Buderus 500 - 28/C, 500 - 24/C, 500 - 24/S Servicing Manual

7214 8900 – 02/2006 GB(EN) For the installer

Servicing manual

Gas wall hung Boiler condensing Buderus 500 - 24/S Buderus 500 - 24/C Buderus 500 - 28/C

Please read thoroughly before attempting fault diagnosis

F The boiler meets the basic requirements of the

appropriate standards and directives. Conformity has been substantiated by the proper documents which - together with the declaration of conformity - are filed with the manufacturer.

Subject to technical modifications!

Constant development efforts may result in minor deviations in illustrations, functional steps and technical data.

Updating the documentation

If you have suggestions for improvement or have found discrepancies, please do not hesitate to contact us.

We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk

2 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006

box 1 List of contents

1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2 Servicing manual user guide . . . . . . . . . . . 10

3 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

4 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

5 Symptoms . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

6 Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

7 Actions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

8 Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

box 2 Preface

These service instructions apply to: Buderus wall-mounted condensing gas boilers 500 - 24/S, 500 - 24/C and 500 - 28/C.

Model: C Type: GB/IE II

13(x)

, C

33(x)

20 mbar, 37 mbar

2H3P

53(x)

, C

73(x)

Power rating: 230 VAC, 50 Hz, IP X4D Fuse rating: 1.25 Ampere slow blow The boiler unit consists of the following components: – 500 Gas condensing boiler

– 28 Maximum output is 28 kW – C Combination boiler (with integrated hot water

supply)

– S System boiler.

9 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Important general instructions for use

Only use the boiler in accordance with its designated use and the service instructions. Installation, maintenance and repair must be carried out by competent service engineers (e.g. CORGI registered). Only use the boiler in conjunction with the accessories and spare parts indicated in the installation, maintenance and service instructions. Other accessories and consumables may only be used if they are expressly provided for the designated use and if system performance and safety are not affected in any way.

The boiler is suitable for connection to fully pumped, sealed water systems ONLY. Adequate arrangements for completely draining the system by provision of draining valves must be provided in the installation pipework.

Pipework from the boiler is routed downwards as standard, but may be routed upwards behind the boiler using the wall spacing frame.

Subject to technical modifications.

As a result of our policy of constant development, there may be small differences between illustrations, functional steps and technical data.

G. C. Aplliance No. :

Buderus 500-24/S 41-110-24 Buderus 500-24/C 41-110-04 Buderus 500-28/C 41-110-03

BENCHMARK' Log Book

All Buderus gas fired boilers now include an installation,

Other manuals available for this boiler are: – user manual;

– installation and maintenance instructions; – wall spacing frame instructions.

commissioning and service record log book. The details of the log book will be required in the event of any warranty work being requested. Please complete the appropriate sections on completion of the installation and commissioning.

REMEMBER: Please hand the log book back to the user.

We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk

Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006 3

General1

1 General

box 3 Regulations and directives

It is a requirement that all gas appliances are installed and serviced by a CORGI registered installer in accordance with the regulations. Failure to service appliances correctly could lead to prosecution. It is in your own interest, and that of safety, to ensure the law is complied with.

It is a requirement and in your own interest, and that of safety that this boiler must be serviced by a CORGI registered installer, in accordance with the relevant requirements of the current Gas Safety (Installation and Use) Regulations, The Building Regulations, current I.E.E. Wiring Regulations and the relevant British Standard Codes of Practise.

Detailed recommendations are contained in the following British Standard Codes of Practice:

BS. 5440:1 Flues (for gas appliances of rated input not

exceeding 70 kW).

BS. 5440:2 Ventilation (for gas appliances of rated

input not exceeding 70 kW).

BS. 5449 Forced circulation hot water systems. BS. 5546 Installation of gas hot water supplies for

domestic purposes (2nd. family Gases).

BS. 6798 Installation of gas fired hot water boilers of

rated input not exceeding 60 kW.

BS. 6891 Low pressure installation pipes. BS. 7593: 1992: Code of practice for treatment of water in

domestic hot water central heating systems.

IGE/UP/1b Tightness testing and purging domestic

sized gas installations.

Health and & Safety Document No. 635.

The Electricity at Work Regulations, 1989.

The manufacturer's notes must not be taken, in any way, as overriding statutory obligations.

The design and construction of the Buderus wall-mounted condensing gas boiler conforms to the basic specifications listed in the European directive governing gas-fired appliances 90/396/EEC, and with respect to EN 625, EN 483 and EN 677.

INOTE:

Observe the corresponding technical rules and the building supervisory and statutory regulations when installing and operating the system.

HWARNING!

Keep the burner-control unit housing CLOSED when working on water-bearing components.

INOTE:

It is mandatory to clean and service the system once a year. This includes an inspection of the entire system to see if it is in full working order. Defects and faults must be eliminated immediately.

INOTE:

When instructions aren’t followed, warranty expires.

INOTE:

Condensing boilers work more efficient if the CH flow/return temperature is as low as possible.

Timber Framed Buildings

If the boiler is to be fitted in a timber framed building it should be fitted in accordance with the Institute of Gas Engineering document IGE/UP/7:1998 and BS 5440:1.

Bathroom Installations

This appliance is rated IP X4D. The boiler may be installed in any room or internal space,

although particular attention is drawn to the requirements of the current IEE (BS.7671) Wiring Regulations and, in Scot land, the electrical provisions of the building regulations applicable in Scotland, with respect to the installation of the boiler in a room or internal space containing a bath or shower.

If the appliance is to be installed or serviced in a room containing a bath or shower then, providing water jets are not going to be used for cleaning purposes (as in communal baths/showers), the appliance can be installed or serviced in Zone 3, as detailed in BS.7671.

Compartment Installations

A compartment used to enclose the boiler should be designed and constructed especially for this purpose. An existing cupboard or compartment may be used, provided that it is modified for the purpose.

In both cases, details of essential features of cupboard/ compartment design, including airing cupboard installation, are to conform to the following: BS 6798 (No cupboard ventilation is required - see 'Air Supply' for details).

It is not necessary to have a purpose-provided air vent in the room or internal space in which the boiler is installed. Neither is it necessary to ventilate a cupboard or compartment in which the boiler is installed, due to the low surface tempera tures of the boiler casing during operation; therefore the requirements of BS 6798, Clause 12, and BS 5440:2 may be disregarded.

The permanent clearances required are: in front: 8 mm below: 21 mm right side: 8 mm left side: 8 mm above: 21 mm

The position selected for installation MUST allow adequate space for servicing in front of the boiler. See table below:

in front: 350 mm below: 180 mm right side: 8 mm left side: 8 mm above: 200 mm

In addition, sufficient space may be required to allow lifting access to the wall mounting bracket. Wall-mounted condensing gas combi boilers must only be operated with Buderus purpose made gas systems, which are certified for this type of boiler.

