STIEBEL ELTRON Engineering and | Heat Pumps Technical Guide

Engineeringandinstallation2017|STIEBELELTRON

DHW Renewables Air conditioning Roomheating

Engineering and installation

Heatpumps

2017

295966

D0000013700-k

STIEBEL ELTRON GmbH & Co. KG | Dr.-Stiebel-Strasse 33

37603 Holzminden | www.stiebel-eltron.de

CONTACT ______________________________________________________

TELEPHONE ____________________________________________________________________

FAX _____________________________________________________________________

YOUR CUSTOMER NUMBER __________________________________________________

(IF APPLICABLE)

DATANORMDOWNLOADFROMTHEINTERNET.

On our website www.stiebel-eltron.de

you will find our standard "DATANORM" forms (ver-

sion 4.0) in section "Fachpartner-Bereich" under the

heading "Produktdaten" as a service for our trade

partners.

FAXREQUEST

Please send us the

DATANORM data set by email:

STIEBEL ELTRON GmbH & Co. KG

Datenservice, Martin Schultze

Dr.-Stiebel-Strasse 33

D-37603 Holzminden

Tel. 05531 702-95139

Fax +49 (0)5531 702-95108

DATANORM 4.0

To work with the tender documentation,

you require a text program capable of handling

DATANORM.

COMPANY ADDRESS (STAMP):

Engineering and installation

Reprinting or duplication, even partially, is only allowed with our express permission.

STIEBEL ELTRON GmbH & Co. KG, 37603 Holzminden

Legal note

Although we have tried to make this technical guide as accurate as possible, we are not liable for any inaccuracies in

its content. Information concerning equipment levels and speciﬁ cations are subject to modiﬁ cation. The equipment

features described in this technical guide are non-binding regarding the speciﬁ cation of the ﬁ nal product. Due to our

policy of continually improving our products, some features may have subsequently been changed or even removed.

Please consult your local dealer for information about the very latest equipment features. The images in this technical

guide are for reference only. The illustrations also contain installation components, accessories and special equip-

ment that do not form part of the standard delivery.

Speciﬁ cation

Dimensions in the diagrams are in millimetres unless stated otherwise. Pressure ﬁ gures may be stated in pascals

(MPa, hPa, kPa) or in bars (bar, mbar). The details of threaded connections are given in accordance with ISO228. Fuse

types and sizes are stated in accordance with VDE. Output details apply to new appliances with clean heat exchang-

ers.

www.stiebel-eltron.com TechnicalGuideforheatpumps| 3

Tableofcontents

CONTACT ______________________________________________________

TELEPHONE ____________________________________________________________________

FAX _____________________________________________________________________

YOUR CUSTOMER NUMBER __________________________________________________

(IF APPLICABLE)

DATANORMDOWNLOADFROMTHEINTERNET.

On our website www.stiebel-eltron.de

you will find our standard "DATANORM" forms (ver-

sion 4.0) in section "Fachpartner-Bereich" under the

heading "Produktdaten" as a service for our trade

partners.

FAXREQUEST

Please send us the

DATANORM data set by email:

STIEBEL ELTRON GmbH & Co. KG

Datenservice, Martin Schultze

Dr.-Stiebel-Strasse 33

D-37603 Holzminden

Tel. 05531 702-95139

Fax +49 (0)5531 702-95108

DATANORM 4.0

To work with the tender documentation,

you require a text program capable of handling

DATANORM.

COMPANY ADDRESS (STAMP):

Engineering and installation

Reprinting or duplication, even partially, is only allowed with our express permission.

STIEBEL ELTRON GmbH & Co. KG, 37603 Holzminden

Legal note

Although we have tried to make this technical guide as accurate as possible, we are not liable for any inaccuracies in

its content. Information concerning equipment levels and speciﬁ cations are subject to modiﬁ cation. The equipment

features described in this technical guide are non-binding regarding the speciﬁ cation of the ﬁ nal product. Due to our

policy of continually improving our products, some features may have subsequently been changed or even removed.

Please consult your local dealer for information about the very latest equipment features. The images in this technical

guide are for reference only. The illustrations also contain installation components, accessories and special equip-

ment that do not form part of the standard delivery.

Speciﬁ cation

Dimensions in the diagrams are in millimetres unless stated otherwise. Pressure ﬁ gures may be stated in pascals

(MPa, hPa, kPa) or in bars (bar, mbar). The details of threaded connections are given in accordance with ISO228. Fuse

types and sizes are stated in accordance with VDE. Output details apply to new appliances with clean heat exchang-

ers.

4 |TechnicalGuideforheatpumps www.stiebel-eltron.com

Tableofcontents

Technicalguideforheatpumps

STIEBEL ELTRON ____________________________________________________ 8

STIEBEL ELTRON is full of energy! _____________________________________________________8

Introduction ________________________________________________________ 10

Introduction _______________________________________________________________________________ 10

Heat pumps protect our energy reserves __________________________________________ 10

Heat pump function ____________________________________________________________________ 11

Energy sources ____________________________________________________________________________12

Heat source: air _________________________________________________________________________ 12

Geothermal heat as the source of thermal energy _______________________________ 13

Operating modes _________________________________________________________________________14

Mono mode / dual mode parallel / mono energetic _____________________________ 14

Dual mode alternative / dual mode partial parallel _____________________________ 15

Renewable Energies Heat Act|EEWärmeG____________________________________________16

Requirements ___________________________________________________________________________ 16

Calculation of the seasonal performance factor _______________________________________17

VDI 4650Part 1 __________________________________________________________________________ 17

DHW heating ______________________________________________________________________________ 18

Calculation of the seasonal performance factor __________________________________ 18

Correction factors_________________________________________________________________________19

Outdoor air, source pump_____________________________________________________________ 20

Overview of seasonal performance factors ____________________________________________21

Air|water heat pumps ________________________________________________________________ 21

Brine|water heat pumps _____________________________________________________________ 22

