Reducing heating costs with solar energy

Technical Series

Solar technology

2

Solar energy is environmentallyresponsible, free and effective.Particularly if you have a solarheating system with highly efficientcollectors and perfectly matchedcomponents made by Viessmann.

Index

3

1 Solar framework

1.1 Available energy1.2 Heat from the sun1.3 Irradiated energy1.4 Influence of alignment,

inclination and shade on theenergy yield

1.5 Overall system optimisation

2 Sizing solar heating systems

2.1 Collector efficiency2.2 Solar coverage2.3 Influence of various parameters

on solar coverage

3 Calculation examples for DHW

heating in a detached house

4 Design and function of

Viessmann solar panels

5 Selection and installation

options for different types of

collector

6 Viessmann system technology:

saving costs and installation

time

6.1 Collectors6.2 DHW cylinders for solar heating

systems6.3 System components

7 Solar heating systems for DHW

heating

8 Integrating solar collectors into

heating systems

9 Solar technology in a new light:

collectors as design features

Page 4

Page 8

Page 10

Page 12

Page 13

Page 14

Page 20

Page 21

Page 22

4

1 Solar framework

Fig. 1: Annual global radiation

Global radiation

1300 1250 1200 1150 1100 1050 1000 950 900

kWh/(m2 p.a.)

In detached houses and two-familyhomes, correctly designed solarcollector systems with matchingcomponents can save between 50 and 60% of the annual energyrequirement for domestic hot water.In summer, additional energy maynot be required at all.

We have been using the sun’s heatsince time immemorial. In summer, it heats our buildings directly, whilstin winter we make use of storedsolar energy in the form of wood,coal, oil and gas, to provide heat forour buildings and domestic hotwater.

To protect fuel reserves accumulatedover millions of years, the heatingindustry has committed itself tofinding more responsible ways ofhandling these precious resources.

One rational way of achieving thisaim is to make direct use of solarenergy by means of solar panels.Thanks to the use of highlysophisticated collectors and aperfectly matched overall system, theeconomic use of solar energy is not just a vision for the future, buta reality for today. Considering thatfuel prices will continue to rise in the years ahead, investing in a solarheating system can be viewed as a genuine investment in the future.

1.1 Available energy

In Germany, on average 1000 kWh/m2 are irradiated, whichcorresponds to roughly 100 litres fueloil or 100 m3 natural gas.

The useful energy which a collectorcan absorb depends on severalfactors. The correct estimation of thedemand to be covered and thematching size of the system arecrucial factors.

The total amount of available solarenergy, too, is relevant: in Germany,the available annual irradiation level lies between 900 and 1300 kWh/(m2 p.a.) (Fig. 1).

Collector type as well as inclinationand orientation also play a vital role.If the solar installation is to beoperated economically, carefuldimensioning of the systemcomponents is essential.

For the rest of the year, the solarDHW heating is supplemented by a second, independent heat source,usually an oil or gas fired lowtemperature boiler or, better still, bya condensing boiler. Solar panels arenot only suitable for DHW heating,but also as backup for your centralheating.

5

Solar framework

A

G

F

K

D

C

H

E

H

B VL

RL

Diffused radiation

Direct solar radiation

Wind, rain, snow,

convection

Convection losses

Thermal conduction losses

A

B

C

D

E

Absorber heat

radiation

Glass cover heat

radiation

Useful collector output

Reflection

F

G

H

K

Fig. 2: Utilisation of solar radiation in the collector

6000

5000

4000

3000

2000

1000

0So

lar

rad

iati

on

[W

h/(

m2

• d

)]

Jan. Feb. AprilMarch May June July Aug. Sept. Oct. Nov. Dec.

Global radiation

Direct radiation

Diffused radiation

Fig. 3: Irradiated daily energy values over a 12 month period

1.2 Heat from the sun

Approx. 1/3 of Germany’s total energy consumption is expended on heating buildings. Energy-conscious construction and, inparticular, economical heatingsystems, can substantially reducethis requirement. This thencontributes to the preservation of valuable energy resources and to the protection of the earth’satmosphere.

Substantial savings potential isoffered by DHW heating. In ourlatitudes, solar panels combined with a central DHW cylinderrepresent an interesting alternativeto boiler operation, especially duringthe summer months.

1.3 Irradiated energy

Solar radiation is an energy forceradiated in all directions, equally, bythe sun. Of that energy, an output of1.36kW/m2, called the solar constant,hits the outer earth’s atmosphere.

This solar radiation is reduced (Fig. 2) through reflection, dispersionand absorption in dust particles andgas molecules. The portion ofradiation which passes unimpededthrough the atmosphere and strikesthe earth’s surface directly is knownas direct radiation.

That part of the solar radiation which is reflected and/or absorbedby dust particles and gas molecules,irradiated back and strikes the earth’ssurface indirectly is known asdiffused radiation.

The sum total of all direct anddiffused solar radiation (Fig. 3) iscalled global radiation Eg. The globalradiation under optimum conditions(clear, cloudless sky at midday)amounts to a max. of 1000 W/m2.With solar panels, as much as 75% of this global radiation can beutilised, depending on the type of collector and the system size.

