System Design Guidelines - Viessmann

System Design Guidelines 

Vitosol 200-F Vitosol 300-T 

Model SP3 

Viessmann solar collectors – 

the right solution for every application 

Using solar energy to heat domestic hot water and to 

provide a backup for space heating 

5167 156 v3.1 05/2008 

Vitosol 200-F 

Flat plate solar collector for installation on pitched 

and flat roofs, and for freestanding installation 

VITOSOL 

Vitosol 300-T 

Vacuum tube solar collector, based on the heat pipe 

principle, for installation on sloped and flat roofs and for 

freestanding installation

Safety, Installation and Warranty Requirements 

2 

Safety, Installation and Warranty Requirements 

Please ensure that these instructions are read and understood before commencing installation. Failure to comply with the 

instructions listed below and details printed in this manual can cause product/property damage, severe personal injury, and/or 

loss of life. Ensure all requirements below are understood and fulfilled (including detailed information found in manual 

subsections). 

H Licensed professional heating 

contractor 

The installation, adjustment, service, 

and maintenance of this equipment 

must be performed by a licensed 

professional heating contractor. 

" Please see section 

entitled “Important 

Regulatory and 

Installation 

Requirements”. 

H Product documentation 

Read all applicable documentation 

before commencing installation. Store 

documentation near boiler in a readily 

accessible location for reference in 

the future by service personnel. 

" For a listing of 

applicable literature, 

please see section 

entitled “Important 

Regulatory and Safety 

Requirements”. 

H Advice to owner 

Once the installation work is 

complete, the heating contractor must 

familiarize the system 

operator/ultimate owner with all 

equipment, as well as safety 

precautions/requirements, shut-down 

procedure, and the need for 

professional service annually. 

H Warranty 

Information contained in 

this and related product 

documentation must be 

read and followed. Failure 

to do so renders warranty 

null and void. 

H Grounding/lightning protection of the 

solar system 

In the lower part of the building, 

install an electrical conductor on the 

solar circuit’s piping system in 

compliance with local regulations. 

Connection of the solar system to a 

new or existing lightning protection or 

the provision of local grounding should 

only be carried out by a licensed 

professional, who must take into 

account the prevailing conditions on 

site. 

CAUTION 

Observe maximum load and distance 

from edge before installing the 

substructure to the roof. If necessary, 

consult with a structural engineer to 

determine if the structure is suitable 

for installing solar collectors. The 

collectors must be securely mounted 

so that the mountings can withstand 

intense wind conditions and local 

snow loads. 

CAUTION 

Gloves and eye protection must be 

worn when handling solar panels. 

CAUTION 

Solar panel connection pipes and 

solar heating fluid can become hot 

enough to cause severe burns. 

Extreme caution must be taken if 

panels have been in a stagnant 

condition (no flow of fluid). 

CAUTION 

Avoid scratching or sudden shocks to 

glass cover of the solar panel. 

CAUTION 

Never step on collectors or solder in 

close proximity to the glass surface 

of the solar panel. 

H Applicability 

Vitosol solar collectors are designed 

for use in closed loop heating systems 

for domestic hot water heating, space 

heating and pool heating via a heat 

exchanger. The use of Viessmann 

heat transfer medium “Tyfocor-HTL” 

is strongly recommended. 

IMPORTANT 

Pool water or potable water cannot be 

pumped directly through the Vitosol 

collectors. Damage to collectors caused 

by corrosion, freezing or scaling will 

void warranty. 

5167 156 v3.1

5167 156 v3.1 

Contents 

Contents Page 

Safety Safety Instructions 

Important Regulatory and Installation Requirements 

General Information About these Instructions 

Product Information 


Basic Principles of Solar Technology Subsidies, Permits and Insurance ................................... 7 

Solar Energy ...................................................... 7 

HExploiting solar energy ............................................ 7 

H Solar radiation ................................................... 8 

H Global radiation .................................................. 8 

H Exploiting solar energy with collectors .............................. 9 

H Influence of alignment, inclination and shade on energy yield ......... 10 

H Inclination and orientation of collectors ............................. 11 

H Angle of inclination ............................................... 11 

Overall System Optimisation ....................................... 12 

Specification Construction and Function of Collectors ............................. 13 

H Vitosol 200-F – flat panel collector ................................. 13 

H Vitosol 300-T – vacuum tube collector based on the heat pipe principle 14 

Collector Efficiency ................................................ 16 

Solar coverage .................................................... 17 

Collector Installation and Mounting Details ........................... 18 

H Installation options for different collector types ..................... 18 

H Vitosol 200-F flat panel collector .................................. 18 

H Support weight requirements - Vitosol 300-T ........................ 24 

General Installation Instructions ..................................... 26 

Notes on Planning and Operation Calculating the Required Absorber Surface Area ...................... 27 

H Calculating the absorber surface area and DHW cylinder capacity ..... 27 

H Calculating the absorber surface area for space heating .............. 28 

Sizing Pipe Diameters and Circulation Pump .......................... 31 

H Sizing pipe diameters ............................................ 34 

H Installation examples for Vitosol 200-F, models SV2 and SH2 ........ 35 

H Collector pressure drop information ................................ 34 

H Sizing pipe circulation pump ...................................... 35 

H Technical information on the Solar-Divicon .......................... 36 

Safety Equipment ................................................. 38 

H Liquid capacity of solar heating system components ................. 37 

H Diaphragm expansion vessel ...................................... 39 

H Technical data for the expansion tank .............................. 43 

H Pressure relief valve ............................................. 41 

H High limit safety cut-out .......................................... 41 

H Thermostatic mixing valve ........................................ 42 

Accessories ...................................................... 43 

3

Contents 

Contents (continued) Page 

System Designs General Information ................................................ 44 

H How to implement the installation ................................. 44 

System Design 1 .................................................. 45 

H Dual-mode DHW heating with Vitocell-B 100 or Vitocell-B 300 

DHW tanks ..................................................... 45 


H Dual-mode DHW heating and space heating backup 

with heating water storage tank ................................... 47 


H Dual-mode DHW heating with two DHW tanks ...................... 50 


H Dual-mode DHW and swimming pool water heating ................. 53 

System Design Extensions .......................................... 56 

H System with bypass circuit ....................................... 56 

H Bypass circuit with solar cell ...................................... 56 

H System with energy-saving mode .................................. 57 

Appendix Calculation Example Based on the Viessmann ”ESOP” Program ........ 58 

H Solar heating systm with dual-coil DHW tank ....................... 58 

Glossary ......................................................... 60 

4 

5167 156 v3.1

5167 156 v3.1 

Safety 


Codes 

The installation of solar heating 

systems might be governed by 

individual local rules and regulations for 

this type of product, which must be 

observed. The installation of this unit 

shall be in accordance with local codes. 

Always use latest editions of codes. 

Mechanical room 

Ensure the mechanical room complies 

with the requirements of the system 

design guideline and/or technical data 

manual. 

Thesolarstoragetankmustbeinstalled 

in a mechanical room which is never 

subject to freezing temperatures. 

If not in use and danger of freezing 

exists in the mechanical room, ensure 

water in tank is drained. 

Workingontheequipment 

The installation, adjustment, service, 

and maintenance of this equipment 

must be done by a licensed professional 

heating contractor who is qualified and 

experienced in the installation, service, 

and maintenance of solar heating 

systems. There are no user serviceable 

parts on this equipment. 

Ensure main power supply to 

equipment, the heating system, and all 

external controls has been deactivated. 

Take precautions in both instances to 

avoid accidental activation of power 

during service work. 

Technical literature 

Literature applicable to all aspects of 

the Vitosol: 

- Technical Data Manual 

- Installation Instructions 

- Start-up/Service Instructions 

- Operating Instructions 

and User’s Information Manual 

- System Design Guidelines 

Please carefully read this manual prior 

to attempting installation. Any 

warranty is null and void if these 

instructions are not followed. 

This product must be installed 

observing not only the necessary 

product literature (see list), but also 

all local, provincial/state plumbing and 

building codes, as they apply to this 

product and all periphery equipment. 

For information regarding other 

Viessmann System Technology 

componentry, please reference 

documentation of the respective 

product. 

We offer frequent installation and 

service seminars to familiarize our 

partners with our products. Please 

inquire. 

The completeness and functionality of 

field supplied electrical controls and 

components must be verified by the 

heating contractor. These include 

pumps, valves, air vents, thermostats, 

temperature and pressure relief 

controls, etc. 

Leave all literature at the installation 

site and advise the system 

operator/ultimate owner where the 

literature can be found. Contact 

Viessmann for additional copies. 

5

General Information 

6 

About these Instructions 

Take note of all symbols and notations intended to draw attention to potential hazards or important product 

information. These include ”WARNING”, ”CAUTION”, and ”IMPORTANT”. See below. 

Product Information 

WARNING 

Indicates an imminently hazardous 

situation which, if not avoided, could 

result in substantial product/property 

damage, serious injury or loss of life. 

CAUTION 

Indicates an imminently hazardous 

situation which, if not avoided, may 

result in minor injury or 

product/property damage. 

IMPORTANT 

Warnings draw your attention to the 

presence of potential hazards or 

important product information. 

Cautions draw your attention to the 

presence of potential hazards or 

important product information. 

Helpful hints for installation, operation 

or maintenance which pertain to the 

product. 

This symbol indicates that additional, 

pertinent information is to be found in 

the adjacent column. 

This symbol indicates that other 

instructions must be referenced. 

Vitosol 200-F, Models SV2, SH2 

Flat panel solar collector with 25 ft. 2 / 

2.3 m 2 collector area. 

Max. stagnation temperature 430°F / 

221°C 

Max. operating pressure 87 psig / 

6bar 

Vitosol 300-T, SP3 Series 

Vacuum tube solar collector with 22 

and 32 ft. 2 /2and3m 2 collector area. 

Max. stagnation temperature 302°F / 

150°C 

Max. operating pressure 87 psig / 

6bar 

5167 156 v3.1

5167 156 v3.1 

Subsidies, Permits and Insurance 

Solar Energy 

Exploiting solar energy 

Solar heating systems for DHW or 

swimming pool heating are subsidised 

by many regional and local authorities. 

Request information about subsidies 

from your local authority. 

Further information is available from our 

sales offices. 

The sun has provided the earth with 

light and heat for billions of years. 

Without it, our existence on earth 

would be impossible. 

We have been using the sun’s heat 

since time immemorial. In summer, it 

heats our buildings directly, while in 

winter we make use of solar energy 

stored in the form of wood, coal, oil and 

gas, to provide heat for our buildings 

and domestic hot water. 

To protect fuel reserves, the heating 

industry has committed itself to finding 

more responsible ways of handling 

these precious resources, which have 

accumulated naturally over millions of 

years. 

One rational way of achieving this aim is 

to make direct use of solar energy by 

means of collectors. 

Basic Principles of Solar Technology 

Your local planning office will be able to 

advise you about whether solar heating 

systems need planning permission. 

Viessmann solar collectors are tested 

for impact resistance, incl. hail impact, 

in accordance with DIN EN 12975-2. 

Nevertheless, we would recommend 

you include the collectors in your 

building insurance, to protect you from 

losses arising from any extraordinary 

natural phenomenon. Our warranty 

excludes such losses. 

Thanks to the use of highly 

sophisticated collectors and a perfectly 

matched overall system, the economic 

use of solar energy is no longer a 

futuristic vision, but a proven everyday 

reality. 

Considering that fuel prices will 

continue to rise in the years ahead, 

investing in a solar heating system can 

be viewed as a ”genuine” investment in 

the future. 

7


2 

Solar irradiation in Wh/(m x d) 

8 

Solar Energy (continued) 

Solar radiation 

Diffused celestial radiation 

Direct solar radiation 

Wind, rain, snow, convection 

Convection losses 

Conduction losses 

Global radiation 

6000 

5000 

4000 

3000 

2000 

1000 

RT 

Heat radiation of the absorber 

Heat radiation of the glass cover 

Useful collector output 

Reflection 

RT Return 

S Supply 

S 

direct 

radiation 

diffused 

radiation 

0 

Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. 

Solar radiation represents a flow of 

energy irradiated uniformly in all 

directions by the sun. Of that energy, 

an output of 429 Btu/h/ft. 2 or 

1.36 kW/m 2 , the so-called solar 

constant, hits the outer earth’s 

atmosphere. 

After penetrating the earth’s 

atmosphere, the solar radiation is 

reduced by reflection, dispersion and 

absorption by dust particles and 

gaseous molecules. That portion of this 

radiation which passes unimpeded 

through the atmosphere to strike the 

earth’s surface is known as direct 

radiation. 

