TECHNICAL DATA, FORMULAS AND CHARTS - Danfoss...

8 STEPS - CONTROL OF HEATING SYSTEMS

CHAPTER 8 • TECHNICAL DATA, FORMULAS AND CHARTS

161

TECHNICAL DATA, FORMULAS AND CHARTS

Diagram for local district heating plants and heating and power plant . . . . . . . . . . . . . . .162

Diagram for heating and domestic hot and cold water . . . . . . . . . . . . . . . . . . . . . . . . . . .163

Heat emission from radiators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .164

Conversion chart for radiators in one-pipe systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .165

Reduction of heat emission from radiators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .166

Heat losses from uninsulated pipes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .167

Pressure drops in steel pipes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .168

Resistance in heating systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .169

Sizes of steel pipes for heating systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .169

Flow chart for thermostatic radiator valves in one-pipe system . . . . . . . . . . . . . . . . . . . . .170

Flow chart for thermostatic radiator valves in two pipe system . . . . . . . . . . . . . . . . . . . . .171

Flow chart for ∆p control valves for risers or circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .172

Flow chart for control valves in heating systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .173

Flow chart for control valves in district heating systems . . . . . . . . . . . . . . . . . . . . . . . . . . .174

Flow chart for ∆p control valves in district heating systems . . . . . . . . . . . . . . . . . . . . . . . .175

Heat requirements for domestic hot water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .177

Flow limiters for one-pipe circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .178

Calculation of one-pipe systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .180

Calculation of two-pipe systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .182

SI-units, Greek alphabet, Physical properties for water . . . . . . . . . . . . . . . . . . . . . . . . . . . .184


162 8 STEPS - CONTROL OF HEATING SYSTEMS

130 °C70 °C

130 °C

130 °C

70 °C

70 °C

130 °C

130 °C

70 °C

70 °C

130 °C

130 °C

70 °C

70 °C

Diagram for local district heating plants connected to a heating and power plant.

Heating andpower plant

Local heating plant

Flue gascooler

Safetyvalve

Exp. tank

Bo

iler

Safetyvalve

Heat exchanger

Accumulator

Heat meter

Flue gascooler

Safetyvalve

Exp. tank

Bo

iler

Safetyvalve

Heat exchanger

Accumulator

Heat meter

Flue gascooler

Safetyvalve

Exp. tankB

oile

r

Safetyvalve

Heat exchanger

Accumulator

Heat meter



163

<6 >6

120-70 °C

90 °C65 °C

Diagram for heating and domestic hot and cold water.

Expansion tank

∆p - control

Flow meter

Domestic hot water

Domestic cold water

Flowmeter> 6 storeys

Heat meterDomestic hot water 60

Domestic cold waterCirculation

Control valve< 6 storeys

Storeys

40 30 25 20 16

0

1,00,90,80,70,6

0,50,40,30,2

0,1

1,1

1,2

0 1,0 2,0 Q

90

60

70

80

50

0,5 1,5 2,5

1

2

4

5

6

3



Heat emission from radiators.

Two-pipe system with thermostaticvalves. Measured 1 : tflow 75 oC, ∆t 8 oCHeat requirement : 0,83, Q = 2,47tflow 80 oC : 2 ∆t 16 oC, Q = 1,23Every point along the horizontal line0,83 gives the same heat emission.

The influence of gravity forces on heat emission from a radiator in a two-pipe system For a correctly sized radiator 3 ( with manual radiator valve in a two-pipesystem ) the heat emission will increases only by 5% when the flowincreases by 23%, 4 , depending on gravity forces. The temperature dropacross the radiator however will decrease by 5 oC and that is significant,because it reduces the capacity of the whole system all the way down tothe heating and power plant.

Resuls ∆t for one- and two - pipe circuits, and required pump capacitywhen thermostatic valves utilize internal and external heat gains.

Two-pipe circuit One-pipe circuitPoint Heat Flow ∆t Circuit resi- Pump ca- Flow ∆t Pump ca-

gain % % oC stance % pacity % % oC pacity %3 0 100 25 100 100 100 25 1005 10 66 33 44 29 100 22,5 1006 20 47 39 22 10 100 20 100

n = 1,3 troom = 20 oC tflow = 90 oC ∆t = 25 oC

∆t oCH

eat

emis

sio

n

Q

12

10

8

6

5

4

165



0,8

0,9

1,0

1,1

1,2

1,3

1,4

1,5

1,6

1,7

1,8

1,9

2,0

2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

90

85

80

75

70

60 65

2 1

Conversion chart for radiators in one-pipe circuits.

Conversion chart for panel and section radiators in one-pipe circuits.Enter the current tflow and temperature drop and find the conver-sion factor, Fc.Multiply the heat requirement by Fc and select size of the radiatoraccording to the new value.

