Steel boilerIssue 2013/10Heat is our elementTechnical guide for contractorsLogano SK655/SK755Output range from 120 kW to 1850 kW

Table of contentsTable of contents

1 Steel boiler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41.1 Types and heating output . . . . . . . . . . . . . 41.2 Applications . . . . . . . . . . . . . . . . . . . . . . . 41.3 Features and benefits . . . . . . . . . . . . . . . . 4

2 Technical description . . . . . . . . . . . . . . . . . . . . . 52.1 Equipment level . . . . . . . . . . . . . . . . . . . . . 52.2 Heating water routing . . . . . . . . . . . . . . . . 62.3 Hot gas routing . . . . . . . . . . . . . . . . . . . . . 62.4 Dimensions and specifications . . . . . . . . . 72.4.1 Logano SK655 dimensions and

specifications . . . . . . . . . . . . . . . . . . . . . . . 72.4.2 Specification and dimensions

Logano SK755 (420 kW to 820 kW) . . . . . . 92.4.3 Specification and dimensions

Logano SK755 (1040 kW to 1850 kW) . . . 112.5 Characteristics . . . . . . . . . . . . . . . . . . . . 132.5.1 Pressure loss on the water side . . . . . . . 132.5.2 Boiler efficiency . . . . . . . . . . . . . . . . . . . . 142.5.3 Standby loss and flue gas temperature . . 15

3 Burner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163.1 Burner selection . . . . . . . . . . . . . . . . . . . 163.2 Burner requirements . . . . . . . . . . . . . . . . 16

4 Regulations and operating conditions . . . . . . . 174.1 Extracts from the regulations . . . . . . . . . 174.2 Pressure Equipment Directive (PED) and

Health & Safety at Work Act [Germany] . . 174.2.1 AREA OF APPLICATION . . . . . . . . . . . . . . 174.2.2 Categories in accordance with the

Pressure Equipment Directive 97/23/EC . 174.2.3 Health & Safety at Work Act [Germany]

regarding steam and hot water boilers . . 184.2.4 Overview of the Health & Safety at

Work Act [Germany] . . . . . . . . . . . . . . . . . 184.3 Operating conditions . . . . . . . . . . . . . . . 184.3.1 Operating requirements . . . . . . . . . . . . . 184.3.2 Operating conditions . . . . . . . . . . . . . . . 184.4 Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194.5 Water treatment . . . . . . . . . . . . . . . . . . . 194.5.1 Definition of terms . . . . . . . . . . . . . . . . . 194.5.2 Prevention of corrosion damage . . . . . . . 194.5.3 Prevention of damage through scale

formation . . . . . . . . . . . . . . . . . . . . . . . . . 204.5.4 Requirements of the fill and top-up water 204.5.5 Application limits for boilers made from

ferrous materials . . . . . . . . . . . . . . . . . . . 214.5.6 Recording the amounts of fill and top-up

water . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234.5.7 Calculation to determine the permissible

amounts of fill and top-up water . . . . . . . 234.5.8 Chemical additives in the heating water . 23

4.5.9 Combustion air . . . . . . . . . . . . . . . . . . . . 23

5 Heating controls . . . . . . . . . . . . . . . . . . . . . . . . 245.1 Logamatic 4000 control system . . . . . . . . 245.1.1 Logamatic 4212 control unit . . . . . . . . . . 245.1.2 Logamatic 4321 and Logamatic 4322

control units . . . . . . . . . . . . . . . . . . . . . . 245.1.3 Logamatic 4324 control unit for high flow

temperatures . . . . . . . . . . . . . . . . . . . . . 245.1.4 Logamatic4411 control panel system . . . 245.2 Logamatic telecontrol system . . . . . . . . . 245.3 Control unit settings . . . . . . . . . . . . . . . . 25

6 DHW heating . . . . . . . . . . . . . . . . . . . . . . . . . . . 276.1 Systems for DHW heating . . . . . . . . . . . . 276.2 DHW temperature control . . . . . . . . . . . . 27

7 System examples . . . . . . . . . . . . . . . . . . . . . . . . 287.1 Information regarding all system

examples . . . . . . . . . . . . . . . . . . . . . . . . . 287.1.1 Hydraulic connection . . . . . . . . . . . . . . . . 287.1.2 Control system . . . . . . . . . . . . . . . . . . . . . 297.1.3 DHW heating . . . . . . . . . . . . . . . . . . . . . . 297.2 Safety equipment to EN 12828 and

EN 12953-6 . . . . . . . . . . . . . . . . . . . . . . . 297.2.1 Requirements . . . . . . . . . . . . . . . . . . . . . . 297.2.2 Arrangement of safety equipment to

EN 12828 ; operating temperature 105 C; shutdown temperature (high limit safety cut-out) 110 C . . . . . . . . . . . . . . . . . . 30

7.2.3 Arrangement of safety equipment to EN 12953-6 ; shutdown temperature (high limit safety cut-out) > 110 C (maximum 120 C for Logano SK655 and SK755) . . . . . . . . . . . . . . . . . . . . . . . 31

7.3 Sizing and installation information . . . . . 327.3.1 Boiler circuit pump in the bypass as shunt

pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327.3.2 Boiler circuit pump as primary

circuit pump . . . . . . . . . . . . . . . . . . . . . . 347.3.3 Low loss header . . . . . . . . . . . . . . . . . . . . 357.4 Single boiler system Logano SK655 and

SK755 with boiler control unit . . . . . . . . 367.5 Single boiler system with Logano SK655 and

SK755 boilers: Logamatic boiler and heating circuit control with hydraulic separation . . . . . . 40

7.6 Single boiler system with Logano SK655 and SK755 with boiler and heating circuit control . . . . . . . . . . . . . . . . . . . . . . . . . . 42

7.7 Single boiler system with Logano SK655 and SK755 with boiler and heating circuit control as well as hydraulic balancing . . 43

7.8 2-boiler system with Logano SK655 and SK755 with boiler and heating circuit control plus hydraulic balancing . . . . . . . 45PD SK655/755 6 720 810 010 (2013/10)2

Table of contents7.9 2-boiler system with Logano SK655 and SK755 as well as Logano plus SB325, SB625 and SB745 gas condensing boilers with boiler and heating circuit control . . . 47

8 Delivery method and installation information . 498.1 Delivery method . . . . . . . . . . . . . . . . . . . 498.2 Installation information . . . . . . . . . . . . . . 49

9 Installation location . . . . . . . . . . . . . . . . . . . . . 509.1 General requirements of the installation

room . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 509.1.1 Combustion air supply . . . . . . . . . . . . . . 509.1.2 Siting combustion equipment . . . . . . . . . 509.2 Handling details . . . . . . . . . . . . . . . . . . . 519.3 Installation dimensions . . . . . . . . . . . . . . 52

10 Additional equipment and accessories . . . . . . 5310.1 Additional safety equipment to EN 12828 5310.1.1Safety equipment . . . . . . . . . . . . . . . . . . 5310.2 Additional devices for sound insulation . 5410.2.1Requirements . . . . . . . . . . . . . . . . . . . . . 5410.2.2Boiler mounts to attenuate

structure-borne noise . . . . . . . . . . . . . . . 5410.2.3Boiler foundation . . . . . . . . . . . . . . . . . . 5610.2.4Flue gas silencer with sealing collar to

insulate against structure-borne noise . . . 5610.3 Further accessories . . . . . . . . . . . . . . . . . 5610.3.1Welded flanges . . . . . . . . . . . . . . . . . . . . 5610.3.2Flue pipe sealing collar . . . . . . . . . . . . . . 5610.3.3Cleaning equipment set . . . . . . . . . . . . . 57

11 Flue system . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5811.1 General requirements of the flue system 5811.2 Flue gas parameters . . . . . . . . . . . . . . . . 59

Keyword index . . . . . . . . . . . . . . . . . . . . . . . . . 60PD SK655/755 6 720 810 010 (2013/10) 3

1 Steel boiler1 Steel boiler

1.1 Types and heating outputWith the Logano SK655 and the Logano SK755, Buderus offers steel boilers with outputs ranging from 120 kW to 1850 kW. The Logano SK655 is available with heating outputs ranging from 120 kW to 360 kW, the Logano SK755 covers the output range from 420 kW to 1850 kW.These boilers feature reversing combustion according to EN 303 for oil or gas. They are suitable for fuel oil EL to DIN 51603-1, natural gas or LPG to DVGW G 260. The boilers can, as an option, be operated with matching pressure-jet oil and gas burners to EN 267 and EN 676, for sufficient heat output. The boilers are made of steel and are designed for a maximum safety temperature of 120 C (shutdown temperature of the high limit safety cut-out).

1.2 ApplicationsThe Logano SK655 and SK755 steel boilers are suitable for all heating systems to EN 12828 (maximum high limit safety cut-out temperature 110 C) and EN 12953-6 (maximum high limit safety cut-out temperature 120 C). Observe country-specific standards.They are used in applications including central heating and DHW heating in apartment buildings, municipal and commercial buildings, in district heating centres and for indirect swimming pool heating.For DHW heating, these boilers can be combined with Buderus DHW cylinders.

1.3 Features and benefitsHigh standard seasonal efficiency [to DIN] and economic viabilityThe large heating surface of the second pass and high grade thermal insulation result in excellent heat transfer as well as low flue gas and standby losses. The result is a standard seasonal efficiency [to DIN] of up to 93 %. Minimum circulation volumes are not required.

Quiet operation with clean combustionThe reversing combustion chamber with low combustion chamber volume loads ensures clean combustion and a high standard seasonal efficiency. Optionally available boiler supports that act to prevent structure-borne noise transfer and flue gas silencers result in significantly lower operating noise.

Easy installationThe factory-fitted thermal insulation and casing of the Logano SK655 and SK755 make it possible to install the boiler quickly and easily.At the factory, these boilers are fitted with all required connections, enabling an easy integration into the heating system. Accessories are matched to these boilers, ensuring an easy and quick installation. For example, a safety assembly matched to these boilers ensures uncomplicated installation (only for safety level according to EN 12828).Predrilled burner plates make fitting third party burners easy.