Water|water heat pumps ____________________________________________________________ 23

System design ____________________________________________________________________________24

General design information __________________________________________________________ 24

Terminology and descriptions ________________________________________________________ 25

Summary of formulae _________________________________________________________________ 27

Regulations, guidelines and directives _____________________________________________ 28

Heat load calculation __________________________________________________________________ 30

Flow temperature ______________________________________________________________________ 31

Heat pump sizing _______________________________________________________________________ 32

Sizing example __________________________________________________________________________ 33

Inverter heat pump sizing ____________________________________________________________ 34

Power supply and tariffs ______________________________________________________________ 35

Heating water quality __________________________________________________________________ 36

Cost calculation to VDI2067 __________________________________________________________ 38

Hydraulic connection into the heat consumer system ___________________________ 41

Heat pumps with buffer cylinder ____________________________________________________ 42

Buffer cylinder with peak load heat generator ___________________________________ 43

Heat pumps without buffer cylinder ________________________________________________ 44

Sizing table for buffer cylinders _____________________________________________________ 45

Refrigerant lines ________________________________________________________________________ 47

DHW heating _______________________________________________________ 48

System design ____________________________________________________________________________48

Sizing table for DHW cylinders _______________________________________________________ 56

Sizing table for DHW cylinders in residential buildings _________________________ 57

Requirements of the DVGWW551 Code of Practice _____________________________ 60

Requirements to DIN1988-200 ______________________________________________________ 61

Modernising older buildings ______________________________________ 62

System design ____________________________________________________________________________62

Dual mode with an existing boiler __________________________________________________ 62

Radiator systems and replacement convectors ___________________________________ 63

Passive and active cooling ____________________________________________________________ 64

Cooling _____________________________________________________________ 64

Cooling load calculation ______________________________________________________________ 65

Cooling load calculation form ________________________________________________________ 66

Heat sinks for cooling operation _____________________________________________________ 67

Sizing examples ________________________________________________________________________ 69

Passive cooling with WPC cool _______________________________________________________ 70

Passive cooling with WPF cool _______________________________________________________ 71

Active cooling with WPC ______________________________________________________________ 72

Active cooling with WPF_______________________________________________________________ 73

Active cooling with WPL cool _________________________________________________________ 74

Underﬂoor cooling _____________________________________________________________________ 75

Ceiling cooling __________________________________________________________________________ 76

Concrete core activation _______________________________________________________________ 77

Fan convectors and cassette units ___________________________________________________ 78

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Tableofcontents

Technicalguideforheatpumps

Air|water heat pumps – outdoor installation __________________ 79

System design ____________________________________________________________________________79

Outdoor installation ____________________________________________________________________ 79

Sound emissions _______________________________________________________________________ 80

Condensate drain _______________________________________________________________________ 84

Air|water heat pumps – indoor installation ____________________ 85

System design ____________________________________________________________________________85

Indoor installation ______________________________________________________________________ 85

Air routing _______________________________________________________________________________ 86

Condensate drain _______________________________________________________________________ 87

Engineering checklist __________________________________________________________________ 88

Air|water heat pumps ___________________________________________ 90

Air|water heat pumps __________________________________________________________________90

Product overview _______________________________________________________________________ 90

Appliance types and applications ___________________________________________________ 91

Inverter air|water heat pumps __________________________________ 92

WPL 07/09/17 ACS classic _____________________________________________________________ 92

WPL 07/09/17 ACS classic ﬂex set ____________________________________________________ 93

WPL 07/09/17 ACS classic compact set _____________________________________________ 98

WPL 07/09/17 ACS classic compact plus set ______________________________________103

WPL 15-25 AC(S) _______________________________________________________________________124

WPL 15/25 I(S)-2 _______________________________________________________________________138

WPL 19/24 I _____________________________________________________________________________152

WPL 19/24 IK____________________________________________________________________________153

WPL 19/24 A ____________________________________________________________________________154

WPL 08/12/16/22/28 Trend ___________________________________________________________174

WPL 33 HT outdoor installation _____________________________________________________188

WPL 33 HT indoor installation _______________________________________________________189

Air|water heat pumps __________________________________________202

WPL 10 AC _______________________________________________________________________________202

WPL cool – outdoor installation ____________________________________________________210

WPL cool – indoor installation ______________________________________________________211

WPL cool – indoor installation, compact __________________________________________ 212

WPIC 3 ___________________________________________________________________________________224

WPL 34/47/57 ___________________________________________________________________________ 238

WPL 44/60/130 AC _____________________________________________________________________248

Air|water heat pump accessories ______________________________275

HM / HM-Trend hydraulic module for air|water heat pumps ____________________ 276

Casings for air|water heat pumps ___________________________________________________ 279

Air routing, wall transition AWG 315 _________________________________________________ 280

Air routing accessories, indoor installation __________________________________________ 283

Other accessories for air|water heat pumps _______________________________________ 284

Support brackets for outdoor installation ____________________________________________ 285

Connection set for WPL 15/20/25 AC(S) ______________________________________________ 286

Split lines ________________________________________________________________________________ 287

Brine|water heat pumps ________________________________________ 290

Brine|water heat pumps _____________________________________________________________ 290

Design information ____________________________________________________________________291

Ground collector _______________________________________________________________________ 292

Sizing table 20 W/m

2

_________________________________________________________________296

Sizing table 25 W/m

2

_________________________________________________________________297

Geothermal probe _____________________________________________________________________ 298

Geothermal probes size DN 25 ______________________________________________________302

Heat transfer medium ________________________________________________________________303

Engineering checklist _________________________________________________________________ 305

Brine|water heat pumps ________________________________________ 306

Brine|water heat pumps _____________________________________________________________ 306

Product overview ______________________________________________________________________ 306

Appliance types and applications __________________________________________________307

WPC 04/05/07/10/13 ___________________________________________________________________308

WPC 04/05/07/10/13 cool _____________________________________________________________309