The portion of the solar radiation which 

is reflected and/or absorbed by dust 

particles and gas molecules and 

irradiated back strikes the earth’s 

surface indirectly is known as diffused 

radiation. 

The total radiation striking the earth’s 

surface is the global radiation Eg, i.e., 

global radiation = direct radiation + 

diffused radiation. 

In the latitudes of North America, the 

typical global radiation under optimum 

conditions (clear, cloudless sky at midday) 

amounts to a max. of 317 

Btu/h/ft. 2 or 1 000 W/m 2 . 

With solar collectors, as much as 75 % 

of this global radiation can be utilised, 

depending on the type of collector. 

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Exploiting solar energy using solar collectors 

The useful energy which a collector can 

absorb depends on several factors. 

The main factor is the total solar energy 

available. 

Annual global radiation in Canada 

Annual global radiation in the United States 

The amount of global energy varies 

from location to location (see maps 

below). 


The type of collector, as well as its 

inclination and orientation, are also very 

important (see page 10). If the solar 

installation is to be operated 

economically, careful dimensioning of 

the system components is also 

essential. 

Btu/ft2 2.5-3kwh/m 

/day 

2 /day 787-945 

3-3.3kwh/m2 /day 945-1040 

3.3 - 3.6 kwh/m2 /day 1040-1134 

3.6 - 3.9 kwh/m2 /day 1134-1228 

3.9 - 4.2 kwh/m2 /day 1228-1323 

4.2 - 4.4 kwh/m2 /day 1323-1386 

4.4 - 4.7 kwh/m2 /day 1386-1481 

>4.7kwh/m2 /day >1481 

Btu/ft 2 /day 

3-4kwh/m 2 /day 945-1260 

4-5kwh/m 2 /day 1260-1575 

5-6kwh/m 2 /day 1575-1890 

6-7kwh/m 2 /day 1890-2205 

Note: Average mean daily global radiation on a south-facing surface tilted at an angle equal to the latitude of the location. 

9



Influence of alignment, inclination and shade on energy yield 

Example: 

30°; 45° south-west 

10 

West 

North 

South 

East 

Annual 

irradiation 

in % 

Angle of 

inclination 

Optimum alignment and inclination 

The solar generator provides the highest 

annual solar yield for a DHW system 

whenfacingsouthwithaninclinationof 

approx. 30 to 35 degrees 

to the horizontal plane. However, the 

installation of a solar heating system is 

still viable even when the installation 

deviates quite significantly from the 

above (south-westerly to south-easterly 

alignment, 25 to 55 degrees 

inclination). 

The graph illustrates the loss of yield 

resulting from an installation of the 

collector array which is less than 

perfect. The graph also indicates that a 

shallower inclination is more favourable, 

if the collector surface cannot be 

pointed south. A solar heating system 

with a 30º inclination and an alignment 

of 45º south-westerly still achieves 

95% of its optimum yield. Even with an 

east-westerly alignment, you can still 

expect 85% with a roof inclination 

between 25º and 40º. 

A more steeply sloped installation 

would be more favourable in winter, but 

the system achieves two thirds of its 

yield during the summer months. On the 

other hand, an angle of inclination less 

than 20 degrees should be avoided, 

otherwise the solar generator will 

become too contaminated, or 

snowcovered. 

Installing the collector array on different 

roofs requires complex hydraulic 

interconnections between the individual 

collectors. 

Every array is equipped with a separate 

collector temperature sensor and a 

separate pump line. 

The increase in energy yield is therefore 

offset by the higher installation costs, 

resulting in a significantly reduced 

cost:benefit ratio. 

Shade reduces energy yield 

Position and size the collector array so 

that the influence of neighbouring 

structures, trees, power lines, etc., 

which throw shadows over the array, is 

minimised. Also consider how 

neighbouring properties will be likely to 

develop over a period of 20 years, as 

regards additional buildings, plants and 

saplings. 

5167 156 v3.1

5167 156 v3.1 


Inclination and orientation of collectors 

Angle of inclination 

Example: 

Deviation from south: 15º east 

IMPORTANT 

The angle of inclination for Vitosol 

300-T collectors must be at least 25º in 

order to guarantee circulation of the 

evaporator liquid in the heat pipe 

Collector plane 

Azimuth angle 


To achieve optimum energy absorption, 

the collectors must be oriented towards 

the sun. 

The angle of inclination and the azimuth 

angle are the dimensions used to 

determine the orientation of the 

collectors. 

Angle of inclination α 

The angle of inclination a is the angle 

between the horizontal and the collector 

plane. 

For pitched roof installations, the angle of 

inclination is determined by the slope of the 

roof. 

The largest amount of energy can be 

captured by the collector’s absorber when 

the collector plane is aligned at right 

angles to the irradiation of the sun. 

Because the angle of irradiation depends 

on the time of day and the time of year, 

the collector plane should be aligned 

according to the position of the sun during 

the phase of maximum energy supply. 

In practice, angles of inclination of 

between 30 and 45º have proven to be 

ideal. 

For most installations in North America, 

for example, an angle of inclination of 

between 25 and 70º is advantageous, 

depending on the period of use. 

Lower angles of inclination are better for 

applications where more energy is 

required in the summer months (i.e. pool 

heating). Higher angles of inclination are 

better for applications where more energy 

is required in the winter months. 

Capturing the maximum amount of energy 

throughout the year can be achieved using 

an angle of inclination equal to the latitude 

of the building site. This is ideal for 

domestic hot water heating applications. 

Azimuth angle 

The azimuth angle describes the deviation 

of the collector plane from south; the 

collector plane aligned to the south is the 

azimuth angle = 0º. 

Because solar irradiation is at its most 

intensive at midday, the collector plane 

should be oriented as closely as possible 

to the south. However, deviations from 

south up to 45º south-east or south-west 

have minimal impact on annual energy 

production. 

11


Overall System Optimization 

A high-quality solar collector cannot by 

itself guarantee the optimum operation 

of a solar installation. This depends 

more on the complete system solution 

as a whole. 

Viessmann supplies all the components 

required for a solar heating system: 

12 

DHW 

I 

Solar collector 

Solar-Divicon (pumping station) 

Overflow container 

Expansion vessel 

Solar manual filling pump 

System fill manifold valve 

H a control unit that is tailored to the 

individual solar heating system, 

H a DHW tank incorporating a solar heat 

exchanger low inside the tank, 

H a preassembled pump station with all 

necessary hydraulic components, 

H design details aimed at achieving 

fast-responding control and therefore 

maximum yields from the solar 

heating system. 

DCW 

Brass elbow c/w sensor well 

Dual-mode DHW tank 

I Tank temperature sensor 

Air separator 

Solar control unit 

Flexible connection pipe 

S R 

Correctly designed solar heating 

systems with well matched system 

components can cover 50 to 80 % of 

the annual energy demand for DHW 

heating in detached and semi-detached 

houses. 

We will be pleased to assist you with 

the design of solar heating systems. 

The elements of a solar heating system 

areshowninthediagram. 

Collector temperature sensor 

Fast air-vent, c/w shutoff valve *1 

R Return to collector 

S Supply from collector 

*1 Install at least one air-vent valve (quick-acting air-vent valve or a manual vent valve, see page 43) at the highest point of 

the system. 

T 

T 

T 

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5167 156 v3.1 

Construction and Function of Collectors 

Vitosol 200-F flat panel collector 

Continuous profiled seal (vulcanised) 

Solar glass cover, 3.2 mm thick 

Meander-shaped copper pipe 

Copper absorber 

Melamine resin foam 

Technical Data Vitosol 200-F, SV2/SH2 

Model Gross Area Absorber 

Area 

Aperture 

Area 

Mineral fiber 

Aluminum frame sections 

Aluminum-zinc bottom panel 

Connection pipe 

Dimensions Weight 

m 2 ft 2 m 2 ft 2 m 2 ft 2 mm in kg lb 

SV2 2.51 27.0 2.32 25 2.33 25.1 1056x 

2380x90 

SH2 2.51 27.0 2.32 25 2.33 25.1 2380x90x 

1056 

41¾x 

93¾x3½ 

93¾x41¾x 

x3½ 

Specification 

Vitosol 200-F flat plate solar collector is 

available as: 

H Vertical version Model SV2 and 

horizontal version Model SH2, each 

offering 2.3 m 2 /25ft 2 absorber 

surface. 

The main component of Vitosol 100 is 

the Sol-Titanium coated copper 

absorber. 

It ensures high absorption of solar 

radiation and low emission of thermal 

radiation. A copper pipe through which 

the heat transfer medium flows is fitted 

to the absorber. The heat transfer 

medium channels the absorber heat 

through the copper pipe. 

The meander-shaped direct flow 

absorber of models SV2 and SH2 

provides an extremely even flow 

through each individual collector in the 

collector arrays. 

The absorber is surrounded by a highly 

insulated collector housing which 

minimises collector heat losses. The 

high quality thermal insulation provides 

temperature stability and is free from 

gas emissions. 

The cover comprises a solar glass panel. 

The glass has a very low iron content, 

thereby reducing reflection losses. 

The collector housing comprises a 

powder-coated aluminium frame 

(recycled aluminium), within which the 

solar glass panel is permanently sealed. 

Model SV2 and SH2 

Up to twelve collectors can be joined to 

form a single collector array. For this 

purpose, the standard delivery includes 

flexible connection pipes, sealed with 

O-rings. 

A general connection kit with clamping 

ring connections enables the collector 

array to be readily attached to the pipes 

of the solar circuit. 

The collector temperature sensor is 

installed in the solar circuit flow via a 

sensor well set. 

52 115 

52 115 

13

Specification 

Construction and Function of Collectors (continued) 

Vitosol 300-T vacuum tube collector 

14 

Evacuated glass tube 

Heat pipe 

Absorber 

Technical Data Vitosol 300-T, 2m 2 /3m 2 

Model Gross Area Absorber 

Area 

Aperture 

Area 

Condenser 

Double pipe heat exchanger 

Dimensions Weight 

m 2 ft 2 m 2 ft 2 m 2 ft 2 mm in kg lb 

2m 2 2.83 30.5 2.05 22 2.11 22.7 1419x 

1996x 

122 

3m 2 4.24 45.6 3.07 33 3.17 34.1 2126x 

1996x 

122 

55¾x 

78½x 

4¾ 

83¾x 

78½x 

4¾ 

45 99 

68 150 

Vitosol 300-T vacuum tube collectors 

areavailableintwotypes: 

20 tube version, 

30 tube version 

The tube shape gives the collector great 

stability and high impact resistence. 

Re-evacuation of the tubes is not 

necessary as the tubes have a 

permanent airtight seal. 

The vacuum in the glass tubes ensures 

optimum heat insulation. Convection 

losses between the glass tube and the 

absorber are almost completely 

eliminated. This enables the utilisation 

of even low radiation levels (diffused 

radiation). The performance of the 

collector does not drop off as 

significantly in cold weather as a flat 

plate collector. On average, 

approximately 30% to 50% higher 

annual solar energy gain than flat plate 

collectors can be expected. 

Built into each vacuum tube is a 

Sol-Titanium coated copper absorber. It 

is a highly selective surface that 

ensures high absorption of solar 

radiation and low emission of thermal 

radiation. 

A heat pipe filled with an evaporator 

liquid is arranged on the absorber. The 

heat pipe is connected to the condenser 

via a flexible coupling. The condenser is 

mounted in a double pipe heat 

exchanger. 

This involves a so-called ”dry 

connection”, i.e. pipes can be rotated or 

replaced even when the installation is 

filled and under pressure. 

Heat is transferred from the absorber to 

the heat pipe. This lets the liquid 

evaporate. The vapour then rises to the 

condenser. 

The heat is transferred to the passing 

heat transfer medium by the 

double-pipe heat exchanger containing 

the condenser which causes the vapour 

to condense. The condensate flows 

back into the heat pipe and the process 

is repeated. 

Please note: 

Theangleofinclinationmustbeatleast 

25º to guarantee circulation of the 

evaporator liquid inside the heat 

exchanger. 

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5167 156 v3.1 

Construction and Function of Collectors (continued) 

Vitosol 300-T (continued) 

Legend 

102mm / 

4” 

Groove for retaining clip 

Specification 

Absorber surface areas of up to 6 m 2 

can be joined to form a single collector 

array. For this purpose, the standard 

delivery includes flexible connection 

pipes, sealed with O-rings. 