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4 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006

Observe the relevant standards, regulations and legislation of the country or region of final use.

ACAUTION!

Use this boiler for its intended purpose only.

ADANGER!

Notes relating to the heating system water.

Thoroughly flush the system before it is filled with water. Use only untreated water or water treatment product such as Sentinel X100 to fill and top up the system. For more information about Sentinel call 0151 420

9563. When using water treatment, only products suitable for

use with Buderus heat exchangers are permitted (e.g. Sentinel X100). Your warranty is at risk if an incorrect water treatment product is used in conjunction with this appliance. For more information, contact Buderus Technical Product Support Department. It is most important that the correct concentration of the water treatment product is maintained in accordance with the manufacturer's instructions. If the boiler is used in an existing system any unsuitable additives MUST be removed by thorough cleaning. BS.7593:1992 details the steps necessary to clean a domestic central heating system. In hard water areas, treatment to prevent lime scale may be necessary - however, the use of artificially softened water is NOT permitted. Under no circumstances should the boiler be fired before the system has been thoroughly flushed. Do not use artificially softened water. Only plastic pipework containing a polymeric barrier should be used. It is allowed to use copper for the first 600 mm.

INOTE:

Notes relating to domestic hot water

z The domestic hot water service must be in

accordance with BS 5546 and BS 6700.

z The boilers are suitable for connection to most types

of washing machine and dishwasher appliances.

z When connecting to suitable showers, ensure that:

a. The shower is capable of accepting mains

pressures and temperatures up to 65 °C.

b. The shower is ideally thermostatic or pressure

balancing.

z Where temporary hardness exceeds 150 mg/litre,

it is recommended that a proprietary scale reducing device is fitted into the boiler cold supply with the requirements of the local water company.

ACAUTION!

Provision must be made to accommodate the expansion of DHW contained within the appliance, where a back flow prevention device is fitted

67989: §5.4.3.

BS.

General 1

box 4 Hazard definitions and abbreviations

Hazard definitions

ADANGER:

Indicates the presence of hazards that will cause severe personal injury, death or substantial property damage.

AWARNING:

Indicates the presence of hazards that can cause severe personal injury, death or substantial property damage.

ACAUTION:

Indicates presence of hazards that will or cause minor personal injury or property damage.

INOTICE:

Indicates special instructions on installation, operation or maintenance that are important but not related to personal injury or property damage.

Abbreviations

AV = Air Vent BCT = Buderus cylinder thermostat BDV = Buderus diverter valve CB = Connection Block CH = Central Heating CHF = Central Heating Flow CHR = Central Heating Return CT = Cylinder Thermostat CWDO = Condensate water drainage outlet DHW = Domestic Hot Water DV = Diverter Valve E=Earth L=Live LSV = Lock Shield Valve MCW = Mains Cold Water N = Neutal JB = Junction Box / RTH Relay PL = Permanent Live Prog = Programmer PRV = Pressure relief valve (safety valve) RT = Room Thermostat RV = ModuLink 250 RF Receiver T=Timer TRV = Thermostatic Radiator Valve WC = Wiring Centre ZV = Two Port Zone Valve

Safe handling of substances

No asbestos, mercury or CFCs are included in any part of the boiler and its manufacture.

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Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006 5

General1

box 5 Technical specifications

Buderus

Hot water capacity (combination boilers)

Rated thermal load for CH

Rated thermal load for preparing DHW

Rated heating capacity for system temperature (modulating from 30° to 100°) Heating curve 75/60 °C

Heating curve 40/30 °C

Seasonal efficiency (SEDBUK) for natural gas

for propane

Maximum gas consumption, hot water/tank

Maximum gas consumption, heating

Boiler efficiency (40/30°C) (lower value/upper value) (full load)

Boiler efficiency (40/30°C) (lower value) (partial load)

Boiler efficiency (40/30°C) (upper value) (partial load)

Boiler efficiency (75/60 °C) (lower value/upper value) (full load)

Boiler efficiency (75/60°C) (lower value/upper value) (partial load)

Chimney loss with burner shut down (standby heat loss) at nominal thermal load

Hot water circuit

ΔT at residual head of 200 mbar

Maximum flow temperature

Permitted system pressure

Expansion vessel

Capacity of expansion vessel

Admission pressure of expansion vessel

Plate heat exchanger

DHW flow rate at 35 °C rise

Supply pressure of hot water

Adjustable DHW temperature

Pipe connections

Condensate outlet

CH flow/return (compression fitting)

MCW inlet / DHW outlet (compression fitting)

Gas on installation frame (compression fitting)

Pressure relief valve

Flue-gas connection

Type of flue-gas connection (model)

Ø Flue gas pipe / combustion-air inlet

Unit 500-24/S 500-24/C 500-28/C

kW 5.7 – 28.5

kW 5.7 – 23.0 5.7 – 23.0 5.7 – 23.0

kW 5.7 – 28.5 5.7 – 23.0 5.7 – 28.5

kW kW

% %

m3/h 3.02 2.43 3.02

m3/h 2.43 2.43 2.43

% 104 / 104 104 / 104 104 / 104

% 107 107 107

% 96.3 96.3 96.3

% 95.7 / 86.2 95.7 / 86.2 95.7 / 86.2

% 94.6 / 85.2 94.6 / 85.2 94.6 / 85.2

% 1.2 1.2 1.2

°C <20 <20 <20

°C 80 80 80

bar 1.0 – 3.0 1.0 – 3.0 1.0 – 3.0

l 7.5 7.5 7.5

bar 1.0 1.0 1.0

l/min – 9.4 11.7

bar – 0.8 - 10.0 0.9 - 10.0

°C – 40 - 60 40 - 60

Ø mm 21.5 21.5 21.5

Ø mm 22.0 22.0 22.0

Ø mm 15.0 15.0 15.0

Ø mm 22.0 22.0 22.0

Ø mm 15 mm (adapter supplied with boiler)

mm 60/100 (accessory)

(with external

tank)

5.3 – 22.0

6.0 – 24.0

90.3

92.3

6.0 – 24.0 5.7 – 28.5

5.3 – 22.0

6.0 – 24.0

90.3

92.3

, C

33(x)

, C

53(x)

13(x)

, C

5.3 – 22.0

6.0 – 24.0

90.3

92.3

73(x)

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6 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006

box 5 Technical specifications

Buderus

Flue-gas readings

Condensate water quantity, natural gas, 40/30 °C

Exhaust-fume mass-flow rate Full load Part-load

Exhaust-fume temperature, full load Heating curve 75/60 °C Heating curve 40/30 °C