Example.Calculated heat requirement: 1.230 W.tflow : 82 oC, ∆t: 15 oC, 1Fc = 1,16 2Converted heat requirement: 1.230 x 1,16 = 1.427 W.

Formula for calculating Fc:

49,33 x ln

t1 - t2[ ]t1 - tr n

t2 - tr( ) nPanel radiator 1,28Section radiator 1,29Convector 1,3 - 1,33

F =

tflow oCFc

∆t oC



a

The control unit has to sense the room temperature to be able to control it.

No enclosure0%

Shelf withopening0%

Shelf close tothe wall10 -2%

Open frontedrecess with ashelf12 -6%

Encased withgrille in front> -15%

Encased withsmall grille infront. Notrecommended.> -30%

Acceptablecabinet.≈ -8 - 10%

Reduction of heat emission from radiators fixed in some type of enclosure

Radiation from a radiator depending on the treatment of thesurface.

Material Surface treatment Radiation %

Steel, cast iron 100

Oil paint 100

Aluminium orcopper bronzes 75

Zinc white 101

Lead white 99

Enamelled White 101

Matt green 96

Aluminium 8

10 - 100 mm 30 - 100 mmAlternativeopenings a+40

> 10

0 m

m

167

0

100

200

300

400

0

20 40 60 80 100 120

80/89 65/76

50/6

40

32

25

20

10

15



Heat losses from uninsulated horizontal pipe.

For vertical pipe reduce by 20%

One-pipe above another reduce by 12%

Three pipes above each other reduce by 20%

Temperature above room temperature oC

Heat emissionW/m pipe DN/0



5 7 10 20 30 mmWG/m

,05 ,07 0,1 0,2 0,3 0,4 0,5

kPa/m

25

15

20

32

40

80

50

100

125

150

,01,015,02

,03,04,05

,07

,1

,15,2

,3

,5,4

,7

1

1,52

345

7

10

4050

1520

30

1,0

2,0

10

100

1000

10

100

1,52

345

7

1520

304050

70

150200

150200

300400500

700

70

5040

15 40 50

0,15

65

3,0

m/s 0

,2

0,3 0,4

0,5

k = 0,00003 mDensity = 1.000 kg/m3

Pressure drop in steel pipes for heating installations.

m3/h DN mm l/s

l/h

0,1

0,20,30,5

1,0

23

,01 ,02 ,03 ,05 0,1 ,2 ,3 ,5 1

12

64

3

2 3 4 5 107

169



∆p for ζ values at differnt rates.

Symbol Units Coefficient of resistance, ζ

Branch tee 1

Through tee 1

Elbow, smooth 0,2

Bend 1

The values for the coefficient of resis-tance for tees, elbows and bends.

The pressure drop is calculated from: ∆p = ζ 0,5 ρ ν2 ,

Recommended portion of pipe losses for different systems or part ofsystems.Type of system Unit Friction %Heating Small buildings 50 - 60

Large buildings 60 - 70Sub-stations Primary and secondary side 20 - 30Distribution pipe net work Primary side 80 - 90

ζ valuem/s

∆p kPa

Sizes of steel pipes for heating systems. Working pressure 1,0 MPa (10 bar)Nominal diameter External diameter Wall thickness Internal diametermm inch mm mm mm8 1/4 13,50 2,25 910 3/8 17,00 2,25 12,515 1/2 21,25 2,75 15,7520 3/4 26,75 2,75 21,2525 1 33,50 3,25 27,0032 1 1/4 42,25 3,25 35,7540 1 1/2 48,00 3,50 41,0050 2 60,00 3,50 53,0065 2 1/2 75,50 3,75 68,0080 3 88,50 4,00 80,50100 4 114,00 4,00 106,00125 5 140,00 4,50 131,00150 6 165,00 4,50 156,00