Straight-forward system designAll boilers can be connected simply and in a straight-forward manner to the heating system, since there is no special need for a minimum flow rate. Not only does this lead to reduced investment outlay and running costs, but also less engineering effort.

Supplied fully wired ready for connectionEasy connection to the heating system due to fully assembled delivery ex works.

Easy maintenance and cleaningThe combustion chamber and the heating surfaces of these boilers are easily accessible through the large door at the front that can be pivoted to the left or right. The smooth steel surfaces of these boilers can be easily cleaned with the cleaning set supplied as standard.

Easy and convenient operationThe control functions that are matched to the respective system hydraulics facilitate easy operation. These boilers can be combined with different Buderus control units. The equipment level of all control units can be extended individually with auxiliary modules. All control unit functions can be adjusted in only a few steps through the push & turn facility.PD SK655/755 6 720 810 010 (2013/10)4

2 Technical description2 Technical description

2.1 Equipment level

Fig. 1 Logano SK755 with Logamatic 4321

The Logano SK655 and SK755 steel boilers are tested to EN 303, type-tested and CE-designated.Quality assurance measures to EN ISO 9001 contribute to the high manufacturing quality and functional reliability. The materials used in the Buderus steel boilers meet the requirements of EN 303 and EN 14394. As a result, these boilers operate safely and reliably.The boilers feature all-round thermal insulation and aluminium sheet casing. The visible steel parts are painted to RAL 5015. The thermal insulation is 50 mm thick. The combustion chamber and the gas to water heat exchangers are easily accessible through large front doors that can be pivoted to the left or right.

Finely stepped output levels The Logano SK655 is available with the following output ratings: 120 kW 190 kW 250 kW 300 kW 360 kWThe Logano SK755 is available with the following output ratings: 420 kW 500 kW 600 kW 730 kW 820 kW 1040 kW 1200 kW 1400 kW 1850 kW

Available components Logamatic 4212, 4321, 4322 and 4324 control units in

a modular design Drilled burner plates, suitable for the corresponding

burner types, onto which the pressure-jet gas and oil burners are mounted

Plenty of matching accessories ( chapter 10, page 53 ff.)

6 720 807 236-11.1TPD SK655/755 6 720 810 010 (2013/10) 5

2 Technical description2.2 Heating water routingCalculated flow and temperature processesA simulation program enabled the calculation of influencing factors, such as heat supply, amount of water, circulation etc. Subject to these factors, the flow and updraught characteristics as well as the temperature distribution within the boiler could be calculated and, step by step, optimised. The results of this simulation program were translated into the design of these steel boilers.

Fig. 2 Second pass with turbulators

Fig. 3 Heating water routing through the Logano SK655 and SK755

RK ReturnVK FlowVSL Safety flow[1] Pipes of the second pass[2] Combustion chamber

2.3 Hot gas routingInside the combustion chamber, the hot gases are reversed and flow towards the front of the boiler, where they are reversed again by the front door and guided into the second pass. They flow through the pipes, where they transfer their heat to the boiler water.

The design and geometry of the second pass ensure a high heat transfer rate from the hot gas to the boiler water.

Fig. 4 Hot gas flow inside the Logano SK655 and SK755

AA Flue outletRK ReturnVK FlowVSL Safety flow

[1] Combustion chamber[2] Flue gas collector[3] Pipes of the second pass

1) SK755 with 1400 kW and 1850 kW output

.

.

.

6 720 807 236-12.1T

RK

VK

VSL

6 720 807 236-01.1T

1

2

2

1

3

VSL (VK1)) VK (VSL1))

6 720 807 236-02.1T

RK

AAPD SK655/755 6 720 810 010 (2013/10)6

2 Technical description2.4 Dimensions and specifications2.4.1 Logano SK655 dimensions and specifications

Fig. 5 Dimensions, Logano SK655 120 kW to 360 kW

Boiler size Abbreviation Unit 120 190 250 300 360Rated output kW 120 190 250 300 360Rated heat input kW 132 209 274 329 393Length LG mm 1522 1668 1817 1895 1933Width BG mm 800 850 890 890 955Height incl. control unitHeight excl. control unit

HHK

mmmm

1157937

12201000

12551035

12551035

13201100

Boiler base frame LGRBGR

mmmm

915420

1110430

1240450

1400450

1373 480

Flue outlet DAAHAA

mmmm

200542

200582

250597

250597

250632

Combustion chamber lengthCombustion chamber diameter

LFR1)

DFR1)mmmm

865390

1060 420

1190450

1350450

1260488

Burner door depthBurner door height

T1)

HB

mmmm

260427

260442

260457

260457

260 477

Minimum blast tube diameter DMB1) mm 130 240 240 240 290Minimum blast tube length LBR1) mm 2) 2) 2) 2) 2)

Burner door swivelling range BT mm 700 760 790 790 860Boiler flow3) VK mm DN65 DN65 DN65 DN65 DN80Boiler return3) RK mm DN65 DN65 DN65 DN65 DN80Flow safety pipe3) VSL mm DN40 DN40 DN40 DN50 DN50Drain DEL

HEL

Inchesmm

1 100

1 100

1 100

1 100

1 100

Cleaning seq RA Inches G 3/8 G 3/8 G 3/8 G 3/8 G 3/8Table 1 Specification and dimensions Logano SK655 120 kW to 360 kW

HB

HK

H

BGR LGR

RK

A3

DAA

A1

VK VSL

A2

LG

HEL

HA

A

HF

DEL

6 720 807 236-03.1T

BG

RA

DELPD SK655/755 6 720 810 010 (2013/10) 7

2 Technical descriptionFlange height VK/VSL/RK HF mm 1005 1065 1095 1095 1165Flange VK/VSL/RK A1

A2A3

mmmmmm

240170400

345205400

495185413

470200573

540225437

Transport weight kg 450 520 610 670 800Water Content l 136 203 233 262 323Gas content l 129 183 238 268 304Flue gas temperature, partial load 60 %4) C 150 150 150 150 150Flue gas temperature, full load 100 %4) C 210 205 202 200 200Flue gas mass flow rate, oil, partial load 60 %5)

kg/s 0.0317 0.0494 0.0646 0.0769 0.0934

Flue gas mass flow rate, oil, full load 100 %5)

kg/s 0.0527 0.0824 0.1076 0.1282 0.1557

Flue gas mass flow rate, gas, partial load 60 %6)

kg/s 0.0314 0.0488 0.0650 0.0778 0.0929

Flue gas mass flow rate, gas, full load 100 %6)

kg/s 0.0523 0.0813 0.1084 0.1297 0.1548

CO2 content, oil % 13 13 13 13 13CO2 content, gas % 10 10 10 10 10Pressure loss on the hot gas side mbar 0.80 1.60 1.54 2.70 3.30Draught required Pa 0 0 0 0 0Maximum permissible temperatureSafety temperature limiter7)

C 120 120 120 120 120

Maximum operating pressure (boiler) bar 6 6 6 6 6CE-designation, product ID CE 101513

1) Fig. 17, page 162) The blast tube must protrude beyond the lining in the burner door.3) Acc. to DIN 2633 (PN 16)4) Relative to average boiler temperature 70C5) Relative to fuel oil HEL, Hi = 11.86 kWh/kg6) Relative to natural gas H/L, Hi = 9.03 - 10.03 kWh/m7) STB 120C only possible with Logamatic 4212 and 4324, otherwise STB 110C

Boiler size Abbreviation Unit 120 190 250 300 360

Table 1 Specification and dimensions Logano SK655 120 kW to 360 kWPD SK655/755 6 720 810 010 (2013/10)8

2 Technical description2.4.2 Specification and dimensions Logano SK755 (420 kW to 820 kW)

Fig. 6 Dimensions, Logano SK755 420 kW to 820 kW

Boiler size Abbreviation Unit 420 500 600 730 820Rated output kW 420 500 600 730 820Rated heat input kW 459 546 655 795 893Length LG mm 2142 2075 2320 2270 2469Width BG mm 955 1040 1040 1040 1040Height incl. control unitHeight excl. control unit

HHK

mmmm

13201100

14301210

14301210

14301320

14301320

Boiler base frame LGRBGR

mmmm

1573480

1503570

1753570

1700650

1900650

Flue outlet DAAHAA

mmmm

250632

300662

300662

350727

350727

Combustion chamber lengthCombustion chamber diameter

LFR1)

DFR1)mmmm

1460488

1390548

1640548

1585624

1785624

Burner door depthBurner door height

T1)

HB

mmmm

260477

260507

260507

260547

260547

Minimum blast tube diameter DMB1) mm 290 290 290 350 350Minimum blast tube length LBR1) mm 2) 2) 2) 2) 2)

Burner door swivelling range BT mm 860 950 950 1060 1060Boiler flow3) VK mm DN80 DN100 DN100 DN125 DN125Boiler return3) RK mm DN80 DN100 DN100 DN125 DN125Flow safety pipe3) VSL mm DN50 DN50 DN50 DN65 DN65Drain DEL

HEL

Inchesmm

1 100

1 100

1 100

1 100

1 100

Cleaning seq RA Inches G 3/8 G 3/8 G 3/8 G 3/8 G 3/8Table 2 Specification and dimensions Logano SK755 420 kW to 820 kW

HB

HK

H

BGR LGR

RK

A3

DAA

A1

VK VSL

A2

LG

HEL

HA

A

HF

DEL

6 720 807 236-03.1T

BG

RA

DELPD SK655/755 6 720 810 010 (2013/10) 9

2 Technical descriptionFlange height VK/VSL/RK HF mm 1165 1255 1255 1255 1365Flange VK/VSL/RK A1

A2A3

mmmmmm

540225637

450365516

450365766

620350541

620350541

Transport weight kg 900 1040 1150 1360 1460Water Content l 367 434 502 607 675Gas content l 350 420 495 618 693Flue gas temperature, partial load 60 %4) C 150 150 150 150 150Flue gas temperature, full load 100 %4) C 200 200 200 198 198Flue gas mass flow rate, oil, partial load 60 %5)

kg/s 0.1085 0.1277 0.1668 0.1868 0.2088

Flue gas mass flow rate, oil, full load 100 %5)

kg/s 0.1809 0.1301 0.278 0.3113 0.348

Flue gas mass flow rate, gas, partial load 60 %6)

kg/s 0.1068 0.1396 0.1674 0.1869 0.2102

Flue gas mass flow rate, gas, full load 100 %6)

kg/s 0.178 0.2168 0.279 0.3116 0.3503

CO2 content, oil % 13 13 13 13 13CO2 content, gas % 10 10 10 10 10Pressure loss on the hot gas side mbar 3.9 4.7 5.59 6.1 6.47Draught required Pa 0 0 0 0 0Maximum permissible temperature for safety temperature limiter7)