Exhaust-fume temperature, partial load Heating curve 75/60 °C Heating curve 40/30 °C

CO2 full load, natural gas standard test gas G20

CO2 full load, natural gas standard test gas G31 propane

Standard emission factor NO

Standard emission factor CO

Flow pressure available for use

Electrical specifications

Mains connection voltage

Electrical protection rating

Electrical power consumption, standby

Electrical power consumption, partial load

Electrical power consumption, full load

Dimensions and weight of boiler

height × width × depth

Weight without casing Weight with casing

Gas

Category of gas as per EN 437 for GB

Gas injector Ø natural gas H (G20)

Gas injector Ø propane P (G31)

Venturi article number

Natural gas H

Propane P

Other items

Pump

Pump over-run time: Heating system default adjustments External cylinder Plate heat exchanger (ECO) Plate heat exchanger (warm start) After service mode

General 1

Unit 500-24/S 500-24/C 500-28/C

l/h 1.6

g/s g/s

°C °C

% 9,2

% 10.3

ppm (mg/kWh) <30

ppm (mg/kWh) <22

Pa 75

Vac 230 (50 Hz)

W 4

W 88

W 110

mm 780 × 460 × 330 780 × 460 × 330 780 × 460 × 330

kg kg

mm 4.45 4.45 4.45

mm 3.45 3.45 3.45

30 33

20 mbar, 37 mbar (natural gas H and propane P)

2H3P

423.072A 423.072A 423.072A

Delivered ready for operation, adjusted to Wobbe index

14.1 kWh/m

Deemed suitable for use with propane after inspection

5 minutes

30 - 40 seconds

1 minute

(with reference to 15 °C, 1013 mbar),

applicable to Wobbe index range

Markings on gas classification plate:

Configured category: G

by a registered Corgi heating engineer.

Markings on gas classification plate:

Configured category: 3P

– –

10.6

4.3

77 55

60 35

IP X4D

31 34

11.3 to 15.2 kWh/m

20 - 2E - 20 mbar

G 31_30-50 mbar.

UP 15-50

5 minutes

–

30 - 40 seconds

30 seconds

1 minute

30 - 40 seconds

30 seconds

31 34

5 minutes

–

1 minute

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Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006 7

General1

box 6 Overview Buderus 500

15 16 17

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8 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006

General 1

box 7 Key to terms

Item 1: Ionisation electrode Item 2: Glow ignitor Item 3: Automatic air vent Item 4: Safety sensor Item 5: Clamp for heat exchanger cover Item 6: Plate heat exchanger Item 7: Condensate trap Item 8: Flow NTC sensor Item 9: DHW flow regulator Item 10: Pressure gauge Item 11: Concentric flue gas adaptor Item 12 Fan Item 13: Frame Item 14: Gas/Air unit Item 15: Sight glass Item 16: Gas valve Item 17: Heat exchanger Item 18: Gas supply pipe Item 19: Identification plate of boiler Item 20: Air silencer tube Item 21: Flue gas pipe Item 22: Flue gas safety temperature limiter (STL) Item 23: Pump 15-50 Item 24: Pressure relief valve discharge pipe Item 25: Syphon Item 26: Identification plate showing gas category Item 27: Connection block Item 28: DBA control panel Item 29: RTH converter / junction box

box 8 General points

AWARNING!

DANGER OF FATAL ACCIDENT FROM EXPLOSIVE FUMES

If you smell gas

z There is a danger of explosion. z No naked lights. No smoking. DO NOT use a naked

light to detect possible leaks.

z DO NOT operate any device that is likely to produce

sparks.

z DO NOT operate electrical switches of any kind

(including telephones, plug-in devices and doorbells)

z Shut off the gas supply at the main valve. z Open doors and windows. z Warn other occupants of the building (but DO NOT

use the house intercom or doorbells).

z Contact the gas supplier from a telephone located

outside the building.

z If you detect an audible gas leak, evacuate the

building immediately, prevent other persons from entering, and notify the police and fire service immediately (from a telephone OUTSIDE the building).

HWARNING!

DANGER OF FATAL ACCIDENT

due to electric shock

ACAUTION!

General information on maintenance work.

IUSER INSTRUCTIONS

Instructions for optimum usage, correct adjustment of the boiler and other useful information.

ACAUTION!

Use eye protection, inhalation protection, hearing, gloves, shoes etc. on the right time.

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Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006 9

Servicing manual user guide2

2 Servicing manual user guide

box 9

This document consists of various sections. These in turn contain subsections/boxes in the form of text or tables.

Subsections/boxes inside text and tables are identified by a small grey box. Each subsection/box is assigned its own identification number.

These subsections/boxes are divided into operating steps. If an operating step involves the taking of a yes/no decision, the right-hand side of the table indicates which subsection / operating step you should proceed (cross reference).

Section

Cross reference to subsection or operating step

Subsection/box

Diagnosis6

box 24

step 28 Check the actuation of the servomotor of the internal three-way valve, see box 186.

step 29 Does the servomotor of the internal three-way valve start up correctly? Yes:

step 30 Replace the servomotor of the internal three-way valve, see box 191.

step 31 Check the power supply cable of the internal three-way valve, see box 192.

step 32 Is the power supply cable of the internal three-way valve in good condition? Yes:

step 33 Replace the cable loom (or the affected part thereof).

step 34 Check the movement of the servomotor of the

see box 212.

step 35 Does the servomotor of the

step 36 Check to ensure that the the

see box 228.

step 37 Has the

step 38 Install the Buderus 24V AC external three-way valve correctly, see box 228. o box 43

step 39 Check to ensure that the

step 40 Does the Buderus 24V AC external three-way valve actuate correctly? Yes:

step 41 Replace the servomotor of the

step 42 Check the wiring of the Buderus 24V AC external three-way valve, see box 221.

step 43 Is the wiring of the

step 44 Replace the wiring of the Buderus 24V AC external three-way valve.

step 45 Check the drive mechanism of the

step 46 Is the drive mechanism of the Buderus 24V AC external three-way valve working correctly? Yes:

step 47 Replace the internal components of the

step 48 Check the wiring of the

On combi boiler supply: hot water available, but no heating operation.

On system boiler supply: no heating operation.

Hot water may be available, but no heating operation.

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24 Servicing manual Gas condensing bo iler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2005

Buderus 24V AC external three-way valve been fitted correctly? Yes:

see box 213 and box 229.

moving plug-and-socket connection and the control panel as per box 288.

box 25

step 1 Check to ensure that the power supply cable to the RTH converter/Junction box has been installed correctly,

see box 286.

step 2 Is the 230V connection to the RTH converter/Junction box fitted correctly? Yes:

step 3 Correctly attach the switch live to terminal 1 and Neutral to terminal 2 on the 230V connector, see box 286.

step 4 Disconnect black leads from terminals 1 & 2 on the back of the DBA and test for continuity between the two

leads.  No continuity check S/L and N connections are made correctly and that there is 230v between the two. Replace RTH converter/Junction box. Continuity reconnect the cables to terminals 1 & 2 and check the connections between the terminals and the DBA.

