1. Euroheat & Power XXXII. Congress, Berlin, "CHP/DHC: The Whole Picture"
Tuesday, 7 June Parallel sessions TECHNICAL 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]10 20 30 40 50 60 70 80 90
100
00:00:00
00:40:00
01:20:00
02:00:00
02:40:00
03:20:00
04:00:00
04:40:00
05:20:00
06:00:00
06:40:00
07:20:00
08:00:00
08:40:00
09:20:00
10:00:00
10:40:00
11:20:00
12:00:00
12:40:00
13:20:00
14:00:00
14:40:00
15:20:00
16:00:00
16:40:00
17:20:00
18:00:00
18:40:00
19:20:00
20:00:00
20:40:00
21:20:00
22:00:00
22:40:00
23:20:00

5. Common failures occurred during hot water substation designing
and maintenance process are as follows:
Incorrect volume of hot water consumed by heat substation installation taken into consideration during its dimensioning,
To low or to high network pressure disposal taken into consideration during control valves dimensioning,
Tendency to taking into account during design preparation bigger valves 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 network parameters,
Generating of sound permeability into house buildings,
Luck of detailed measurements of small and short lasting energy consumption for example for hand washing,
Legionella appearance within hot water circulation.

6. 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.

7. 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.

8. 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 Directive relevant CEN standards

9. Temperature (Max/Min) ˚C
Temperature and pressure differences existing in European DH systems
Country
Temperature (Max/Min) ˚C
Pressure (MPa)
Austria
120/70
2.5
Denmark
1.6
Finland
France
110/70
1.0
Germany
130
Hungary
125
Italy
Poland
125/70
Slovenia
Sweden
120

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

11. National Building codes for Domestic Hot Water
Country
Temperature (Min) ˚C
(standards established for comfort and disinfections against legionella)
Temperature (Max) ˚C
Standard established to secure against the burning skin)
Austria - 50
Denmark 65
Finland 60
France
Germany
55-60
Hungary 40
Italy 48 53
Poland
45(before )/
55(after )
55(before )
60(after )
Slovenia
Sweden

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

13. Pressure for cold water (MPa)
Country
Pressure for cold water (MPa)
Austria -
Denmark
1.0
Finland
France
0.7
Germany
Hungary
Italy
0.5
Poland
0.6
Slovenia
0.6/1.0
Sweden

14. An average European consumption is 36 liters per day and per person at 60°C starting from cold water at 10°C.
Simultaneously there are countries where design principles require to take into account liters / day/ person.
It causes a significant over dimensioning of heat substation and internal installation and increases unreasonably investment costs.
There are much more such differences and there is no technical and economical use to keep them further.

15. Guidelines will contain principles for dimensioning of heat substations 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 together with functional requirements and control valves, with paying special attention for balance of DHW consumption.
Technical recommendations for conventional connection principles will be created, too.

16. 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 valves Other equipment: strainers , temperature meters and expansion Vessels
Service and maintenance
Quality Control

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

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

19. Biofilm - common problem in DHW installations
Biofilm is composed of populations or communities of microorganisms adhering to environmental surfaces.
Biofilm may be found on essentially any environmental surface in which sufficient moisture is present.
Their development is most rapid in flowing systems where adequate nutrients are available.

20. Bacteria are depositing on a surface of water together with organic and 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 further development
Forming the micro colony as a result of reproduction of bacterium
Forming the biofilm consisting of various microorganisms
Biofilm shaped completely

21. 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.

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

23. BEFORE

24. AFTER

25. BEFORE

26. AFTER

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

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

29. 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