WPF 04/05/07/10/13/16 _______________________________________________________________322

WPF 04/05/07/10/13/16 cool _________________________________________________________323

WPF 5/7/10/13/16 basic ______________________________________________________________336

WPF 10/13/16 M _______________________________________________________________________346

WPF 20/23/26/29/32 Set ______________________________________________________________354

WPF 20/27/35/40/52/66 _______________________________________________________________360

WPF 27 HT ______________________________________________________________________________361

WPF 80-132 Set ________________________________________________________________________371

Brine|water heat pump accessories ___________________________375

Groundwater module __________________________________________________________________ 376

Brine distributor WPSV ________________________________________________________________ 378

Brine set WPSB _________________________________________________________________________ 379

Brine circuit pumps ____________________________________________________________________ 381

DWS1 brine pressure switch __________________________________________________________ 383

6 |TechnicalGuideforheatpumps www.stiebel-eltron.com

Tableofcontents

Technicalguideforheatpumps

Water|water heat pumps _______________________________________384

Brine|water heat pumps with water as heat source __________________________384

Well installation _______________________________________________________________________385

Well pump ______________________________________________________________________________387

Engineering checklist _________________________________________________________________ 389

Water|water heat pumps _______________________________________390

Product overview ______________________________________________________________________ 390

Appliance types and applications __________________________________________________391

Water|water heat pumps _____________________________________________________________ 392

WPW 06/07/10/13/18/22 Set _________________________________________________________ 392

Water|water heat pumps _____________________________________________________________ 404

WPW 10/13/17/22 Trend ______________________________________________________________ 404

WPW 7/10/13/18/22 basic Set _______________________________________________________416

Heat pump control units _________________________________________424

WPM heat pump manager ____________________________________________________________ 432

Relay set for high efﬁciency pumps __________________________________________________ 436

Additional controller for mixer and swimming pool________________________________ 438

Remote controls ________________________________________________________________________ 440

Additional sensor for the heat pump system ________________________________________ 441

Internet Service Gateway ______________________________________________________________ 442

Electrical distributor panel ____________________________________________________________ 444

STB-FB safety temperature controller for underﬂoor heating _____________________ 445

Accessories for DHW heating ____________________________________447

Accessories for DHW heating __________________________________________________________ 447

DHW cylinder SBBE 301/302 WP, SBBE 401/501 WP SOL ___________________________ 448

Pipe assembly RBS 301-501, 401.2-501.2 ____________________________________________ 450

DHW cylinder SBB 301/302 WP, SBB 401/501 WP SOL ______________________________ 452

Corrugated pipe connector, heat exchanger _________________________________________ 454

DHW cylinder SBB 300/400/500 WP Trend ___________________________________________ 456

Integral cylinder HSBC200 ____________________________________________________________ 458

Mixer circuit pump assembly for integral cylinder __________________________________ 461

Cylinder and hydraulic module HSBB 3 ______________________________________________ 462

Cylinder and hydraulic module HSBB 200 classic ___________________________________ 466

DHW cylinder SBB 751/1001, SBB 751/1001 SOL ____________________________________ 468

Thermal insulation WDH 751/1001 SBB ______________________________________________ 470

Charging stations WTS 30/40 E ________________________________________________________ 472

DHW cylinder SBB 600/800/1000 WP SOL ____________________________________________ 476

Thermal insulation WDH 600/800/1000 SBB _________________________________________ 478

Instantaneous water cylinders SBS 601/801/1001/1501 W and W SOL ___________ 480

Thermal insulation WDH 601/801/1001/1501 SBS ___________________________________ 482

Additional accessories _________________________________________________________________ 483

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Tableofcontents

Technicalguideforheatpumps

Heating system hydraulic accessories ___________________________486

Wall mounted buffer cylinder SBP 100 _______________________________________________ 486

Buffer cylinder SBP 100 ________________________________________________________________ 488

Buffer cylinder SBP 200/400/700 E ___________________________________________________ 490

Buffer cylinder SBPE 400 ______________________________________________________________ 492

Thermal insulation WDH 1000/1500 SBP and WDH 1000/1500 cool _______________ 496

Flange ___________________________________________________________________________________ 497

Buffer cylinder/gas condensing boiler SBP 750/950 G _____________________________ 498

Other heating system hydraulic accessories ____________________504

Heating circuit pumps __________________________________________________________________ 504

Compact installation WPKI for buffer cylinder SBP 100 ____________________________ 508

Compact installation WPKI for buffer cylinder SBP 200/400/700 __________________ 509

Compact installations WPKI for hydraulic connection to the heating system ____ 510

Accessories for compact installations ________________________________________________ 511

Circulation pumps for compact installations _________________________________________ 512

Low loss headers _______________________________________________________________________ 513

Threaded immersion heaters BGC ____________________________________________________ 514

Flanged immersion heaters FCR 28 __________________________________________________ 515

Filter sets ________________________________________________________________________________ 516

Heating diverter valve _________________________________________________________________ 517

Mixing valves ___________________________________________________________________________ 518

STB-FB safety temperature controller for underﬂoor heating _____________________ 519

Softening device for heating systems ________________________________________________ 520

Pressure hoses for ﬂow and return lines ____________________________________________ 521

Fan convector for heating______________________________________________________________ 522

Ceiling cassettes for heating and cooling ____________________________________________ 526

Fan convector for heating and cooling _______________________________________________ 530

Accessories ______________________________________________________________________________ 533

Support bracket ________________________________________________________________________ 533

Appendix __________________________________________________________534

Key _______________________________________________________________________________________534

8 |TechnicalGuideforheatpumps www.stiebel-eltron.com

STIEBEL ELTRON is a group of companies with a decidedly interna-

tional outlook, and can rightly claim to be a global market leading

supplier of technology for building services and renewable en-

ergy equipment. For more than 90 years, our company's success

has depended upon its level of technical competence, high quality

standards, innovation, reliability and customer-oriented service.