6

Solar framework

Fig. 4: Influence of alignment, inclination and shade on the irradiated energy

1.4 Influence of alignment,

inclination and shade on the energy

yield

In Germany, the solar heating systemprovides the highest yield over anannual average when facing southwith an inclination of approx. 30 to45 degrees to the horizontal plane.However, the installation of a solarheating system is still viable evenwhen the installation deviates quitesignificantly from the above (south-westerly to south-easterly alignment,25 to 70 degrees inclination) (Fig. 4).

A lower inclination is morefavourable if the collector surfacecannot be pointed south. A solarcollector system with a 30 degreeinclination and an alignment of 45 degrees south-west still achievesalmost 95% of its optimum yield.Even with an east or west alignment,you can still expect up to 85% with a roof slope between 25 and 40degrees.

A steeply raked collector surfaceoffers the advantage of a balancedenergy provision all the year round.On the other hand, an angle ofinclination less than 20 degreesshould be avoided, otherwise thecollector will become toocontaminated.

-10

-10°

-20

-20°

-30

-30°

-40-40°

-50-50°

-60-60°

-70-70°

-100-100°

-110-110°

-120-120°

-140

-140

°-150

-150°

Annual

irradiation levelin %

Angle of

inclination

30

40

50

60

70

80

90

95

100

10°

20°

30°

40°

50°

60°

70°

80°

90°

+10

+10

°

+20

+20

°

+30

+30°+4

0+4

0°

+50+50°

+60+60°

+70+70°

+80+80°

+100+100°

+110+110°

+120+120°

+130+130°

+140+140°

+150

+150°

+160

+160°

+170

+170°

-130

-130°

-160

-160

°

-170

-170

°

10° 20° 30° 40° 50° 60° 70° 80° 90°

: example: 30°; 45° south-west; ≈ 95%

NorNorthth

Westest

Southouth

EastEast

α

α

α

Fig. 5: Collector orientation with angle ofinclination α

N

W O

S

90°

75°

60°

45°

30°

15°

0°

90°75°

60°45°30°

15

15°

Collector level

Angle of azimuth

Fig. 6: Example – angle of azimuth 15° east

Angle of inclination α

The angle of inclination α is theangle between the horizontal and thesolar collector (Fig. 5). For pitchedroof installations, the angle ofinclination is determined by theslope of the roof. The largest amountof energy can be captured by thecollector’s absorber, when thecollector plane is aligned at rightangles to the irradiation of the sun.

Angle of azimuth

The angle of azimuth (Fig. 6)describes the deviation of thecollector plane from the south; withthe collector plane aligned to thesouth, the angle of azimuth = 0°.Because solar irradiation is at itsmost intensive at midday, thecollector plane should be oriented as closely as possible to the south.However, deviations from south upto 45° south-east or south-west arealso acceptable. Higher deviationscan be compensated through slightlylarger collector areas.

7

Solar framework

Fig. 7: Solar heating system comprising matching components

1.5 Overall system optimisation

A high-quality solar panel alone,cannot guarantee the optimumoperation of a solar installation. This depends more on the systemsolution as a whole (Fig. 7).

Viessmann supplies all thecomponents required for a solarheating system:

– a control unit that is tailored to theindividual solar heating system,

– a DHW cylinder incorporating asolar heat exchanger low insidethe cylinder,

– design details aimed at achievingfast-responding control andtherefore maximum yields fromthe solar heating system.

In detached houses and two-familyhomes, correctly designed solarheating systems with matchingsystem components can savebetween 50 and 60% of the annualenergy requirement for domestic hotwater.

Air separator

Flexibleconnection pipe

Collector temperaturesensor

Cylinder temperaturesensor

Dual-mode

DHW cylinder

Fill valve Manual solar filling pump

Solarcontroller

Expansion vessel

Drip tray

Air vent valve

Solar Divicon

Solarcollector

Fig. 8: Components of a solar heating system

8

2 Sizing solar heating systems

Table 1: Comparative values for optical efficiency and thermal loss coefficient

Eff

icie

ncy

Temperature difference between environment and average collector temperature [K]

Vitosol 100

Vitosol 250

Vitosol 300

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

00 10 20 30 40 50 60 70 80 90 100

Vitosol 200

I

II

III IV

I

II

III

IV

Solar heating system for DHW with low coverage

Solar heating system for DHW with higher coverage

Solar heating system for DHW and central heating backup

Solar heating system for process heat / solar air conditioning

Fig. 10: Collector efficiency levels

Collector area

Absorber area

Aperture size

(solar active surface area)

Fig. 9: Collector area details

2.1 Collector efficiency

Some of the solar radiation whichhits the collectors is ”lost” throughreflection off the glass pane andthrough absorption (Fig. 2). Theoptical efficiency level η0 takes theselosses, and those created during thetransfer of energy into the processmedium, into consideration. The optical efficiency level is themaximum of the curve, when thedifference between the collector and the ambient temperature is zero, and the collector loses noenergy to the environment.

When collectors heat up, theytransfer energy to the ambiencethrough thermal conduction, thermal radiation and convection (air movement). These losses areallowed for by the thermal losscoefficients k1 and k2 (Table 1). Theyare subject to the temperaturedifferential ∆ϑ between the absorberand the ambience.