Buderus 24V AC external three-way valve is actuated correctly,

Buderus 24V AC external three-way valve in correct condition?

Buderus 24V AC external three-way valve between the connection box or

Buderus 24V AC external three-way valve, 

Buderus 24V AC external three-way valve operate correctly? Yes:

Buderus 24V AC external three-way valve has been fitted correctly,

Buderus 24V AC external three-way valve, see box 218.

Buderus 24V AC external three-way valve, see box 222.

Buderus 24V AC external three-way valve, see box 225.

o step 30

o step 31

No:

o box 43

o box 42

No: o step 33

o box 43

o step 36

o step 39

No:

o step 45

o step 38

No:

o step 41

o step 42

No:

o box 43

o step 47

Yes:

o step 44

No:

o box 43

o box 42

o step 47

No:

o box 43

o step 4

o step 3

No:

o box 43



Operating step number

Explanation of this subject starts in this box. The following boxes can be relevant as well.

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10 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006

3 Operation

box 10 Operation

box 11

Operation

General points

The central boiler can be run from the DBA control panel (item 1).

3 4 5 6

item 1: Mains switch 0/1 item 2: Reset button item 3: Service button item 4: Display item 5: Menu button item 6: Adjusting arrow UP item 7: Adjusting arrow DOWN

You can navigate through the menu structure of the central boiler using the service button, reset button,

C-button and

D-button (item 2, 3, 5, 6 and 7) and the display (item 4),

box 12 to 14.

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Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006 11

Operation3

box 12 Normal Operation menu

step 1

step 2

step 3

step 4 Continue with Normal Operation menu ?

step 5

step 6 Keep the

[24] Current CH flow temperature, in °C. See also box 20.

Keep the

D-button pressed.

[00] current DHW flow rate, in litres per minute

Release the

D-button. → step 1

C-button pressed.

Yes:

No:

→ step 6

→ step 5

step 7

[0h] Operating code. See also box 20

In this case: The boiler is ready for operation. No current heat requirement.

box 13 Service Mode menu (no hot water is available during service-mode operation)

step 1 [24] Current CH flow temperature, in °C. See also box 20.

step 2 Activate service mode?

step 3

step 4

step 5 Briefly press the

step 6

step 7 Exit partial-load service mode?

step 8

step 9 Briefly press the

step 10

Press the

A-button once.

,24] As soon as the spanner symbol on the left-hand side of the display and the flame appear, the boiler will

run for 30 minutes in service mode. The maximum CH flow temperature (as configured in the “Settings” menu) applies in this case.

C-button.

Partial-load service mode Adjust the gas/air ratio as required. See box 233 and box 143.

Press the

A-button once.

[lo] is activated. Check the gas/air ratio and ionisation current.

C-button.

Full-load service mode accordingly box 230.

,hi] is activated. Check the working gas input pressure, or analyse the exhaust gas

Yes:

No:

Yes:

No:

→ step 4

→ step 3

→ step 1

→ step 8

→ step 6

step 11 Exit full-load service mode?

step 12

step 13 Service mode is deactivated.

Press the

A-button once, or wait for service mode to expire (after 30 minutes).

Yes:

No:

→ step 12

→ step 10

→ step 1

box 14 Settings menu

step 1 [24] Current CH flow temperature, in °C. See also box 17.

step 2 Open “Settings” menu?

step 3 Press the

step 4 Is boiler a combination boiler with warm start ? Yes:

step 5

step 6 Adjust configured hot water mode ? Yes:

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[pr# ( H / I ) Configured hot water mode. As soon as [pr# is displayed, you can verify the current hot

water mode, or adjust it as required. See also box 18.

E-button once.

Yes:

No:

→ step 3

→ step 1

→ step 4

→ step 5

→ step 9

→ step 7

→ step 8

12 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006

box 14 Settings menu

step 7

Use single or multiple operation of the

[pr# ( H ): Hot water mode to ECO, [pr`( I ): Hot water mode to warm start.

step 8

step 9

Press the

E-button once.

[60) As soon as the DHW temperature (in °C) appears on the display [60), you can read the current

DHW temperature, or adjust it as required. See also box 18.

D- and C-buttons to activate and disable hot water mode.

Operation

step 10

step 11

step 12

step 13

step 14

step 15

Adjust DHW temperature ? Yes:

Lower: lower the DHW temperature with the Higher: increase the DHW temperature with the

Press the

[pr' ( K / L ) Configured heating mode. As soon as [pr' is displayed, you can verify the current

heating mode, or adjust it as required. See also box 18.

Adjust configured heating mode ?

Use single or multiple operation of the

[pr. (K ): Heating mode on, [pr; (L ): Heating mode off.

step 16 Press the

step 17

step 18

step 19

step 20

step 21 Press the

[80. Configure CH flow temperature, in °C. See also box 18. As soon as [80. is displayed, you can verify

the current CH flow temperature, or adjust it as required.

Adjust CH flow temperature ?

Lower: lower the CH flow temperature with the Higher: increase the CH flow temperature with the

Has at least 10 seconds passed without a button being pressed and/or was mains supply interrupted ?

E-button once.

D-button.

C-button.

D- and C-buttons to activate and disable heating mode.

D-button.

C-button.

No:

Yes:

No:

Yes:

No:

Yes:

No:

→ step 11

→ step 12

→ step 15

→ step 16

→ step 19

→ step 20

→ step 22

→ step 21

step 22 Any adjustments that you have made will now be confirmed.

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→ step 1

Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006 13

Function4

4 Function

box 15 Boiler Functions

Start phase

step 1 Turn the mains switch to “ON”.

step 2 Turn the operating switch on the DBA control panel of the boiler to position “1“ (ON) – see also box 11.

step 3 Is a 3-way valve fitted? Yes:

step 4 Is the 3-way valve set to “hot water mode”? Yes:

step 5 The Buderus 24V AC external 3-way valve is turned to “heating mode” in 7.5 seconds, while an internal 3-way

step 6

step 7

step 8

step 9 Has the pre purge been completed correctly? Yes:

step 10 Deal with fault. The error code, which is now displayed, can be found in box 20. Deal with the fault.

step 11

step 12 Start of pump over-run time via the heating system.

step 13 Has the pump over-run time expired? Yes:

step 14 Is the boiler set to warm start for hot water and/or is an external storage-type water heater connected? Yes:

step 15 Is the plate heat exchanger triggered and/or is the temperature in the external storage-type water heater at least

step 16 Is there a current heat requirement from the (room) temperature controller? Yes:

step 17 Is the current CH flow temperature lower than 7 °C (frost protection)? Yes:

step 18 The pump stops.

step 19 Has the pump been out of use for more than 24 hours? Yes:

step 20 Is the plate heat exchanger triggered and/or is the temperature in the external storage-type water heater at least

step 21 Is there a current heat requirement from the (room) temperature controller? Yes:

valve is turned to “heating mode” in 2 seconds.

