Page 1
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
Page 2
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
Page 3
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
, 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
Page 4
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.
-
-
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
4 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 5
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.
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 5
Page 6
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
, C
33(x)
, C
53(x)
13(x)
, C
5.3 – 22.0
6.0 – 24.0
90.3
92.3
73(x)
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
6 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 7
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
x
General 1
Unit 500-24/S 500-24/C 500-28/C
l/h 1.6
g/s
g/s
°C
°C
°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
II
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
3
(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
3
.
30 - 40 seconds
30 seconds
31
34
5 minutes
–
1 minute
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 7
Page 8
General1
box 6 Overview Buderus 500
1
2
3
11
12
13
14
15
16
17
18
10
19
4
5
6
7
8
9
20
21
22
23
24
25
26
27
28
29
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
8 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 9
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.
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 9
Page 10
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.
We reserve the right to make technical modifications Buderus Ltd • http://www.buderus-domestic.co.uk
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.
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
10 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 11
3 Operation
box 10 Operation
box 11
Operation
3
General points
1
The central boiler can be run from the DBA control panel
(item 1).
3 4 5 6
2
1
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
7
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.
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 11
Page 12
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:
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
[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:
No:
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
Page 13
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
3
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.
E-button once.
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.
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
→ step 1
Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006 13
Page 14
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?
5 °C below the temperature set at the DBA control panel?
No:
No:
No:
No:
No:
Yes:
No:
No:
No:
No:
Yes:
No:
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
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
14 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 15
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:
No:
No:
No:
No:
No:
No:
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.
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 15
Page 16
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:
No:
No:
No:
→ step 52
→ step 57
→ step 53
→ step 50
→ step 53
→ step 13
→ step 66
→ box 36
→ step 68
→ step 67
→ step 13
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
16 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 17
5Symptoms
box 16 Display icons
Symptoms 5
Display
indication
F
G
H
I
J
K
L
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]
1x
A C [hi]
1x
A
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
1)
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.
[//]
1)
= 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
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 17
Page 18
Symptoms5
box 20 Display codes
Display indication
z
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[0a]
C[0c]
C[0e]
C[0h]
C[0l]
C[0u]
C[0y]
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?
No
1)
Yes
2)
No
1)
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
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
18 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 19
box 20 Display codes
Symptoms 5
Display indication
Display
z
code
C[2p]
C[3a]
?3l]
?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
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
1)
No
1)
No heating operation and no hot water. box 32
2)
No heating operation and no hot water. box 34
2)
No
1)
No heating operation and no hot water. box 36
2)
No heating operation and no hot water. box 37
2)
No
1)
Diagnosis
box 27
box 29
box 36
?9l]
?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
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 19
Page 20
Symptoms5
box 20 Display codes
Display indication
z
Display
code
?9p]
?9y]
?ef]
?e1]
to
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
No heating operation and no hot water. box 41
1)
?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
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
20 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 21
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
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 21
Page 22
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
→ box 42
→ step 17
No:
→ step 16
→ box 42
→ step 25
No: → step 19
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
22 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 23
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
Page 24
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
Page 25
Diagnosis 6
box 23
step 2 Check to ensure that the preset room temperature or heating configuration of the Buderus controls or ON/
OFF controller has been adjusted to a high enough setting (see operating instructions).
step 3 Is the preset room temperature or heating configuration of the Buderus controls or ON/OFF controller
adjusted to a high enough setting?
step 4 Adjust the preset room temperature controller or heating configuration of the Buderus controls or
ON/OFF controller to a higher setting (see operating instructions).
step 5 Check to see if the “heating requirement” (K) indicator lights up on the display, see box 11.
step 6 Does the “heating requirement” (K) indicator light up? Yes:
step 7 Check the Buderus controls or ON/OFF controller as per box 177.
step 8 Is the Buderus controls or ON/OFF controller working correctly? Yes:
step 9 Replace the thermostat cable.
step 10 Replace the Buderus controls or ON/OFF controller. → box 42
step 11 Check to ensure that the CH flow temperature at the DBA control panel or on the Buderus controls or ON/
OFF controller is adjusted to a high enough setting as per box 14 and box 61 .