The thermal loss coefficient andoptical efficiency lead to the collectorefficiency curve, which can becalculated in accordance with thefollowing formula

η = η0 – k1 · (∆ϑ / Eg) – k2 · (∆ϑ2 / Eg)

(Fig. 10).

Information on the collector surfaces

Three sets of collector surface detailsare specified in the collectordatasheets (Fig. 9).

For most subsidy programs, thegross surface area (length x width of external dimensions) is decisivewhen applying for subsidies.

The aperture area (opening) definesthe effective collector area necessaryfor sizing the system.

The absorber area denotes theselectively coated area which iseffective with regard to radiation,subject to installation location andcollector design. It is of little usewhen comparing solar panels.

Collector Optical Heat loss coefficient Gross areatype efficiency k1 [W/(m2·K)] k2 [W/(m2·K)] [m2]

η0 [%]*

Vitosol 100– type s/w 2.5 84 3.36 0.013 2.71– type 5 DI 84 4.16 0.0073 5.25Vitosol 200 84 1.75 0.008 1.50 / 2.94 / 4.38Vitosol 250 77.5 1.476 0.0075 1.67Vitosol 300 82.5 1.19 0.009 2.94 / 4.38

∗η0 relative to:– aperture area for Vitosol 100 and 250– absorber area for Vitosol 200 and 300

9

Sizing solar heating systems

DHW consumption [l/d]

Ap

ert

ure

[m

2]

60%

50%

40%

10

8

6

4

2

00 50 100 150 200 250 300 350 400

Vitosol 100

DHW consumption [l/d]

Ap

ert

ure

[m

2]

10

8

6

4

2

00 50 100 150 200 250 300 350 400

Vitosol 200, 250 and 300

60%

50%

40%

Fig. 11: Solar cover from Vitosol collectors

Reference system

100 litre/day

300 litre/day

400 litre/day

Collector inclination 30°Collector inclination 60°Fixed orientation west

Fixed orientation south-west

Vacuum tubes*

Hanover

Freiburg

* With comparable aperture

Solar cover for DHW heating [%]

0 20 40 60 80

61

74

51

43

60

59

50

59

53

68

71

10 30 50 70 90

Fig. 12: Influence of various parameters on the solar coverage (calculated with the latest ESOPsoftware, version 2.0)

Reference system:

– meteorological records for Würzburg– 4 person household with a DHW consumption of 200 litres/day, 45 °C– 2 Vitosol 100 collectors, type s/w 2.5– 45 degree roof pitch, roof oriented towards south– dual-mode DHW cylinder, 300 litres capacity

Selection of a suitable collector type

Various factors must be consideredat the planning stage for theselection of the right type ofcollector. These are: the availability ofspace, installation conditions, otherframework conditions (e.g. longperiods out of use during schoolholidays), and the temperaturedifferential between the averagecollector temperature and theoutside air. This decision willinfluence the collector efficiency. The higher the collector operatingtemperature, the higher its outputand therefore the yield of vacuumtube collectors (Fig. 10).

2.2 Solar coverage

The solar coverage indicates whatpercentage of the energy requiredannually can be covered by the solarheating system.

The higher the selected solarcoverage, the more conventionalenergy is saved. This causes excessheat in summer and generally loweraverage collector efficiency.

Fig. 11 indicates the realistic coverwhich can be achieved with varioustypes of collector, relative to:– roofs facing south,– roof pitch of 45° and– DHW standby temperature of

45 °C.

2.3 Influence of various parameters

on solar coverage

The bars in Fig. 12 indicate thecoverage to be expected fordeviations from the referencesystem. Regarding the effects ofsystem orientation, see also Fig. 4.

3 Calculation examples for DHW

heating in a detached house

10

System details

– Detached house in Würzburg– Roof pitch 45 degrees– Orientation south– Number of occupants 4; medium

demand for domestic hot water– DHW temperature: ϑW = 45 °C

Cold water temperature: ϑK = 10 °C– During bad weather and outside

the solar heating times, a Viessmann oil or gas fired boiler delivers the residual heat required for DHW heating

– Collector type: 2 Vitosol 100 with a total aperture area of 5 m2

DHW demand

Selected DHW demand according toVDI 2067, DHW temperature: 45 °C

VP = 50 litres/(day · person)

For four occupants, this results in aDHW demand of 200 litres per day.

Cylinder capacity

The total DHW cylinder capacity(solar calorifier capacity + standbycapacity) should be sized on thebasis of 1.5 to 2 times the dailydemand. Given the selected DHWtemperature inside the DHW cylinderof ϑcyl = 60 °C and twice the dailydemand:

2 · VP · P · (ϑW – ϑK)

Vcyl min= –––––––––––––––––––

ϑcyl – ϑK

2 · 50 · 4 · (45 – 10)= –––––––––––––––––––

60 – 10

= 280 litres

In this case, we would recommendthe DHW cylinders Vitocell-B 100 orVitocell-B 300 with 300 litrescapacity.

Table 2: DHW demand according to VDI 2067

Table 3: Required aperture (data based on meteorological records for Würzburg)

DHW demand Vp

[litres/(d · pers.)]