C 120 120 120 120 120

Maximum operating pressure (boiler) bar 6 6 6 6 6CE-designation, product ID CE 101513

1) Fig. 17, page 162) The blast tube must protrude beyond the lining in the burner door.3) Acc. to DIN 2633 (PN 16)4) Relative to average boiler temperature 70C5) Relative to fuel oil HEL, Hi = 11.86 kWh/kg6) Relative to natural gas H/L, Hi = 9.03 - 10.03 kWh/m7) STB 120C only possible with Logamatic 4212 and 4324, otherwise STB 110C

Boiler size Abbreviation Unit 420 500 600 730 820

Table 2 Specification and dimensions Logano SK755 420 kW to 820 kWPD SK655/755 6 720 810 010 (2013/10)10

2 Technical description2.4.3 Specification and dimensions Logano SK755 (1040 kW to 1850 kW)

Fig. 7 Dimensions, Logano SK755 1040 kW to 1200 kW

Fig. 8 Dimensions, Logano SK755 1400 kW to 1850 kW

6 720 807 236-04.1T

HB

HK H

BGR LGR

VK

A1 A2VSLRK

SG

A3

LG

HEL

HA

A

HF

DEL

DAARA

BK

BG

DEL

SG

H BH K H

BGR LGR

VK

A1 A2

VSLRK

A3

LG

H EL

H AA

HF

DEL

DAA

6 720 807 236-13.1T

RA

BK

BGPD SK655/755 6 720 810 010 (2013/10) 11

2 Technical descriptionBoiler sizeAbbreviatio

n Unit 1040 1200 1400 1850Rated output kW 1040 1200 1400 1850Rated heat input kW 1138 1313 1532 2024Length LG mm 2600 2882 3050 3340Width BK mm 1470 1470 1610 1730Height incl. control unitHeight excl. control unit

HHK

mmmm

14751340

14751340

16121460

17301545

Boiler base frame LGRBGR

mmmm

1960820

2260820

2316880

2720860

Flue outlet DAAHAA

mmmm

350797

350797

4001070

4001145

Combustion chamber lengthCombustion chamber diameter

LFR1)

DFR1)

1) Fig. 17, page 16

mmmm

1845710

2145710

2120780

2520860

Burner door depthBurner door height

T1)

HB

mmmm

260592

260592

300635

320685

Minimum blast tube diameter DMB1) mm 350 350 350 350Minimum blast tube length LBR1) mm 2)

2) The blast tube must protrude beyond the lining in the burner door.

2) 2) 2)

Burner door swivelling range BT mm 1170 1170 1280 1385Boiler flow3)

3) Acc. to DIN 2633 (PN 16)

VK mm DN125 DN125 DN150 DN200Boiler return3) RK mm DN125 DN125 DN150 DN200Flow safety pipe3) VSL mm DN80 DN80 DN80 DN100Drain DEL

HEL

Inchesmm

1 100

1 100

1 100

1 100

Cleaning seq RA Inches G G G G Flange height VK/VSL/RK HF mm 1475 1475 1612 1732Flange VK/VSL/RK A1

A2A3

mmmmmm

620595569

620595870

725725673

925925670

Transport weight kg 1790 2070 2660 3600Water Content l 822 942 1339 1655Gas content l 934 1071 1275 1710Flue gas temperature, partial load 60 %4)

4) Relative to average boiler temperature 70C

C 150 150 150 150Flue gas temperature, full load 100 %4) C 198 195 195 195Flue gas mass flow rate, oil, partial load 60 %5)

5) Relative to fuel oil HEL, Hi = 11.86 kWh/kg

kg/s 0.2651 0.3049 0.3571 0.4725Flue gas mass flow rate, oil, full load 100 %5) kg/s 0.4418 0.5082 0.5952 0.7875Flue gas mass flow rate, gas, partial load 60 %6)

6) Relative to natural gas H/L, Hi = 9.03 - 10.03 kWh/m

kg/s 0.2671 0.3089 0.36 0.4761Flue gas mass flow rate, gas, full load 100 %6) kg/s 0.4451 0.5148 0.5999 0.7935CO2 content, oil % 13 13 13 13CO2 content, gas % 10 10 10 10Pressure loss on the hot gas side mbar 7.25 7.74 7.13 9.17Draught required Pa 0 0 0 0Maximum permissible temperature for safety temperature limiter7)

7) STB 120C only possible with Logamatic 4212 and 4324, otherwise STB 110C

C 120 120 120 120

Maximum operating pressure (boiler) bar 6 6 6 6CE-designation, product ID CE 101513Table 3 Specification and dimensions Logano SK755 1040 kW to 1850 kWPD SK655/755 6 720 810 010 (2013/10)12

2 Technical description2.5 Characteristics2.5.1 Pressure loss on the water sideThe pressure loss on the water side is the pressure differential between the boiler flow and return connections. The pressure loss on the water side depends on the VK/RK connector size and the heating water flow rate.

Fig. 9 Pressure loss on the water side Logano SK655/SK755

pH Pressure lossVH Heating water flow rate1 SK655: 120 kW2 SK655: 190 kW, 250 kW, 300 kW3 SK655/SK755: 360 kW, 420 kW4 SK755: 500 kW, 600 kWCalculation example for SK655 250 kW:Given T = 15 K c = 4.19 kJ/kg K DensityWater = approx. 1000 kg/m3

PH calculated as follows:

Result m = 14320 kg/h

Result The intersection of the straight line 2 and VH = 14.3

m3/h results in PH = 35 mbar

Fig. 10 Pressure drop on the water side Logano SK755

pH Pressure lossVH Heating water flow rate1 SK755: 730 kW, 820 kW, 1040 kW, 1200 kW2 SK755: 1400 kW3 SK755: 1850 kW

1

10

100

100101VH [m3/h]

pH [mbar]

1 2 3 4

6 720 640 417-04.2T

Q m c T=

m Qc T--------------------=

m 250 kW4,19 kJ/kg K 15 K------------------------------------------------------------ 3600 s/h=

VH14320 kg/h1000 kg/m3----------------------------------- 14,3 m3/h= =

1

10

100pH [mbar]

100010010VH [m3/h]

1 2 3

6 720 640 417-05.2TPD SK655/755 6 720 810 010 (2013/10) 13

2 Technical description2.5.2 Boiler efficiencyThe boiler efficiency K identifies the ratio between the rated output and the rated heat input. It is shown subject to the average boiler water temperature and the boiler output.

Fig. 11 Boiler efficiency subject to the average boiler water temperature (average value for the complete model range) - LoganoSK655

Hi Efficiency, net calorific valueK Average boiler temperature1 Boiler efficiency at stage 1 (partial load 60 %)2 Boiler efficiency at stage 2 (full load 100 %)Calculation example for average boiler water temperature:

K Average boiler temperatureTRK Return temperatureTVK Flow temperature

Fig. 12 Boiler efficiency subject to the average boiler water temperature (average value for the complete model range) - LoganoSK755

Hi Efficiency, net calorific valueK Average boiler temperature1 Boiler efficiency at stage 1 (partial load 60 %)2 Boiler efficiency at stage 2 (full load 100 %)

Fig. 13 Boiler efficiency and flue gas temperature subject to the boiler load at an average boiler water temperature of 70 C - Logano SK655

Hi Efficiency, net calorific valueQ/Qmax Relative boiler loadA Flue gas temperature1 Boiler efficiency2 Flue gas temperature

Fig. 14 Boiler efficiency and flue gas temperature subject to the boiler load at an average boiler water temperature of 70 C - Logano SK755

Hi Efficiency, net calorific valueQ/Qmax Relative boiler loadA Flue gas temperature1 Boiler efficiency2 Flue gas temperature

The minimum average boiler temperatures for the examples in Fig. 11 and 12 at = 10 K are: 55 C for oil combustion 65 C for gas combustion

90

91

92

93

94

95

96

50 60 70 80K [C]

1

2

Hi [%]

6 720 640 417-06.2T

KTVK TRK

2---------------------------------=

90

91

92

93

94

95

96

50 60 70 80K [C]

1

2

Hi [%]

6 720 640 417-08.2T

90

92

94

96

98

0 10 20 30 40 50 60 70 80 90 100100

120

140

160

180

200

Q/Qmax [%]

A [C]

1

6 720 640 417-07.2T

2

Hi [%]

90

92

94

96

98

0 10 20 30 40 50 60 70 80 90 100100

120

140

160

180

200

Q/Qmax [%]

A [C]

1

6 720 640 417-33.2T

2

Hi [%] PD SK655/755 6 720 810 010 (2013/10)14

2 Technical description2.5.3 Standby loss and flue gas temperatureThe standby loss is part of the rated heat input that is required to achieve the specified boiler water temperature. The cause of this loss is the cooling down of the boiler through radiation and convection during the standby time (burner idle time).

Radiation and convection result in part of the output being transferred continuously from the boiler surface to the ambient air. In addition to this surface loss, the boiler can also cool down to a lesser degree through the chimney draught. The flue gas temperature depends on the average boiler water temperature and the boiler load.