step 12 Is the CH flow temperature adjusted to a high enough setting? Yes:
step 13 Are enough thermostatic valves open on the radiators, convectors, etc? Yes:
step 14 Open more thermostatic valves on the radiators, convectors, etc.
step 15 Adjust the CH flow temperature as per box 14 and box 61. Ensure that the Buderus controls or
ON/OFF controller are calling for a heating demand.
step 16 Check to ensure that the CH flow temperature is correctly adjusted, see box 14.
step 17 Is the CH flow temperature adjusted to a high enough setting? Yes:
step 18 Adjust the CH flow temperature to a higher setting, see box 14.
step 19 Is the CH flow temperature of the boiler sufficient to heat the building? Yes:
step 20 Install a larger boiler.
step 21 Is there a hot water supply? Yes:
step 22 Is an internal 3-way valve fitted? Yes:
step 23 Check the movement of the servomotor of the internal 3-way valve, see box 181.
step 24 Does the servomotor of the internal 3-way valve move correctly? Yes:
step 25 Check the drive mechanism of the internal 3-way valve, see box 195.
step 26 Is the drive mechanism working correctly? Yes:
step 27 Replace the drive mechanism of the internal 3-way valve, see box 198. → box 42
step 28 Check the actuation of the servomotor of the internal 3-way valve, see box 185.
step 29 Does the servomotor of the internal 3-way valve start up correctly? Yes:
Yes:
→ step 5
No: → step 4
→ box 42
→ step 11
No:
→ step 7
→ step 9
No:
→ step 10
→ box 42
→ step 13
No:
→ step 15
→ step 16
No: → step 14
→ box 42
→ box 42
→ step 19
No: → step 18
→ box 42
→ step 21
→ step 20
No:
→ box 42
→ step 22
No: → box 41
→ step 23
No:
→ step 34
→ step 25
No:
→ step 28
→ box 42
No:
→ step 27
→ step 30
No: → step 31
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 25
Page 26
Diagnosis6
box 23
step 30 Replace the servomotor of the internal 3-way valve, see box 190. → box 42
step 31 Check the power supply cable of the internal 3-way valve, see box 191.
step 32 Is the power supply cable of the internal 3-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 Buderus 24V AC external 3-way valve, see box 211.
step 35 Does the servomotor of the Buderus 24V AC external 3-way valve operate 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 Install the Buderus 24V AC external 3-way valve correctly, see box 227.
step 39 Check to ensure that the Buderus 24V AC external 3-way valve is actuated correctly,
see box 212 and box 228.
step 40 Does the Buderus 24V AC external 3-way valve actuate correctly? Yes:
step 41 Replace the servomotor of the Buderus 24V AC external 3-way valve, see box 217.
step 42 Check the wiring of the Buderus 24V AC external 3-way valve, see box 220.
step 43 Is the wiring of the Buderus 24V AC external 3-way valve in correct condition? Yes:
step 44 Replace the wiring of the Buderus 24V AC external 3-way valve.
step 45 Check the drive mechanism of the Buderus 24V AC external 3-way valve, see box 221.
step 46 Is the drive mechanism of the Buderus 24V AC external 3-way valve working correctly? Yes:
step 47 Replace the internal components of the Buderus 24V AC external 3-way valve, see box 224. → box 42
step 48 Check the wiring of the Buderus 24V AC external 3-way valve between the connection box or moving plug-
and-socket connection and the DBA control panel as per box 287.
box 24
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.
step 1 Check to ensure that the power supply cable to the RTH converter/Junction box has been installed correctly,
see box 285.
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 285.
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.
step 5 Is the volt free connection to the RTH converter/Junction box fitted correctly? Yes:
step 6 Check to ensure that the connections of the external control unit are attached to terminal 1 and 2 of the
connection block, indicated by a clock inside a rectangle, see box 286 and box 285 (item 3).