DHW temperature 45 °C

In domestic dwellings

High demand 60 to 100

Average demand 30 to 60

Basic demand 15 to 30

In hotels, B&Bs,

residential homes*

Rooms withbath and shower 170 to 260

Rooms with bath 135 to 200

Rooms with shower 75 to 135

Residential homes, guest houses 40 to 75

* for larger systems we would recommendmeasuring the DHW consumption prior tosizing the system

Application Required aperture area A Vitosol Vitosol Vitosol

100 200/250*1 300

DHW heating(coverage 60%)Detached/two-family house m2/person 1.2 – 1.5 0.8 – 1.0 0.8 – 1.0Apartment block m2/person 0.8 – 1.1 0.6 – 0.8 0.6 – 0.8

Heating a domestic dwelling m2/m2

living space

Indoor swimming pool*2

(during April to September)with cover m2/m2 pool surface area 0.40 0.30 0.30without cover m2/m2 pool surface area 0.50 0.40 0.40

Open air swimming pool*3

(during April to September)with cover m2/m2 pool surface area 0.70 0.50 0.50without cover m2/m2 pool surface area 0.90 0.70 0.70

*1 Increase sizing of aperture by 20% for wall mounted collectors*2 Swimming pool reference temperature 24 °C, assumed rate of cooling 0.5 K/day*3 Swimming pool reference temperature 22 °C, assumed rate of cooling 1 K/day

Calculate guide values usingthe ESOP simulation program

Aperture area

For practical purposes, the estimatesin Table 3, based on fixedmeteorological conditions, aresufficiently accurate. For an overviewof the solar coverage for DHWheating, a calculation using the ESOP software is recommended,incorporating user habits. Thecalculated coverage should liebetween 50 and 60%.

ESOP solar software

Figures 13 and 14 indicate thecalculation results for theaforementioned detached house inWürzburg – these were obtainedusing ESOP, the software for solarheating systems. ESOP calculates the necessary absorber surface areaaccording to freely selectable inputs,simulates the system characteristicsand provides statements about thesolar coverage, fuel savings and thereduction of emissions.

Calculation examples for DHW

heating in a detached house

11

Fig. 13: Solar cover for DHW heating of a detached house

Fig. 14: Emissions

0

20

40

60

80

100

Dec.Nov.Oct.Sep.Aug.Jul.Jun.MayApr.Mar.Feb.Jan.

So

lar

co

vera

ge [

%]

24

41

62

75

86 8689

8683

59

2924

0

200

400

600

800

1000

CO2 SO2 NOx CO Dust

w/o solar system

with solar system

Em

issio

ns [

kg

/p.a

.]

Given the above system conditions,an annual average coverage of DHWheating by solar energy of approx.60% results. During the summermonths, the DHW may only need a little backup heating.

Saving electricity with solar heating

systems

You can save even more energy, byrunning your washing machine ordishwasher with solar-heated water.Washing machines and dishwashersuse most of their power requirementfor heating water. If the solar heatingsystem largely provides this capacity,a household of four can reduce theirelectricity bills by at least another € 50 p.a..

Subsidies, grants and approvals

Information about current subsidiesand grants [in Germany] can bechecked under www.viessmann.com.

Permits for the installation of solarheating systems are not universallythe same. Your local planning officewill be able to advise you aboutwhether solar heating systems needplanning permission.

4 Design and function of Viessmann

solar panels

Viessmann solar panels – something

for everyone

The Vitosol solar range (Fig. 15)offers the right solution for almostevery need and demand:

– Vitosol 100 flat panel collectorsexcel with their attractivecost:benefit ratio. Vitosol 100 areoffered in two sizes, 2.5 and 4.76 m2. The 2.5 m2 panels can besupplied for horizontal or verticalorientation. Vitosol 100, type 5DI(4.76 m2) (Fig. 16) is a special flatpanel collector for integration into a pitched roof.

– Vitosol 200 and Vitosol 250 aredirect flow high-performancevacuum tube collectors, that areideal for installation in any location.

– Vitosol 300 is a vacuum tubecollector that operates according tothe heat pipe principle, providingdry connection and integraloverheating protection.

Benefits of Viessmann solar panels

In spite of their different designs, allfour collector types offer commonbenefits.

All are made from high-gradematerials, such as stainless steel,aluminium, copper and stabilisedspecial solar glass. These improveoperational reliability and service life substantially. The stability andresistance of all of these collectortypes have been verified by thequality test of the SPF Institute inRapperswil.

The high levels of effectiveness ofthese collectors is achieved byabsorbers utilising a Sol-titaniumcoating, integrated pipes and highlyefficient thermal insulation.

Fig. 15: Viessmann Vitosol solar collector range

Fig. 16: Flat panel collector Vitosol 100, type 5DI

The evacuated glass pipes of Vitosol200, 250 and 300 additionally reducethermal losses. A special plug-insystem has been developed tofacilitate easy pipe connectionbetween individual Viessmann solarcollectors.

This avoids the need for anyadditional pipework and extensivethermal insulation, thus significantlyreducing assembly times. Solar flowand return are mounted on one sidefor easy installation; routing one pipeabove and one below the roof coveris not required.

The selection of recyclable materialsand a design which makesdismantling easy, helps Viessmannsolar collectors meet therequirements set for the ”Blue Angel” certificate of environmentalexcellence (RAL-UZ 73).