A connection kit with clamping ring 

connections enables the collector array 

to be readily connected to the pipes of 

the solar circuit. 

The collector temperature sensor is 

installed in a sensor mounting on the 

flow pipe in the connection housing of 

the collectors. 

15

Specification 

Collector Efficiency 

Some of the solar radiation striking the 

glassofthecollectorsis”lost”dueto 

reflection and absorption. The optical 

efficiency ηo takes these losses into 

account. 

When the collectors heat up, they 

transfer heat to the environment as the 

result of conduction, radiation and 

convection. These thermal losses are 

allowed for by the heat loss factors k1 

and k2 . 

16 

The heat loss factors and optical 

efficiency combine to form the collector 

efficiency curve which can be 

calculated on the basis of the following 

formula: 

η = ηo − k1 ⋅ ∆T 

− k2 ⋅ 

Eg 

∆T2 

Eg 

Eg= radiation intensity (W/m 2 ) 

∆ T=Temperature difference between 

ambient air and collector fluid ºC 

Collector type Opt. efficiency Heat loss factors Spec. thermal 

level 

capacity 

*1 i % 

kJ/( 2 ηo K) 

*1 in % k1 in 

W/(m2 · K) 

k2 in 

W/(m2 · K2 p y 

) 

kJ/(m2 · K) 

Vitosol 200-F 79.3 

3.95 

0.0122 6.4 

Vitosol 300-T 82.5 

1.19 

0.009 5.4 

*1 ηo basedonabsorberarea 

H 

0.9 

Efficiency 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 

0 10 20 30 40 50 60 70 80 90 100 

Temperature difference in degrees C between ambient air and collector fluid 

Vitosol 300-T 

Vitosol 200-F 

If the difference between the collector 

and ambient temperature is zero, the 

collector loses no heat to the 

environment, and the efficiency η is at 

its maximum level; this is known as the 

optical efficiency ηo. 

The thermal capacity is a measure of 

the thermal inertia of the collector, and 

shows the response behaviour of the 

collector when heating and cooling. A 

low thermal capacity is of advantage 

with wide ranging temparature and 

weather conditions typical in northerly 

climates. 

The table below lists comparative 

values for the optical efficiency and the 

heat loss factors as tested in European 

certification labs. 

Vitosol 200-F and 300-T are both 

tested and certified in North America to 

SRCC OG-100. 

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Solar Coverage 

Vitosol 200-F 

Absorber surface in m 2 Absorber surface in m 2 

0 13 26 40 53 66 79 92 

ltrs/day 

106 USG/day 

Vitosol 300-T 

DHW consumption 

DHW consumption 

Reference system 

100 litres/day 



Collector inclination 30° 

Collector inclination 60° 

Westerly orientation 

South-west orientation 

*1 

Vacuum tubes 

Hannover 

Freiburg 

USG/day 

0 13 26 40 53 66 79 92 

ltrs/day 

106 USG/day 

Influence of various parameters on solar coverage 

*1 For comparable absorber surface area. 

0 20 40 60 80 

Solar cover rate in % 

45 

45 

52 

56 

55 

62 

61 

61 

69 

76 

77 

Specification 

The solar coverage value indicates 

what percentage of the energy required 

annually for domestic hot water 

applications can be covered by the solar 

heating system. 

The absorber surface area should be 

sized so that the ”production” of 

surplus heat is just about avoided 

during the summer months. 

The higher the solar cover rate, the 

lower the efficiency, since a high cover 

rate has the effect of raising the 

temperature level of the solar circuit. 

This results in increased heat losses 

and lower seasonal efficiency. 

The diagrams show the coverage values 

that can be achieved with the various 

collector types, based on 

H the meteorological records for a 

typical location at 49° latitude, 

H south-facing roofs, 

H a roof pitch of 45º and 

H a DHW temperature of 113°F / 45ºC 

in the standby tank. 

This data represents approximate guide 

values. 

Note: 

Solar fractions will be higher for 

locations in southern parts of the USA 

due to higher levels of radiation. 

Reference system: 

H 4-person household with hot water 

consumption of 53 USG/day / 200 

litres/day 

H 2 Vitosol 200-F collectors, model 

SV2 and SH2 

H 45º roof inclination 

H South-facing roof orientation 

H Dual-mode DHW cylinder, 300 litres 

H Meteorological records for a typical 

location at 49° latitude 

The bars indicate the expected 

coverage values for deviations from the 

reference system. 

17

Specification 

Collector Installation and Mounting 

Installation options for different collector types 

Sloped roofs - rooftop installation 

Required roof area 

18 

Viessmann offers universal mounting 

systems to simplify installation. The 

mounting systems are suitable for 

virtually all forms of roofs, as well as 

installation on flat roofs or ground 

mounted free-standing installations. 

Fitting Collector type 

Pitched roofs A Vitosol 200-F, model SV2 

Vitosol 300-T 

B Vitosol 200-F, model SH2 

Flat roofs C Vitosol 200-F, model SV2, SH2 

Vitosol 300-T 

Freestanding installation D Vitosol 200-F, model SV2, SH2 

Vitosol 300-T 

Collector Type A mm A in B mm B in 

Vitosol 200-F, 

type SV2 2380 93 3/4 1056 + 16* 1 41 5/8 + 5/8* 1 

Vitosol 200-F, 

type SH2 1056 41 5/8 2380 + 16* 1 93 3/4 + 5/8* 1 

Vitosol 300-T, 

type SP3, 2m2 2031 80 1418 + 102* 1 55 3/4 + 4* 1 

Vitosol 300-T, 

type SP3, 3m2 2031 80 2127 + 102* 1 83 3/4 + 4* 1 

*1 Add this value for every additional collector. 

5167 156 v3.1

5167 156 v3.1 

Collector Installation and Mounting (continued) 

Vitosol 200-F flat panel collector 

Flat collectors are ideally suited for 

domestic hot water and swimming pool 

heating applications. 

Both vertical and horizontal types are 

suitable for installation on pitched roofs. 

The selection of method of installation 

is influenced by the structural 

characteristics of the building. 

Sloped Roofs Installation Details 

c 

Collector 

Lag bolt 

Mounting rail 

Roof bracket 

Model SH2 has been specially designed 

for installation on flat roofs and for 

freestanding installation. 

Viessmann offers a universal fastening 

system to simplify installation. The 

fastening system is suitable for virtually 

all forms of roof and roofing. 

Collector Dimension a b c 

Model SV2 

Model SH2 

a 

inches 

mm 

inches 

mm 

b 

93¾ 

2 380 

41¾ 

1 138 

74¾ - 82½ 

1 900 - 2 100 

19½ - 35½ 

500 - 900 

3½ 

89 

3½ 

89 

Specification 

Installation kits are available for 

installing collectors on flat roofs. 

An engineering evaluation is required to 

establish additional superimposed loads 

from wind or snow, as described in the 

local building code. Retain the services 

of a professional structural engineer to 

calculate additional live loads due to the 

installation of solar collectors on the 

roof. 

40 

10 

19

Specification 


Flat roof installation 

The collectors should be installed with 

an angle of inclination of 35 º to 45 º if 

the load capacity of the roof allows 

this. Maintain a minimum distance of 

2m/6ft from the roof edge in all 

installations. 

Outsideofthisareayoumay 

experience significant increases in wind 

turbulance. The system will also be 

hard to access if modifications are 

required. If the roof size dictates a 

modification of the array distribution, 

ensure that arrays of the same size are 

created. 

Determining the collector row distance 

“z” 

When installing several collector rows in 

sequence, exact dimensions (dimension 

“z”) must be maintained to prevent 

unwanted shade. 

Determine angle of the sun β. 

Collector row distance ”z” (all 

dimensions in mm) 

20 

l 

α 

z = Collector row distance 

l = Collector height 

(see page 13 and 14) 

z 

β 

A collector system must be secured by 

additional weights against slippage and 

lifting (see table on the following page). 

Slippage is the movement of the 

collectors on the roof surface due to 

wind, because of insufficient friction 

between the roof surface and the 

collector system. 

H Collectors secured against slippage 

require more ballast weight, but no 

additional attachment to the roof or 

substructure. 

This should be chosen so that the 

midday sun on Dec. 12 can fall onto the 

collector without creating shade. 

In North America, this angle is 

dependent upon latitude and is between 

13 º (Edmonton) and 41 º (Miami). 

H Collectors secured against lifting 

require less ballast weight, but 

additional attachment to the roof or 

building structure with wires, cables 

or other sufficient means. 

Example 

Boston is located approx. 42.5 º latitude. 

Angle of the sun β= 90 º -23.5 º -latitude 

(23.5 º should be accepted as the 

constant) 

90 º -23.5 º -42.5 º =24 º 

l · sin (180º - ( α+ β )) 

z = 

sin β 

Vitosol 200-F, type SV2 

l = 2380mm 

α= 45 º β =24 º (Boston) 

2385mm 0 sin (180º - 69 º ) 

z = 

sin 24º 

z = 5474mm 

Collector type Vitosol 200-F Vitosol 300-T 

Type SV2 


l 

α 

β 

α 

= Collector angle of inclination 

= Angle of the sun 

Type SH2 



Angle of sun β 35º 45º 35º 45º 35º 45º 55º 

15.0º 7059 7880 3140 3550 5991 6772 7349 

17.5º 6292 7035 2799 3130 5340 5970 6419 

20.0º 5712 6320 2541 2812 4848 5363 5716 

22.5º 5256 5758 2338 2561 4461 4886 5164 

25.0º 4887 5303 2174 2359 4148 4500 4716 

27.5º 4582 4926 2038 2191 3888 4180 4346 

Min. 6 ft/ 

2m 

Roof edge 

Collector 

array 

Min. 6 ft/ 

2m 

5167 156 v3.1

5167 156 v3.1 


Vitosol 200-F flat panel collector (continued) 

Please refer to Vitosol 200-F Installation 

instructions for additional information on 

collector mounting on 5285 710. 

A 

An evaluation by a professional 

structural engineer is required to 

calculate additional live loads due to the 

installation of solar collectors on a roof. 

Vitosol 200-F, type SV2 and SH2 

Collector angle of inclination - 25 º or 45 º 

Ballast to be applied and maximum load on the substructures of flat roofs to DIN 1055 

Specification 

Collector angle of inclination 25º 45º 

Ballast against slippage* 1 Ballast against lifting* 1 Ballast against slippage Ballast against lifting 

Installation height above ground m up 8 20 up 8 20 up 8 20 up 8 20 

to to to to to to to to to to to to 

Ballast to be applied 

8 20 100 8 20 100 8 20 100 8 20 100 

Type SV2 kg 315 554 793 144 304 465 508 842 1213 128 224 346 

Type SH2 kg 323 561 800 155 315 476 492 845 1198 132 254 375 

* 1 See description on page 20. 

Collector supports 

The collector supports are pre-assembled. They consist of foot support A, bearing supports and adjustment pieces. The 

upper adjustment pieces contain holes for adjusting the angle of inclination. 

Connection cross ties are required for 1 to 6 collectors connected in a series. 

A Foot support 

IMPORTANT 

Type SV2 

Foot support hole dimensions 

80 

11 

50 

75 

100 1620 

1795 

Type SH2 

Foot support hole dimensions 

80 

11 

50 

75 

100 722 

897 

21

Specification 


Vitosol 200-F 

Installation on substructures 

22 

X 

Y 

X 

* 1 For calculating dimension “z”, see page 20 

Installation with ballast 

X 

Y 

X 

* 1 For calculating dimension “z”, see page 20 

A 

A 

Z* 1 

Z* 1 

A Connection cross ties 

A Connection cross ties 

Collector type x mm x in y mm y in 

SV2 590 23 1/4 481 19 

SH2 1920 75 5/8 481 19 

5167 156 v3.1

5167 156 v3.1 


Vitosol 300-T sloped roof installation details 

1600mm / 

63” 

Collector 

Roof bracket 

Roof joist 

Collector installation rail with tube mountings 

Roof sheathing complete with shingles 

Lag bolt 

1650mm / 

65” 

230mm / 

9” 

340mm / 

13.4” 

2m 2 version 1419mm/55 3 /4” 102mm / 4” 3m 2 version 2126mm/83 3 /4” 

Deviations from south 

can be compensated by 

axial rotation of the 

vacuum tubes. 

Specification 

23

Specification 


Flat roof support weight requirements - Vitosol 300-T 

Collector angle of inclination of 25º 

Weight of supports 

Installation height above ground ft. 

m 


* 1 See description on page 20. 