,00{ The display on the DBA control panel of the boiler is checked (maximum of one second). [24] Current CH flow temperature, in °C. See also box 20. C [0u] The boiler begins to warm up. Start of pre purge phase.

The fan runs for 15 seconds at about 60 % of maximum speed.

Checking phase

Operating phase

C [0h] Operating code. See also box 20. The boiler is ready for operation.

No current heat requirement.

The pump over-run time:

– via the heating system, factory-adjusted to 5 minutes; – via the external reservoir, set to 30-40 seconds; – via the plate heat exchanger (ECO), set to 30-40 seconds; – via the plate heat exchanger (warm start), set to 30 seconds; – after service mode, 1 minute.

5 °C below the temperature set at the DBA control panel?

No:

Yes:

No:

Yes:

No:

→ step 4

→ step 6

→ step 5

→ step 6

→ step 11

→ step 10

→ step 18

→ step 14

→ step 15

→ step 16

→ step 28

→ step 16

→ step 46

→ step 19

→ step 62

→ step 18

→ step 23

→ step 20

→ step 28

→ step 21

→ step 46

→ step 22

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14 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006

Function 4

box 15 Boiler Functions

step 22 Is the current CH flow temperature lower than 7 °C (frost protection)? Yes: → step 62

No:

→ step 23

step 23 The pump is run for 10 seconds in order to prevent it from seizing up.

No:

Yes:

No:

→ step 18

→ step 25

→ step 28

→ step 26

→ step 46

→ step 27

→ step 62

→ step 24

→ step 32

→ step 72

→ step 39

→ step 34

→ step 35

→ step 32

→ step 29

→ step 38

→ step 46

→ step 19

step 24 Have 10 seconds elapsed? Yes:

step 25 Is the plate heat exchanger triggered and/or is the temperature in the external storage-type water heater at least

5 °C below the temperature set at the DBA control panel?

step 26 Is there a current heat requirement from the (room) temperature controller? Yes:

step 27 Is the current CH flow temperature lower than 7 °C (frost protection)? Yes:

step 28 The symbol “

step 29

step 30

step 31 Does the ionisation current exceed 1.4 µA (microamperes) within 5 seconds? Yes:

step 32

step 33 Is the temperature in the plate heat exchanger higher than the temperature entered via the DBA control panel? Yes:

step 34 Is the CH flow temperature 46 °C higher than the preset DHW temperature and/or higher than 93 °C? Yes:

step 35

step 36 The symbol ”

step 37 The fan stops after 30 seconds.

step 38 Is the CH flow temperature lower than the preset DHW temperature plus 35°C? Yes:

step 39 The gas valve is closed and the burner is shut down.

step 40 The symbol

step 41 Start of pump over-run time via the cylinder.

step 42 The fan stops.

step 43

step 44 The 3-way valve turns to the heating mode setting for two seconds.

step 45 Is there a current heat requirement from the (room) temperature controller? Yes:

step 46 The symbol

step 47

step 48

C [0c] The fan runs at 49 % of capacity.

The 3-way valve turns to the hot water setting for two seconds. The glow ignitor is activated for two seconds.

C [0l] Ignition phase: The gas valve is opened. The glow ignitor is activated for one second, followed by

alternating half-second periods of inactivity and activity until five seconds have elapsed.

C [=h] The boiler is in hot water mode. If there has been a power cut: The startup load on the boiler is 49%

for the first 13 seconds for the purposes of flow monitoring. It is then increased or decreased accordingly. The symbol ”

C [0y] The gas valve is closed and the burner is shut down.

Start of pre purge phase (10 seconds).

C [0h] The pump stops.

The symbol “

C [0c] The fan runs at 49 % of capacity. The pump is started up.

The glow ignitor is activated for seven seconds.

C [0l] Ignition phase: The gas valve is opened.

H" or “I" for hot water mode on the DBA control panel display lights up.

G “ lights up.

G “ goes out.

G goes out.

H" or “I" goes out.

K lights up.

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Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006 15

Function4

box 15 Boiler Functions

step 49 Does the ionisation current exceed 1.4 µA (microamperes)) within 5 seconds? Yes: → step 50

No:

→ step 72

step 50

step 51 Is there a heating requirement from the (room) temperature controller? Yes:

step 52 Is the heat system flow temperature 6 °C higher than the target setting?

step 53

step 54 The symbol

step 55 The fan stops.

step 56 Is the CH flow temperature

step 57 The symbol “

step 58

step 59 The symbol ”

step 60 Start of pump over-run time via the heating system. The pump over-run time via the heating system is 5 minutes.

step 61 The fan stops.

step 62 The symbol “

step 63

step 64

step 65 Does the ionisation current exceed 1.4 µA (microamperes) within 5 seconds? Yes:

step 66

step 67 Is the current CH flow temperature higher than 15 °C? Yes:

step 68 The symbol “

step 69

step 70 Start of pump over-run time via the heating system. The pump over-run time via the heating system is 5 minutes.

step 71 The fan stops.

[-h] The boiler is in heating mode. The symbol G lights up.

The startup load on the boiler is 49% for the first 13 seconds for the purposes of flow monitoring. It is then increased or decreased.

(The target setting is entered at the DBA control panel if room-temperature adjustment is required)

C [0y] The gas valve is closed and the burner is shut down.

G goes out.

≥ 6 °C lower than the target setting? Yes: → step 47

K “ goes out.

C [0h] The gas valve is closed and the burner is shut down.

G “ goes out.

Start of the post purge phase of fan (10 seconds).

K “ lights up.

C [0c] The fan starts up. The pump is started up.

The glow ignitor is activated for seven seconds.

C [0l] Ignition phase: The gas valve is opened.

C [-h] The symbol ” G “ lights up. The boiler is in heating mode.

K goes out.

C [0h] The gas valve is closed. The burner is shut down. The symbol G goes out.

Start of the post purge phase of fan (10 seconds).