Five national and international production facilities, 24 subsidi-

aries around the world, plus sales organisations and represent-

atives in 120 countries translate into a truly global presence for

STIEBELELTRON. Approximately 40 percent of the company's turn-

over comes from export.

We take ideas and turn them into innovations that move markets.

As a company driven by engineering expertise, we aim to deliv-

er results and turn our excellent products into groundbreaking

system solutions – because we want to be actively engaged in

shaping the future.

Our products have long been distinguished by excellent reliability,

high quality and a long service life. We have been developing

highly efﬁcient electrical appliances since 1924, and in our busi-

ness, we rely on our 3000employees and their expertise at every

stage of development – from the initial design right through to the

manufacture of the ﬁnal product.

The result is a portfolio of over 2000 products in the ﬁelds of DHW,

renewables, air conditioning and room heating. Thanks to smart

combinations, we are able to offer more than 30,000 system solu-

tions that can help you equip your home for the future.

Since 2015 at our head ofﬁce in Holzminden, we have been run-

ning the Energy Campus – a ﬂagship project for sustainable con-

struction that makes careful use of resources. Our training and

communication centre brings together high quality architecture

and communication technology, and as a Plus Energy building, it

generates more energy than it consumes.

This is in keeping with our brand promise "Full of energy" and

creates a space where the spirit of STIEBELELTRON can be experi-

enced both in theory and practice.

Introduction

STIEBELELTRONisfullofenergy!

STIEBEL ELTRON

www.stiebel-eltron.com TechnicalGuideforheatpumps| 9

Electricity – the energy source of the future

Renewable energies will become the norm for our energy supply.

as more and more people recognise the beneﬁts of green and

self-generated power from renewable sources.

The goal of the energy transition is independence from fossil fuels

Fossil fuels are in decline on the electricity market – too harmful to

the climate and ever more scarce. Nowadays, alternative energies

from the sun, wind and water are being used to generate power.

This means electricity will remain our primary energy source well

into the future. So it is only logical to act in good time to convert

the largest energy consumer in your home – the heating system

– to these futureproof forms of energy. As nearly 90% of energy

consumed in the home is used for heating and hot water, this

makes perfect sense. So there is plenty of scope for implementing

the energy transition in your own home.

As one of the most important manufacturers of products in the

heating, ventilation, air conditioning and domestic hot water

equipment sector, we feel a great level of responsibility towards

our environment.

In recent decades, we have invested much time and a great deal

of care in the development of heat pumps. This has evolved into a

reliable technology that guarantees maximum convenience.

The selection criteria

Whether in new builds or for renovations, on the roof, in the cel-

lar or the utility room, our range of heat pumps covers a wide

range of heating technology requirements both efﬁciently and

conveniently.

Our heat pumps use the energy available freely from the outdoor

air, the groundwater or the ground itself. For every heat source,

various appliance versions are available for streamlined integra-

tion into any system.

The right combination

In addition to the heat demand, efﬁcient heating of DHW is usu-

ally also required. We fulﬁl this requirement with DHW cylinders

of various types and with various designs and functions that are

speciﬁcally matched to our heat pumps.

Some of our compact heat pumps for indoor installation already

include a built-in DHW cylinder. Integration into a heat pump

minimises space demand and saves additional costs, especially

in new builds. In addition to the typical ﬂoor mounted cylinder,

our product range also includes instantaneous water cylinders

and integral cylinders with a built-in heating buffer cylinder. Spe-

cial heating buffer cylinders and DHW cylinders for integration in

solar thermal systems or additional heat sources complete our

product range.

Here, too, we fulﬁl our quality promise: STIEBELELTRON was the

ﬁrst manufacturer to obtain the EEA (European Enamel Authority)

quality certiﬁcate for its DHW cylinder enamel coating.

The accessories

Our accessories – from simple pressure hoses through to user

friendly control systems with internet connection – have been de-

signed specially for our heat pumps and meet the highest quality

requirements.

The matched assemblies and components ensure a trouble-free,

quick and cost effective installation of your heat pump system.

All accessories are matched both to each other and to our heat

pumps, thereby contributing to the overall system's reliability.

Our range of heat pumps

» Efficient, reliable and highly integrated heat pumps

» Prize-winning appliances that fulfil current aesthetic expecta-

tions

» Heat pumps for outdoor air, ground and groundwater heat

sources

» Heat pumps for indoor, outdoor and split installation

» Highly efficient appliances with output-dependent control and

reliable inverter technology

» Networked systems with internet connection and remote main-

tenance capability

» Effective use of economy tariffs and solar power generated on

site

Introduction

STIEBELELTRONisfullofenergy!

10 |TechnicalGuideforheatpumps www.stiebel-eltron.com

Advanced heat pumps save energy and reduce emissions

Heat is a fundamental human need. Many people today not only

consider economic aspects when they think of heating, but also

consider the environmental impact. That both can be combined

effectively is shown by the development of the heat pump. Heat

pumps utilise the energy that is permanently present in air, water

and in the ground, and convert it into useful heating energy. This

method of reclaiming almost inexhaustible useful heat does not

harm the environment.

Heat pumps are regulated subject to the outside temperature.

The control unit safeguards the selected set temperature. As a

result, the heat pump achieves an excellent ratio between "har-

vested" heating energy and consumed primary energy. To put it

into ﬁgures:

A heat pump enables up to ﬁve kWh of heating energy to be

generated using onekWh of electrical energy by utilising energy

stored in the air, in groundwater or in the ground.

Their compact design requires little space and ensures easy in-

stallation. The minimal effort needed for installation makes the

air|water heat pump the easiest version to choose. Sited either

indoors or outdoors, a heat pump can obtain usable heat from the

outside air down to approximately -20°C.

The importance of environmentally responsible products is con-

tinually increasing when it comes to making purchasing deci-

sions. Our heat pumps transform the basic concept of heating

homes ecologically and economically into reality.