12

13

5 Selection and installation options

for different types of collector

Vitosol 100, type 2.5 s and w

Vitosol 100 flat panel collectors witha 2.5 m2 aperture are offered asvertical or horizontal versions. Both are suitable for installation onpitched roofs. The selection ofmethod of installation, installation on top of roof coverings or roofintegration, are influenced by therespective building conditions (Fig. 17). In new builds, for example,roof integration is preferable.

Vitosol 100, type 5DI

Vitosol 100, type 5DI large area flatpanel collectors with 4.92 m2

aperture are offered for integrationinto pitched tiled roofs.

Vitosol 200

Vitosol 200 vacuum tube collectorscan provide a high solar gainbecause of their direct flow principle,so you can install them anywhere.These collectors are especiallysuitable for installation on flat roofsor on the walls of buildings, butequally suit installation on top ofpitched roofs.

Vitosol 250

Vitosol 250 vacuum tube collectorsare direct flow high-performancecollectors, ideally suited toinstallation anywhere around thebuilding. They are suitable forinstallation on pitched and flat roofs,as well as on walls.

Vitosol 300

Vitosol 300 vacuum tube collectorsare based on the heat pipe principle.For that reason, they must beinstalled with a slope of at least 25°.One of their characteristic features istheir integral overheating protection.

E

F

A

C

D

B

Fig. 17: Installation options for various types of collector

Installation location

Pitched roofs

Flat roofs

Freestandinginstallation

Walls / balcony rails /balustrades*2

(For this type of installation, werecommend increasing theabsorber surface / aperture surface by 20%).

Collector type

Vitosol 100, type sVitosol 100, type 5DI (only roof integration)

Vitosol 200Vitosol 250Vitosol 300Vitosol 100, type wVitosol 200Vitosol 250

Vitosol 200Vitosol 250Vitosol 100, type wVitosol 300

Vitosol 100, type w*1

Vitosol 200Vitosol 250Vitosol 300

Vitosol 200Vitosol 250

A

B

C

D

E

F

*1) not recommended for dusty ground*2) 20% larger than for alternative installation methods

6 Viessmann system technology:

saving costs and installation time

14

Fig. 19: Vitosol 100 with a total aperture of 2.5 m2

Fig. 18: Vitosol 100 flat panel collector

Fig. 20: Viessmann plug-in system

6.1 Collectors

Vitosol 100

Flat panel collector

Flat panel collectors are ideal fordomestic hot water and heatingswimming pool water.

Vitosol 100 flat panel collectors (Fig. 18) comprise an absorber withSol-titanium coating, which ensuresthe high level of collector efficiency.A meandering copper tube isconnected to the absorber and issurrounded by the process medium.The process medium channels theabsorber heat through the copperpipe. The absorber is surrounded bya highly insulated collector housingwhich minimises collector heatlosses.The collector cover is made from asolar glass pane whose low ferrouscontent reduces reflection losses.This solar glass is 4 mm thick,making it particularly weather-resistant. The solar glass pane andcollector frame are connected by adeep endless seal. Rain or melt watercannot penetrate into the lowercollector section.

With its individual colours andattractive design, Vitovolt 100 offersnew opportunities to colourcoordinate roof and solar panels. Thenew edge trims particularly help tocreate a harmonious transition fromsolar panel to roof cover. The edgetrims are available as accessory forroof integration and installation ontop of roofs. The collector frames andthe edge trims are supplied asstandard in a brown finish (Fig. 19).

Upon request, frame and edge trimcan be supplied in all other RALcolours, enabling the system to bematched to the roof colour. That way,the solar panel becomes an integralpart of the roof design (see thephotograph on the title page).

Viessmann system technology:

saving costs and installation time

15

Vitosol 200

Vacuum tube collector

Vacuum tube collectors are used for domestic hot water, heatingswimming pool water and for centralheating backup.

Vitosol 200 (Fig. 21 and 22) comprisehighly evacuated solar glass tubes.Heat losses are so low that Vitosol 200 collectors provide energyfor DHW heating or central heating,even at low outside temperatures.Absorbers with a Sol-titaniumcoating are integrated into allvacuum tubes. A coaxial heatexchanger pipe, through which theprocess medium flows, is connectedto the absorber panel.

Both coaxial pipe connectorsterminate in the header and manifoldpipe in the thermally insulatedcollector head section (Fig. 23).

Vitosol 200 vacuum tube collectorsare particularly suitable forinstallation on flat roofs or on walls.They can also be installedlongitudinally on pitched roofs, i.e. with the head section on thecollector side.

The optimum absorber orientationcan be adjusted by turning thevacuum tubes around their own axis. Deviations from south can be partially compensated by therotation of the vacuum tubes. Theangle is limited to 25° to prevent the absorbers casting shadows over each other.

Fig. 21: Vitosol 200 vacuum tube collector

Fig. 22: Vitosol 200, type D10 and D20 Fig. 23: Vitosol 200, type D10 and D20

Viessmann system technology:

saving costs and installation time

16

Fig. 24: Vitosol 250 vacuum tube collector

Fig. 25: Vitosol 250 Fig. 26: Vitosol 250 – tubes can be replacedindividually

Vitosol 250

Vacuum tube collector

Vacuum tube collectors are used for domestic hot water, heatingswimming pool water and for centralheating backup.