Fig. 15 Standby loss and flue gas temperature, subject to the average boiler water temperature - Logano SK655

qB Standby lossA Flue gas temperatureK Average boiler temperature1 Flue gas temperature (full load 100 %)2 Standby loss3 Flue gas temperature (partial load 60 %)

Fig. 16 Standby loss and flue gas temperature, subject to the average boiler water temperature - Logano SK755

qB Standby lossA Flue gas temperatureK Average boiler temperature1 Flue gas temperature (full load 100 %)2 Standby loss3 Flue gas temperature (partial load 60 %)

100

120

140

160

180

200

0

0,1

0,2

0,3

0,4

50 60 70 80K [C]

qB [%]

2

3

6 720 640 417-09.2T

1

A [C]

qB [%] A [C]

K [C]0

0,1

0,2

50 60 70 80100

120

140

160

180

200

3

2

1

6 720 640 417-45.2TPD SK655/755 6 720 810 010 (2013/10) 15

3 Burner3 Burner

3.1 Burner selection Either pressure-jet oil or gas burners can be used with the Logano SK655 and SK755 steel boilers. The pressure-jet oil burners must be approved to EN 267, and the pressure-jet gas burners to EN 676. 2-stage or modulating burners can be used.When selecting a burner take into account that the pressure drop on the hot gas side must be overcome reliably. When positive pressure at the flue outlet is required (sizing of the flue system), this must be taken into consideration in addition to the pressure drop on the hot gas side.To make engineering and installation easier, burners and drilled burner plates are available as accessories for the Logano SK655 and SK755 boilers. The boilers are supplied with a dummy plate.

3.2 Burner requirementsObserve the installation instructions issued by the burner manufacturer where the burner installation is concerned.

Fig. 17 Burner installation dimensions

DFR Combustion chamber diameter (dimensions page 7 to page 12)

DMB Maximum diameterLFR Combustion chamber length

(dimensions page 7 to page 12)T Burner door depth

(dimensions page 7 to page 12)1) The blast tube must protrude beyond the lining

in the burner door.

For further details regarding these burners and associated burner plates, see the current Buderus heating equipment catalogue. The selection of a suitable burner for the specific project can be discussed in detail with the Buderus sales office.

Boiler sizeMaximum diameter

DMB[kW] [mm]Logano SK655120 130190 240250 240300 240360 290Logano SK755420 290500 290600 290730 350820 3501040 3501200 3501400 3501850 350Table 4 Burner dimensions for Logano SK655 and SK755

DMB

6 720 640 417-10.1il

DFR

T

LFR

1)PD SK655/755 6 720 810 010 (2013/10)16

4 Regulations and operating conditions4 Regulations and operating conditions

4.1 Extracts from the regulationsThe Logano SK655 and SK755 steel boilers comply with the requirements of EN 303 and EN 14394 and are approved up to 120 C according to the Pressure Equipment Directive. They are suitable for heating systems in line with the requirements to EN 12828 and the additional requirements to EN 12953-6.Observe the following regarding creation and operation of the system: Standard building regulations Statutory regulations Country-specific regulationsInstallation, oil and gas connection, flue gas connection, commissioning, power supply, maintenance and repair work must only be carried out by authorised contractors.

ApprovalThe local gas supply utility may need to be notified of and approve the installation of a steel boiler with gas

burner. We recommend clarifying the match between boiler and flue system with the relevant bodies at the planning stage. Where required, inform your local flue gas inspector prior to commissioning. It may be necessary to obtain a permit for the flue system at regional level.

Annual inspection and demand-dependent maintenanceTo ensure functional reliability and energy quality, an inspection by a heating contractor is recommended at least annually. If any condition requiring maintenance work is identified in the course of an inspection, that maintenance work must be carried out as required. We recommend to system users to enter into a maintenance and inspection contract with a heating contractor or the burner manufacturer.

4.2 Pressure Equipment Directive (PED) and Health & Safety at Work Act [Germany]4.2.1 AREA OF APPLICATIONThe Pressure Equipment Directive applies to safety temperatures > 110 C; i.e. a boiler equipped with a high limit safety cut-out 110 C is excluded from the provision of the Pressure Equipment Directive and from

the Health & Safety at Work Act [Germany] where the requirements for products that must be supervised is concerned.

4.2.2 Categories in accordance with the Pressure Equipment Directive 97/23/ECThe Pressure Equipment Directive identifies four categories, split according to the respective pressure:volume product, into which boilers fall.

+ Applicable Not applicable

Boiler size Category I Category II Category III Category IV

p V 50 p V 200 p V 1000 p V > 1000V > 1000 or p V > 3000

[kW]Logano SK655120 + 190...360 + Logano SK755420...500 + 600...1850 +Table 5 Categories in accordance with the Pressure Equipment Directive 97/23/EC PD SK655/755 6 720 810 010 (2013/10) 17

4 Regulations and operating conditions4.2.3 Health & Safety at Work Act [Germany] regarding steam and hot water boilersThe Health & Safety at Work Act [Germany] enacted on the 3 October 2002 and applicable to hot water and steam boiler systems as of 1 January 2003 specifies demanding requirements, particularly for boilers in category III and category IV.

Reservation with regard to granting permission (paragraph 13 BetrSichV) [Germany] Assembly, installation and the operation of category IV boilers require permission from the relevant authority [Germany].

Inspection prior to commissioning (paragraph 14 BetrSichV)Boilers category I and II can be checked in situ, i.e. as part of the system, by an authorised person (master heating system builder). Boilers in categories III and IV

must be checked by an authorised supervisory body in situ, prior to commissioning.

Repeat inspections (paragraph 15 BetrSichV)Boilers in category III with a pressure:volume product p V greater than 1000 and boilers in category IV must be checked regularly by an authorised supervisory body in situ: External inspection no later than after 12 months Internal inspection no later than after three years Strength test no later than after nine yearsThe test intervals must be determined by the system user based on a safety-technical assessment, the result of which must be checked by an authorised supervisory body.

4.2.4 Overview of the Health & Safety at Work Act [Germany]

+ required not required

4.3 Operating conditions4.3.1 Operating requirementsThe operating conditions listed in tab. 7 are part of the warranty conditions for Logano SK655 and SK755 steel boilers. These operating conditions are ensured through

a suitable hydraulic circuit and boiler circuit control (hydraulic connection, page 28).

4.3.2 Operating conditions

Reservation with regard to granting permission

Inspection prior to commissioning

Repeated inspections

13 14 15Boiler category I (up to 50 bar l) +1)

1) May be carried out by an authorised person (e.g. master heating system builder). Deviations from the setting of deadlines mentioned above are also possible. The deadlines are generally set after the risk assessment and the technical safety assessment.

+1) Boiler category II (up to 200 bar l) +1) +1) Category III boilers (up to 1000 bar litres) + +1) Category III boilers (> 1000 bar litres) + +Category IV boilers (> 3000 bar litres) + + +

Table 6 Overview of the Health & Safety at Work Act [Germany]

Boiler operating conditions

Logano

Minimum flow rate Minimum return temperature in C

With operating interruptions

With oil combustion With gas combustionTwo-stage

burnerModulating

burnerTwo-stage

burnerModulating

burnerIn conjunction with a Logamatic control unit for modulating low temperature operationSK655

SK755

No requirements1)

1) Ensure that the return temperature sensor FV/FZ is always surrounded by water.

50 50 60 60 No requirements

The boiler is shut down automatically by the

Logamatic control unitIn conjunction with a Logamatic control unit for constant boiler water temperatures, e.g. Logamatic 4212 with ZM427, or with auxiliary external control unitSK655

SK755

No requirements1) 50 50 60 60 No requirements

Table 7 Operating conditions for Logano SK655 and SK755PD SK655/755 6 720 810 010 (2013/10)18

4 Regulations and operating conditions4.4 FuelOperation with fuel oilThe Logano SK655 and SK755 steel boilers can be operated with fuel oil EL to DIN 51603. All boilers, without restriction, are also suitable for rapeseed oil. Pressure-jet burners for rapeseed oil can be obtained from burner manufacturers on request.

Operation with gasAll steel boilers are suitable for natural gas E, natural gas LL or LPG. Observe the burner manufacturer's details.The gas quality must comply with the requirements of the DVGW Code of Practice G 260 [Germany]. To be able to adjust the gas throughput, install a gas meter that can be checked even in the lower load range of the burner. This also applies to LPG systems.Biogas (e.g. gas from waste disposal or sewerage works) can also be used. There are special operating conditions for this which must be observed. Pressure-jet burners for biogas are available from burner manufacturers on request.

Additional operating conditions for operation with biogasThe following operating conditions must be met: Operate boiler at constant temperature Never permit operating interruptions Maintain a minimum return temperature above the

dew point (in this case at least 68 C), i.e. return temperature raising measures

Ensure minimum boiler water temperature of 83 C Clean and maintain the boiler regularly, possibly clean

chemically and then preserve Combustion of biogas/waste gas (quality in line with

DVGW G262, table 3): Proportion of sulphur and sulphur compounds in

the gas up to a maximum of 1500 mg/m3 (approx. 0.1 % by volume)

Proportion of chlorine and chlorine compounds in the gas up to a maximum of 50 mg/m3

Proportion of fluoride and fluoride compounds in the gas up to a maximum of 25 mg/m3

In view of the high degree of corrosiveness, and in variance from Fig. 8.5 of our general sales, delivery and payment terms, the warranty period is limited to 2 years.

4.5 Water treatmentAs pure water cannot be used for heat transfer, water quality is important. Poor water quality can lead to limescale formation and corrosion. Consequently, particular attention must be paid to water quality, water treatment and, above all, continuous water monitoring. Water treatment is an essential factor in ensuring trouble-free operation, availability, a long service life and the efficiency of the heating system.

4.5.1 Definition of termsLimescale formation is the formation of hard deposits on walls inside hot water heating systems. These deposits are made up of substances contained in the water, primarily calcium carbonate.Heating water is any water used for heating purposes in a hot water heating system.Fill water is the water used to fill the entire heating system on the heating water side for the first time and with which it is then heated up.Top-up water is any water used to top up the system on the heating water side after the first time it is heated up.Operating temperature is the temperature captured at the flow connector of the heat appliance in a hot water heating system when operating correctly.Water volume Vmax is the maximum volume of untreated fill and top-up water in m3 that may be introduced into the system over the entire service life of the boiler.Corrosion-inhibiting sealed unvented systems are heating systems in which no significant amount of oxygen ingress into the heating water is possible.