Exclusive technology – hot water included

Hot water and cosy living are our business. You can also safe-

guard your domestic hot water supply with our DHW cylinders.

Have you already considered separating your DHW heating from

your heating system? For a higher DHW demand, e.g. on com-

mercial premises, a heat pump can also be used solely for DHW

heating.

Irrespective of whether you want to provide a central or decentral-

ised supply, we offer a complete range of energy efﬁcient electric

appliances.

Introduction

Heatpumpsprotectourenergyreserves

www.stiebel-eltron.com TechnicalGuideforheatpumps| 11

Heat pump principle

The heat transfer medium (refrigerant) makes the most important

contribution towards the function of a heat pump. The refrigerant

can evaporate at the lowest temperatures.

If outdoor air or water is routed via a heat exchanger through

which the refrigerant is circulating, the latter extracts heat from

the heat source. In this process, the refrigerant changes from its

liquid to its gaseous state.

In this process, the heat source cools down by a few degrees.

In the next step, the refrigerant is passed through a compressor

after which it is under a higher pressure. The increase in pressure

also raises the temperature of the refrigerant; in other words, the

medium is "pumped" to a higher temperature level.

This requires electrical energy. With suction gas-cooled compres-

sors, motor heat is not lost. Motor heat is routed with the com-

pressed refrigerant into a downstream condenser.

Here, the refrigerant transfers its absorbed energy to the circulat-

ing system of the hot water heating system and is thus converted

back into a liquid state again.

The prevalent pressure of the refrigerant is reduced in an expan-

sion valve and the cycle starts again.

Heat pump coefﬁcient of performance

The coefﬁcient of performance

ε

WP

is equal to the quotient of heat-

ing output Q

WP

and electrical power consumption P

WP

in accordance

with the following equation:

ߝ

ௐ௉

ൌ

ܳ

ௐ௉

ܲ

ௐ௉



This equation determines the efﬁciency, showing by how much

the heat energy yield exceeds the input energy.

This coefﬁcient of performance is subject to the temperature of the

heat source and that of the heat consumer. The higher the heat

source temperature and the lower the heat consumer tempera-

ture, the higher the coefﬁcient of performance.

It always relates, as a current value, to a speciﬁc operating

condition.

Schematic diagram: heat pump refrigerant circuit

4

3

2

12

5

9

11

10

7

8

1

6

26_03_01_0359

1 Environmental energy

2 Evaporator

3 Suction line, gaseous refrigerant, low pressure

4 Compressor

5 Pressure line, gaseous refrigerant, high pressure

6 Heating energy

7 Flow

8 Return

9 Liquid line, liquid refrigerant, high pressure

10 Expansion valve

11 Injection line, liquid refrigerant, low pressure

12 Condenser

Introduction

Heatpumpfunction

12 |TechnicalGuideforheatpumps www.stiebel-eltron.com

Heat source: air

Air heated by the sun is universally available. Even at -20°C out-

door air temperature, heat pumps can still extract sufﬁcient ener-

gy for heating mode.

Air as a heat source is typically at its coldest when the most heat-

ing energy is needed.

A heat pump can extract heat from air as a heat source down to

approximately -20°C. . However, the coefﬁcient of performance

falls as the heat source temperature decreases.

One solution is to combine a heat pump with a second heat gen-

erator that supports the heat pump during the short but particu-

larly cold season.

One particular beneﬁt is the ease of installation of air|water heat

pumps, as no extensive ground work or well drilling is required.

Heat source: water

Groundwater is a good store of solar energy. Even on the coldest

days in winter, temperatures of +7°C to +12°C are maintained.

The constant temperature level of the heat source enables the

heat pump to achieve an almost constant coefﬁcient of perfor-

mance all the year round.

Although groundwater of suitable quality is not universally avail-

able in sufﬁcient quantities, it is worthwhile using groundwater

when possible.

Utilising this heat source requires the drilling of a delivery well

and a return well.

The use of groundwater usually requires the approval of the local

water board [check local regulations]. Your local water board will

advise you about the possibility of utilising these waterways.

Schematic diagram: air as heat source

26_03_01_0360

Schematic diagram: groundwater as heat source

26_03_01_0361

Energysources

Heat source: air

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Heat source: ground with a geothermal collector

In Central Europe, even on cold winter days the ground remains

sufﬁciently warm below a depth of approx. 1.20m to 1.50 m to

enable an economical heat pump operation.

For a geothermal collector, you need a sufﬁciently large area of

land for the pipe system that absorbs the geothermal heat. You

need approximately two to three times as much surface area

(ground) as the living area to be heated.

In dry, sandy soil, the geothermal collector can extract be-

tween 10 and 15W/m² and up to 40 W/m² in ground that carries

groundwater.

The geothermal collector contains an environmentally friendly

brine mixture that cannot freeze and which transports the yielded

energy to the heat pump evaporator through the pipes.

If your property is large enough, you have an inexhaustible re-

serve of energy and ideal conditions for a brine|water heat pump.

Heat source: ground with a geothermal probe system

Vertical geothermal probes take up little space. Using special-

ist drilling equipment, geothermal probes can be sunk into the

ground down to a depth of around 100m.

Geothermal probes comprise a probe foot and vertical probe

pipes made from plastic. A brine mixture that extracts heat from

the ground circulates through the plastic pipework.

The extraction rate is dependent on the soil condition. The ex-

traction rate is between approx. 30 and 100 W per metre of the

geothermal probe. Subject to heat pump and ground conditions,

several geothermal probes can be linked up to form a single heat

source system.

In certain countries such systems need to be registered with and

possibly authorised by the local water board.

Schematic diagram: geothermal collector as heat source

26_03_01_0362

Schematic diagram: geothermal probe as heat source

30 - 100 m

26_03_01_0363

Energysources

Geothermalheatasthesourceofthermalenergy

14 |TechnicalGuideforheatpumps www.stiebel-eltron.com

Operating modes

The following terminology is used for the method by which a heat

pump is operated:

Mono mode

The heat pump is the sole provider of heating in the building.