→ box 41
No: → step 33
→ box 42
→ step 36
No:
→ step 39
→ step 45
No:
→ step 38
→ box 42
→ step 41
No: → step 42
→ box 42
→ step 47
No:
→ step 44
→ box 42
→ box 41
No:
→ step 47
→ step 4
No: → step 3
→ box 42
→ step 6
No: → step 8
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
26 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 27
Diagnosis 6
box 24
step 7 Is there a permanent link between terminal 1 and 2 on the volt free connecter? Yes: → step 8
No:
→ step 9
step 8 Check the cable connection between the RTH converter/Junction box and terminal 1 and 2 on the DBA.
step 9 Check the external cable connections and control devices.
step 10 Has the malfunction been repaired? Yes:
box 25
The switch optimisation program is activated. This program is activated if there is,
C [0a]
step 1 Check to ensure that the connections of the control device are correctly fitted at the boiler and control device.
step 2 Is the control device connected correctly? Yes:
step 3 Connect the control device correctly.
step 4 Carry out a visual examination where possible, and use a multimeter to check the electrical resistance of the
thermostat lead. Check for breakages and loose contacts.
step 5 Is the thermostat cable in good condition? Yes:
step 6 Replace the thermostat cable.
step 7 Check to ensure that enough thermostatic valves are open on the radiators, convectors, etc.
step 8 Are enough thermostatic valves open on the radiators, convectors, etc? Yes:
step 9 Open more thermostatic valves on the radiators, convectors, etc.
step 10 Attempt to rectify the fault by temporarily replacing the room thermostat or external temperature-dependent
controller.
step 11 Has the malfunction been repaired? Yes:
box 26
C [0y]
more frequently than once every 10 minutes, a heating water requirement from an
Buderus controller or ON/OFF controller signal. This means that the boiler cannot
be restarted until at least 10 minutes have elapsed since initial startup of the burner.
Operating code
The flow NTC 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.
Operating code
→ box 42
→ box 42
No:
→ box 41
→ step 4
No:
→ step 3
→ box 42
→ step 7
No: → step 6
→ box 42
→ step 10
No:
→ step 9
→ box 42
→ box 42
→ box 41
No:
step 1 Check to ensure that the CH flow temperature at the DBA control panel is higher than that entered at the
controller, see box 61.
step 2 Is the CH flow temperature at the DBA control panel adjusted correctly? Yes:
step 3 Adjust the CH flow temperature at the DBA control panel to a higher setting, see box 61.
step 4 Check to ensure that enough thermostatic valves are open on the radiators, convectors, etc.
step 5 Are enough thermostatic valves open on the radiators, convectors, etc? Yes:
step 6 Open more thermostatic valves on the radiators, convectors, etc.
step 7 Check to see if a hot tap or taps have been opened on brief, consecutive occasions.
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 27
No:
No:
→ step 4
→ step 3
→ box 42
→ step 7
→ step 6
→ box 42
Page 28
Diagnosis6
box 26
step 8 Have a hot water tap or taps been opened briefly and consectutively on several occasions? Yes: → step 9
No:
→ box 15
step 9 Inform the user that the fault has been caused by opening hot taps on many brief, consecutive occasions.
step 10 Check the electrical resistance of the DHW temperature sensor, see box 104.
step 11 Is the electrical resistance of the DHW temperature sensor in order? Yes:
step 12 Replace the DHW temperature sensor.
box 27
The flow NTC sensor or safety sensor has detected that the current CH flow
C [0y]
C [2f]
C [2p]
temperature is higher than 95 °C.
Blocking boiler-fault code
The flow NTC sensor and safety sensor have not, after burner startup, detected any
temperature increase in the heating system water, or the temperature difference
between the flow NTC sensor and safety sensor is excessive.
Blocking boiler-fault code
The flow NTC sensor has detected a temperature increase in the heating system
water of more than 5 °C/sec.