A 

24 

lbs per support A 

kg per support A 

lbs per support B 

kg per support B 

Secured against slippage* 1 Secured against lifting* 1 

up to 26 

up to 8 

2m2 Version 

168 

76 

225 

102 

3m 2 

Version 

256 

116 

342 

155 

Support A 

Support B 

Model 2m 2 Version 3m 2 Version 

Dimension X inches 

mm 

Dimension Y inches 

mm 

Surface area (X x Y) ft. 2 

m 2 

Weight of lbs 

collector kg 

B 

76¼ 

1940 

56¾ 

1440 

30 

2.80 

99 

45 

76¼ 

1940 

84½ 

2149 

44½ 

4.15 

150 

68 

26 to 66 

8to20 

2m2 Version 

284 

129 

392 

178 

3m 2 

Version 

430 

195 

593 

269 

up to 26 

up to 8 

2m2 Version 

57 

26 

141 

64 

3m 2 

Version 

90 

41 

220 

100 

26 to 66 

8to20 

2m2 Version 

112 

51 

276 

125 

3m 2 

Version 

176 

80 

421 

191 

5167 156 v3.1

5167 156 v3.1 


Flat roof support weight requirements - Vitosol 300-T (continued) 

Collector angle of inclination of 45º 


Installation height above ground ft. 

m 


A 

lbs per support A 

kg per support A 

lbs per support B 

kg per support B 

Secured against slippage Secured against lifting 

up to 26 

up to 8 

2m2 Version 

H20 

225 

102 

377 

171 

3m 2 

Version 

344 

156 

564 

256 

Support A 

Support B 

Model 2m 2 Version 3m 2 Version 

Dimension X inches 

mm 

Dimension Y inches 

mm 

Surface area (X x Y) ft. 2 

m 2 

Weight of lbs 

collectors kg 

B 

60¼ 

1530 

56¾ 

1440 

24 

2.20 

99 

45 

60¼ 

1530 

84½ 

2149 

35 

3.27 

150 

68 

26 to 66 

8to20 

2m2 Version 

390 

177 

633 

287 

3m 2 

Version 

586 

266 

948 

430 

up to 26 

up to 8 

2m2 Version 

-- 

-- 

161 

73 

3m 2 

Version 

-- 

-- 

245 

111 

Specification 

26 to 66 

8to20 

2m2 Version 

-- 

-- 

302 

137 

3m 2 

Version 

-- 

-- 

454 

206 

25

Specification 

General Installation Instructions 

26 

H Vitosol solar collectors are hailproof. 

Nevertheless we recommend to 

include bad weather and hail damage 

coverage into your home owners 

insurance package. Our warranty does 

not cover such damages. 

H Please observe local building code 

guidelines for maximum load 

restrictions on the substructure and 

for necessary distance to roof edge. 

H Make sure to remove snow off 

collectors if more than 20” / 50 cm 

have accumulated. 

H Mount collectors carefully, so that 

even during storm and bad weather 

mounting clamps can absorb any 

tension. 

H An access door or skylight should be 

provided in the roof in the vicinity of 

the collectors to facilitate inspection 

and maintenance work. 

H When there is a relatively large 

distance between the collector panel 

and the roof ridge, a snow board must 

be installed above the collector panel 

in regions where heavy snowfalls can 

be expected. 

H Filling the solar heating systems with 

Viessmann “Tyfocor-HTL” heat 

transfer medium is highly 

recommended. Other heat transfer 

fluids may be suitable if they have the 

same temperature range (-35ºC / 

-31ºF to 170ºC / 338ºF) and are 

non-toxic. 

H Use high temperature insulation 

materials. In pump idle mode and with 

strong solar irradiation, collectors 

could reach an idle temperature of 

over 200 º C / 392ºF. Protect pipe 

insulation and sensor cables against 

attack by birds and animals. 

H Grounding and lightning protection of 

the solar heating system 

An electrically conductive connection 

ofthepipeworksystemofthesolar 

circuit should be implemented in the 

lower part of the building in 

accordance with local regulations. 

Connection of the collector system to 

a new or existing lightning protection 

system or the provision of local 

grounding should only be carried out 

by a licensed professional, taking local 

conditions into account. 

5167 156 v3.1

5167 156 v3.1 

Calculating the Required Absorber Surface Area 

Calculating the absorber surface area and DHW tank capacity 

Absorber surface area 

Estimates based on meteorological 

conditions such as annual global 

radiation, cloud cover etc. are 

sufficiently accurate for practical 

purposes. In order to obtain a 

comprehensive summary of the solar 

coverage for domestic hot water 

heating, it is recommended that this 

estimate should form the basis of a 

calculation carried out using a solar 

computer simulation. Viessmann can 

provide design support and computer 

simulations upon request. Contact your 

local Viessmann sales representative. 

The cover rate determined by this 

program should be 50 to 60 % for 

relatively small systems (detached 

house), and at least 40 % for larger 

systems (apartment block). 

Guide values for estimating the required 

absorber surface area can be drawn 

from the table on page 30. 

The absorber surface area calculated on 

the basis of this table has proved to be 

accurate in practice. 

Typical Solar Storage and Collector Selection 

# People 

in household 

2 

3-4 

5-6 

Daily DHW Demand 

@ 50ºC/120ºF 

120L 

32 gal. 

180-240L 

48-63 gal. 

300-360L 

79-95 gal. 

The basis for designing a solar DHW 

heating system is the DHW daily 

demand. It can be estimated based on 

the following table: 

Residential 

properties *1 

High demands 

Average demands 

Low demands 

Solar Tank 

Capacity 

200L 

53 gal. 

300L 

79 gal. 

450L 

120 gal. 

DHW Demand 

Vp 

litres/(d · person) 

For DHW temps 

temps. 

45ºC 60ºC 

50 - 80 35-56 

30- 50 21-35 

15 - 30 11-21 

Notes on Planning and Operation 

DHW tank capacity (solar storage) 

The following values can be used as a 

basis for calculating the cylinder 

storage capacity: 

The total available solar DHW tank 

capacity (dual-coil tank or preheating 

tank) should be sized on the basis of 

1.5 to 2 times the daily requirements. 

For fluctuating DHW demand use larger 

storage (daily demand x2). For relatively 

constant demand use value 1.5. 

The minimum solar storage tank volume 

should be based on 50 liter/m 2 / 

1.25gal/ft 2 collector absorber area. 

Vitosol 200-F Flat Plate 

Collectors SH2/SV2 

1 1x2m 2 

2 1x3m 2 

Vitosol 300-T 

Tube Collectors 

3 1x2m 2+ 1x3m 2 

27


Calculating the Required Absorber Surface Area 

System for space heating backup - DHW cylinder and collector 

Energy requirement or gain (%) 

100 

75 

50 

25 

0 

Jan. 

Feb. 

Mar. 

Apr. 

May 

Jun. 

Jul. 

Aug. 

Sep. 

Oct. 

Nov. 

Dec. 

A Space heating requirement for one house (typical construction) 

B Space heating requirement for one low energy house 

C Hot water requirement 

D Solar energy yield at 5 m 2 absorber surface (2 flat collectors) 

E Solar energy yield at 15 m 2 absorber surface (6 flat collectors) 

Concentrating exclusively on the central 

heating demand can lead to problematic 

oversizing of the system. 

For low energy houses (heat demand 

less than 50 kWh/(m 2 p.a.), solar 

coverage of 20 to 25% refers to the 

total energy demand, incl. provision for 

DHW heating. 

28 

E 

D 

A 

B 

C 

For buildings with a higher energy 

demand the coverage drops lower. 

Use the Viessmann ESOP calculation 

program when making sizing 

calculations. 

Max. connectable collector area when 

using Vitocell tanks must follow the 

chart on page 31. 

The period when the greatest amount of 

solar energy is available does not 

coincide with the time when the most 

heat is required. 

While the heat consumption for DHW 

heating is relatively constant 

throughout the year, only very little 

solar energy is available at the times 

when the heat demand for central 

heating is at its highest (see diagram). 

A relatively large absorber area is 

required to provide central heating 

backup. In summer, this can result in 

stagnation in the solar circuit. Systems 

for heating backup require additional 

storage tanks and controls. 

The basis for sizing a solar heating 

system for central heating backup is the 

space heating demand of the building 

during spring, autumn and in winter, as 

well as the heating demand in summer 

(i.e. the demand for DHW heating). 

Heat demand in summer, e.g to avoid 

condensation in cellars, to use 

underfloor heating in bathrooms, 

increases the demand. For efficient 

operation of a solar central heating 

backup, the collector area should be 2 

to 2.5 times larger than the DHW heat 

demand in summer requires. 

To avoid excessive summer time 

temperature stagnation avoid using 

collector areas greater than 3 times 

whatwouldbeusedforDHW 

requirements only. 

5167 156 156 v3.1

5167 156 v3.1 

Calculating the Required Absorber Surface Area (continued) 

Swimming pool water heating system - heat exchanger and collector 

Open-air swimming pools 

Open-air swimming pools are mainly 

used between May and September [in 

northern USA]. The energy demand 

required depends mainly on the leakage 

rate, evaporation, loss (water must be 

replenished cold) and the transmission 

heat loss. Through using a cover, the 

evaporation and consequently the 

energy demand of the pool is reduced 

to a minimum. The largest energy input 

comes direct from the sun, which 

shines onto the pool surface. Therefore 

the pool has a ”natural” base 

temperature which can be shown in the 

adjacent diagram as an average pool 

temperature over the operating time. 

A solar heating system in no way alters 

this typical temperature pattern. The 

solar application leads to a definite 

increase in the base temperature. 

Subject to the ratio between the pool 

surface and the collector area, a 

different temperature can be reached. 

The adjacent diagram shows with 

which ratio of aperture or absorber area 

to the pool surface what average 

temperature increase can be reached. 

This ratio is independent of the collector 

type used due to the comparably low 

collector temperatures and the 

operating period (summer). For this 

reason, unglazed collectors are most 

often used for outdoor pools. 

Indoor swimming pools 

Indoor swimming pools generally have a 

higher target temperature than open-air 

pools and are used throughout the year. 

If, over the course of the year, a 

constant pool temperature is required, 

indoor swimming pools must be heated 

in dual-mode. To avoid sizing errors, the 

energy demand of the pool must be 

measured. For this, suspend heating the 

water for 48 hours and determine the 

temperature at the beginning and end of 

the test period. The daily energy 

demand can therefore be calculated 

from the temperature difference and the 

capacity of the pool. For new builds, 

the heat demand of the swimming pool 

must be calculated. 

Note 

Revising and maintaining the pool 

temperature at a higher base level using 

a conventional heating system does not 

alter this ratio. However, the pool will 

be heated up much more quickly. 

20 

15 

10 

5 

0 

Jan Feb MarApr May Jun JulAug Sep Oct Nov Dec 

Average pool temperature in 0C25 

Average temperature increases 

in degrees C/day 

8 

7 

6 

5 

4 

3 

2 

1 

0 

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 

Ratio-absorber area to the pool surface 

(open-air swimmimg pool) 

On a summer day (clear skies), a 

collector system used to heat a 

swimming pool in northern USA 

produces energy of approx. 4.5kWh/m2 

absorber area. 

Calculation example for Vitosol 200-F 

Pool surface: 36 m 2 

Average pool depth: 1.5m 

Pool capacity: 54m 3 

Temperature loss 

on 2 days: 2ºC 

Daily energy demand: 

kWh 

54m3⋅1K⋅1.16 = 62.6kWh 

Km 3 


Collector area: 

Location Boston 

40m 2 Upper surface 

1.5m deep 

protected position 

covered at night 

62.6 kWh 

4.5 kWh/m 2 

This corresponds to 6 collectors. 

=13.9m 2 

For a first approximation (cost 

estimate), an average temperature loss 

of 1C/day can be used. With an average 

pool depth of 1.5m an energy demand 

of 1.74kWh/day is required to maintain 

the base temperature. It is therefore 

sensible to use approx. 0.4m 2 absorber 

area per m 2 of pool surface. 

29


Calculating the Required Absorber Surface Area (continued) 

Guide values for sizing solar heating systems (continued) 

H Absorber surface area (data based on meteorological records for a site at 49° latitude) 

Application Required absorber 

surface area A 60 % 40 up to 50 % 

for coverage of Vitosol 200-F Vitosol 300-T Vitosol 200-F Vitosol 300-T 

DHW heating 

Detached & semi-detached 

houses 

Multi-occupancy dwellings 

30 

ft. 2 /person 

m 2 /person 

ft. 2 /person 

m 2 /person 

Information regarding the DHW cylinder 

When sizing the solar heating system, 

observe the max. aperture area which 

may be connected to the different DHW 

cylinders. 