This operating mode is suitable for all low temperature heating

systems up to 60°C ﬂow temperature.

Dual mode parallel / mono energetic

Down to a certain outside temperature, the heat pump alone de-

livers the required heating energy. A second heat generator starts

at low temperatures. The share of the heat pump in the annual

capacity is higher than with dual mode alternative operation.

This operating mode is suitable for underﬂoor heating systems

and radiators up to the maximum heat pump ﬂow temperature.

Mono energetic

The heating system uses no second form of energy. The heat pump

operates with outside air temperatures down to –20°C. Upon de-

mand, an electric emergency/booster heater starts at very low

outside air temperatures.

In mono energetic operating mode, the heat pump and the sec-

ond heat generator are electrically operated.

Mono mode operation

WP

Q

N

100 %

-15 +20 °C

T

A

26_03_01_1238

QN Heat load

WP Heat pump

TA Outside temperature

Dual mode parallel and mono energetic mode

ZH

WP

Q

N

100%

BV

-15 +20 °CT

E

T

A

26_03_01_1239

BV dual mode point

QN Heat load

WP Heat pump

TE Start

ZH Booster heater / booster heating

from second heat generator

TA Outside temperature

Coverage according to DIN 4701-10

Coverage α

Ha

in dual mode parallel operation

DualmodepointT

E

°C -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 +1 +2 +3 +4 +5

Coverage 1.00 0.99 0.99 0.99 0.99 0.98 0.97 0.96 0.95 0.93 0.90 0.87 0.83 0.77 0.70 0.61

Operatingmodes

Monomode/dualmodeparallel/monoenergetic

www.stiebel-eltron.com TechnicalGuideforheatpumps| 15

Dual mode – alternative

Down to an outside temperature determined by the system setup,

such as 0°C, the heat pump delivers the entire heating ener-

gy. When the temperature falls below that value, the heat pump

switches itself off and the second heat generator takes over the

heating operation.

This operating mode is suitable for all heating systems above

60°C ﬂow temperature.

Dual mode, partially parallel

Down to a certain outside temperature, the heat pump alone

delivers the required heating energy. The second heat generator

starts when the temperature falls below that value. The heat pump

is switched off when the ﬂow temperature is no longer sufﬁcient.

The second heat generator supplies the entire heating output.

This operating mode is suitable for all heating systems above

60°C ﬂow temperature.

Dual mode alternative operation

ZH

WP

Q

N

100%

BV

-15 +20 °CT

U

T

A

26_03_01_1240

BV dual mode point

QN Heat load

WP Heat pump

ZH Booster heater / booster heating

from second heat generator

TU Changeover point

TA Outside temperature

Dual mode partially parallel operation

ZH

WP

Q

N

100%

BV

-15 +20 °CT

U

T

E

T

A

26_03_01_1241

BV dual mode point

QN Heat load

WP Heat pump

TE Start

ZH Booster heater / booster heating

from second heat generator

TU Changeover point

TA Outside temperature

Coverage according to DIN 4701-10

Coverage α

Ha

in dual mode alternative operation

DualmodepointT

U

°C -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 +1 +2 +3 +4 +5

Coverage 0.96 0.96 0.95 0.94 0.93 0.91 0.87 0.83 0.78 0.71 0.64 0.55 0.46 0.37 0.28 0.19

Operatingmodes

Dualmodealternative/dualmodepartialparallel

16 |TechnicalGuideforheatpumps www.stiebel-eltron.com

Renewable Energies Heat Act (EEWärmeG) in new builds

The German Renewable Energies Heat Act (EEWärmeG) entered

into force on 1January 2009. In Germany, the goal is to increase

the proportion of renewables in the ﬁnal energy consumption for

heating, cooling and DHW to 14% by 2020.

The Renewable Energies Heat Act (EEWärmeG) came into force in

2009 and makes the use of renewable energies mandatory in new

buildings with living space or available area of 50m² or more. The

law places minimum requirements on the efﬁciency of the system

used and on its contribution towards covering the thermal ener-

gy demand. This refers to the calculated annually required ﬁnal

energy demand for generating heat in buildings, not the primary

energy demand. The use of geothermal energy, environmental

energy, solar energy and biomass is deﬁned as renewables. Vari-

ous alternative measures such as improved thermal insulation or

the use of ventilation systems with heat recovery are also possible.

Combination of several measures

Compliance with the mandatory use of renewable energies can be

accomplished via individual measures or a combination of several

measures. This requires the percentages of the actual use of a

heat pump, solar thermal system, biomass or alternative meas-

ures to correspond to 100 % in total in relation to the intended

use.

Example: If a heat pump is combined with a solar thermal system,

it is sufﬁcient if the heat pump covers 25% and the solar ther-

mal system 7.5% of the building's thermal energy demand. Both

requirements are thereby 50% fulﬁlled. The mandatory use of

renewable energies is fulﬁlled over all.

Renewable Energies Heat Act (EEWärmeG) for existing buildings

The Heat Act also presents the possibility of extending the manda-

tory use of renewables to existing buildings. In Baden-Württem-

berg, mandatory use has been implemented since January 2010.

As under federal law in Germany, the heat demand as deﬁned by

the Energy Saving Ordinance (EnEV) must also be covered pro-

portionally (min. 10 %) when heating systems are replaced by

renewables, alternative measures, or both. Other states are fol-

lowing, for example Berlin.

Public subsidy

The installation of heating heat pumps is subsidised by public

funds. This subsidy comes from the Federal Ofﬁce for Economic

Affairs and Export Control (BAFA). For this, system efﬁciency is

subject to stricter requirements such as seasonal performance

factors. It is also possible to apply for low interest loans from

Germany's reconstruction loan corporation, the Kreditanstalt

für Wiederaufbau (KfW), under its "Energy efﬁcient building"

programme.