4.5.2 Prevention of corrosion damageIn most cases, corrosion plays only a minor role in heating systems. That is based on the fundamental requirement that the system is a corrosion-inhibiting sealed unvented system, i.e. one that prevents a continuous ingress of oxygen.Continuous ingress of oxygen leads to corrosion and can thus cause rusting and the formation of rust sludge. Sludge formation can not only cause blockages and therefore a diminished heat supply but also deposits (similar to limescale deposits) on the hot surfaces of heat exchangers.The most important factor with regard to ingress of oxygen is generally pressure maintenance and, in particular, the function, correct sizing and adjustment (pre-charge pressure) of the expansion vessel. Check the function and pre-charge pressure annually. If continuous ingress of oxygen cannot be prevented (e.g. due to plastic pipes that are permeable to oxygen) or if the system cannot be designed as a sealed unvented system, anti-corrosion measures such as the addition of approved chemical additives or system separation by means of a heat exchanger are necessary.Oxygen binding agents can be used, for example, to bind the oxygen.PD SK655/755 6 720 810 010 (2013/10) 19

4 Regulations and operating conditionsThe pH value of untreated heating water should be between 8.2. and 10.0. It should be noted that the pH value will change following commissioning, especially due to the loss of oxygen and limescale deposition. We recommend checking the pH value after several months of heating system operation.The water can be alkalised by the addition of trisodium phosphate, if necessary.

4.5.3 Prevention of damage through scale formationVDI 2035-1 Prevention of damage to hot water central heating systems through limescale formation, issue 12/2005 applies to potable water systems to DIN 4753 and hot water heating systems to DIN 12828 with a design operating temperature of up to 100 C.

One of the aims of the current edition of VDI 2035-1 is to simply its application. For this reason, standard values for the amount of limescale-forming substances (total alkaline earths) for specified heat output ranges are recommended. The specifications are based on practical

experience that shows that damage due to limescale formation is dependent on the total heat output, the system volume, the cumulative volume of fill and top-up water used over the service life of the system and the boiler design.The details given below in respect of Buderus boilers are based on many years of experience and service life tests, and specify the maximum cumulative amount of fill and top-up water subject to output, water hardness and boiler material. This ensures compliance with the aims of VDI 2035-1 Prevention of damage through limescale formation in hot water heating systems.Warranty claims in respect of Buderus boilers are only valid in conjunction with the requirements specified herein and a fully completed system log.

4.5.4 Requirements of the fill and top-up waterTo protect boilers against limescale damage over their entire service life and to ensure trouble-free operation, the total amount of limescale-forming substances in the fill and top-up water in heating systems must be restricted.Therefore, the fill and top-up water has to meet certain requirements that are dependent on the total boiler output and the resulting total volume of water in the heating system ( tab. 8).The permissible amount of water based on the fill water quality can be determined simply with the aid of the graphs in Fig. 18, page 21, and Fig. 19, page 22, or with a calculation method to determine the permissible amounts of fill and top-up water ( chapter 4.5.7, page 23).

If additives or antifreeze (where approved by Buderus) are used in the heating system, check the heating water regularly in accordance with the manufacturer's instructions. Carry out all necessary corrections ( chapter 4.5.8, page 23).

For operating temperatures > 100 C water treatment is always required, regardless of the boiler size (total hardness in the heating and boiler circuit and fill and top-up water < 0.11 dH).

total boiler output Requirements regarding water hardness and the amount of fill and top-up water Vmax[kW]Q 50 Vmax: no requirements50 Q 600 Vmax: calculate according to diagrams in Fig. 18 and Fig. 19 as well as formula 1Q > 600 Water treatment is generally required (total hardness to < 0.11 dH)Regardless of output For systems with very large water content (> 50 l/kW), water should generally be

treated.Table 8 Requirements for fill and top-up water for boilers made from ferrous materialPD SK655/755 6 720 810 010 (2013/10)20

4 Regulations and operating conditions4.5.5 Application limits for boilers made from ferrous materials

Fig. 18 Boilers 50 kW to 150 kW made from ferrous materialsHW Water hardnessVmax Maximum fill and top-up water over the entire

service life of the boiler 1 Boilers up to 150 kW2 Boilers up to 130 kW3 Boilers up to 110 kW

ExampleGiven: Boiler output Q = 105 kW System volume VA = approx. 1.1 m3

Result: At a water hardness level of 22dH, the maximum

amount of fill and top-up water is approx. 1.8 m3. This system can be filled with untreated tap water.

HW [dH]6 720 640 417-35.2T

Vmax [m3]

1

2

0

2

4

6

8

10

12

0 5 10 15 20 25 30

3

Measures are required above these output curves; fill with untreated tap water below the curves. In multi-boiler systems (< 600 kW total boiler output) the output curves for the smallest single boiler apply.

One suitable measure for boilers made from ferrous material is, for example, total softening ( current Buderus catalogue, technical customer service, provision of mobile water treatment systems).PD SK655/755 6 720 810 010 (2013/10) 21

4 Regulations and operating conditionsFig. 19 Boilers > 150 kW to 600 kW made from ferrous materials

HW Water hardnessVmax Maximum fill and top-up water over the entire

service life of the boiler 1 Boilers up to 600 kW2 Boilers up to 500 kW3 Boilers up to 400 kW4 Boilers up to 300 kW5 Boilers up to 250 kW6 Boilers up to 200 kW

ExampleGiven: Boiler output Q = 295 kW System volume VA = approx. 7.5 m3

Result: At a water hardness level of 18dH, the maximum

amount of fill and top-up water is approx. 6.0 m3. The amount of fill water is already greater than the

permissible amount of fill and top-up water. Fill the system with treated water.

0

5

10

15

20

25

30

35

40

45

0 5 10 15 20 25 30HW [dH]

Vmax [m3]

6 720 640 417-36.2T

1

3

4

5

6

2

Measures are required above these output curves; fill with untreated tap water below the curves. In multi-boiler systems (< 600 kW total boiler output) the output curves for the smallest single boiler apply.

One suitable measure for boilers made from ferrous material is, for example, total softening ( current Buderus catalogue, technical customer service, provision of mobile water treatment systems).PD SK655/755 6 720 810 010 (2013/10)22

4 Regulations and operating conditions4.5.6 Recording the amounts of fill and top-up waterFor heating systems > 50 kW, it is compulsory to use a water meter and to keep an operator's log.You will find the log with the technical documents supplied with Buderus boilers. Warranty claims in respect of Buderus boilers are only valid in conjunction with the requirements specified herein and a fully completed log.

4.5.7 Calculation to determine the permissible amounts of fill and top-up water

The fill and top-up water has to meet certain requirements depending on the total boiler output and the resulting water volume of a heating system.Use the following formula to calculate the maximum amount of fill water for heating systems 600 kW that may be introduced without treatment:

F. 1 Calculation of the maximum amount of water that may be introduced without treatment

Ca(HCO3)2 Concentration of calcium hydrogen carbonate in mol/ m

Q Boiler output in kW (for multi-boiler systems, the output of the smallest boiler)

Vmax Maximum quantity of untreated fill and top-up water that may be introduced over the whole service life of the boiler in m

ExampleCalculation of the maximum permissible amount of fill and top-up water Vmax for a heating system with a total boiler output of 420 kW. The analysis values for carbonate hardness and calcium hardness are quoted in the older unit dH.Carbonate hardness: 15.7 dHCalcium hardness: 11.9 dHFrom the carbonate hardness, we obtain:Ca (HCO3)2 = 15.7 dH 0.179 = 2.8 mol/m3

From the calcium hardness, we obtain:Ca (HCO3)2 = 11.9 dH 0.179 = 2.13 mol/m3

The lower of the two values calculated from the calcium and carbonate hardness is the definitive figure for calculating the maximum permissible water volume Vmax.

4.5.8 Chemical additives in the heating waterIf plastic pipes that are permeable to oxygen are used in underfloor heating systems, the corrosion process can be prevented by adding chemicals into the heating water. In such cases, ask the manufacturer of these chemical additives for a certificate verifying the compatibility with different parts of the system and the materials used in the heating system.

Using antifreezeFor decades now, antifreeze based on glycol has been used in heating systems, such as Antifrogen N made by Clariant (sold via the Buderus wholesale network).The use of alternatives is acceptable, subject to such products being the equivalent of Antifrogen N.Observe the information supplied by the antifreeze manufacturer. Follow the manufacturer's details regarding mixing ratios.The specific thermal capacity of Antifrogen N antifreeze is lower than the specific thermal capacity of water. To enable the transfer of the required heat output, increase the required flow rate accordingly. This should be taken into account when sizing the system components (e.g. pumps) and the pipework. In addition, a higher flue gas temperature results, lowering the boiler efficiency.As the heat transfer medium has a higher viscosity and density than water, take the higher pressure drop through the pipework and other system components into account. Check the resistance of all plastic or non-metallic components in the system separately.

4.5.9 Combustion airWhere combustion air is concerned, ensure that it is not heavily contaminated with dust and contains no halogenated compounds. Otherwise there would be a risk of damage to the combustion chamber and the secondary heating surfaces.Halogen compounds are highly corrosive. These are contained, for example, in spray cans, thinners, cleaning & degreasing agents and in solvents.Design the combustion air supply so that, for example, no extract air is drawn in from chemical cleaners or paint shops. Special requirements apply to the supply of combustion air in the installation room ( page 50).

Vmax 0,0626Q

Ca HCO3 2------------------------------------=

Vmax 0,0626420 kW

2,13 mol/m3------------------------------------- 12,3 m3= =

Chemical additives that have not been certified by the manufacturer as harmless must not be used.PD SK655/755 6 720 810 010 (2013/10) 23

5 Heating controls5 Heating controls

5.1 Logamatic 4000 control systemA control unit is required to operate the boilers. The Buderus-Logamatic control systems are of modular design. This enables the selection of well-matching and economical units for all applications and stages of development in the proposed heating system.Subject to requirements and the heating system layout, the following are available for selection as the boiler control system: Logamatic 4212 control unit (ZM427 for boiler

operating conditions) Logamatic 4321 und 4322 control units Logamatic 4324 control unit for high flow

temperature Logamatic4411 control panel systemA burner control panel may be required for the contactors controlled by the control unit. Alternatively, the contactors can be integrated into the Buderus control panel system.