Blocking boiler-fault code
No:
→ box 42
→ box 41
→ step 12
The flow NTC sensor and safety sensor have detected a CH flow temperature of over
[4a]
[4e]
step 1 Are the servicing valves open? Yes:
step 2 Open the servicing valves, see box 53.
step 3 Is the pressure in the heating system at least 1 bar? Yes:
step 4 Fill and vent the heating system, see box 52.
step 5 Are enough thermostatic valves open on the radiators, convectors, etc? Yes:
step 6 Open more thermostatic valves on the radiators, convectors, etc.
step 7 Check the flow NTC sensor and safety sensor, see box 104.
step 8 Are the flow NTC sensor and safety sensor in order? Yes:
step 9 Replace the flow NTC sensor or safety sensor, see box 116. → box 42
step 10 Check the cable between the flow NTC sensor or safety sensor for short circuits, see box 112.
step 11 Check the pump, see box 89 to 100.
step 12 Is the pump working correctly? Yes:
step 13 Replace the pump, see box 101.
step 14 Check to ensure that the internal by-pass valve in the boiler or the external overflow valve in the heating
system are working correctly. Possible to adjust external overflow valve to max. 25 kPa (if fitted).
step 15 Is the by-pass valve working correctly? Yes:
105 °C.
Locking boiler-fault code
Short circuit between flow NTC sensor or safety sensor.
Locking boiler-fault code
→ step 3
No:
→ step 2
→ step 5
No:
→ step 4
→ step 7
No:
→ step 6
→ box 42
→ step 10
No:
→ step 9
→ step 14
No:
→ step 13
→ box 41
No: → step 14
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
28 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 29
Diagnosis 6
box 27
step 16 Replace the by-pass valve. → box 42
box 28
The flue-gas STL (fume-monitoring device) has detected a temperature higher than
[1c]
step 1 Check to ensure that the restrictor baffle has been installed as per box 261, item 1.
step 2 Has the restrictor baffle been fitted? Yes:
step 3 Fit the restrictor baffle, see box 261, item 1.
step 4 Check the entire system of flue gas pipe for restrictions.
step 5 Is the entire system of flue gas pipe in full working order? Yes:
step 6 Deal with restriction.
step 7 Check the flue-gas STL, see box 120.
step 8 Is the flue-gas STL working correctly? Yes:
step 9 Replace the flue-gas STL, see box 129.
step 10 Check the wiring of the flue-gas STL, see box 126.
step 11 Is the wiring of the flue-gas STL in full working order? Yes:
step 12 Replace the cable loom (or the affected part thereof).
box 29
C [3a]
105°C. The flue-gas STL is open.
Locking boiler-fault code
The tacho signal from the fan has failed during the operating phase.
Blocking boiler-fault code
→ step 4
No:
→ step 3
→ box 42
→ step 7
No:
→ step 6
→ box 42
→ step 10
No:
→ step 9
→ box 41
No: → step 12
→ box 42
The tacho signal from the fan is not present during the pre-operative or operating
[3l]
step 1 Check to ensure that both plug-and-socket connections of the fan are correctly fitted, see box 246, item 1.
step 2 Are the plug-and-socket connections fitted correctly? Yes:
step 3 Reconnect the plug-and-socket connection of the fan.
step 4 Check fan, 230V AC supply, see box 66 or box 287.
step 5 Does activation take place correctly? Yes:
step 6 Check the power supply cable of the fan (230V AC), see box 69.
step 7 Is the power supply cable of the fan in full working order? Yes:
step 8 Replace the cable loom (or the affected part thereof).
step 9 Check tacho cable of fan, see box 73.
step 10 Is the tacho cable in full working order? Yes:
step 11 Replace the cable loom (or the affected part thereof).
step 12 Check to ensure that the mains voltage at the earthed (grounded) plug is between 195V and 253V AC.
phase.
Locking boiler-fault code
No:
No:
No:
No:
→ step 4
→ step 3
→ box 42
→ step 9
→ step 6
→ box 41
→ step 8
→ box 42
→ step 12
→ step 11
→ 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 29
Page 30
Diagnosis6
box 29
step 13 Is the mains voltage sufficient? Yes: → step 15
No:
→ step 14
step 14 The cause of the fault lies in the electrical system.
step 15 Replace fan, see box 76.
step 16 Has the malfunction been repaired? Yes:
box 30
No current of air after a certain time.
[3l]
step 1 Attempt to rectify the fault by temporarily replacing the fan, see box 76.
step 2 Has the malfunction been repaired? Yes:
box 31
[3y]
Locking boiler-fault code
The fan runs too slowly or too fast.