No:

Yes:

No:

→ step 52

→ step 57

→ step 53

→ step 50

→ step 53

→ step 13

→ step 66

→ box 36

→ step 68

→ step 67

→ step 13

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16 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006

5Symptoms

box 16 Display icons

Symptoms 5

Display indication

I J

Key to display indication

Service mode

Ionisation signal (flame monitoring)

Hot water mode “ECO” setting or hot water requirement

Hot water mode “warm start” setting or hot water requirement

Standby, hot water mode to “warm start”

Heating mode or heating requirement

Summer operation, no heating mode, hot water only

box 17 Display readings

Display readings

[24]

Key to display reading

Current CH flow temperature

box 18 Control-panel settings

Button

Display Setting

Key to display setting

Unit

°C

Range

[30]

Unit

–

Range

Factory default setting

[80]

1x A<24]

C[lo]

A C [hi]

E[pr#

E [60)

Service mode

Service mode, partial load % 25

Service mode, full load % 100

End service mode (or wait for 30 minutes)

Hot water mode Only applies to combi boilers

DHW temperature

H = Hot water supply to ECO

I = Hot water mode to warm start

°C

40 – 60

K = Heating mode ON

E[pr'

Heating mode

L = Heating mode OFF

E [80.

[//]

= flashing

When it appears on the display at a system boiler, please connect a link between terminal 3 and 4 on the back side of the

CH flow temperature

DBA control panel (hot water cylinder sensor) or make sure that the hot water cylinder sensor is fitted securely.

box 19 Displaycodes

Normaly you see the current CH flow temperature. By pushing the "C"-button you will see the current operation code.

Blocking:

The boiler stops heating and will wait until the blocking is solved.

Locking:

Displaycode is blinking and also a blinking wrench "F" appears. The boiler stops heating and the pump is still running. The only

way to stop the locking is by pushing the reset "

B" button.

°C

30 – 80

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Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006 17

Symptoms5

box 20 Display codes

Display indication

Display

code

Key to display code

[//]

[//)

Standby Hot water mode to “warm start”. box 21

C [0h]

Standby Applies to boilers with hot water supply,

C [0h]

C [0h] C:-h. C:=h)

C[0a]

C[0c]

C[0e]

C[0h]

C[0l]

C[0u]

C[0y]

?1c]

C[2f]

1) This error code may deactivate again automatically after a specific time (without reset). Heating and hot water are now available once more.

2) In the event of this malfunction, the pump is started up and remains in continuous operation in order to minimise the possibility of the heating system freezing up.

Standby Applies to boilers with hot water supply,

Operating phase: The boiler is in heating mode.

Operating phase: The boiler is in hot water mode. The symbol “ G ” lights up.

Operating phase: Pump over-run time via the external cylinder/hot water heater. The symbol “ G “ is off.

Operating phase: The switch optimisation program is activated. This program is activated if there is, more frequently than once every 10 minutes, a heating water requirement from an RC or ON/OFF control signal. This means that the boiler cannot be restarted until at least 10 minutes have elapsed since initial startup of the burner.

Pre-operative phase: The boiler prepares for burner startup whenever a heating requirement or hot water requirement arises.

Ready for operation: The boiler is in ready mode. There is a current heat requirement, but too much energy has been supplied.

Standby for operation: The boiler is in ready mode. There is no current heat requirement.

Ignition phase: The gas valve is activated.

Startup phase: The boiler starts up after activation of the mains power supply or completion of a system reset. This code is displayed for a maximum of 4 minutes.

Operating phase: The flow sensor has detected that the current CH flow temperature is higher than the temperature entered at the control unit, or that it is higher than the CH flow temperature calculated according to heating requirements, or that it is higher than the CH flow temperature calculated for the purposes of hot water supply.

Fault: The flow sensor or safety sensor has detected that the current CH flow temperature is higher than 95°C.

Fault: The flue-gas STL (fume-monitoring device) has detected a temperature higher than 105°C. The flue-gas STL is opened.

Fault: The flow sensor and safety sensor have, after burner startup, not detected any temperature increase in the heating water, or they have determined that the temperature difference between The flow sensor and safety sensor is too high.

Reset

required?

Yes

Other symptoms

No indication on DBA control panel display. box 21

No (or insufficient) hot water, radiators, convectors, etc. may be heated without current heat requirement.

hot water available, no heating operation. Applies to boilers without hot water supply,

no heating operation.

hot water available, no heating operation.

The heating circuit is warmed up without a heat requirement.

Pump over-run time: Heating system factory default setting = 5 minutes; for details of hot water and service mode see box 5.

The target room-temperature may not be reached. box 25

Heat request, but no respons of the boiler box 285

Recycling phase: The fan runs for 15 seconds at about 60% of maximum speed.

"Extraction of residual fumes in boiler"

The target room-temperature may not be reached. box 26

The target room-temperature may not be reached. box 27

No heating operation and no hot water. box 28

Diagnosis

box 22

box 23

box 24

box 22

box 27

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18 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006

box 20 Display codes

Symptoms 5

Display indication

Display

code

C[2p]

C[3a]

?3l]

?3y]

?4a]

?4e]

?4l]

?4p]

C[6a]

?6a]

:6c]

?6c]

C[6l]

?7c]

!88|

?9a]

?9f]

?9h]

Key to display code

Fault: The flow sensor has detected a temperature increase, in the heating system water, of over 5 °C/sec.

Fault: The tacho signal from the fan has failed during the operating phase.

Fault: The tacho signal from the fan is not present during the preoperative or operating phase.

Fault: No current of air after a certain time.

Fault: The fan runs too slowly or too fast.

Fault: The flow sensor and safety sensor have detected a CH flow temperature of over 105 °C.

Fault: The sensor test has failed.

Fault: The contacts of the flow sensor and safety sensor are shorted to each other, or there is a short-circuit to earth (ground), or the flow or safety sensor has detected a CH flow temperature of above 130 °C.

Fault: The contacts of the flow sensor or safety sensor are broken.

Fault: During the ignition phase, the system has detected an insufficient ionisation current.

Fault: After four startup attempts, the system has detected an insufficient ionisation current.

Fault: The system has detected an ionisation current before burner startup.

Fault: An ionisation current has been measured as soon as the burner shuts down.

Fault: The flame goes out during the operating phase.

Fault: The power supply was shut off during a crucial breakdown.

Operating phase: Display test during startup phase: The code is displayed for a maximum of 1 second.

Fault: The DBA control panel is defective.

Fault: The contacts of the gas valve have been broken.

Fault: The DBA control panel is defective.

Reset

required?