30

5070100

200300

5007001000

0,1 ,2 ,3 ,4 ,5 ,7 1,0 2 3 kPa

0,01 ,02 ,03 ,07 ,1 ,2 ,3 mWG

,001 ,002 ,004,006 0,01 ,02 ,03 Bar

,01

,02,03

,05,07,1

,2,3

,05

4 5 7 10 20

,7 1 2

,04 ,06 0,1 ,2

,5

15

2025



Flow chart for RTD-G 15, 20 and 25

RTD - G 15, 20 and 25

l/h l/sValve size

∆pva

lve

171



3

5710

2030

5070100

,001

,002,003

,005,007,01

,02,03

1 2 3 4 5 7 10 20 30 kPa

0,1 0,2 ,3 ,4 ,5 ,7 1 2 3 mWG

0,01 ,02 ,04 ,06 0,1 ,2 ,3 Bar

,1

,05,07

500300200

N

1

23

4567

3

5710

2030

5070100

,001

,002,003

,005,007,01

,02,03

1 2 3 4 5 7 10 20 30 kPa

0,1 0,2 ,3 ,4 ,5 ,7 1 2 3 mWG

0,01 ,02 ,04 ,06 0,1 ,2 ,3 Bar

,1

,05,07

500

300200

N

1

23

456

7

Flow chart for thermostatic valves in two-pipe system

l/h l/sPre-set value

∆pva

lve

Pre-set value 1 2 3 4 5 6 7 N

kv values 0,04 0,08 0,12 0,20 0,27 0,36 0,45 0,60

Pre-set value 1 2 3 4 5 6 7 N

kv values 0,10 0,15 0,17 0,25 0,32 0,41 0,62 0,83

l/h l/sPre-set value

∆pva

lve

RTD - N 15

RTD - N 20 - 25



0,1

0,20,30,50,71,0

23

5710

0,1

0,20,3

0,50,71,0

23

,03

,05,07

1 2 3 4 5 7 10 20 30 40 60 80 kPa

0,1 0,2 ,3 ,4 ,5 ,7 1 2 3 4 5 7 mWG

0,01 ,02 ,04 ,06 0,1 ,2 ,3 ,4 ,5 ,7 Bar

520

8

,8

1,62,54,06,310

1

Flow chart for ∆p control valves for riser or circuit in heating systems.

ASV-P, PV 15-40 and ASV-M 15-40

m3/h l/skvs-value

∆pva

lve

Working range: ASV-P 10 kPaASV-PV 5 - 25 kPa.

Minimum available ∆p for good functioning: 8 kPa.

ExampleQ: 300 l/h. ∆p riser: 7kPa. ∆p radiator including valve: 5 kPa.∆p-control kv 1,6. ∆pvp = 3,4 kPa, 1Necessary ∆p = 7+5+8 = 20 kPa.

173



0,1

0,2

0,3

0,50,71,0

23

5710

0,1

0,20,3

0,50,71,0

23

,03

,05,07

1 2 3 4 5 7 10 20 30 40 60 100 200 kPa

0,1 0,2 ,3 ,4 ,5 ,7 1 2 3 4 5 7 10 15 20 mWG

0,01 ,02 ,04 ,06 0,1 ,2 ,3 ,4 ,5 ,7 1,0 1,5 2 Bar

10

57

150

50

3020

100

200

2030

50

,4,631,01,62,54,06,3

1016254063

100145

Flow chart for control valves in heating systems.

m3/h l/skvs-value

∆pva

lve

Formulas.∆p : bar. Q: m3/h. kv = ; ∆p = ; Q = kv √ ∆p ;

Q√∆p

Qkv( )2

∆p : kPa. Q: l/h. kv = 0,01 ; ∆p = 0,01 ; Q = 100x kv √ ∆p ;Q

√∆pQkv( )2

∆p : kPa. Q: l/s. kv = 36 ; ∆p = 36 ; Q = √ ∆p ;Q

√∆pQkv( )2 kv

36

Q

Q

Q



0,1

0,2

0,3

0,50,71,0

23

5710

0,1

0,20,3

0,50,71,0

23

,03

,05,07

1 2 3 4 5 7 10 20 30 40 60 100 200 kPa

0,1 0,2 ,3 ,4 ,5 ,7 1 2 3 4 5 7 10 15 20 mWG

0,01 ,02 ,04 ,06 0,1 ,2 ,3 ,4 ,5 ,7 1,0 1,5 2 Bar

10

57

150

50

3020

100

200

2030

50

,4,631,01,62,54,06,3

1016254063

100145

Flow chart for valves in district heating systems.

m3/h l/skvs-value

∆pva

lve

175



0,1

0,20,30,50,71,0

23

5710

0,1

0,20,3

0,50,71,0

23

,03

,05,07

1 2 3 4 5 7 10 20 30 40 60 80 kPa

0,1 0,2 ,3 ,4 ,5 ,7 1 2 3 4 5 7 mWG

0,01 ,02 ,04 ,06 0,1 ,2 ,3 ,4 ,5 ,7 Bar

520

8

,8

1,62,54,06,310

1

m3/h l/skvs-value

∆pva

lve

AVP 15 - 32

Flow chart for ∆p control valves in district heating systems.