Vitosol 250 (Fig. 24) is a direct flowhigh-performance collector, ideallysuited to installation anywherearound the building.

The vacuum tube is the specialfeature of the new Vitosol 250. It ismade completely from glass andretains its vacuum reliably andpermanently. Tubes in Vitosol 200and 300 can be individually replaced(Fig. 26).

Vitosol 250 is delivered in a standardformat comprising 20 fitted tubes(Fig. 25). Flow and return pipes areintegrated into the head section.Along with the proven Viessmannassembly system, this ensures easyinstallation.

Viessmann system technology:

saving costs and installation time

17

Fig. 27: Vitosol 300 heat pipe vacuum tube collector

Fig. 28: Vitosol 300 Fig. 29: Highly effective ”Duotec” double-pipeheat exchanger

Vitosol 300

Heat pipe vacuum tube collector

Vacuum tube collectors are used for domestic hot water, heatingswimming pool water and for centralheating backup.

Vitosol 300 (Fig. 27 and 28) is a heatpipe collector. An absorber with aSol-titanium coating, to which a heatpipe is attached, is integrated into avacuum tube. The process mediumcirculates through the heat pipe andevaporates when heated. The heat istransferred to the solar circuit via aheat exchanger in a condenser in thehead section. This re-condenses themedium.

In Vitosol 300, the heat exchangebetween the condenser and the solarcircuit takes place in a dry state, i.e.without direct contact between thevarious liquids. The patented andhighly effective Duotec double-tubeheat exchanger almost completelysurrounds the condenser (Fig. 29).

In order to fully utilise the solarenergy, every collector tube is able to pivot so that the absorber can beturned towards the sun. Deviationsfrom the south can be partiallycompensated by rotating the vacuumtubes (maximum 25°).

Vitosol 300 vacuum tube collectorsare suitable for pitched and flat roofs(with supports). The collector angleof inclination must be at least 25°, toensure the circulation of the processmedium inside the heat exchangertube.

18

Viessmann system technology saves

costs and installation time

Vitocell-B 300

The powerful Vitocell-B 300 dual-mode stainless steel DHW cylinderwith 300 or 500 litres capacity (Fig. 31) is designed for dual-modeDHW heating. The lower indirect coiltransfers the heat from the solarpanels to the DHW, whereas theupper indirect coil enables DHWheating, on demand, by the boiler.Vitocell-B 300 is made from high-alloy stainless steel. Its surface is andremains homogeneous and thereforehygienic. Dual-mode DHW cylinderswith 500 litres capacity are suppliedwith removable soft PUR foaminsulation for easier handling.

Multi-mode heating water calorifier

with integral DHW heating

Vitocell 333

Vitocell 333 (Fig. 32) is a multi-modecombination cylinder, which isprepared for the simultaneousconnection of several heat sources. It is also possible to link oil and gasfired boilers, solid fuel boilers, solarheating systems and heat pumps tothis cylinder.

Fig. 32: Vitocell 333/353 – multi-modecombination cylinder

Fig. 30: Vitocell-B 100 – dual-mode steel DHWcylinder with Ceraprotect enamel coating

Fig. 31: Vitocell-B 300 – dual-mode DHWcylinder made from stainless steel

6.2 DHW cylinders for solar heating

systems

Viessmann solar heating systems –

matching and complete

Viessmann offers matching andcomplete solar heating systems,comprising flat and vacuum tubecollectors, DHW cylinders, Diviconpumping stations, Vitosolic controlunits and heat exchangers.

DHW cylinder for DHW heating in

dual-mode operation

Vitocell-B 100

The heat absorbed by the solarcollectors is transferred in the dual-mode Vitocell-B 100 with 300 or 500 litres capacity (Fig. 30) to theDHW via the lower indirect coil. Anindirect coil arranged in the upperarea and heated by a boiler, reheatsthe domestic hot water upondemand. Where required, DHW canalso be heated through an electricimmersion heater. The DHW cylinderis protected against corrosion by aCeraprotect enamel coating and anadditional cathode (magnesium orimpressed current anode).

Vitocell 353

Vitocell 353 (Fig. 32) is a multi-modecombination cylinder, which isprepared for the simultaneousconnection of several heat sources.As well as oil and gas fired boilers, it is also possible to link solid fuelboilers, solar heating systems andheat pumps to this cylinder. Thestratification loading system ensuresthe layering of solar energy heatedwater at different temperatures,making DHW heated by solar energyavailable very quickly.

Vitocell 050

Heating water calorifier

For storing heating water inconjunction with solar heatingsystems, Viessmann offers theVitocell 050 heating water calorifierwith 200, 600 and 900 litres capacity.This helps to keep the DHW cylindersmall (for hygiene considerations),particularly in larger systems.