At a design output of 600W/m 2 and a 

temperature difference between DHW 

temperature (at the height of the solar 

13 - 16 

1.2 - 1.5 

8.6 - 11.8 

0.8 - 1.1 

heat exchanger, lower indirect coil) and 

solar circuit return (lower than 10 º C), 

the max. number of collectors 

mentioned in the table (values apply to 

all Viessmann collectors) should not be 

exceeded. 

8.6 - 10.8 

0.8 - 1.0 

6.5 - 8.6 

0.6 - 0.8 

DHW Tank Capacity Max. connectable number of collectors 

Vitocell-B 

100/300 

Vitocell-B 

100/300 

Vitocell-V 

100/300 

10.8 - 13 

1.0 - 1.2 

6.5 - 8.6 

0.6 - 0.8 

6.5 - 8.6 

0.6 - 0.8 

4.3 - 6.5 

0.4 - 0.6 

If a higher system temperature range is 

acceptable, then the number of 

collectors can be no more than doubled. 

Vitosol 200-F Vitosol 300-T 2m 2 Vitosol 300-T 3m 2 

300 L/79 gal. 4 5 3 

450 L/120 gal. 7 7 5 

200 L/53 gal. 

300 L/79 gal. 

450 L/120 gal. 

3 

4 

7 

4 

5 

7 

3 

3 

5 

5167 156 156 v3.1

5167 156 v3.1 

Sizing Pipe Diameters and Circulation Pump 

Solar heating system operating modes 

Volume flow in the collector array 

Generally, very low flow rates are 

required for Vitosol collectors. This 

results in small pipe and pump 

requirements. There are different 

operating modes, which depend on the 

total area of collectors installed, and 

piping requirements. 

At the same irradiation level, and 

consequently the same collector output, 

a higher flow rate means a lower 

temperature spread in the collector 

circuit; a lower flow rate means a 

higher temperature spread. With a high 

temperature spread, the average 

collector temperature increases, i.e the 

operating efficiency of the collector 

drops accordingly. Therefore, with 

lower flow rates the use of electrical 

energy (pump size) reduces and a 

smaller size connection pipe is possible. 

To safeguard a safe flow rate and a 

turbulent flow, Vitosol flat-plate 

collectors require a flow rate of at least 

15 liters/(h . m 2 ) . Vitosol tube collectors 

require at least 25 liters/(h . m 2 ). 

Generally, when setting the collector 

volume flow, the necessary volume 

flow of the connected heat exchanger 

should also be taken into account. 

1. High-flow mode 

For solar heating systems up to 

270º ft. 2 /25m 2 absorber surface 

area, we recommend the high flow 

operation. This reduces the temperature 

spread between supply and return. 

The higher flow rate requires a slightly 

larger pipework size, and larger pump 

sizes. 

In the high-flow operating mode, the 

pipes can be sized on the basis of a 

flowrate of 

H Vitosol 200-F: approx. 40 liters/h per 

m 2 absorber surface area (approx. 

0.18 gpm/m 2 absorber surface area). 

H Vitosol 300-T: 60 liters/h per m 2 

absorber surface area 

(0.27 gpm/m 2 absorber surface area). 

2. Low-flow mode 

For large solar installations (larger than 

270 ft. 2 /25m 2 absorber surface area), 

low flow mode operation can be used.. 

Advantages of the low-flow mode: 

H A high temperature level is reached 

quickly in the collector circuit. 

H The low flow rate in the collector 

circuit means that much smaller pipe 

sizes are required. 

H A smaller pump capacity is required 

resulting in lower electrical 

consumption. 

In the low-flow operating mode, the 

pipes can be sized on the basis of a 

flowrate of 

H Vitosol 200-F: approx. 15 liters/h per 

m 2 absorber surface area (approx. 

0.07 gpm/m 2 absorber surface area). 

H Vitosol 300-T: approx. 25 litrers/h per 

m 2 absorbed surface area (approx. 

0.11gpm/m 2 absorber surface area) . 

With both collector models, a uniform 

flow rate through all collectors is 

guaranteed if the Viessmann piping 

layout drawings are followed. To reduce 

the amount of installation work required 

for the piping, it is advisable to connect 

two rows of collectors with all piping 

connections on one side of the array. 

Pipe installation information 

To minimise the pressure drop through 

the piping of the solar heating systems, 

the flow velocity in the copper pipe 

should not exceed 3.5ft/s. We 

recommend flow velocities between 1.3 

and 2.3ft/s. At these flow velocities, 

pressure drops of between 1 and 2.5 

mbar/m pipe length occur. 

For the installation of the collectors, we 

recommend the use of commercial 

copper pipe and red bronze fittings or 

stainless steel pipe. The cross-sections 

should be sized as for a conventional 

heatingsystemonthebasisofflow 

rate and velocity (see the tables below). 


IMPORTANT 

Do not use galvanized pipes, galvanized 

fittings or graphitised gaskets. Hemp 

should be used only in conjunction with 

pressure and temperature-resistant 

sealant. 

IMPORTANT 

The components used must be resistant 

to the heat transfer medium (for 

composition, see the datasheet for the 

specific collector). 

IMPORTANT 

The thermal insulation of external piping 

must be resistant to temperature, UV 

radiation and to attack by birds or 

animals. 

Insulate internal ”hot” pipework 

according to current practice (fire 

protection, touch protection), e.g. using 

high-temperature resistant insulation, 

as offered by Armacell. 

31


Sizing Pipe Diameters and Circulation Pump (continued) 

Sizing pipe diameters (continued) 

Vitosol 200-F (high-flow operating mode), 40 liters/(h . m 2 ) or 0.18gpm/m 2 

Number of 

collectors 


Volume flow gpm 

liters/min 

Flow velocity ft./s 

m/s 

Pressure drop in the 

pipework 

32 

ft. of 

head/ft. 

mbar/m 

0.8 

3.1 

2 3 4 5 6 8 10 12 

1.2 

4.6 

1.6 

6.2 

Vitosol 300-T (high-flow operating mode), 60 liters/(h . m 2 ) or 0.3gpm/m 2 

Absorber 

surface area 


liters/min 


m/s 

Pressure drop 

in the 

pipework 

2.1 

7.8 

1.3 to 2.3 

0.4 to 0.7 

0.11 to 0.27 

1.0 to 2.5 

2.5 

9.3 

3.3 

12.4 

4.1 

15.5 

m 2 2 3 4 5 6 8 10 12 15 

ft. of 

head/ft. 

mbar/m 

0.53 

2 

0.8 

3 

1.1 

4 

1.3 

5 

Vitosol 200-F (low-flow operating mode), 15 liters/(h . m 2 ) or 0.07gpm/m 2 

Number of 

collectors 


Volume flow 


m/s 

Pressure drop in the 

pipework 

gpm 

liters/min 

ft. of 

head/ft. 

mbar/m 

0.3 

1.2 

1.6 

6 

1.3 to 2.3 

0.4 to 0.7 

0.11 to 0.27 

1.0 to 2.5 

2.1 

8 

2.6 

10 

3.2 

12 

4.9 

18.6 

2 3 4 5 6 8 10 12 

0.5 

1.8 

0.6 

2.3 

Vitosol 300-T (low-flow operating mode), 25 liters/(h . m 2 ) or 0.11gpm/m 2 

Absorber 

surface area 


liters/min 


m/s 

Pressure drop 

in the 

pipework 

0.8 

2.9 

0.7 to 1.3 

0.2 to 0.4 

0.11 to 0.27 

1.0 to 2.5 

m 2 2 3 4 5 6 8 10 12 15 

ft. of 

head/ft. 

mbar/m 

0.21 

0.8 

0.3 

1.2 

0.45 

1.7 

0.6 

2.1 

0.7 

2.5 

0.7 to 1.3 

0.2 to 0.4 

0.11 to 0.27 

1.0 to 2.5 

0.92 

3.5 

0.9 

3.3 

1.25 

4.7 

1.1 

4.2 

1.53 

5.8 

1.3 

5.0 

4.0 

15 

1.85 

7.0 

1.64 

6.2 

5167 156 v3.1

5167 156 v3.1 


Installation examples (hydraulic connection) 

Vitosol 200-F, type SV2/SH2 

High -flow operation 

Installation of collectors, connection on 

alternate sides, max. 12 

collectors. 

B 

Ø 28x1 

Low-flow operation 

max. 12 

Ø 28x1 

C 

A 

Installation of collectors, connection on 

alternate sides, max. 10 

collectors. 

B 

Ø 18x1 

max. 10 

Vitosol 300-T, type SP3 

Ø 18x1 

C 

A 

Installation on pitched roofs (max. 6 per 

array) 

Connection from the left (preferred 

option) 

C 

A 

B 

Ø 18x1 

Supply (hot) 

Return 

Air vent valve (shut-off type) 

Installation of collectors, single-sided 

connection, max. 10 collectors. 

max. 10 

C 

A 

Ø 28x1 

B 

Ø 28x1 

Installation of collectors, single-sided 

connection, max. 8 collectors. 

max. 8 

Connection from the right 

C 

A 

Ø 18x1 

B 

Ø 18x1 

C 

A 

B 

Ø 18x1 


Supply (hot) 

Return 


Supply (hot) 

Return 


33



Collector pressure drop information (relative to water, approx. 30% higher for Tyfocor HTL @ 40 º C) 

Vitosol 200-F, flat plate collector Vitosol 300-T vacuum tube collector 

model SV2 and SH2 

”w.c. mbar 

800 2000 

Pressure drop 

Calculating pressure drop 

The total pressure drop of the solar 

heating system consists of: 

H collector resistance values, 

H pipe resistance values, 

H individual resistance values of the 

fittings and 

H individual resistance values of the 

fittings and 

H resistance values of the heat 

exchanger in the DHW tank. 

34 

400 1000 

200 500 

160 400 

120 300 

80 200 

40 100 

20 50 

40 

12 30 

0.5 1 

0.3 

2 

0.5 

3 4 5 

0.8 1.11.3 

Waterflow 

l/min 

gpm 

Pressure drop 

“w.c. 

mbar 

80 200 

40 100 

32 80 

24 60 

20 50 

16 40 

12 30 

8 20 

4 10 

3.2 8 

2.4 6 

2 5 

1.6 4 

1.2 3 

0.8 2 

For calculation of total pressure drop 

H Collectors connected in series: 

Total pressure drop = sum of the 

individual resistance values 

H Collectors connected in parallel: 

Total pressure drop = individual 

pressure drop (assuming all individual 

resistance values are equal). 

1 

1 

0.3 

Waterflow 

1x2m 2 

1x3m 2 

2 x model 2m 2 

1 x model 2m 2 and 1 x model 3m 2 

2 x model 3m 2 

2 

3 

4 

0.5 0.8 1.1 

5 

1.3 

6 

1.6 

10 

2.6 

ltr/h 

GPM 

5167 156 v3.1

5167 156 v3.1 


Sizing the circulation pump 

If the flowrate and pressure drop of the 

entire system are known, the pump is 

selected on the basis of the pump 

characteristics. 

Variable-speed pumps which can be 

matched to the system by switching 

are the most suitable. 

To simplify the installation and selection 

of the pumps and safety equipment, 

Viessmann supplies the Solar-Divicon. 

The Solar-Divicon comprises 

H pre-assembled and sealed valves and 

safety assembly, 

H flow regulating valve with meter to 

control the solar heating system 

during commissioning and operation, 

H flow check valves, 

H system pump (2 sizes available), 

H pressure gage, 

H 2 thermometers, 

H 2 isolation valves, 

H pressure relief valve, 87 psig / 6 bar. 

A 

B 

C 

VL RL 

D 

A 

E 

Two models of Solar-Divicon are 

available: 

Model DN 20 

H up to 12 Vitosol 200-F collectors 

H up to 20 m 2 absorber surface area 

with Vitosol 300-T, 

Model DN 25 

H up to 18 Vitosol 200-F collectors 

H up to 30 m 2 absorber surface area 

with Vitosol 300-T. 

Final determination of which 

Solar-Divicon model to use must be 

based on system layout and pipe sizes 

used. 

