( in case of heat exchange group substation).

  3. Domestic Hot Water heat demand for 50 flats [KW] 100 90 80 70 60 50 40 30 20 10 0 18:00:00 21:20:00 22:00:00 20:40:00 22:40:00 23:20:00 12:00:00 20:00:00 08:40:00 09:20:00 10:00:00 10:40:00 11:20:00 17:20:00 18:40:00 19:20:00 00:00:00 06:00:00 12:40:00 13:20:00 14:00:00 14:40:00 15:20:00 16:00:00 16:40:00 08:00:00 00:40:00 01:20:00 02:00:00 02:40:00 04:00:00 04:40:00 05:20:00 06:40:00 07:20:00 03:20:00

  4. Common failures occurred during hot water substation designing and maintenance process are as follows: • Incorrect volume of hot water consumed by heat substationinstallation taken intoconsideration during its dimensioning, • To low or to high network pressure disposal taken intoconsideration during control valves dimensioning, • Tendency to taking into account during design preparation biggervalves and pumps than it resulted from calculations, • Wrongly dimensioned heat exchangers, • Overestimated investment costs, • Too high return temperature of network water, • Too high level of electricity consumption, • Problems with hot water stability during its differentiated consumption, • Increased failure frequency of control valves, • Too high sensitiveness of heat substation for changes in networkparameters, • Generating of sound permeability into house buildings, • Luck of detailed measurements of small and short lastingenergy consumption for example for hand washing, • Legionella appearance within hot water circulation.

  5. Common failures occurred during hot water installation designing and maintenance process of are as follows: • Too high dimensions of hot water pipes and circulation, • Too long hot water expectation time after tap opening, • Fluctuations of DHW temperature during its consumption, • Lack of hydraulic control valves in installation, • Too high temperature decreases in hot water circulation – danger of Legionella appearance, • Too high flows within DHW circulation, • Noises in installation, • Irregular temperature level in different parts of installation, • Lack of water circulation at its ends – good conditions for Legionella incubation, • Penetration of existing installation by cold water resulted from lack of check valves ( especially in wash machines connected to hot water installation )and high pressure differences between hot and cold water, • Lack of vertical insulation pipes in existing old hot water installations and circulation.

  6. Guidelines worked out by “task force” will be an important aid during correct investment process for DH and designing companies that prepare modernization works of heat substation and hot water installations.

  7. Guidelines will be executed according to: • Pressure Equipment EU Directive • Measurement Instrument EU Directive • Buildings EU Directive • Energy Services EU Directive • Eco-design EU Directive • Energy End Use Efficiency EU Directive • Energy Performance of Buildings EU Directiverelevant CEN standards

  8. Temperature and pressure differences existing in European DH systems

  9. DISTRICT HEATING NETWORK EHP recommended Temperature -120˚C EHP recommended Pressure – 1.6 MPa

  10. National Building codes for Domestic Hot Water

  11. EHP recommended Max hot tap water temperature - 60˚C EHP recommended Min hot tap water temperature - 50˚C

  12. Pressure for cold water

  13. An average European consumption is 36 liters per dayand per person at 60°C starting from cold water at 10°C. Simultaneously there are countries where designprinciplesrequire to take into account110-130 liters / day/ person. It causes a significant over dimensioning of heatsubstationand internal installation and increasesunreasonablyinvestment costs. There are much more such differences and there is notechnical and economical use to keep them further.

  14. Guidelines will contain principles for dimensioning of heatsubstations including the network from the substations to the hot water tap, domestic hot water circulation systems, choice of heat exchangers and hot water storage tanks togetherwith functional requirements and control valves, with paying special attention for balance of DHW consumption. Technical recommendations for conventional connection principles will be created, too.

  15. Guidelines will include also recommendations for: • Heat exchangers for heating • Pumps • Safety equipment: safety valves • Heat meters • Valves: by-pass valves, back-flow valves, shut-off valves drain valvesOther equipment: strainers , temperature meters and expansionVessels • Service and maintenance • Quality Control

  16. The final result will be the “ Euroheat & Power recommendations of technicalrequirements for the district heating substation “ which is planned to be completed till the end of 2006.

  17. DHW temperature diagram from heat substation with oversized control valve.

  18. Biofilm - common problem in DHW installations Biofilm is composed of populations or communities of microorganismsadhering to environmental surfaces. Biofilm may be found on essentially any environmental surfacein which sufficient moisture is present. Their development is most rapid in flowing systems whereadequate nutrients are available.

  19. Bacteria are depositing on a surface of water together with organicand inorganic compounds in the form of the coat • Reversible process of binding of bacteria with a membrane • Depositing of bacteria in an irreversible process and their furtherdevelopment • Forming the micro colony as a result of reproduction of bacterium • Forming the biofilm consisting of various microorganisms • Biofilm shaped completely

  20. Example of effective modernization of heat substation. Results were as follows: ● stable DHW temperature, ● all hot water tanks were eliminated, ● returned water temperature was decreased of 60%, ● water flow decreased and were obtained very good ● results of disposal pressure for all DH system sections. Positive effects were possible to obtain due to consequent dimensioning of control valves based on utilization of full assuming disposal pressure (installation of sometimes 2- 4 times smaller valves in relation to previous ones) and detailed estimation of hot water consumption in heat substations.

  21. AVERAGE HOURLY FLOW FOR THREE SUMMER MONTHS IN 1990; 1996; 2002 YEARS June 1990 July 1990 August 1990 June 1996 July 1996 August 1990 June 2002 July 2002 August 2002 [t/h] 3500,0 3112 3062 3300,0 2942 3100,0 2900,0 2700,0 2500,0 2009 1986 2300,0 1913 2100,0 1900,0 1493 1386 1700,0 1303 1500,0 1300,0 1100,0 900,0 700,0 500,0 August 1990 August 1990 August 2002 June 1996 June 2002 June 1990 July 2002 July 1996 July 1990

  22. BEFORE

  23. AFTER

  24. BEFORE

  25. AFTER

  26. 40 000 Annual consumption of electric energy in OPEC Gdynia 35 000 30 000 25 000 20 000 15 000 10 000 [MWh] 5 000 0 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 YEAR

  27. Conclusions: • Guidelines can have a direct impact for increase in technical levelof investment projects and significant decrease in investment costs. • In this way DH companies will be able to compete effectively with gasand oil supplied heat only boilers. • Correctly carried out investment process will assure very high levelof offered by us services and simultaneously will cause reductionof maintenance costs. • Guidelines can become basis for implementation of conventional technicalsolutions which will allow to minimizing costs of heatsubstations designing and production costs of compact heat substations. • OPEC Gdynia is a good example that guidelines can be an excellenthandbook for carrying out effective modernization processof existing heat substations. • A total effect will bring rational reduction of primary fuel utilization and greenhouse gases emission.

  28. Task Force creating European guidelines for the preparation of domestic hot water recognized it as very significant from technical and economical point of view . So Task Force would be grateful for any comments and conclusions from DH companies whose knowledge and experience could be effectively used within the framework of project. In case of any comment and conclusions please contact Task Force’s Secretary Mrs. Norela Constantinescu [norela.constantinescu@euroheat.org]

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