27.1.2006 Mirja Tiitinen 1 Dimensioning standard for domestic hot water Euroheat&Power RTD Workshop...

27.1.2006Mirja Tiitinen

1

Dimensioning standard for domestic hot water

Euroheat&Power RTD Workshop2.-3.2.2006 Brussels

Mirja TiitinenFinnish Energy Industries


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Research project, years 2004 – 2005

“The design flow and temperature criteria of hot tap water in respect of the microbiological water quality in district-heated residential buildings”

Finnish Energy IndustriesMinistry of the EnvironmentHelsinki EnergyE.On Finland OyjVantaa EnergyHelsinki University of Technology


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Objectives

• To establish temperature criteria for hot tap water based on

the growth temperatures of microbes in the hot-water network

• To supplement and specify earlier studies carried out on the

subject

• To produce a new design principle for the design flow of hot

tap water as the basis for an official standard

• To compare the new design principle with criteria used in

Finland and Sweden


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Number of bacteria colonies of Legionella as a function of temperature and time

Increase

Decrease

Nu

mb

er

of

ba

cte

rial c

olo

ny

pm

y/l]

Time [h]

Example of increase / decrease in various temperatures


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Research locations

• 26 locations in the Helsinki region

• Different types of residential buildings with district heating

– Number of apartments 6-220

– 9 terraced houses, 5 small apartment buildings, 6

medium-sized apartment buildings and 6 large apartment

buildings


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Measurements

HelenMetering

DVD

Measuring data

PC

Sofware

HUT

Data analysis

Tele network

Apartment building

Copper

ADSL modem

District heating

heat exchanger

Domestic hot water


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Maximum flows

0

1

2

3

4

5

6

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230

Number of apartments

flow

[l/s

]

D1 design 0,8 l/s,apartm.

D1 design 0,5 l/s,apartm.

Measured maximum flows

F:101 design 2004

Isännöitsemänne kohde


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Maximum flows of different durations

0

0,25

0,5

0,75

1

1,25

1,5

1,75

2

2,25

2,5

2,75

0 20 40 60 80 100 120 140 160 180 200 220


Flo

w [l

/s]

Max 30 s max 60 s max

Mean value curve for maximums 30 s mean value curve for maximums 60 s mean value curve for maximums


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Flow duration curvesF

low

l/s

Time [%]

Over 100

51 – 90

20 - 50

Under 20

Number of apartments:


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Outgoing and return temperatures (average)

40

42

44

46

48

50

52

54

56

58

60

EK4K17 K2 K4 K3

K14 EK1EK6 K5 K8

EK2K10 K11 K20 K19 K12 K13 K6

K18 K9 K7K16 EK3

Tem

pera

ture

[°C

]


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Suggested design flow

0,0

1,0

2,0

3,0

4,0

5,0

6,0

0 50 100 150 200 250


Flo

w [

l/s]

Maximum flows

New design flow

D1 design flow

FVF:101 design 2004


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• Equation for the new design principle

qAS.MAX is the mean location-specific maximum flow (Usually 0.5 l/s,location or 0.6 l/s,location)

Θ is the probability that qAS.MAX is used during maximum consumption (0.005)

Q is the sum of the standard flow of the connected water taps

A is the factor that takes into account how often design flow q is exceeded (2.8)

MAXASMAXASMAXAS QqAqQqq ... )(

Suggested design flow


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Summary of the research project

• The design flows currently used in Finland don't correspond

with the measured flows

– in smaller buildings measured flows were higher

– in bigger buildings measured flows were lower

• The maximum flow, the 30-second maximum flow and the 1-

minute maximum flow were very close to one another

• The mean values of the water temperatures going into the

network were reasonably good

• The return temperature of circulation was too low in most

locations


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Dimensioning of the dhw control valve,example :

Effect 310 kWFlow 1,65 l/sec.

Pressure difference available 250 kPa(in normal operational conditions)-heat exchanger 20 kPa-pipelines 5 kPaAvailable for the valve 225 kPa


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”Old” dimensioning custom


Pressure difference given 60 kPa-heat exchanger 20 kPa-pipelines 5 kPaDimensioning pressure difference for the valve 35 kPa


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Valve: flow 1,65 l/sec, 35 kPa

0

1

2

3

4

5

6

0 10kv-value

flow

, l/s

ec

300 kPa

250 kPa

200 kPa

150 kPa

100 kPa

50 kPa

35 kPa

kvs-value10,0

pressure difference:

1,65 l/sec


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0

10

20

30

40

50

60

70

80

0 2 4 6 8 10 12 14 16

Result


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Valve: flow 50 % = 0,83 l/sec,35 kPa

0

1

2

3

4

5

6

0 2 4 6 8 10

kv-value

flow

, l/s

ec

300 kPa

250 kPa

200 kPa

150 kPa

100 kPa

50 kPa

35 kPa

kvs-value5,0


0,83 l/sec


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Result

0

10

20

30

40

50

60

70

0 2 4 6 8 10 12 14 16


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“Correct” dimensioning


Pressure difference given 250 kPa-heat exchanger 20 kPa-pipelines 5 kPaDimensioning pressure difference for the valve 225 kPa


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Valve: flow 1,65 l/sec, 225 kPa

0

1

2

3

4

5

6

0 2 4 6 8 10

kv-value

flow

, l/s

ec

300 kPa

250 kPa

200 kPa

150 kPa

100 kPa

50 kPa

35 kPa

kvs-value4,0


1,65 l/sec


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Result

0

10

20

30

40

50

60

70

0 2 4 6 8 10 12 14 16


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Conclusions

• Domestic hot water valve shall be dimensioned with correct

flow and correct pressure difference

• Correct flow is the actual maximum flow which can be

expected to occur during normal conditions

• Correct dimensioning Δp is the pressure difference during

normal operational conditions

27.1.2006 Mirja Tiitinen 1 Dimensioning standard for domestic hot water Euroheat&Power RTD Workshop...

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