1 Pressure relief valve, 87 psig/6 bar 

2 Expansion tank connection 

3 Pressure gage, 0-6 bar/0-87 psig 

4 Temperature gage c/w integrated 

shut-off valves and flow check 

valves 

5 Pump 

6 Flow meter 

7 Insulation door 

8 Flush and fill manifold 

9 Air separator (locked under 

insulation) 

VL Flow 

RL Return 

Shut-off valve 

Thermometer 

Non-return valve 

Solar circuit circulation pump 

Flow rate indicator 

The solar circuit pump line is constructed as the pump line of the Solar-Divicon. 


IMPORTANT 

The Solar-Divicon and the solar pump 

line are not suitable for direct contact 

with swimming pool water or potable 

water. 

IMPORTANT 

Always install Solar-Divicon at a lower 

height than the collectors to prevent 

steam from entering the expansion 

vessel in the event of stagnation. 

IMPORTANT 

For systems which are installed in the 

roof space or involve short pipe lengths, 

a preliminary vessel should be provided 

if necessary. 

35



Technical information on the Solar-Divicon 

Solar-Divicon Model DN 20 DN 25 

Circulation pump (Model: Wilo) STARS16U15 STARS21U25 

Rated voltage V AC 115 AC 115 

Maximum delivery GPM 16 16.7 

Maximum head ft. 20.7 21.1 

Flow meter (setting range) USG/min 0.5 to 5 1to10 

Flow meter (setting range) ltrs/min 1 to 20 5to40 

Pressure relief valve psig, 

bar 

Maximum operating temperature °F, 

°C 

Maximum operating pressure psig, 

bar 

Connections (Compression fittings Ø): 

Solar circuit 

Solar expansion tank 

Safety relief valve 

Characteristics 

36 

inches 

mm 

inches 

mm 

inches 

mm 

Pump model DN 20 Pump model DN 25 

87 

6 

248 

120 

87 

6 

1/2 

22 

3 /4 

22 

3 /4 

22 

87 

6 

248 

120 

87 

6 

3 /4 

22 

3 /4 

22 

3 /4 

22 

5167 156 v3.1

5167 156 v3.1 

Safety Equipment 

Liquid capacity of solar heating system components 

Vitosol 200-F, model SV2 

Vitosol 200-F, model SH2 

Vitosol 300-T, model 2m 2 

model 3m 2 

Solar-Divicon (pumping station for the 

collector circuit) 

USG 

liters 

USG 

liters 

USG 

liters 

USG 

liters 

USG 

liters 

Vitocell-B 100 Tank capacity USG 

liters 

Heating water capacity of bottom coil USG 

liters 

Vitocell-B 300 Tank capacity USG 

liters 

Heating water capacity of bottom coil USG 

liters 

Vitocell-V 300, Tank capacity 

(with indirect coil/s) 

USG 

liters 

Heating water capacity of coil USG 

liters 

53 

200 

3.2 

11.9 


Copper pipe, type M Dimension 3 /8” ½” ¾” 1” 1¼” 1½” 

Water content USG/ft. pipe 

0.0083 0.013 0.027 0.045 0.068 0.095 

79 

300 

2.6 

10 

79 

300 

2.9 

11 

79 

300 

2.9 

11 

0.48 

1.83 

0.65 

2.48 

0.32 

1.20 

0.47 

1.80 

0.08 

0.30 

120 

450 

3.3 

12.5 

79 

300 

3.9 

15 

120 

450 

4 

15 

37


Safety Equipment 

DHW 

F 

G 

Collector 

Safety valve 

Solar-Divicon 

Pre-cooling vessel (see below) 

Diaphragm expansion vessel 

Dual-mode DHW cylinder 

High limit safety cut-out (see 

page 41) 

Information regarding the heat transfer 

medium 

Heat transfer media containing glycol 

can be damaged, if they are subjected 

for long periods of temperatures above 

170ºC / 338ºF. This can lead to the 

system suffering from sludge and hard 

deposits, particularly in conjunction 

with other contaminants (flux and 

oxidized deposits). 

Therefore, after completing the 

installation, thoroughly flush out the 

system. After filling the system with 

process medium, ensure that heat is 

transferred inside the system, i.e. that 

38 

T 

RL Return 

VL Flow 

KW 

h Static height The solar heating system must be 

h 

D 

T 

C 

VL RL 

E 

A 

B 

longer periods of stagnation are 

prevented. System must be air-tight as 

glycol deterioration is always worse in 

presence of O2 molecules. Check the 

glycol every 2 years. 

Information regarding pre-cooling 

vessels 

Pre-cooling vessels or stratification 

cylinders in solar heating systems 

protect the diaphragm expansion vessel 

from over heating if stagnation occurs. 

The installation of such vessels is 

recommended if the content of the 

pipework between the collector array 

Content litres Number of collectors 

protected in respect to temperature, 

pressure and discharge of liquid in 

accordance with local regulations. 

The collector circuit must be protected 

in such a way that at the highest 

possible collector temperature (= idle 

temperature) no heat transfer medium 

can escape from the safety valve. 

This is achieved through the appropriate 

sizing of the expansion vessel and 

matching of the system pressure. 

For total pipework lengths shorter than 

10m/32ft, we recommend the 

installation of a pre-cooling vessel and 

diaphragm expansion vessel into the hot 

supply pipe and only the pressure relief 

valve into the return pipe. 

Information regarding stagnation 

System idle periods, e.g. due to defects 

or incorrect operation, can never be 

ruled out. For this reason solar heating 

systems must be protected according 

to the current technical standards 

against the potential difficulties which 

may arise from idle periods, i.e. 

systems cannot be damaged or cause 

damage if idle periods occur. Collectors 

and connection pipes are designed for 

the maximum expected temperatures in 

case of stagnation. Temperatures over 

170ºC / 338ºF have a detrimental 

effect on the process medium. When 

designing the collector array it should 

be ensured that the system can 

“breathe” properly (e.g. do not route 

solar pipes above the collector array). 

and the expansion vessel is lower than 

50% of the capacity of the correctly 

sized expansion vessel. The reference 

value is the total volume which 

evaporates in idle conditions. 

Sizing: 

Capacity of the correctly sized 

expansion vessel less the content of 

the return line between the collector 

array and the expansion vessel. 

Determining the capacity of the 

pre-cooling vessel: 

1.5 x collector content x number of 

collectors. 

Vitosol SV2 Vitosol SH2 Vitosol 300-T 2m2 Vitosol 300-T 3m2 12 4 3 6 4 5167 

156 v3.1

5167 156 v3.1 

Safety Equipment (continued) 

Diaphragm expansion tank 

A 

B 

Delivered 

condition 

(3 bar/45 psig 

pressure) 

Process medium 

Nitrogen filling 

A 

D 

C 

Solar heating 

system filled 

without 

heat effect 

Specification - Viessmann expansion tank 

A 

Øa B 

Øa 

Expansion 

tank 

A 18 

25 

40 

B 50 

80 

Content 

litres 

b 

Operating 

pressure 

bar 

10 

10 

10 

10 

10 

Ø a 

mm 

280 

280 

354 

409 

480 

A 

E 

C 

Under max. 

pressure at the 

highest process 

medium temperature 

Nitrogen buffer 

Safety water seal, min. 3l/0.8gal 

b 

b 

mm 

370 

490 

520 

505 

566 

Connection 

R 

¾” 

¾” 

¾” 

1 

1” 

Weight 

kg 

7.5 

9.1 

9.9 

12.3 

18.4 

B 50 10 409 505 1” 12.3 


Construction and operation 

A diaphragm expansion tank is a 

sealed expansion vessel whose gas 

space (nitrogen filling) is separated 

from the liquid space (heat transfer 

medium) by a diaphragm and whose 

inlet pressure is subject to the system 

height. 

To safely prevent steam being 

created during the operating stage, 

collectors must indicate a pressure of 

at least 15 psig / 1 bar in their cold 

state. 

The expansion tank inlet pressure is 

then higher by an amount of 

0.45 psig x static height (h) in ft. 

or 0.1 bar x static height (h) in m. 

In hot conditions, the system pressure 

rises by approx. 15 to 30 psig/1 to 

2bar. 

Maximum idle temperature of 

collectors: 

Vitosol 200-F, Models SV2, SH2 

Flat panel solar collector with 25 ft. 2 / 

2.3 m 2 collector area. 

Max. shutdown temperature 

430°F / 221°C 

Max. operating pressure 

87 psig /6 bar 

Vitosol 300-T, SP3 Series 

Vacuum tube solar collector with 22 

and 32 ft. 2 /2and3m 2 collector 

area. 

Max. shutdown temperature 

302°F / 150 °C 

Max. operating pressure 

87 psig /6 bar 

To ensure that no heat transfer 

medium can escape from the pressure 

relief valve, the expansion tank must 

be sufficiently large to accommodate 

the liquid content of the collector 

when steam forms (stagnation). 

IMPORTANT 

The cold fill inlet pressure (gas space) 

must be adjusted on site as follows: 

15 psig + 0.45 psig x static height in 

ft 

1 bar + 0.1 bar x static height in m 

The system operating pressure must 

be 4.5 to 7.5 psig/0.3 to 0.5 bar 

higher than the inlet pressure of the 

diaphragm expansion tank. The 

waterseal should be 0.005x the total 

liquid content of the system but not 

less than 3 liters. 

39



Technical data for the expansion tank (continued) 

The nominal capacity of the expansion 

vessel is calculated according to the 

equation 

VN = (Vv + V2 + z ⋅ Vk ) ⋅ (pe + 1) 

pe − pst Whereby 

VN= nominal capacity of the 

diaphragm expansion tank 

in liters 

Vv = safety water seal (here heat 

transfer medium) in litres 

Vv = 0.005 · VA in litres 

(min. 3 litres) 

VA= liquid capacity of the entire 

system (see page 42). 

pst = nitrogen inlet pressure of 

expansion vessel in bar 

pst =1 bar + 0.1 · h 

h =static head of the system in 

m (see drawing on page NO TAG) 

z = number of collectors 

Vk = collector capacity in litres 

(see page 37). 

V2 = volume increase when the 

system heats up 

V2 = VA · β 

b =expansion quotient ( β=0.13 

for Viessmann heat transfer 

medium from –20 to 120ºC) 

pe = permissible end pressure in bar 

pe =psi –0.1·psi 

psi =safety valve blow off 

pressure 

40 

WARNING 

Do not use expansion tanks that are 

not designed for solar heating 

systems. Temperatures during 

stagnation periods can reach 

extremely high levels, which could 

result in serious injuries from hot 

system fluid discharging from 

pressure relief valve. 

WARNING 

Do not undersize expansion tank. 

Calculation example 

Solar heating system with: 

2 Vitosol 200-F, type SV2 @ 1.83 litres 

Liquid capacity: VA = 25 litres 

Static head: h = 5 m 

Permissible final pressure: pe =5.4bar 

(ü) 

(Safety valve blow off pressure: 6 bar) 

VN = (Vv + V2 + z ⋅ Vk ) ⋅ (pe + 1) 

pe − pst Vv =VA · 0.005 

Vv =0.125 litres, selected 3 litres 

(see previoys page). 

V2 =VA ·b 

V2 =3.25 litres 

pst =1.5 bar + 0.1 bar/m · 5 m 

pst =2.0 bar 

(3 + 3.25 + 2 ⋅ 1.83) ⋅ (5.4 + 1) 

VN = 

5.4 − 1.5 

VN =16.3 litres 

Due to the possibility of steam 

collecting in the solar circuit pipe, we 

recommend multiplying the calculated 

value VN by a safety factor of 1.5. 

Select a 25 liter expansion vessel. 

Selection table for expansion tanks, 

subject to collector model (in 

conjunction with a 6 bar safety valve) 

These details provide only guide values; 

a final calculation must be carried out. 

Vitosol 200-F, model SV2 

Number of 

collectors 

System 

capacity 

VA 

liters 

Static 

head 

h(m) 

2 20 5 25 

10 

3 25 5 25 

10 40 

4 32 5 40 

10 

5 35 5 40 

10 50 

Vitosol 200-F, model SH2 

Number of 

collectors 


capacity 

VA 

liters 

Static 

head 

h 

m 

2 20 5 25 

10 40 

3 30 5 40 

10 

4 35 5 40 

10 50 

5 40 5 50 

10 80 

Vitosol 300-T 

Absorber 

surface 

area 

m 2 


capacity 

VA 

liters 

Static 

head 

h(m) 

3 16 5 18 

10 

4 18 5 18 

10 

5 23 5 18 

10 25 

6 25 5 25 

10 

9 35 5 40 

10 

Expansion 

tank 

capacity 

liters 

Expansion 

tank 

capacity 

liters 

Expansion 

tank 

capacity 

liters 

5167 156 v3.1

5167 156 v3.1 


Pressure relief valve 

High limit safety cut-out 

The operating pressure of the pressure 

relief valve is the maximum system 

pressure +10 %. 