Compliance with mandatory use with a solar thermal system

» At least 15% of the thermal energy demand covered via solar

radiation energy. With solar thermal systems, this meets the

requirement.

• Collector surface at least 4 % of the living area in sin-

gle-family and two-family houses

• Collector surface at least 3% of the living area in apart-

ment buildings (more than 2 residential units)

» Collectors must bear the EU test mark "Solar Keymark"

Compliance with mandatory use via alternative measures

» EnEV maximum values for primary energy demand and trans-

mission heat loss HT' undershot by at least 15%

» At least 50% of the thermal energy demand covered by heat

pumps with waste heat utilisation

» At least 50% of the thermal energy demand covered by venti-

lation systems with heat recovery

» At least 50% of the thermal energy demand covered by com-

bined heat and power generation systems

» At least 50% of the thermal energy demand from local or dis-

trict heating networks covered by renewable energies

Compliance with mandatory use with a heat pump

Air|water heat pump

» At least 50% of the thermal energy demand covered

» Seasonal performance factor for room heating at least 3.5

» Seasonal performance factor for combined room heating and

DHW heating at least 3.3

» Installation of an electricity and heat meter required

Brine|water heat pump

» At least 50% of the thermal energy demand covered

» Seasonal performance factor for room heating at least 4.0

» Seasonal performance factor for combined room heating and

DHW heating at least 3.8

» Installation of an electricity and heat meter required for flow

temperatures of over 35 °C

RenewableEnergiesHeatAct|EEWärmeG

Requirements

www.stiebel-eltron.com TechnicalGuideforheatpumps| 17

Seasonal performance factor

The seasonal performance factor of a heat pump represents the

ratio of the heat supplied annually for heating and DHW heating

to the consumed power. The seasonal performance factor is a ba-

sic measure of the energy efﬁciency of a heat pump system.

Determining the seasonal performance factor is, for example, a

requirement for the specialist company declaration and the appli-

cation for the market incentive programme of the Federal Ofﬁce

for Economic Affairs and Export Control (BAFA).

The seasonal performance factor does not just apply to certain

operating states such as the COP. The seasonal performance factor

is the basis for system comparisons and viability studies.

Calculation in accordance with VDI 4650 Part 1

The seasonal performance factor depends on a large number of

factors that relate to the framework conditions of operation. Fac-

tors that inﬂuence the seasonal performance factor include, for

example, the heat source temperature, the heating ﬂow temper-

ature and its curve over the heating season, use of the electrical

emergency/booster heater, the proportion of DHW heating, the

energy consumption for auxiliary drives and the temperature dif-

ferential between the heating ﬂow and the heating return.

These inﬂuencing variables are taken into account in the calcu-

lation according to VDI 4650. The coefﬁcients of performance de-

termined under standard conditions are matched with corrective

factors to operating conditions that deviate.

The calculation according to VDI 4650 applies to electric heat

pumps for room heating and DHW heating up to a rated heating

output of 100KW.

Calculation programs are available online for our specialist

partners.

Seasonal performance factor, room heating

The seasonal performance factor for room heating is calculated

subject to the heat source. The standard outside temperature

must be taken into account in the case of air|water heat pumps,

i.e. the location and its climatic conditions. The changing outside

air temperatures are included in the calculation via the coefﬁ-

cients of performance at various operating points.

A heat source temperature that is constant all year round is

assumed for brine| water heat pumps and water|water heat

pumps.

1 Total seasonal performance factor



































b

WP

Total seasonal performance factor of the heat pump system

x Room heating proportion of the total heat demand (stand-

ard 0.82)

y DHW heating proportion of the total heat demand (stand-

ard 0.18)

α Heat pump coverage (Table 7)

b

h

Seasonal performance factor, room heating (equation 2,

equation 3)

b

w

Seasonal performance factor, DHW heating (equation 4,

equation 5, equation 6)

2 Seasonal performance factor

Room heating, air | water heat pumps

ߚ

௛

ൌ

ሺ

ߝ

ேଵ

כܨ

ణଵ

൅ߝ

ேଶ

כܨ

ణଶ

൅ߝ

ேଷ

כܨ

ణଷ

ሻ

כܨ

οణ



bh Seasonal performance factor, heating system

ε

N1

COP A-7/W35

ε

N2

COP A2/W35

ε

N3

COP A10/W35

F∆ϑ Correction factor, heating as per Table 2

3 Seasonal performance factor

Room heating, brine | water heat pumps

ߚ

௛

ൌ

ߝ

ே

כܨ

ణ

כܨ

οణ

ܨ

௉



b

h

Seasonal performance factor, heating system

ε

N

COP, heat source ground at B0/W35, groundwater at B10/

W35

F

ϑ

Correction factor, ground as per Table 3 / groundwater as

per Table 4

F

∆ϑ

Correction factor, heating as per Table 2

F

P

Correction factor, source pump as per Table 6

Calculationoftheseasonalperformancefactor

VDI4650Part1

18 |TechnicalGuideforheatpumps www.stiebel-eltron.com

DHW heating

The total seasonal performance factor for systems in pure heating

mode or systems with combined heating and DHW heating can be

determined as per VDI 4650 Part 1. The calculation is also possible

for a separate DHW heat pump.

Allowance must be made for the proportions of the total heat de-

mand, because in most cases higher temperatures are required

for DHW heating than in heating mode. VDI 4650 suggests 18% as

the proportion for DHW heating. If the standard heat load is low

or for a larger number of persons, this proportion can increase.