5.1.1 Logamatic 4212 control unitThe conventional Logamatic 4212 control unit is suitable for operation with a constant boiler water temperature. Where a higher-ranking control is used, e.g. a Logamatic 4411 (DDC systems and building management systems), the Logamatic 4212 control unit transfers the burner switching commands to the burner.The standard equipment contains the safety equipment for a 2-stage burner operation. Boiler circuit actuators and boiler circuit pumps can be switched with the ZM427 auxiliary module, thereby safeguarding the boiler operating conditions. Furthermore, the ZM427 module facilitates an enabling of the burner stages with a higher-ranking control using floating contacts.

5.1.2 Logamatic 4321 and Logamatic 4322 control units

The Logamatic 4321 control unit enables the low temperature operation of these boilers and provides the operating conditions in conjunction with the 2-stage or modulating burner in a single boiler system.Up to eight heating circuits with actuator can be controlled with corresponding function modules. The range of functions also includes the complete boiler circuit control with optional switching of a boiler circuit actuator and one boiler circuit pump.2-boiler and 3-boiler systems require a Logamatic 4321 control unit for the first boiler that functions as the master device and a Logamatic 4322 control unit as the lag appliance for each of the second and third boilers. The combination of devices with corresponding function modules can control up to 22 heating circuits with actuator.

5.1.3 Logamatic 4324 control unit for high flow temperatures

The Logamatic 4324 digital control unit can be used for permitted floor-standing oil and gas boilers, which are allowed to be operated up to a max. shutdown temperature (high limit safety cut-out) of 120 C. Single stage, two-stage and modulating burners, as well as dual-fuel burners, can be activated. Multi-boiler systems can also be controlled with the FM459 strategy module in the Logamatic 4324 control unit. For this, each boiler must have a Logamatic 4324 control unit.The maximum possible control temperature (boiler set temperature) is 105 C.

5.1.4 Logamatic4411 control panel systemThe Logamatic 4411 control panel system from Buderus is the comprehensive solution, representing advanced control technology for complex heating systems that require a system-specific control.The local sales office assists with the engineering and supplies optimum system solutions for each individual case. This also applies to programmable logic controls (DDC systems) and building management systems.

5.2 Logamatic telecontrol systemThe Logamatic telecontrol system is the ideal addition to all Buderus control systems. It comprises several software and hardware components and enables heating contractors to provide even better customer support and services via a powerful remote control facility. It can be used in rental apartment buildings, holiday homes as well as in medium and large heating systems. The Logamatic telecontrol system is suitable for remote monitoring, parameter setting and fault diagnosis in heating systems. It offers ideal conditions for heat supply concepts and maintenance and inspection contracts.

The technical guide Modular Logamatic 4000 control system contains more detailed information on the Logamatic 4212, 4321, 4322 and 4324 control units.

The technical guide Logamatic Telecontrol system contains more detailed information.PD SK655/755 6 720 810 010 (2013/10)24

5 Heating controls5.3 Control unit settings

The purpose of optimum control unit settings is to achieve long burner runtimes and avoid rapid temperature changes in the boiler. Gentle temperature changes result in a longer service life of the heating system. The control strategy of the control unit must therefore be prevented from becoming ineffective, i.e. through the boiler water controller switching the burner on and off. Maintain the minimum differential between the

selected shutdown temperature of the high limit safety cut-out, the temperature controller, the maximum boiler water temperature and the maximum temperature demand ( tab. 9, 10 and 11 page 25).

Select set temperatures for the heating circuits that are as low as possible.

Start heating circuits (e.g. when starting up in the mornings) at 5-minute intervals.

Settings for boiler water controller and maximum boiler water temperatureThe boiler water controller is only designed to provide emergency operation with an adjustable boiler water temperature if the control electronics fail. In standard control mode, the function of the boiler water controller is provided by the maximum boiler water temperature. The maximum boiler water temperature can be selected in the control unit in the "Boiler parameters" menu, under menu item "Max. shutdown temperature".

We recommend using a Buderus Logamatic control unit from the 4000 series.

The maximum boiler water temperature can be selected on the control unit (MEC) in the "Boiler parameters" menu, under menu item "Max. shutdown temperature".

If the Buderus Logamatic 4000 control unit is used, burner modulation in standard mode is not enabled for 3 minutes. Never modulate upwards more quickly than this.

Adjustable parameter (max. temperature)

Logamatic 4321/4322

High limit safety cut-out (STB)1)

1) Set the high limit safety cut-out and temperature controller as high as possible, but ensure the settings are at least 5 K apart.

110 C

at least 18 K

minimum 5 K

Temperature controller (TR)1)

105 C minimum 6 K

Max. boiler water temperature

99 C minimum 7 K

Max. temperature demand2) of heating circuit3) and DHW4)

2) Both temperature demands must always be at least 7 K under the maximum boiler water temperature.

3) The temperature demand of heating circuits equipped with an actuator is composed of the set flow temperature and the "Boiler rise" parameter in the heating circuit data menu.

4) The temperature demand of DHW heating is composed of the set DHW temperature and the "Boiler rise" parameter in the DHW menu.

92 C

Table 9 Adjustable parameter Logamatic 4321/4322

Caution: the Logamatic 4324 control unit has its own applicable minimum safety distances.

Adjustable parameter (max. temperature) Logamatic 4324High limit safety cut-out (STB)1)

1) Set the high limit safety cut-out and temperature controller as high as possible, but ensure the settings are at least 5 K apart.

120 C minimum 5 K

Temperature controller (TR)1)2)

2) The TR does not function on the Logamatic 4324 in automatic mode.

105 C minimum 6 K

Max. boiler water temperature

112 C minimum 7 K

Max. temperature demand3) of heating circuit4) and DHW5)

3) Both temperature demands must always be at least 7 K under the maximum boiler water temperature.

4) The temperature demand of heating circuits equipped with an actuator is composed of the set flow temperature and the "Boiler rise" parameter in the heating circuit data menu.

5) The temperature demand of DHW heating is composed of the set DHW temperature and the "Boiler rise" parameter in the DHW menu.

105 C

Table 10 Adjustable parameter Logamatic 4324

Adjustable parameter (max. temperature)

Logamatic 4212 with ZM427

High limit safety cut-out (STB)1)

1) Set the high limit safety cut-out and temperature controller as high as possible, but ensure the settings are at least 5 K apart.

120 C minimum 5 K

Temperature controller (TR)

105 C

Table 11 Adjustable parameter Logamatic 4212PD SK655/755 6 720 810 010 (2013/10) 25

5 Heating controlsControl unit settings

Fig. 20 Control unit settings, example for Logamatic 4321

[1] High limit safety cut-out[2] Control thermostat[3] F1, F2 Fuse[4] MEC[5] Burner emergency operation switch[6] On/Off switch Select temperatures ( tab. 9, 10 and 11 page 25) at

high limit safety cut-out [1] in the control unit and at temperature controller [2].

Select the maximum boiler water temperature at the MEC [4].

Example DHW demand:Sum of the set DHW temperature (60 C) the "Boiler rise" parameter (20 C) in the "DHW" menu:60 C + 20 C = Maximum temperature demand 80 C

Example heating circuits:Sum of the set temperature of the heating circuit with mixer with the highest temperature required (70 C) and the "Boiler rise" parameter (5 C) in the "Heating circuit data" menu:70 C + 5 C = Maximum temperature demand 75 C

Notes on setting third party control units

The third party control unit (building management system or PLC controllers) must ensure a maximum internal boiler water temperature that is sufficiently different from the high limit safety cut-out. It must also be ensured that the control electronics rather than the boiler water controller switch the burner on and off.

The control unit must ensure that the burner is switched to low load before being shut down. If this is not observed, the safety shut-off valve (SAV) in the gas train may lock out.

Select control equipment that allows a gentle start-up with a time delay when the system is cold.

After the burner demand, an automatic timer (for example) should limit the burner to low load for a period of approx. 180 seconds. This prevents uncontrolled starting and stopping of the burner when the heat energy demand is restricted.

It must be possible to show the number of burner starts on the control unit used (or alternatively on the burner control unit).

The maximum temperature demand is not a value that is directly selected. The maximum temperature demand is composed of the set temperature and the rise.

All maximum temperature demands must always be 7 K below the maximum selected boiler water temperature.

1 2 3 4 5 66 720 806 032-47.2T

NOTICE: System damage due to incorrect sensor position!The sensors of the high limit safety cut-out (STB) and of the temperature controller (TR) must be fitted at the installation location on the top of the boiler. In the case of third party control units,

match the sensor immersion sleeve to the diameter of the sensors used.

Do not change the length of the immersion sleeve.

Unit ValueTemperature control unit s 40Monitor/limiter s 40Minimum difference between burner on and off temperatures

K 7

Table 12 CONDITIONS OF USEPD SK655/755 6 720 810 010 (2013/10)26

6 DHW heating6 DHW heating

6.1 Systems for DHW heatingThe Logano SK655 and SK755 steel boilers can also be used to provide DHW heating. The Buderus Logalux DHW cylinders, which are matched to the boiler output, are suitable. These are available as vertical and horizontal versions in different sizes with 150 l to 6000 l capacity. Depending on the application, they are equipped with an internal indirect coil or an external heat exchanger ( Fig. 21 and fig. 22).

Fig. 21 DHW heating according the cylinder principle with internal indirect coils

Fig. 22 DHW heating according to the primary store principle with external heat exchangers

Key to Fig. 21 and Fig. 22:AW Hot water outletEK Cold water inletRH Heating medium return (to the boiler)RS Cylinder returnVH Heating medium flow (from the boiler)VS Cylinder flowThe cylinders can be used singly or in combination with other cylinders. With the primary store system, different cylinder sizes and different heat exchanger sets can be combined. System solutions are therefore available for any demand and many applications.

6.2 DHW temperature controlThe DHW temperature is set and regulated either by means of a module inside the boiler control unit or via a separate control unit dedicated to DHW heating. The control units for DHW heating are specifically matched to the heating control unit and offer many application options. For more detailed information on this, see the technical guides Sizing and selecting DHW cylinders and Modular control system Logamatic 4000.