Viessmann system technology saves

costs and installation time

Fig. 33: Viessmann solar heating system withcondensing boiler and dual-mode DHW cylinder

Fig. 36: Vitotrans 200 heat exchanger

Fig. 35: Vitosolic 100 and 200 control units

Fig. 34: Solar-Divicon pump station

19

6.3 System components

(Fig. 33)

Solar-Divicon pump station for all

hydraulic functions and thermal

protection

All essential safety and functionequipment, such as thermometer,ball valves with check valves,circulation pump, flow meter,pressure gauge, safety valve andthermal insulation are combined in one compact assembly (Fig. 34).

Control units

Solar energy is particularly efficientlyutilised with the intelligent Vitosolicenergy management system incombination with the solar collectorsin the Vitosol product range. TheVitosolic 100 and 200 solar controlunits are suitable for single andmulti-circuit solar heating systems,and cover all conventionalapplications. Data is exchanged viathe KM BUS with the weathercompensated Vitotronic boilercontrol unit.

Vitosolig ensures that the energy”harvested” on the roof is utilised as effectively as possible for DHWheating or for central heating backup.Vitosolic 100/200 communicates withthe boiler control unit and switchesthe boiler off, as soon as sufficientsolar energy is available – and thatreduces your heating costs.

Vitosolic 100

(Fig. 35 l.h. side)

Attractively priced solar control unitfor single circuit systems:

– Simple operation in accordancewith the Vitotronic controlphilosophy.

– Two-line display with informationabout current temperatures andpump operating conditions.

– Small casing dimensions.

Solar collector

Dual-mode DHW cylinder

Solar-DiviconGas fired

condensing boiler

Vitosolic

Vitosolic 200

(Fig. 35 r.h. side)

Solar control unit for multi-circuitsystems with dedicated operatorinterface for up to four independentsolar circuits:

– Simple operation in accordancewith the Vitotronic controlphilosophy.

– High operating conveniencethrough four-line plain text displaywith menu assistance.

– For all conventional applications: – multi-cylinder operation, – swimming pool water heating, – central heating backup.

– Large wiring chamber for easyinstallation.

Heating swimming pool water

Viessmann offers Vitotrans 200 heatexchangers (Fig. 36) with variousoutput stages for heating swimmingpool water. The heat exchangersurfaces and connections are madefrom high-grade, corrosion resistantstainless steel.

7 Solar heating systems for DHW

heating

20

Solar heating system with

dual-mode DHW cylinder

(Fig. 37)

Dual-circuit system, comprising:– solar collector system,– oil/gas fired boiler,– dual-mode DHW cylinder.

DHW with solar energy

Solar circuit pump ➃ is switched ONand the DHW cylinder is heated up,when a temperature differencehigher than the value set in Vitosoliccontrol unit ➀ is measured betweencollector temperature sensor ➁ andcylinder temperature sensor ➂ . Thetemperature inside the DHW cylindercan be limited by the electronic limitthermostat incorporated in Vitosolic 100 ➀ .

DHW heating by the boiler

The upper indirect coil of the DHWcylinder is heated by a boiler. TheDHW control thermostat, to which aDHW cylinder temperature sensor ➄of the boiler control unit isconnected, starts cylinder loadingpump ➅ .

Solar heating system with

two DHW cylinders

(Fig. 38)

Dual-circuit system, comprising:– solar panel system,– oil/gas fired boilers,– two DHW cylinders, (application: for example, an existingDHW cylinder should also be used).

Fig. 37: DHW heating with solar panels and a dual-mode DHW cylinder

TT

2

1

54

3

6

Fig. 38: DHW heating with solar panels and two DHW cylinders

TT

2

1

4

6

7

5

B A

8 Integrating solar collectors into

heating systems

21

T

M

2

1

3

456

7

T

Solar heating system for DHW

heating and central heating backup

(Fig. 39)

Dual-circuit system, comprising:– solar collector system,– oil/gas fired boiler,– multi-mode combination cylinder.

Heating the combination cylinderthrough the solar heating system

Solar circuit pump ➃ is switched ONand the combination cylinder isheated up, when a temperaturedifference higher than the value setin Vitosolic control unit ➀ ismeasured between collectortemperature sensor ➁ and lowercylinder temperature sensor ➂ . Thetemperature inside the combinationcylinder can be limited by theelectronic limit thermostatincorporated in Vitosolic 200 ➀ . Thelocation of solar heat exchanger ➆inside the combination cylinderensures that even small amounts ofheat, generated during periods oflittle sunshine, can be utilised.

Fig. 39: Dual-mode DHW heating and supplementing the heating function

Heating the combination cylinder byboiler

The combination cylinder is heatedby the boiler (Fig. 37 and Fig. 38) ifthe actual water temperature atupper cylinder temperature sensor ➄falls below the set heating watertemperature.

Instantaneous DHW heating

The heated DHW inside thecorrugated stainless steel pipe ➅ isimmediately available to be drawnoff. Cold incoming water is heated bythe heating water as it flows throughthe corrugated stainless steel pipe.When large volumes of DHW aredrawn off, the heating water insidethe combination cylinder coolsdown. This triggers temperaturesensor ➄ to start the boiler, therebyguaranteeing constant DHWconvenience at all times.