Locking boiler-fault code
No:
No:
→ box 42
→ box 42
→ box 41
→ box 42
→ box 41
step 1 Check the plug-and-socket connection of the fan tacho cable.
This is the narrow plug, see box 78, item 2.
step 2 Is the plug-and-socket connection in full working order? Yes:
step 3 Reconnect the plug-and-socket connection, see box 78, item 2.
step 4 Check tacho cable of fan, see box 73.
step 5 Is the tacho cable in full working order? Yes:
step 6 Replace the tacho cable.
step 7 Check to ensure that the mains voltage at the earthed (grounded) plug is between 195V and 253V AC.
step 8 Is the mains voltage sufficient? Yes:
step 9 The cause of the fault lies in the electrical system. → box 42
step 10 Check to see if there is a restriction in the fan, burner, heat exchanger or flue-gas system.
step 11 Is there a restriction? Yes:
step 12 Deal with restriction.
step 13 Check to see if there is a second fan in the flue gas pipe or air inlet system.
step 14 Is a second fan fitted? Yes:
step 15 Take second fan out of service.
step 16 Check to see if the fan impeller has come loose at the motor spindle, see box 76.
step 17 Has the fan come loose? Yes:
step 18 Replace fan, see box 76.
step 19 Has the malfunction been repaired? Yes:
→ step 4
No:
→ step 3
→ box 42
→ step 7
No:
→ step 6
→ box 42
→ step 10
No:
→ step 9
→ step 12
No: → step 13
→ box 42
→ step 15
No:
→ step 16
→ box 42
→ step 18
No:
→ step 19
→ box 42
No:
→ box 41
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
30 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 31
Diagnosis 6
box 32
The flow NTC sensor has detected a temperature of over 105 °C.
[4a]
step 1 Check the flow rate in the heating circuit.
step 2 Are all servicing valves and thermostat valves closed? Yes: → step 4
step 3 Check all servicing valves and thermostat valves for correct functioning
step 4 Open all servicing valves and thermostat valves.
step 5 Has the malfunction been repaired? Yes:
box 33
[4e]
step 1 Check the flow NTC sensor and safety sensor and their wiring for short circuits, see box 104 to 115 and
box 287.
step 2 Are the flow NTC sensor and safety sensor, along with their wiring, in correct working order? Yes:
step 3 Replace the flow NTC sensor, safety sensor, cable loom or corresponding component of the cable loom,
see box 116.
box 34
[4l]
Locking boiler-fault code
The sensor test has failed.
Locking boiler-fault code
The contacts of the flow NTC 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.
Locking boiler-fault code
No: → step 3
→ box 42
No:
→ box 41
→ box 41
No: → step 3
→ box 42
step 1 Are the servicing valves open? Yes:
No:
step 2 Open the servicing valves, see box 53.
step 3 Is the pressure of the heating system water at least 1 bar? Yes:
No:
step 4 Fill and vent the heating system, see box 52.
step 5 Are enough thermostatic valves open on the radiators, convectors, etc? Yes:
No:
step 6 Open more thermostatic valves on the radiators, convectors, etc.
step 7 Check the flow NTC sensor and safety sensor, see box 104.
step 8 Are the flow NTC sensor and safety sensor functioning correctly? Yes:
No: → step 9
step 9 Replace the flow NTC sensor or safety sensor, see box 116.
step 10 Check the cables of the flow NTC sensor and safety sensor, see box 112.
step 11 Are the cables in order? Yes:
No:
step 12 Replace the cable loom (or the affected part thereof).
step 13 Check the pump, see box 89 to 100.
step 14 Is the pump working correctly? Yes:
No:
→ step 3
→ step 2
→ step 5
→ step 4
→ step 7
→ step 6
→ box 42
→ step 10
→ step 13
→ step 12
→ box 42
→ box 41
→ step 15
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 31
Page 32
Diagnosis6
box 34
step 15 Replace the pump, see box 101. → box 42
box 35
The contacts of the flow NTC sensor or safety sensor are broken.