0,1

0,2

0,3

0,50,71,0

23

5710

0,1

0,20,3

0,50,71,0

23

,03

,05,07

1 2 3 4 5 7 10 20 30 40 60 100 200 kPa

0,1 0,2 ,3 ,4 ,5 ,7 1 2 3 4 5 7 10 15 20 mWG

0,01 ,02 ,04 ,06 0,1 ,2 ,3 ,4 ,5 ,7 1,0 1,5 2 Bar

10

57

150

50

3020

100

200

2030

50

,631,01,62,54,06,3

101625

5080

125

20

Flow chart for ∆p control valves in district heating systems.

m3/h l/skvs-value

∆pva

lve

IVD-IVFS kvs 0,63 - 25,0 m3/h

AFP kvs 50 - 125 m3/h

∆p-regulator, working range: IVD 5 - 50 and 20 - 250 kPa.AFP 20 - 120 and 50 - 250 kPa

Maximum ∆p valve IVF kvs: 0,63 and 1,0 = 1.000 kPa2,5 = 630 kPa4,0 - 25 = 800 kPa

Maximum ∆p valve AFP: 1.200 kPa

177



0

0,5

1,0

1,5

2,0

2,5

050100150200250300350400

1 10 50 100 150 200 250

Heat requirement for hot water according to the Swedish Board of District Heating

Domestic hot water, Q L/s. Effect, P kW

Number of apartments.



0,07

0,1

0,15

0,2

0,3

0,4

0,5

0,6

0,70,8

1,00,9

20 30 40 50 60 70 80m /h

3 ∆p kPav

0,2 0,3 0,4 0,5 0,6 0,7 0,8

∆

p Barv

1

2

3

4

5

8

6,5

0,2

0,3

0,4

0,5

0,7

2,0

1,5

1,00,90,8

0,6

20 30 40 50 60 70 80m /h

3 ∆p kPav

0,2 0,3 0,4 0,5 0,6 0,7 0,8

∆

p Barv

10

1214

2

4

6

8

Flow limiter, ASV-Q 15, Flow limiter, ASV-Q 20

Set values

Set values

ASV-Q Capacity l/h Set value

15 100 - 800 1 - 820 200 - 1400 2 - 1425 400 - 1600 4 - 1632 500 - 2500 5 - 30

179



2,0

1,71,5

1,2

1,00,90,80,7

0,6

0,5

0,4

30 40 50 60 70 80m /h

3 ∆p kPav

0,3 0,4 0,5 0,6 0,7 0,8

∆

p Barv

10

121416

4

6

8

4,0

3,0

2,0

1,5

1,2

1,00,90,80,70,6

0,5

0,4

m /h3

30 40 50 60 70 80∆p kPav

0,3 0,4 0,5 0,6 0,7 0,8

∆

p Barv

5

15

10

20

25

30

Flow limiter, ASV-Q 25, Flow limiter, ASV-Q 32

Set values

Set values



Calculation of one-pipe system

6

31 m6 m6 m6 m6 m

1200

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1200

1200

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1200

1200

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1200

1200

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1200

6 m 6 m 6 m

1200

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1200

1200

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1200

1200

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1200

1200

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1200

3 x

12 =

36

m

1,5 m

0

2345

23456

789

1

1010 m

181



Calculation of one-pipe system



Calculation of two-pipe system

12001200 1200 120012001200 1200 1200

1200 12001200 12001200 12001200 1200

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

1000

3 m 6 m 6 m 6 m

123456

7

8

9

10

11

12

13

14

15

16

17

3 m

3 m

31 m

183



Calculation of two-pipe system



SI-units.Effect, P. Pressure, p.W kcal/h Pa kPa bar mWG1 0,85985 1 0,001 0,00001 0,0001

1,163 1 1.000 1 0,01 0,1

100.000 100 1 10

10.000 10 0,1 1

Flow, Q (ϕ). Temperature, t (θ).l/s m3/h Kelvin K Celsius oC1 3,6 0 -273,15

0,278 1 273,15 ± 0

373,15 100

Greek alphabet.

Α α Β β Γ γ ∆ δ Ε ε Ζ ζ Η η Θ θ Ι τ alfa beta gamma delta epsilon seta eta theta iota

Κ κ Λ λ Μ µ Ν ν Ξ ξ Ο ο Π π Ρ ρ Σ σkappa lamda my ny xi omikron pi ro sigma

Τ τ Υ υ ϑ ϕ Χ χ Ψ ψ Ω ωtau ypsilon phi chi psi omega

Physical properties for water.

Temperature Pressure Density Isobaric heatυ oC p kPa ρ kg/m3 capacitivity

cp J/ (kg x K)

0 - 999,84 421810 - 999,70 419220 - 998,205 418230 - 995,65 417840 - 992,2 417850 - 998,14 418160 - 983,21 418470 - 977,78 419080 - 971,80 419690 - 965,33 4205100 1,3 958,35 4216110 43,26 951,0 -120 98,54 943,1 4245130 170,11 934,8 -140 261,36 926,1 4287150 375,97 916,9 -

185



TECHNICAL DATA, FORMULAS AND CHARTS - Danfoss...

Documents

Transcript of TECHNICAL DATA, FORMULAS AND CHARTS - Danfoss...