The DHW proportion is set at 0 % when:

» no DHW is required

» the DHW is not heated via the heating heat pump

» the DHW is not heated via a DHW heat pump

DHWheating

Calculationoftheseasonalperformancefactor

4 Seasonal performance factor, DHW, air|water heat pumps































b

W

Seasonal performance factor, DHW heating

ε

N1

COP A-7/W35

ε

N2

COP A2/W35

ε

N3

COP A10/W35

F

∆ϑ

Correction factor, DHW heating as per Table 2

5 Seasonal performance factor, DHW, brine|water heat

pumps

ߚ

ௐ

ൌ

ߝ

ே

כܨ

ణ

כܨ

οణ

ܨ

௉



bW Seasonal performance factor, DHW heating

ε

N

COP, heat source ground at B0/W35, groundwater at B10/

W35

F

ϑ

Correction factor, ground as per Table 3 / groundwater as

per Table 4

F

∆ϑ

Correction factor, heating as per Table 2

F

P

Correction factor, source pump as per Table 6

6 Seasonal performance factor, DHW, DHW heat pumps with

cellar air

















b

W

Seasonal performance factor, DHW heating

ε

N

COP for heating from 15°C to 50°C (air temperature 15°C)

F

1

Correction factor for deviating temperatures at the test bed

(as per Table 1)

Table 1 – Correction factor, cellar air heat pump

DHWtemperature,testbed CorrectionfactorF

1

°C

45 0.95

50 1.00

55 1.05

60 1.10

65 1.15

Interim values for F1 are interpolated in linear fashion.

www.stiebel-eltron.com TechnicalGuideforheatpumps| 19

4

Table 2 – Correction factor, room heating/DHW heating F∆ϑ

Temperaturedifferential Underfloorheating

system

Radiatorheatingsystem DHWheating

Testbed 35°C/28°C 55°C/45°C Air|waterheatpump Brine|waterheatpump

3K 1,041 1,072 1,041 1,072

4K 1,031 1,061 1,031 1,061

5K 1,020 1,051 1,020 1,051

6K 1,010 1,041 1,010 1,041

7K 1,000 1,031 1,000 1,031

8K 0.990 1,020 0.990 1,020

9K 0.980 1,010 0.980 1,010

10K 0.969 1,000 0.969 1,000

For the temperature differential at the test bed to EN 14511, refer

to the speciﬁcations of the selected heat pump.

Table 3 – Correction factor, ground Fϑ

Minimumbrineinlet

temperature

Underfloorheating

system

Radiatorheating

system

°C Flow35°C Flow55°C

5 1,150 0.956

4 1,137 0.943

3 1,125 0.930

2 1,113 0.917

1 1,100 0.904

0 1,087 0.890

-1 1,074 0.877

-2 1,062 0.864

Standard value for geothermal probe = 2°C, geothermal collector

= 0°C.

Table 4 – Correction factor, groundwater with intermediate heat

exchanger Fϑ

Groundwater

temperature

Underfloorheating

system

Radiatorheating

system

Flow35°C Flow55°C

5 0.916 0.698

6 0.935 0.718

7 0.954 0.737

8 0.973 0.756

9 0.992 0.776

10 1,011 0.795

11 1,030 0.815

12 1,049 0.834

13 1,068 0.853

14 1,087 0.873

15 1,106 0.892

16 1,125 0.912

17 1,144 0.931

18 1,163 0.950

Standard value, groundwater = 10 °C. Applies only to systems

with intermediate heat exchanger. A 3K temperature differential

was factored in for these systems.

Correctionfactors

Heating,DHW,ground,groundwater

20 |TechnicalGuideforheatpumps www.stiebel-eltron.com

Table 5 – Correction factor, outdoor air Fϑ1, Fϑ2, Fϑ3

Standardoutside

temperature

Correctionfactor Underfloorheating

system,newbuild

Underfloorheat-

ingsystem,older

buildings

Radiators,newbuild Radiators,older

buildings

°C Flow35°C Flow35°C Flow55°C Flow55°C

-10 Fϑ1 0.085 0.066 0.066 0.051

-10 Fϑ2 0.854 0.766 0.707 0.635

-10 Fϑ3 0.134 0.250 0.116 0.217

-12 Fϑ1 0.128 0.104 0.101 0.081

-12 Fϑ2 0.824 0.762 0.686 0.635

-12 Fϑ3 0.108 0.205 0.094 0.179

-14 Fϑ1 0.167 0.137 0.133 0.109

-14 Fϑ2 0.795 0.746 0.666 0.626

-14 Fϑ3 0.094 0.182 0.082 0.160

-16 Fϑ1 0.266 0.224 0.214 0.180

-16 Fϑ2 0.700 0.668 0.590 0.564

-16 Fϑ3 0.083 0.168 0.073 0.147

The correction factors apply to 12°C and 15°C.

Table 6 – Correction factor, source pump F

P

Heatpumpheating

output

Geothermalprobe,

geothermalcollec-

tor

Groundwaterwith

intermediateheat

exchanger

< 10kW 1,075 1,325

10 - 20kW 1,075 1,275

> 20kW 1,075 1,215

The correction factor F

P

can be calculated for the construction pro-

ject if the power consumption of the heat source pump is known.

Make allowance for the brine and groundwater pump in the case

of systems with an intermediate heat exchanger.

ܨ

௉

ൌͳ൅

ܲ

௉

ܲ

ௐ௉



P

Source pump power consumption

P

WP

Heat pump power consumption

Table 7 – Heat pump coverage α for mono energetic operation

Dualmodepointϑ

Biv

°C -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2

Coverage

α

1.00 0.99 0.99 0.99 0.99 0.98 0.97 0.96 0.95 0.93 0.90 0.87 0.83

» The design of most air|water heat pumps is mono energetic

(dual mode point -5°C).

» Operation of brine|water heat pumps and water|water heat

pumps is normally in mono mode (coverage α = 1.0).

» Set the coverage α to 1.0 for dual mode systems with an oil/gas

boiler.

» Do not include the second heat generator when calculating the

seasonal performance factor.

Correctionfactors

Outdoorair,sourcepump

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STIEBEL ELTRON Engineering and | Heat Pumps Technical Guide

STIEBEL ELTRON Engineering and | Heat Pumps Technical Guide

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