[4p]
step 1 Check the flow NTC sensor and safety sensor, see box 104.
step 2 Are the flow NTC sensor and safety sensor functioning correctly? Yes:
step 3 Replace the flow NTC sensor and safety sensor, see box 116.
step 4 Check the cable of the flow NTC sensor and safety sensor, see box 112.
step 5 Are the cables in order? Yes:
step 6 Replace the cable loom (or the affected part thereof).
box 36
C [6a]
Locking boiler-fault code
The system has detected an insufficient ionisation current during the ignition phase.
Blocking boiler-fault code
→ step 4
No: → step 3
→ box 41
No:
→ step 6
→ box 42
The system has detected an insufficient ionisation current after four startup
[6a]
step 1 Is the heating system propane gas-fired? Yes:
step 2 Ensure that no nitrogen remains in the gas tank or gas flow pipes.
You should also consult your gas utility company.
step 3 Check whether the gas tap is open, see box 59.
step 4 Is the gas tap open? Yes:
step 5 Open the gas tap, see box 59. → step 63
step 6 Check the static and working gas pressure, see box 230.
step 7 Are the static and working gas pressures correct? Yes:
step 8 Check to see if there is a restriction in the pipework between the gas tap and gas valve.
step 9 Is there a restriction? Yes:
step 10 Deal with restriction.
step 11 Check for restrictions in the remaining section of the gas flow pipe.
step 12 Is there a restriction? Yes:
step 13 Deal with restriction.
step 14 Has the gas flow pipe been bled of air? Yes: → step 16
step 15 Vent the gas flow pipe of air, see box 239.
step 16 Check to see if the glow ignitor activates with the operating code C [0c], see box 130.
step 17 Does the glow ignitor activate with the operating code
attempts.
Locking boiler-fault code
→ step 2
No: → step 3
→ step 63
→ step 6
No:
→ step 5
→ step 14
No: → step 8
→ step 10
No: → step 11
→ step 63
→ step 13
No:
→ step 38
→ step 63
No:
→ step 15
→ step 62
C [0c]?Yes:→ step 21
No:
→ step 18
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
32 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 33
Diagnosis 6
box 36
step 18 Check the power supply cable of the glow ignitor, see box 137.
step 19 Is the power supply cable in full working order? Yes:
step 20 Replace the cable loom (or the affected part thereof). → step 62
step 21 Check the electrical resistance of the glow ignitor, see box 134.
step 22 Is the electrical resistance of the glow ignitor in order? Yes:
step 23 Replace the glow ignitor, see box 140.
step 24 Place the boiler in full-load operation, see box 13, and check whether the glow ignitor activates with the
step 25 Does the glow ignitor activate with the operating code
step 26 Connect a digital pressure gauge, see box 233 and 234. Open the gas cock and place the boiler into
step 27 Does the gas valve open with the operating code
step 28 Check the plug-and-socket connection on the gas valve, see box 161.
step 29 Is the plug-and-socket connection in full working order? Yes:
step 30 Reconnect the plug-and-socket connection at the gas valve. → step 62
step 31 Check whether the gas valve receives power with the operating code
step 32 Does the gas valve receive power? Yes:
step 33 Replace the gas valve, see box 174.
step 34 Check the power supply cable of the gas valve, see box 167.
step 35 Is the wiring in order? Yes:
step 36 Replace the cable loom (or the affected part thereof).
step 37 Check whether the incoming gas supply is of sufficient capacity.
step 38 Is the incoming gas supply of sufficient capacity? Yes:
step 39 Upgrade internal pipe work. → step 62
step 40 Consult your gas utility company accordingly.
step 41 Measure the gas/air ratio during the startup phase, see box 233.
step 42 Is the gas/air ratio correctly adjusted? Yes:
step 43 Adjust the gas/air ratio, see box 233.
step 44 Check to ensure that the correct gas injector, see box 83, item 1, and the correct Venturi,
step 45 Is the correct gas injector and Venturi fitted? Yes:
step 46 Fit the correct gas injector and/or Venturi, see box 5.
operating code
operation, see box 59 or box 13. Check whether the gas valve opens with the operating code
see box 87, item 1, are fitted as specified. See also box 5.
C [0c] .
C [0c] ?Yes:→ step 26
C [0l] ?Yes:→ step 41
C [0l] , see box 164.