DHW heating with solar energy

The DHW cylinder will be heated bythe solar circuit, if a temperaturedifferential greater than the value setat the Vitosolic control unit ismeasured between collectortemperature sensor ➁ and thetemperature sensor of cylinder,

. The temperature inside DHWcylinder can be limited by theelectronic limit thermostatincorporated in Vitosolic 200 ➀ .Circulation pump ➆ will be startedvia the second temperaturedifferential set in Vitosolic 200, assoon as the temperature in DHWcylinder is higher than that of DHWcylinder . This then also utilisesDHW cylinder to exploit theavailable solar energy.

DHW heating by boiler

The boiler loads DHW cylinder (Fig. 38) if the actual temperature atthe DHW cylinder temperaturesensor ➄ falls below the settemperature.

A

A

B

B

B

A

9 Solar technology in a new light:

collectors as design features

Fig. 41: City of tomorrow, Malmö, Sweden

22

Technology as part of architecture

Viessmann solar collectors areinnovative in their utilisation of solarenergy. No matter where these flatpanel or tubular solar collectors areinstalled on top of a roof, on a wall orintegrated into the roof, they createnew aesthetic opportunities forbuilding design. Coupled with a high degree of functionality, thesesystems can be imaginativelyincorporated into modernarchitecture (Fig. 40).

Intelligent alternatives to

conventional construction concepts

Vacuum tube collectors fromViessmann provide interestingopportunities for new designconcepts as single or as linkedassemblies. This is because solarcollectors are not simply matched tothe design of a building, they arealso used as structural constructionelements. These high performancecollectors can be an innovative partof the building design and theiroptical effect is striking. Theircoloured glass tubes, for instance,would endow any building withinstant visual impact.

The blue-print of an ecological citybecame impressive reality in Malmö(Sweden), the ”City of tomorrow”(Fig. 41). 500 living units cover theirentire energy demand exclusivelyfrom renewable resources. Vitosol250/300 collectors represent anessential part of their heatingprovision. With just 300 m2 collectorarea the avant-garde appearance of this estate demonstrates thesuccessful innovative integration oftechnology into architecture. Anothermilestone of functional aesthetics:the wall mounted solar heatingsystem from Viessmann at theStudentenwerk, Leipzig, wasawarded the Saxony 2001Environmental Prize (Fig. 42).

Fig. 40: Nord LB Hannover

Fig. 42: Studentenwerk Leipzig – awarded theenvironmental prize of Saxony

Solar technology in a new light:

collectors as design features

23

A synthesis of functional and

aesthetic design

Vacuum tube collectors utilise freesolar energy and offer endlesscreative opportunities for design.Their installation location is notlimited to walls or roofs, Viessmannsolar heating systems are veryeffective as wide projections or asfreestanding structures. Whilst thecollectors absorb solar energy, theirlamellar structure can provideeffective shade (Fig. 43).

Viessmann's many different versionsof collectors make them versatileenough for almost any form ofinstallation. One of the pioneers isthe Vitosol 100 flat panel collectorwhich is perfect roof integration, withits special assembly sets. The Vitosol250 vacuum tube collector, on the other hand, can be installed in any position, e.g. on a wall or on a flat roof, even without supports. In addition, they can be mounted on a balcony railing, as well ashorizontally or vertically on pitchedroofs.

A range of colours in an attractive

design

Vitosol 100 provides completely newperspectives for matching roof andsolar collectors. The new edge trimshelp to create a harmonioustransition from collector surface to roof. Upon request, frame andedge trim can be supplied in all RALcolours, for a perfect match with theroof colour (Fig. 44).

This makes this highly effective solarcollector with Sol-titanium coatingan integral part of the roof design.Coupled with a high degree offunctionality, Viessmann solarheating systems offer interestingoptions for appealing architecture.

Fig. 44: Vitosol solar collectors – for attractive roof designs

Fig. 43: Heliotrop, Freiburg with vacuum tube collectors

Viessmann offers

you a diverse

range of products,

which are uniform

in quality and

adaptable enough

to be able to meet

any demand and

any requirement

Wall mounted oil

and gas fired

condensing boilers

The Viessmann Group

The Viessmann Group employsapproximately 6800 staff worldwide andis one of the foremost manufacturers ofheating equipment. For freestandingboilers, Viessmann is the mostsuccessful brand in Europe. TheViessmann brand stands for competenceand innovation. The Viessmann Groupoffers a comprehensive range of top-quality, high-tech products along withperfectly matched modular components. For all their diversity, our products haveone thing in common: a consistentlyhigh standard of quality that is reflectedin operational reliability, energy savings,environmental compatibility and user-friendliness.

Many of our developments point theway forward for the heating sector, both in terms of conventional heatingtechnologies and in the field ofrenewable forms of energy, such as solarand heat pump technology.

In all our developments we pursue ourphilosophy of always achieving thegreatest possible benefit: for ourcustomers, the environment and ourpartners, the heating contractors.

The Viessmann Group:

Viessmann Werke

D-35107 Allendorf (Eder)

Tel.: + 49 6452 70 - 0

Fax: + 49 6452 70 - 2780

www.viessmann.com

Viessmann UK Office:

Viessmann Limited

Hortonwood 30,Telford

Shropshire,TF1 7YP, GB

Tel.: + 44 1952 675000

Fax: + 44 1952 675040

e-mail: info-uk@viessmann.com

Subject to technical modifications9446 750 -1 GB 11/2004