EKRS

VS

AW

6 720 640 417-11.2T

EKRH

VH

AW

6 720 640 417-12.2TPD SK655/755 6 720 810 010 (2013/10) 27

7 System examples7 System examples

7.1 Information regarding all system examples

The examples in this section show the options for the hydraulic connection of the Logano SK655 and SK755 steel boilers without safety criteria.For detailed information regarding the number, equipment level and control of the heating circuits as well as on the installation of DHW cylinders and other consumers, see the respective technical guides.The DHW heating systems shown can be implemented as DHW cylinder or primary store system.Each system example is a non-binding recommendation for a certain version of the heating system. Practical implementation is subject to currently applicable technical rules.Information regarding further options for system layout and engineering aids are available from the staff in Buderus sales offices.

7.1.1 Hydraulic connection

Steps for controlling the return and boiler water temperatureThe Buderus Logamatic 4321, 4322, 4324 and 4212 control units with the ZM427 auxiliary module, together with the corresponding boiler or heating circuit actuators, ensure the required minimum return temperature.Alternatively, the Logamatic 4321, 4322 and 4324 control units enable operation with minimum boiler water temperature.

For demand-dependent system suggestions with explanations of the respective functions and application limits, see page 32 to page 48.

Heating circuit pumpsSize pumps in central heating systems in accordance with current technical rules.

Dirt trapsDeposits in the heating system can lead to local overheating, noise and corrosion. Any resulting boiler damage falls outside the warranty obligations.To remove dirt and sludge, flush an existing heating system thoroughly prior to installing and commissioning a boiler. In addition, we recommend the installation of dirt traps or a blow-down facility.Dirt traps retain contaminants and thereby prevent operating faults in control devices, pipework and boilers. Fit these near the lowest point of the heating system in an easily accessible position. Clean the dirt traps every time the heating system is serviced.

Position of strategy flow temperature sensorIn multi-boiler systems with strategy flow temperature sensor (FVS), the sensor should be located as close to the boiler system as possible. This rule does not apply if a low loss header is used to provide hydraulic balance. Additional time lag due to long distances between the boiler system and the strategy flow temperature sensor has a negative effect on the control characteristics, especially in the case of boilers with modulating-control burners.

Allow for the temperature sensors required for raising the return temperature in the form of immersion sensors.PD SK655/755 6 720 810 010 (2013/10)28

7 System examples7.1.2 Control systemOperating temperatures should be controlled with the Logamatic control unit taking account of the outside temperature. It is possible to control individual heating circuits in room temperature-dependent mode (with a room temperature sensor in a reference room). For this, the actuators and heating circuit pumps are constantly actuated by the Logamatic control unit. Number and version of the controllable heating circuits are dependent on the selection and equipment level of the control unit. The Logamatic control unit also activates the burner, independently of whether these are 2-stage or modulating pressure-jet burners. Different types of burners can also be combined in multi burner systems. Three-phase burner and three-phase pumps must be electrically connected on site. These are activated by the Logamatic control unit (230 V).

7.1.3 DHW heatingGiven an appropriate design, the DHW temperature control by means of a a Logamatic control unit offers special functions, such as the activation of a DHW circulation pump or thermal disinfection to protect against the growth of legionella bacteria, for example.

7.2 Safety equipment to EN 12828 and EN 12953-6

7.2.1 RequirementsNo claim is made as to the completeness of the diagrams or the corresponding design information for system examples. Each system example is a non-binding recommendation for certain versions of the heating system. The practical implementation is subject to currently applicable technical rules. Safety equipment should be installed in accordance with local regulations.EN 12828 specifies the safety equipment for safety temperatures up to 110 C. For safety temperatures in excess of 110 C refer to EN 12953-6.Furthermore, consider the additional requirements regarding the system operation as specified in the Health & Safety at Work Act. The schematic diagrams in Fig. 23 to Fig. 26 can be used as engineering aids.

For more detailed information, see the technical guides to the control units.

For more detailed information on this subject, see the technical guide Sizing and selecting DHW cylinders.PD SK655/755 6 720 810 010 (2013/10) 29

7 System examples7.2.2 Arrangement of safety equipment to EN 12828 ; operating temperature 105 C; shutdown temperature (high limit safety cut-out) 110 C

Boiler 300 kW; operating temperature 105 C; shutdown temperature (high limit safety cut-out) 110 C direct heating

Fig. 23 Safety equipment to EN 12828 for boilers 300 kW with high limit safety cut-out 110 C

The schematic diagrams show the safety equipment to EN 12828 for the system versions referred to here with no claim to completeness. Practical implementation is subject to currently applicable technical rules.

Boiler > 300 kW; operating temperature 105 C; shutdown temperature (high limit safety cut-out) 110 C direct heating

Fig. 24 Safety equipment to EN 12828 for boilers > 300 kW with high limit safety cut-out 110 C

Key to Fig. 23 and Fig. 24:RK ReturnVK Flow[1] Heat sources [2] Shut-off valve, flow/return[3] Temperature controller (TR)[4] High limit safety cut-out (STB)[5] Temperature capturing facility[6] Diaphragm safety valve MSV 2.5 bar/3.0 bar or[7] Lift spring safety valve HFS 2.5 bar[8] Flash trap; not required in systems > 300 kW if a

high limit safety cut-out (with a limit of 110 C) and a maximum pressure limiter are additionally provided for each boiler instead.

[9] Maximum pressure limiter[10] Pressure gauge[11] Low water indicator (not in systems 300 kW).

Alternatively one minimum pressure limiter or a replacement measure approved by the manufacturer is provided for each boiler

[12] Non-return valve[13] Boiler drain & fill valve (KFE)[14] Expansion line[15] Shut-off valve protected against unintentional

closure, e.g. by sealed cap valve[16] Drain upstream of diaphragm expansion vessel[17] Diaphragm expansion vessel (EN 13831)

1) The maximum achievable flow temperature in combination with Logamatic control units is approx. 18 K below the shutdown temperature (high limit safety cut-out).

2

1110

13156/7

12 1314 15

1617

2 13

RK

VK

51)

41)31)

1 300 kW

6 720 640 417-13.1il

2

119

13156/7

12 1314 15

1617

2 13

RK

VK

8

0,5 %

P

1> 300 kW

10 51)

41)31)

6 720 640 417-14.1ilPD SK655/755 6 720 810 010 (2013/10)30

7 System examples7.2.3 Arrangement of safety equipment to EN 12953-6 ; shutdown temperature (high limit safety cut-out) > 110 C (maximum 120 C for Logano SK655 and SK755)

Shutdown temperature (high limit safety cut-out) > 110 C, example 1 direct heating

Fig. 25 Safety equipment to EN 12953-6 for boilers with high limit safety cut-out > 110 C; example: maintaining pressure via a gas buffer

The figures show the safety equipment to EN 12953-6 schematically for the system versions shown without claim to completeness.The diagrams only show versions where the pressure is maintained via a gas buffer and pressure maintaining pump. See also EN 12953-6 for other versions of pressure maintenance with different types of safety equipment.If the high limit safety cut-out is > 110 C, observe further requirements (e.g. repeat inspections etc.) as specified in the Health & Safety at Work Act [Germany].Practical implementation is subject to currently applicable technical rules. Implementing the system engineering with reference to the responsible supervisory authority is recommended.

Shutdown temperature (high limit safety cut-out) > 110 C, example 2 direct heating

Fig. 26 Safety equipment to EN 12953-6 for boilers with high limit safety cut-out > 110 C; example: maintaining pressure via a pressure maintaining pump

Key to Fig. 25 and Fig. 26:RK Return VK Flow[1] Hot water boiler[2] Maximum pressure limiter [PSZ+A+][3] Pressure display facility[4] Water level controller[5] Flash trap[6] Pressure relief valve[7] Minimum water level limiter [LSZ-A-][8] Temperature limiter [TZA+A+][9] Control thermostat[10] Temperature display facility[11] Fill & sample facility for water level test[12] Shut-off valve locked to prevent unintentional

closing[13] Sealed expansion vessel[14] Minimum pressure limiter [PSZ-A-][15] Non-return valve[17] Shut-off valve (return)[18] Line to the sealed expansion vessel[19] Feed pump[20] Heating facility[22] Pressure maintaining pump[23] Pressure regulator[24] Automatic shut-off valve (closed at zero volt)[25] Water level display[26] Open expansion vessel[27] Pressure maintaining valve - if closed at zero volt or

if the actual pressure is lower than the minimum pressure, item 24 can be omitted

[28] Shut-off valve with option to connect a pressure gauge

[30] Minimum temperature controller (if required)[31] Drainage system

6 720 640 417-15.1il 6 720 640 417-16.1ilPD SK655/755 6 720 810 010 (2013/10) 31

7 System examples7.3 Sizing and installation information7.3.1 Boiler circuit pump in the bypass as shunt pump

Fig. 27 Sample hydraulic circuit for a single boiler system with boiler circuit pump in the bypass for Logano SK655 and SK755

FR Return temperature sensorKR Flow-check valvePK Boiler circuit pumpRK ReturnSR Actuator, return temperature raising facilitySV Pressure relief valveVHK Heating circuit flow rateVK FlowVPK Boiler circuit pump flow rateVSL Safety flow

Boiler circuit pump flow rate VPKThe boiler circuit pump, also known as a shunt pump, is required to control the return temperature (flow past the sensor). The control characteristics can also be optimised using the boiler circuit pump. This makes it possible to minimise switching during the heat-up phase. This results in lower emissions.