The pressure relief valve must comply 

with all local codes. 

The pressure relief valve must be 

matched to the output of the collector 

or the collector assembly and be able to 

handle their maximum output of 

900w/m 2 . 

The Vitosolic 200 solar control unit is 

equipped with an electronic limit 

thermostat which is preset in the 

factory to 167ºF / 75ºC and can be 

adjusted. 

For systems with a sufficiently large 

DHW capacity, this protection is 

adequate, as the maximum operating 

temperature does not exceed 23ºF / 

11ºC. 

An additional mechanical high limit 

safety cut-out is required, if the DHW 

tank capacity is less than 40 liters/m 2 

collector surface area. 


IMPORTANT 

When use is made of water containing 

antifreeze or synthetic heat transfer 

media which are miscible with water 

(e.g. Viessmann heat transfer medium) 

and whose boiling point is higher than 

that of water, the blow off and 

discharge pipes must be run to an open 

container capable of accommodating 

the total capacity of the collectors. 

Use only pressure relief valves designed 

for a maximum of 87 psig / 6 bar and 

248ºF / 120ºC bearing the markings 

”S” (solar) as part of the product 

identification. 

IMPORTANT 

Solar-Divicon is equipped with a pressure 

relief valve for max. 87 psig / 6 bar and 

248ºF / 120ºC. 

Example: 

Vitosol 200-F flat collector x 4=, 

approx. 7 m 2 absorber surface area 

DHW cylinder with 300 litres capacity 

300 

7.5 = 40 litres/m2 , 

e.g. no high limit safety cut-out 

required. 

41



Thermostatic mixing valve 

42 

DHW 

WARNING 

DCW 

The domestic hot water temperature 

must be limited to 140 °F / 60 °C by 

installing a mixing device, e.g. a 

thermostatic anti-scald mixing valve. 

Solar storage tank 

Thermostatic anti-scald mixing 

valve 

A thermostatic mixing valve is required 

for all solar systems to prevent 

domestic hot water temperatures higher 

than 140 ºF / 60 ºC (local codes may 

require different temperature settings). 

Install an anti-scald mixing valve 

designed for potable domestic hot 

water systems. 

5167 156 v3.1

5167 156 v3.1 

Accessories 

Threaded elbow 

For the installation of the DHW tank 

temperature sensor into the tank return. 

Comes as standard equipment with 

Vitocell-B 100 tanks and is an 

accessory with Vitocell-B 300 tanks. 

Air separator 

22 

40 

R1” 

160 (220) 

111 

. 

290 

22 

approx. 225 

38 

For installation in the supply pipe of the 

solar circuit, preferably upstream of the 

inlet to the DHW tank. 

With automatic air-vent valve, shut-off 

valve and locking ring connection. 

This is not required if a Solar Divicon 

modelDN20orDN25isused. 

Quick-acting air-vent valve (with tee) 

approx. 166 

For installation at the highest point of 

the system. 

With shut-off valve and locking ring 

connection. 

Flexible connection pipe 

22 

22 

65 

1000 

22 

Stainless steel corrugated pipe with 

thermal insulation and compression 

fitting connection. 

Comes with thermal insulation. Set of 2 

per package. 


Solar manual filling pump 

R ½” 

220 

15 

For replenishing and raising the 

pressure. 

43

System Designs 

General Information 

How to implement the installation 

44 

WARNING 

With temperatures over 140°F / 

60°C, the DHW temperature must be 

limited to 140°F / 60°C by installing 

a mixing device, e.g. a thermostatic 

mixing valve (DHW tank accessory). 

For our climatic zone: dual systems 

In our climatic zone, solar radiation is 

insufficient to cover the entire 

requirements for domestic hot water or 

swimming pool heating as well as space 

heating by means of solar energy. 

Therefore, a solar heating system for 

DHW or swimming pool water heating 

and/or central heating should always be 

combined with another heat generator. 

In dual systems, for example, an oil or 

gas-fired boiler supplies the additional 

heat required. 

Over the following pages, we have 

described methods of operation and 

used design suggestions to illustrate 

various installation ideas involving 

different equipment specifications. A 

summary is provided which lists 

essential control equipment. 

The temperatures stated are guide 

values; other values may be set to meet 

particular requirements. 

The circulation pumps referred to in 

these examples (standard delivery with 

Solar-Divicon) are AC pumps. 

DHW tank backup by the boiler is 

suppressed by the Vitosolic, when the 

anticipated heat requirement for DHW 

heating is expected to be covered by 

the solar heating system. This may 

require the use of the optional 

expansion boards. 

When connection between the Vitosolic 

and the boiler control (Vitodens 

programming unit, Vitotronic 300 or 

Dekamatik) is made via the KM-BUS, 

the setpoint temperature for boiler 

backup of DHW is reduced, stopping 

the boiler from coming on. 

Abbreviations used in the examples: 

DCW Domestic cold water 

DHW Domestic hot water 

R Return 

S Supply 

5167 156 v3.1

5167 156 v3.1 

System Design 1 

Dual-mode DHW heating with Vitocell-B100 or Vitocell-B 300 DHW tanks 

- with Vitosolic 200 or GL 30 control 

DHW heating without solar energy 

The top part of the DHW tank is heated 

by the boiler. 

The DHW tank temperature sensor 

of the boiler control unit switches tank 

heating circulation pump . 

Installation diagram 

F 

C 

DHW 

28 E 

5 

21 

6 

7 

5 

G H 


Solar-Divicon 

Taps 

*1 High limit safety cut-out, see page 41. 

DHW heating with solar energy 

When a temperature difference higher 

than the value set in control unit is 

measured between collector 

temperature sensor and tank 

temperature sensor , solar circuit 

circulation pump is switched ON 

and the DHW tank is heated up. 

The temperature in the DHW tank is 

limited by the electronic limit 

thermostat in control unit or by 

high limit safety cut-out (if 

required). 

D 

3 

1 

2 

DHW circulation 

DHW circulation output of the boiler 

control unit or timer installed on site 

B 

4 

S R 


When the preset temperature is 

exceeded, these devices switch OFF 

solar circuit circulation pump .The 

electronic temperature limit is set at the 

factory. 

A 

DCW 

Heating circuit 

Oil/gas-fired boiler 

DHW cylinder 

45


System Design 1 (continued) 

Dual-mode DHW heating with Vitocell-B100 or Vitocell-B 300 DHW tanks 

- with Vitosolic 200 or GL 30 control (continued) 

Control equipment required 

Item Description 

Control of DHW cylinder loading by solar energy 

Number Part no. 

1 Vitosolic 200 

or 

1 7134 552 

GL 30 control 

7134 450 

2 Collector temperature sensor 1 Included in 

standard 

equipment for 

item 1 

3 DHW tank temperature sensor *1 1 Included in 

standard 

equipment for 

item 1 

4 Solar circuit circulation pump 

1 7133 454 

(standard equipment of Solar-Divicon, see page 35) 

or 

7133 455 

5 High limit safety cut-out (see page 41) *2 Control of DHW tank loading by the boiler 

1 Supplied on site 

6 DHW tank temperature sensor 1 Included in 

standard 

equipmentofboiler 

control unit *2 

7 Circulation pump for DHW tank loading 1 DHW tank 

accessory 

*1 Installation requires a threaded elbow (standard delivery for Vitocell-B 100, accessory for Vitocell-B 300 ). 

*2 Accessory with Vitodens. 

46 

WARNING 





5167 156 v3.1

5167 156 v3.1 


Dual-mode DHW heating and space heating backup with heating water storage tank 

- with Vitosolic 200 


The upper indirect coil of the DHW tank 

is heated by a boiler. The DHW tank 

temperature sensor of the boiler 

control unit switches circulation pump 

to heat up the DHW tank. 


Solar circuit circulation pump is 

switched ON and the DHW is heated 

up, when a temperature difference 

higher than the value set in control unit 

is measured between collector 

temperature sensor and DHW 

temperature sensor . 

The temperature in the DHW is limited 

by the electronic limit thermostat in 

control unit or by high limit safety 

cut-out (if required). 



solar circuit circulation pump . 

The electronic temperature limit is set 

at the factory. 

Space heating without solar energy 

Diverter valve remains at zero volts 

(setting ”AB-B”), if the differential 

temperature between heating water 

storage tank temperature sensor 

(discharge) and space heating return 

temperature sensor falls below the 

value set at control unit .Noflow 

through the heating water storage tank 

takes place. 

The boiler provides heat to the heating 

circuit according to the heating curve 

set at the boiler control unit. 


Space heating with solar energy 

Heating water storage tank circuit 

circulation pump and circulation 

pump for storage tank heating are 

switched ON and the heating water 

storage tank is heated up, when a 

temperature difference higher than the 

differential temperature preset in 

control unit is measured between 

collector temperature sensor and 


(re-loading) . The temperature inside 

the heating water storage tank will be 


thermostat in control unit . 


exceeded, this device switches the 

storage tank circuit circulation pump 

and OFF. 

Circulation pump is switched OFF 

for approx. 2 minutes, roughly every 

15 minutes (adjustable time), to check 

whether the temperature at the 

collector temperature sensor is high 

enough to change over to DHW tank 

loading. 

Control unit switches diverter valve 

to position ”AB-A” and the space 

heating return water will be channelled 

into the boiler via the storage tank, if 

the temperature differential between 


(discharge) and space heating return 

temperature sensor exceeds that set 

at control unit . If the temperature of 

the pre-heated return water is 

insufficient, the boiler re-heats the 

water to the necessary flow 

temperature level. 

47




Refer to Viessmann sample layout drawing #5 for 

alternate layout. (contact Viessmann sales rep. for 

details) 

48 

qP 

qQ G 


Solar-Divicon 

Solar pump line 

Taps 

qR 

qT 

9 


A 

qW 

AB 

B 

D 

H 

DHW 

5 

21 

6 

7 

K 

5 

1 




3 

2 

B 

4 

S R 

DCW 

qE 

Heating water storage tank 


DHW tank 

A 

C 

5167 156 v3.1

5167 156 v3.1 


Dual-mode DHW heating and space heating backup with heating water storage tank 

- with Vitosolic 200 (continued) 



Item Description Number Part no. 

Control of DHW tank loading by solar energy 

1 Vitosolic 200 1 7134 450 


standard 

equipment for 

item 1 


standard 

equipment for 



item 1 

1 7133 454 

or 

7133 455 

5 High limit safety cut-out (see also page 41) 1 Supplied on site 

8 Circulation pump (relayering) 

Control of DHW tank loading by the boiler 



standard 

equipment of the 

boiler control unit 

7 Circulation pump for DHW tank loading 

Space heating control with solar energy 

1 DHW tank 

accessory 

9 Return temperature sensor (heating circuit) 1 7170 965 

qP Temperature sensor (storage tank), discharge 1 7170 965 

qQ Temperature sensor (storage tank, re-loading) 1 Included in 

standard 

equipment for 

item 1 

qW Three-way diverter valve 1 Supplied on site 

qE Solar circuit circulation pump for storage tank heating 

(part of the solar pump line, see page 35) 


qR Circulation pump for storage tank heating 1 Supplied on site 

qT Heat exchanger 1 Supplied on site 

*1A threaded elbow (standard delivery for Vitocell-B 100, accessory for Vitocell-B 300 ) is recommended for this installation. 

Note: 

Heating water storage tank , circulation pump for storage tank and heat exchanger can all be replaced with an 

indirect-fired storage tank, c/w internal heat exchanger coil (e.g. Vitocell-V 100). 

WARNING 





49



Dual-mode DHW heating with two DHW tanks 


50 


DHW tank 2 is heated by the boiler. The 

DHW tank thermostat with connected 

tank temperature sensor of the 

boiler control unit switches circulation 

pump to heat up the DHW tank. 

DHW circulation pump 8b (if installed) 

is switched ON and circulation pump 

8a is switched OFF, so that the DHW 

circulation only affects DHW tank . 


Solar circuit circulation pump is 

switched ON and DHW tank 1 is heated 

up, when a temperature difference 

higher than the value set in control unit 

is measured between collector 

temperature sensor and tank 

temperature sensor . 

The temperature in DHW tank 1 is 




required). 


exceeded, this device switches OFF 



factory. 