Yes2)No heating operation and no hot water. box 29

Yes2)No heating operation and no hot water. box 30

Yes2)No heating operation and no hot water. box 31

Yes

Yes2)No heating operation and no hot water. box 33

Yes

Yes2)No heating operation and no hot water. box 35

Yes

Yes2)No heating operation and no hot water. box 38

Yes2)No heating operation and no hot water. box 39

Yes2)No heating operation and no hot water. box 41

Yes2)No heating operation and no hot water. box 40

Yes2)No heating operation and no hot water. box 41

Other symptoms

No heating operation and no hot water. box 32

No heating operation and no hot water. box 34

No heating operation and no hot water. box 36

No heating operation and no hot water. box 37

Diagnosis

box 27

box 29

box 36

?9l]

1) This error code may deactivate again automatically after a specific time (without reset). Heating and hot water are now available once more.

2) In the event of this malfunction, the pump is started up and remains in continuous operation in order to minimise the possibility of the heating system freezing up.

Fault: The contacts of the gas valve have been broken.

Fault: The DBA control panel is defective.

Yes2)No heating operation and no hot water. box 40

Yes2)No heating operation and no hot water. box 41

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Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006 19

Symptoms5

box 20 Display codes

Display indication

Display

code

?9p]

?9y]

?ef]

?e1]

Key to display code

Fault: The DBA control panel is defective.

Fault: Short circuit in the gas valve.

Fault: The contacts of the KIM (EEPROM on the DBA control panel circuit board) may be loose or short-circuited.

Fault: The DBA control panel is defective.

Reset

required?

Yes2)No heating operation and no hot water. box 41

Yes box 41

Yes2)No heating operation and no hot water. box 41

Other symptoms

No heating operation and no hot water. box 41

?e4] ?ea] ?ec]

Fault:

C[re]

1) This error code may deactivate again automatically after a specific time (without reset). Heating and hot water are now available once more.

2) In the event of this malfunction, the pump is started up and remains in continuous operation in order to minimise the possibility of the heating system freezing up.

Reset is carried out. This code appears after the reset button 5 seconds.

B is pressed for

Applies only to a system-blocking error (flashing display code)

Diagnosis

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20 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006

6 Diagnosis

box 21

Diagnosis 6

[\/\/\|

step 1 Check to ensure that the power supply cable to the mains switch box has been installed correctly.

step 2 Is the power supply cable to the mains switch box correctly installed? Yes: → step 4

step 3 Install the power supply cable correctly, see box 54. → box 42

step 4 Check to ensure that the operating switch on the boiler DBA control panel is set to position “1” as per box 55.

step 5 Is the operating switch on the boiler DBA control panel set to “I” (ON)? Yes: → step 7

step 6 Turn the operating switch on the DBA control panel of the boiler to position “1” (ON), see box 55. → box 42

step 7 Check to the ensure that there is a 230V AC power supply at the mains switch.

step 8 Is there a 230V AC supply at the mains switch? Yes: → step 10

step 9 Deal with any problem in the electrical system. → box 42

step 10 Measure the resistance of the 230V AC power supply cable.

step 11 Is the resistance of the 230V AC power supply cable within the specified limits? Yes: → step 22

step 12 Replace the cable loom (or the affected part thereof). → box 42

step 13 Use a multimeter to check the fuse on the inside of the DBA control panel, see box 62 to 65.

step 14 Is the fuse working correctly? Yes: → box 41

step 15 Replace fuse, see box 62.

step 16 Is there any indication on the DBA control panel display? Yes: → box 42

step 17 Turn the operating switch on the DBA control panel of the boiler to position “0” (OFF), see box 43.

step 18 Disconnect the following boiler components from the electrical power supply:

step 19 Check the fuse again for correct functioning. Use a multimeter to check the fuse on the inside of the DBA

step 20 Is the fuse working correctly? Yes:

step 21 Replace fuse again, see box 62.

step 22 Turn the operating switch on the DBA control panel of the boiler to position “1” (ON), see box 55.

step 23 Is there any indication on the DBA control panel display? Yes:

step 24 Use a multimeter to check the power supply cables of the pump (box 95), the fan (box 69) and the glow ignitor

step 25 Are the cables in order? Yes: → step 27

step 26 Replace the cable harness (or the affected part thereof).

step 27 Turn the operating switch on the DBA control panel of the boiler to position “0” (OFF), see box 43.

step 28 Connect the power supply plug of the pump in reverse.

step 29 Turn the operating switch on the DBA control panel of the boiler to position “1” (ON), see box 55.

No indication on DBA control panel display.

– pump, see box 92 – fan, see box 71, item 1.

control panel, see box 62.

(box 137) for signs of short circuiting.

Replace fuse again, see box 62.

No: → step 3

No: → step 6

No: → step 9

No: → step 21

No: → step 15

No: → step 17

→ step 22

No:

→ step 21

→ step 27

No: → step 24

No: → step 26

→ box 42

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Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006 21

Diagnosis6

box 21

step 30 Is there any indication on the DBA control panel display? Yes: → step 33

No: → step 31

step 31 Replace the pump, see box 101.

step 32 Replace fuse again, see box 62. → step 33

step 33 Turn the operating switch on the DBA control panel of the boiler to position “0” (OFF), see box 43.

step 34 Connect the power supply plug of the fan in reverse.

step 35 Turn the operating switch on the DBA control panel of the boiler to position “1” (ON), see box 55.

step 36 Is there any indication on the DBA control panel display? Yes: → box 42

step 37 Replace fan, see box 76. → step 38

step 38 Replace fuse again, see box 62.

box 22

No (or insufficient) hot water, radiators, convectors, etc. may be heated without current heat requirement.

step 1 Set the operating switch on the boiler DBA control panel to position “0“ (OFF), see box 43, and set the other

DBA control panel operating switch to position “1“ (ON), see box 55.

step 2 Open a hot water tap.

step 3 Check that the hot water pipe directly beneath the (external) storage-type water heater warms up.

step 4 Does the pipe warm up (to approx. 60 °C)? Yes:

step 5 The cause of this fault does not lie with the boiler, but with the mains water supply. Check to see if the

MCW inlet and DHW outlet have been incorrectly connected to the (external) storage-type water heater.

step 6 Are the pipes connected correctly? Yes:

step 7 Connect the pipeworks correctly.

step 8 Close the shut-off valve in the MCW inlet and open a hot water tap at random to see if water is still flowing.

step 9 Is this the case? Yes:

step 10 The cause is a defective (thermostat-controlled) mixer tap, a thermostat-controlled mixer valve or a short

circuit between the hot- and cold water circuits.

step 11 Check to see if any other external part of the drinking-water system is a possible cause.

step 12 Are such items detected? Yes:

step 13 Place the affected components out of service.

step 14 Check

to ensure that the pre-adjusted setting corresponds to the hot water to ensure that the DHW temperature is adjusted to a high enough setting, see box 61. to see if the hot water supply has been shut off by the control system (ModuLink 250 RF).

step 15 Are the adjustment settings in order? Yes:

step 16 Adjust the settings. step 17 Check to see if the “hot water mode” indicator (H) or (I) lights up on the display, see box 11. step 18 Does the “hot water mode” indicator (H) or (I) light up? Yes:

step 19 Check the turbine flow-meter, see box 104, or DWH temperature sensor of any external storage-type water

heater that might be fitted.