F. 2 Calculating the flow rate of the boiler circuit pump

c Specific heat capacityc = 1.16 10-3 kWh/(l K) = 1/860 kWh/(l K)

K Temperature differential for sizing the boiler circuit pump 30 K to 50 K (30 K for optimised heat-up characteristics)

QK Rated output in kWVPK Flow rate of the boiler circuit pump in l/h

Heating circuit flow rate VHK

F. 3 Calculating the flow rate of the heating circuits

c Specific heat capacityc = 1.16 10-3 kWh/(l K) = 1/860 kWh/(l K)

QHK Heating circuit heat input demand in kWR Heating circuit return temperature in CV Heating circuit flow temperature in CVHK Flow rate of the heating circuits in l/h

VK RK

KRPK

SR

90 C

70 C

FR

VHK

VPK

B

C

A

D

E H

F

G

6 720 807 236-06.2T

V PKQK

K c-------------------------=

V HKQHK

V R c------------------------------------------=PD SK655/755 6 720 810 010 (2013/10)32

7 System examplesTotal boiler flow rate VKgesThe boiler circuit pump head results from the following: Boiler pressure drop at the selected flow rate VPK Pipework pressure drop Individual pressure drop values in the boiler circuit

(path: ACDB, Fig. 27)The total boiler flow rate cannot simply be calculated by adding up the individual flow rates, because of the pump and system curves. However, the simple addition is adequate for a rough calculation as an initial estimate.

F. 4 Calculating the total boiler flow rate

VHK Flow rate of the heating circuits in l/hVKges Maximum total flow rate through the boiler in l/

h (approximation)VPK Flow rate of the boiler circuit pump in l/h

ExampleGiven: Rated output QK = 1200 kW Heating circuit flow temperature V = 90 C Heating circuit return temperature R = 70 C Temperature differential (selected) K = 30 KResult: VPK = 34400 l/h (path: CD, Fig. 27) VHK = 51600 l/h

(paths: CF, DG and EH, Fig. 27) VKges ~ 86000 l/h

(paths: AC and BD, Fig. 27)

Base the sizing of the pipework in the boiler circuit on a flow velocity of 1 m/s to 1.5 m/s.

V Kges V

PK V

HK+PD SK655/755 6 720 810 010 (2013/10) 33

7 System examples7.3.2 Boiler circuit pump as primary circuit pump

Fig. 28 Sample hydraulic circuit for a 2-boiler system with boiler circuit pump as primary circuit pump for Logano SK655 and SK755

FR Return temperature sensorFVS Strategy flow temperature sensorPK Boiler circuit pumpRK ReturnSR Actuator, return temperature raising facilitySV Pressure relief valveVHK Heating circuit flow rateVK FlowVPK Boiler circuit pump flow rateVSL Safety flow

Boiler circuit pump flow rate VPKFor systems with primary circuit pumps (e.g. in the case of low loss headers or non-pressurised distributors) installing the boiler circuit pump into the return is recommended.

F. 5 Formula with sizing factor for estimating the flow rate of the boiler circuit pump in a 1-boiler system

F. 6 Formula with sizing factor for estimating the flow rate of the boiler circuit pump in a 2-boiler system

Size of calculation for formula 5 and formula 6:VHK Flow rate of the heating circuits in l/hVKges Total boiler circuit flow rate in l/hIn 2-boiler systems, distribute the pump rates of the boiler circuit pumps according to the boiler outputs. Where several heating circuits are constantly operated with high flow temperatures and maximum flow rate, the flow rate of each boiler circuit pump should correspond to the flow rate of the heating circuit pumps. For systems with gas condensing boilers, there are special requirements to be followed, e.g. maintaining as low a return temperature as possible. The pump rate of the boiler circuit pump may need to be adjusted to the pump rate of the heating circuits.

Sizing the 3-way valveSize the 3-way valve for the flow rate that has been calculated. When doing so, observe the pressure loss when the valve is fully open, as the control quality is influenced by the proportional pressure loss.

Head of the primary circuit pumpThe boiler circuit pump head results from the following: Boiler pressure drop at the selected flow rate VPK Pipework pressure drop Individual pressure drop values in the boiler circuit

(path: ADEH, Fig. 28)ExampleGiven: Heating circuit heat input demand QHK = 4000 kW Heating circuit flow temperature V = 90 C Heating circuit return temperature R = 70 C Sizing factor (selected) = 1.3 Heating circuit flow rate VHK = 172000 l/hResult: VKges = VHK 1.3 = 172000 l/h 1.3 = 223600 l/h

(paths: CD and EF, Fig. 28)Divide the total flow rate calculated for the boiler circuit side according to the rated outputs (here 50/50 %): Boiler circuit pump flow rate

VPK = 111800 l/h (paths: AC, BG and FH, Fig. 28)

VK RK VK RKAA HH

C D

F

B GB G

E90 C

70 C

FVS

SR1SR2

PK2 PK1

FR2 FR1

VHK

VPK1VPK2

6 720 807 236-07.2T

V Kges, 1 V

HK (1,0 ... 1,2)=

V Kges, 2 V

HK (1,2 ... 1,5)=PD SK655/755 6 720 810 010 (2013/10)34

7 System examples7.3.3 Low loss headerA low loss header (hydraulic balancing) is used to hydraulically separate the boiler circuit and the heating circuits.Installing a low loss header brings many benefits: Sizing boiler circuit pump and actuators is easy.

Interaction between the heating water flow inside the boiler and in the heat consumer circuits is prevented. Boiler and heat consumers are only supplied with the assigned water flow.

May be used in single and multi-boiler systems, subject to the heating circuit control system.

Actuators on both sides of the low loss header provide optimum operation if they are sized correctly. The hydraulic balancing line can also be used as a sludge trap, subject to being sized correctly ( page 28).

Where there is a large pressure drop on the water side and large distances between boiler and heating circuits, a split into primary and secondary side is possible.

Sizing the low loss headerCorrect sizing is crucial to the function of the low loss header. To ensure good separation with the simultaneous function as a dirt separator, size the line in such a way that there is virtually no pressure drop between the flow and return. At the nominal amount of water, a flow velocity of 0.1 m/s to 0.2 m/s can be expected. This also enables the simultaneous use as a sludge trap. To be able to capture the heating circuit flow temperature, provide a sensor well of 200 mm to 300 mm length in the upper area of the hydraulic balancing line on the heating circuit side.

F. 7 Calculating the size of the low loss header

D Diameter of the hydraulic balancing line in mv Flow velocity in m/sVKges Total boiler circuit flow rate in

m3/h

ExampleGiven: Total flow rate VKges = 223.6 m3/h Flow velocity (assumption) v = 0.2 m/sResult: Diameter of the hydraulic balancing line

D ~ 0.63 m

Fig. 29 Main diagram of a low loss header

RH Heating system returnRK ReturnVH Heating system flowVK Flow[1] Female connection for an air vent valve[2] Female connection for a sensor well "[3] Perforated partition[4] Quick-acting valve

DVKges

v---------------- 1

2827--------------=

3

4

D

VHVK

RHRK

D 12

6 720 640 417-19.1il

5 D

34 DPD SK655/755 6 720 810 010 (2013/10) 35

7 System examples7.4 Single boiler system Logano SK655 and SK755 with boiler control unit

Fig. 30 System example Logano SK655 and SK755

FK Boiler temperature sensorFZ Auxiliary temperature sensor PK Boiler circuit pumpSK Boiler circuit actuatorZM427Expansion module1 On the heat/cooling source or on the wall6 In the 4212 control unit4212 Logamatic 4000

AREA OF APPLICATION Logano SK655 and SK755 boilers Boiler control with a conventional Logamatic 4212

control unit plus ZM427 auxiliary module in conjunction with a heating circuit controller or with special applications

Control of the boiler circuit and heating circuit is only possible using the Logamatic 4321 control unit

14212

6ZM427

Logano SK655 / SK755

Buderus

FK

M SK

PK

FZ

6 720 805 735-01.2T

The circuit diagram is only a schematic illustration.For information on all system examples, see page 28.PD SK655/755 6 720 810 010 (2013/10)36

7 System examplesFunction descriptionThe Logamatic control unit safeguards the minimum boiler return temperature. If the actual return temperature captured by the FZ temperature sensor falls below the set value whilst the burner is switched on, the control unit reduces the system flow rate towards the boiler by activating the SK boiler circuit actuator. At the same time, hot water from the flow is mixed into the cold water returning from the system to achieve the set return temperature.The boiler circuit actuator is opened towards the consumer circuits once the minimum return temperature has been reached.

Special design information This arrangement is ideally suited for a modernised

system where the heating circuit control is provided by the higher ranking control (third party control unit).

This requires an FZ auxiliary temperature sensor.

Selecting control equipment

For more detailed information, see the technical guides to the control units.

Logamatic 4212 control unit

Logamatic 4212 (optional full equipment level)blue auxiliary equipmentLogamatic 42121) Conventional control unit for mounting inside the boiler for operation with a constant boiler water temperature with TR (90/105 C) temperature controller; for activating single or 2-stage burners, adjustable high limit safety cut-out STB (100/110/120 C). Including burner cable, stage 2.

1) For boiler temperatures over 80 C, the high limit safety cut-out must be set to 110 C or 120 C

Standard equipmentSafety equipmentZM425 Central module for display, incl. thermometer and burner fault indicator, with two slots for hours run meter for the burner stages 1 and 2Optional equipmentZM426 Auxiliary module for the use of a second high limit safety cut-out, set to 100 C without flash trapZM427 Auxiliary module to safeguard the boiler operating conditions for steel boilers with minimum return temperature, for steel boilers and floor standing gas condensing boilers with external condensing heat exchanger (operating flow temperature control) and to provide a hydraulic shut-off in multi-boiler systems, including flow temperature sensorZB Hours run meterSensor pocket R , 100 mm long for Logamatic cylindrical sensors

Table 13 Possible equipment level of the Logamatic 4212 control unit in connection with the system example in fig. 30

6 720 640 417-41.2T

Logamatic 4321 control unit

Logamatic 4321 (optional full equipment level)blue auxiliary equipmentLogamatic 43211) for single boiler system or as master control unit for the first boiler in a multi-boiler system, with (105 C) temperature controller and adjustable high limit safety cut-out (100/110 C), for activating single stage, 2-stage or modulating burners. Including burner cable for stage 2, boiler water temperature sensor and outside temperature sensor. Space for up to four function modules.

1) For boiler temperatures over 80 C must be set to 110 C or 120 C, the high limit safety cut-out

Standard equipmentSafety equipmentCM431 Controller moduleZM434 Central module for activating burners and boiler circuit functions; with manual operating levelMEC2 Digital user interface for setting parameters and checking the control unit; integral room