Circulation pump 8a is switched ON, 

when the temperature at sensor in 

DHW tank 1 exceeds that at sensor 

in DHW tank 2. 

The DHW circulation covers both DHW 

tanks. This feeds the water heated in 

DHW tank 1 into DHW tank 2. This 

way, DHW tank 2 is also heated by 

solar energy. 

DHW circulation pump 8b (if installed) 

for DHW tank 2 is controlled by the 

boiler control unit. 

Circulation pump 8a will be switched 

OFF if the temperature in DHW tank 2 

rises above that in DHW tank 1. 

WARNING 





5167 156 v3.1

5167 156 v3.1 


Installation diagram (system with two DHW cylinders with indirect coils) 

F 

E 28 


Solar-Divicon 

Taps 


C 


5 

21 

DCW 

7 

DHW 

D 

8b 

2 1 

G H K 

8a 

6 

qP 

1 

5 

9 




3 

2 

B 

4 

S R 


DHW tank 2 

DHW tank 1 


A 

DCW 

51



Dual-mode DHW heating with two DHW tanks 



Item Description 

Control of DHW tank 1 loading by solar energy 

Number Part no. 

1 Vitosolic 200 1 7134 552 


standard 

equipment for 

item 1 


standard 

equipment for 

item 1 


1 7133 454 


or 

7133 455 


6 

Control of DHW tank 2 loading by the boiler 

DHW tank temperature sensor 1 Included in 

standard 

equipmentofboiler 

control unit *2 

7 Circulation pump for DHW tank loading *3 1 Accessories 

DHW tank 

8 

DHW circulation changeover 

DHW circulation pump or circulation pump (relayering) 1 Supplied on site 

9 Temperature sensor tank 1 1 Included in 

standard 

equipment for 

item 1 

qP Temperature sensor tank 2 1 7170 965 

*1 The screw-in elbow which is available as an accessory for the DHW cylinder is recommended for installation purposes. 

*2 Accessory with Vitodens. 

*3 Part of the standard delivery with Vitodens (for types with DHW heating). 

52 

WARNING 





5167 156 v3.1

5167 156 v3.1 


Dual-mode DHW and swimming pool water heating 



The top part of the DHW tank is heated 

by the boiler. 

The DHW tank temperature sensor 

of the boiler control unit switches tank 

heating circulation pump . 


Solar circuit circulation pump for DHW 

heating is switched ON and the 

DHW tank is heated up, when a 

temperature difference higher than the 

value set in control unit is measured 

between collector temperature sensor 

and DHW tank temperature 

sensor . 


heating is switched OFF, and solar 

circuit circulation pump for swimming 

pool heating is switched ON (see 

”Swimming pool water heating”), if the 

temperature at DHW tank temperature 

sensor is so high that the actual 

temperature difference falls below the 

set differential temperature. 

The temperature in the DHW tank is 




required). 





factory. 


Swimming pool water heating 


heating is switched OFF, and solar 

circuit circulation pump for 

swimming pool heating is switched ON, 

if the temperature at DHW tank 

temperature sensor is so high, that 

the temperature difference falls below 

the set differential temperature for 

DHW heating. 

The temperature at collector 

temperature sensor must then be 

higher by the temperature difference for 

swimming pool water heating set in 

control unit than the temperature at 

temperature sensor (swimming pool) 

. 

Swimming pool water limit thermostat 

(max. limit) switches circulation 

pump OFF when the desired set 

water temperature has been reached. 

Circulation pump is switched OFF 

for approx. 2 minutes roughly every 

15 minutes (adjustable time), to check 

whether the temperature at the 

collector temperature sensor is high 

enough to change over to DHW tank 

loading. 

When the solar energy is insufficient to 

heat the swimming pool water, the 

heating of the swimming pool water will 

be taken over by the oil/gas-fired boiler 

via temperature sensor in heat 

exchanger 2. 

The filter time and any boiler backup 

should fall outside those times when 

heating by solar energy can be 

expected. 

53




54 

G 

D 

F 28 

L 


Solar-Divicon 

Solar pump line 

Taps 



5 

21 

DHW 

6 

7 

H K 

qT 

qR 

5 

E 

3 

8 

DCW 

1 

M qE qQ N 

2 1 

O 

2 





Dual-mode DHW tank 

B C 

4 

S R 

9 

A 

qP 

Swimming pool 

Heat exchanger 2 

Heat exchanger 1 

Filter system with pump 

5167 156 v3.1

5167 156 v3.1 


Dual-mode DHW and swimming pool water heating 




Item Description Number Part no. 

Control of DHW tank loading by solar energy 

1 Vitosolic 200 1 7134 552 


standard 

equipment for 

item 1 


standard 

equipment for 

4 Circulation pump for the solar circuit 


item 1 

1 7133 454 

or 

7133 455 


8 Circulation pump 1 Supplied on site 

Control of DHW tank loading by the boiler 


standard 

equipment of the 

boiler control unit 

7 Circulation pump for DHW tank loading 1 DHW tank 

accessory 

9 

Control of swimming pool heating by solar energy 

Temperature sensor (swimming pool) 1 Included in 

standard 

equipment for 

item 1 

qP Solar circuit circulation pump for swimming pool heating 

(part of the solar pump line, see page 35) 


qQ Swimming pool limit thermostat (max. limit) 

Control of swimming pool heating by the boiler 


qE Temperature sensor (heat exchanger 2) 1 7170 965 

qR Limit thermostat (max. limit) 1 Supplied on site 

qT Circulation pump for swimming pool water heating 1 Supplied on site 

*1A threaded elbow (standard delivery for Vitocell-B 100, accessory for Vitocell-B 300) is recommended for this installation. 

WARNING 





55


System Design Extensions 

Bypass circuit 

To improve the start-up characteristics 

of the system or for systems with 

several collector arrays, operation with 

a bypass circuit is feasible. 

Version 1 - bypass circuit with collector temperature sensor and bypass sensor 

The Vitosolic 200 records the collector 

temperature via the collector 

temperature sensor. If the set 

temperature difference between the 

collector temperature sensor and the 

S3 

56 

VL 

S1 

R5 

R1 

RL 

cylinder sensor is exceeded, the bypass 

pump is switched ON. 

If the temperature difference between 

the bypass sensor and the cylinder 

R1 Solar circuit pump 

R3 Bypass pump 

S1 Collector temperature sensor 

S3 Bypass sensor 

Version 2 - bypass circuit with solar cell (e.g. with an external heat exchanger) 

For this system version, the solar circuit 

pump takes on this additional function. 

The Vitosolic 200 records the solar 

intensity via the solar cell. 

CS 

S1 

VL 

R1 

RL 

The solar circuit pump will be switched 

ON, if the set irradiation threshold is 

exceeded. 

CS Solar cell 



temperature sensor is exceeded by 2.5 

K the solar circuit pump is switched ON 

and the bypass pump is switched OFF. 

Note 

The pump of the Solar-Divicon is used 

as the bypass pump and the pump of 

the solar circuit pump line is used as 

the solar circuit pump. 

The pump will be switched OFF, if the 

irradiation falls below the set switching 

threshold (shutdown delay approx. 

2min). 

5167 156 v3.1

5167 156 v3.1 

System Design Extensions (continued) 

System with energy-saving mode 

Version 3 - bypass circuit with solar cell and collector temperature sensor 

The Vitosolic 200 records the solar 

intensity via the solar cell. 

If the set irradiation threshold is 

exceeded, the bypass pump is switched 

ON. The bypass pump is switched OFF 

CS 

S1 

VL 

R5 

R1 

RL 

and the solar circuit pump will be 

switched ON, if the set temperature 

difference between the collector 

temperature sensor and cylinder 

temperature sensor is exceeded. 

CS Solar cell 


R5 Bypass pump 



The bypass pump will also be switched 

OFF if the irradiation falls below the set 

switching threshold (shutdown delay 

approx. 2.5 min). 

Note 

The pump of the Solar-Divicon is used 

as the bypass pump and the pump of 

the solar circuit pump line is used as 

the solar circuit pump. 

57

Appendix 

Calculation Example Based on the Viessmann “ESOP” Program 

Solar heating system with dual-coil DHW tank 

11 kW 

58 


45 °C 

300 litres 

2 x Vitosol 200-F 

Azimuth: 0° 

Inclination: 45° 

Results of simulation over a one-year period 

DHW solar fraction 59.8 % 

System efficiency 36.2 % 

Heat yield of collector circuit 2 214 kWh 

Irradiation on reference surface 6.12 MWh 

Heat requirement for DHW heating 2 975 kWh 

Natural gas savings 274 m 3 

CO2 emissions avoided 520 kg 

5167 156 v3.1

5167 156 v3.1 

Calculation Example Based on the Viessmann “ESOP” Program (continued) 

Solar heating system with dual-coil DHW tank (continued) 

Coverage 59.8% 

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

Period: 1.1. – 31.12. 

System parameters 

Collector circuit details 

2 collectors Model: Vitosol 200-F 

Total surface area, gross: 5.42 m 2 Net: 4.99 m 2 

Angle of inclination: 45º Azimuth: 0º 

DHW cylinder with two indirect coils 

Capacity: 300 l Model: Vitocell-B 100 (300 litres) 

DHW consumer 

Type: Detached house 200 l per day at 45 ºC set temperature, 365 days 

Cold water 

February: 8 ºC August: 12 ºC 

Weather statistics 

A location at 49º latitude Total annual global radiation: 1101.08 kWh/m 2 

Appendix 

59

Appendix 

Glossary 

Absorber 

Device contained inside a solar collector 

for absorbing radiation energy and 

transferring this as heat to a liquid. 

Absorption 

Absorption of radiation. 

Condenser 

Device in which vapour is precipitated 

as liquid. 

Convection 

Transfer of heat by a flowing medium. 

Convection creates energy losses 

caused by a difference in temperature, 

e.g. between the glass plate of the 

collector and the hot absorber. 

Dispersion 

Interaction of radiation with matter by 

which the radiation direction is altered; 

total energy and wavelength remain 

unchanged. 

Efficiency 

The efficiency of a solar collector is the 

input/output ratio of the collector. 

Relevant variables are, for example, the 

ambient and absorber temperatures. 

Emission 

Radiation of beams, e.g. light or 

particles. 

Evacuation 

Evacuating air from a container. This 

reduces the air pressure and creates a 

vacuum. 

60 

Heat loss coefficients k1 and k2 

k1 is the constant component of the 

heat loss of a collector and is usually 

designated as k value (unit: W/(m 2 · K)). 

k2 is the quadratic component of the 

temperature-dependent heat loss 

(unit: W/(m 2 ·K 2 )). 

Any informative statement about the 

heat losses of a collector requires both 

values to be quoted. 

Heat pipe 

Closed, capillary container which 

contains a small quantity of highly 

volatile liquid. 

Heat transfer medium 

Fluid which picks up the useful heat in 

the absorber of the collector and 

transfers it to a user (heat exchanger). 

Photovoltaic effect 

Gaining electrical energy from solar 

energy. 

Radiation energy 

Quantity of energy transmitted by 

radiation. 

Radiation level (irradiation) 

Radiation power, impacting per unit 

surface, expressed in W/m 2 ,or 

Btu/h/ft. 2 . 

Selective surface 

The absorber in the solar collector has 

been given a highly selective coating to 

improve its efficiency. This specially 

applied coating enables the absorption 

to be maintained at a very high level for 

the incident sunlight spectrum 

(approx.94 %). The emission of the 

long-wave heat radiation is largely 

avoided. 

The high-selectivity black chromium 

coating is very durable. 

Stagnation 

Condition of a collector when no heat is 

being conducted away by the heat 

transfer medium. 

Vacuum 

A space devoid of air. 

5167 156 v3.1

5167 156 v3.1 

61

62 

5167 156 v3.1

5167 156 v3.1 

63

Viessmann Manufacturing Company (U.S.) Inc. 

45 Access Road 

Warwick, Rhode Island • 02886 • USA 

Tel. (401) 732-0667 • Fax (401) 732-0590 

www.viessmann-us.com • info@viessmann-us.com 

64 

Viessmann Manufacturing Company Inc. 

750 McMurray Road 

Waterloo, Ontario • N2V 2G5 • Canada 

Tel. (519) 885-6300 • Fax (519) 885-0887 

www.viessmann.ca • info@viessmann.ca 

5167 156 v3.1 Technical information subject to change without notice. 

Printed on environmentally friendly 

(recycled and recyclable) paper.

System Design Guidelines - Viessmann

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