[60) box 14 supply.

→ step 32

No: → step 37

→ box 42

→ step 5

No: → step 39

→ step 8

No:

→ step 7

→ box 42

→ step 10

No:

→ step 11

→ box 42

→ step 13

No:

→ box 42

→ step 17

No:

→ step 16

→ box 42

→ step 25

No: → step 19

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22 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006

Diagnosis 6

box 22

step 20 Is the turbine flow-meter working correctly (along with DHW temperature sensor of any external storage-type

water that might be fitted)?

step 21 Replace the turbine flow-meter, or DHW temperature sensor of any external storage-type water heater that

might be fitted.

step 22 Check the cable of the turbine flow-meter, see box 112, or cable of the DHW temperature sensor of any

external storage-type water heater that might be fitted.

step 23 Is the cable correctly connected and free of damage? Yes:

step 24 Replace the cable loom (or the affected part thereof).

step 25 Check to ensure that the boiler starts up to supply hot water, see box 15.

step 26 Does the boiler start up? Yes:

step 27 Interpret current display codes box 20 and deal with fault.

step 28 Check to ensure that the tap flow rate is correctly adjusted, see box 180.

step 29 Is the tap flow rate correctly adjusted? Yes:

step 30 Correctly adjust the tap flow rate, see box 180.

step 31 Is an internal 3-way valve fitted? Yes:

step 32 Check the movement of the servomotor of the Buderus 24V AC external 3-way valve, see box 211.

step 33 Does the servomotor of the Buderus 24V AC external 3-way valve move correctly? Yes:

step 34 Check the movement of the servomotor of the internal 3-way valve, see box 181..

step 35 Does the servomotor of the internal 3-way valve move correctly? Yes:

step 36 Check to ensure that the the Buderus 24V AC external 3-way valve has been fitted correctly,

see box 227.

step 37 Has the Buderus 24V AC external 3-way valve been fitted correctly? Yes:

step 38 Fit the Buderus 24V AC external 3-way valve in the correct way, see box 227.

step 39 Check the drive mechanism of the internal 3-way valve, see box 195.

step 40 Is the drive mechanism of the internal 3-way valve working correctly? Yes:

step 41 Replace the drive mechanism of the internal 3-way valve, see box 198.

step 42 Check the circulation for debris, see box 97.

step 43 Is there any debris in the pump? Yes:

step 44 Clean the pump, see box 97. → box 42

step 45 The following components must be checked for soiling and/or damage:

- combustion-air inlet pipework

- heat exchanger

- flue-gas pipework.

step 46 Are the above-mentioned components clean and free of damage? Yes:

step 47 Clean and/or replace the corresponding components.

Yes: → step 22

No:

→ step 21

→ box 42

→ box 41

No:

→ step 24

→ box 42

→ step 28

No:

→ step 27

→ box 42

→ step 31

No:

→ step 30

→ step 34

No:

→ step 32

→ step 36

No:

→ step 63

→ step 39

No:

→ step 57

→ step 69

→ step 38

No:

→ box 42

→ step 42

No:

→ step 41

→ box 42

→ step 44

No:

→ step 45

→ step 48

No: → step 47

→ box 42

We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk

Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006 23

Diagnosis6

box 22

step 48 Check the standing and working gas pressures, see box 230.

step 49 Are the standing and working pressures correct? Yes:

step 50 If the standing and working gas input pressures are not detected, consult your gas utility company. → box 42

step 51 Check the gas/air ratio, see box 233.

step 52 Is the gas/air ratio correct? Yes:

step 53 Adjust the gas/air ratio, see box 233.

step 54 Check the plate heat exchanger or the external hot water cylinder for furring.

step 55 Is the plate heat exchanger or hot water cylinder furred up? Yes:

step 56 Decalcify the plate heat exchanger and/or hot water cylinder, see from box 269.

step 57 3-way valve: Check the startup of the servomotor of the internal 3-way valve, see box 181 and box 185.

step 58 Does the servomotor of the internal 3-way valve start up correctly? Yes:

step 59 Replace the servomotor of the internal 3-way valve, see box 190.

step 60 Check the wiring of the internal 3-way valve, see box 191.

step 61 Is the cable correctly connected and free of damage? Yes:

step 62 Replace the cable loom (or the affected part thereof). → box 42

step 63 Check to ensure that the Buderus 24V AC external 3-way valve has actuated correctly,

see box 212 and box 228 parts 1 and 2.

step 64 Does the Buderus 24V AC external 3-way valve actuate correctly? Yes:

step 65 Replace the servomotor of the Buderus 24V AC external 3-way valve, see box 217.

step 66 Check the wiring of the Buderus 24V AC external 3-way valve, see box 220.

step 67 Is the wiring of the Buderus 24V AC external 3-way valve in correct condition? Yes:

step 68 Replace the wiring of the Buderus 24V AC external 3-way valve.

step 69 Check the drive mechanism of the Buderus 24V AC external 3-way valve, see box 221.

step 70 Is the drive mechanism of the Buderus 24V AC external 3-way valve working correctly? Yes:

step 71 Replace the drive mechanism of the Buderus 24V AC external 3-way valve, see box 221.

step 72 Check the wiring of the Buderus 24V AC external 3-way valve between the connection box or moving plug-

and-socket connection and the motor of the Buderus 24V AC external 3-way valve, see box 287.

step 73 Is the wiring in order? Yes:

step 74 Replace the cable loom (or the affected part thereof).

box 23

On combi boilers: hot water available, but no heating operation. On system boilers: no heating operation.

Hot water may be available, but no heating operation.

step 1 Check to ensure that the power supply cable to the mains switch box has been installed correctly, see box 54.

→ step 51

No:

→ step 50

→ step 54

No: → step 53

→ box 42

→ step 56

No:

→ box 41

→ box 42

→ step 59

No:

→ step 60

→ box 42

→ box 41

No:

→ step 62

→ step 65

No:

→ step 66

→ box 42

→ step 71

No:

→ step 68

→ box 42

→ step 42

No: → step 71

→ box 41

No:

→ step 74

→ box 42

We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk

24 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006

+ 56 hidden pages

Buderus 500 - 28/C, 500 - 24/C, 500 - 24/S Servicing Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

1 General

2 Servicing manual user guide

3 Operation

4 Function

5Symptoms

6 Diagnosis