C [0l] .
→ box 41
No:
→ step 20
→ step 24
No: → step 23
→ step 62
No:
→ step 23
No:
→ step 28
→ step 31
No:
→ step 30
→ step 33
No: → step 34
→ step 62
→ box 41
No:
→ step 36
→ step 62
→ step 40
No:
→ step 39
→ step 62
→ step 44
No:
→ step 43
→ step 62
→ step 47
No: → step 46
→ step 62
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 33
Page 34
Diagnosis6
box 36
step 47 The following components must be checked for soiling, damage and/or correct installation:
– condensate trap and syphon, see box 256
– combustion-air inlet pipework
– air silencer pipework
– seal between the Venturi and fan
– Venturi, see box 86
– gas injector, see box 83, item 1
– fan
– connection between the fan and burner
– burner
– heat exchanger
– system of flue-gas pipe and air inlet pipeworks
– pressure control valve, see box 85
– earth (ground) lead of ionisation circuit, see box 160.
step 48 Are the above-mentioned components clean, free of damage and/or correctly intalled? Yes:
step 49 Clean, replace and/or correctly install the components concerned.
step 50 Measure the ionisation current, see box 143.
step 51 Is the ionisation current in order? Yes:
step 52 Check the plug-and-socket connection between the ionisation electrode and cable loom, see box 144.
step 53 Is the plug-and-socket connection in full working order? Yes:
step 54 Correctly insert the plug into its socket → step 62
step 55 Check the cable of the ionisation electrode, see box 151.
step 56 Is the wiring in order? Yes:
step 57 Replace the cable loom (or the affected part thereof).
step 58 Check the ionisation electrode and replace as required, see box 155.
step 59 Temporarily disconnect the flue-gas pipework from the top of the boiler.
Run the boiler at low mode, see box 13. Check to see if the fault has been rectified.
step 60 Has the malfunction been repaired? Yes:
step 61 The cause of the fault lies in the flue-gas system. Take the boiler out of operation.
step 62 Switch the boiler off and then on again at the operating switch.
step 63 Is the error code still displayed? Yes:
step 64 Has an error
step 65 Interpret the display code with box 20 and deal with the fault.
step 66 Has the entire table box 36 been covered? Yes:
C [6a] reoccurred? Yes: → step 66
→ step 50
No:
→ step 49
→ step 62
→ step 62
No:
→ step 52
→ step 55
No:
→ step 54
→ step 58
No: → step 57
→ step 62
→ step 62
→ step 61
No: → step 62
→ box 42
→ step 64
No:
→ box 42
No: → step 65
→ box 41
→ step 1
No:
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
34 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 35
box 37
:6c]
Diagnosis 6
The system has detected an ionisation current before burner startup.
Locking boiler-fault code
step 1 Is the ionisation current displayed? Yes:
step 2 Disconnect the plug-and-socket connection, see box 144.
step 3 Is the ionisation current still displayed? Yes:
step 4 Check the plug-and-socket connection between the ionisation electrode and cable loom, see box 144.
step 5 Is the plug-and-socket connection in full working order? Yes:
step 6 Correctly insert the plug into its socket. → step 11
step 7 Check the cable of the ionisation electrode, see box 151.
step 8 Is the wiring in order? Yes:
step 9 Replace the cable loom (or the affected part thereof).
step 10 Check the ionisation electrode, see box 149 or box 155.
step 11 Is the ionisation electrode working correctly? Yes: → step 14
step 12 Replace the ionisation electrode, see box 155.
step 13 Switch the boiler off and then on again at the operating switch.
step 14 The following components should be checked for soiling, damage and/or correct installation:
- syphon, see box 256
- flue-gas pipework.
step 15 Check the pressure control valve, see box 85.
step 16 Is the pressure control valve working correctly? Yes:
step 17 Replace or clean the pressure control valve, see box 85.
box 38
An ionisation current has been measured as soon as the burner shuts down.
[6c]
Locking boiler-fault code
→ step 2
No:
→ step 1
→ step 12
No:
→ box 41
→ step 7
No:
→ step 6
→ step 10
No: → step 9
→ step 13
→ box 42
No:
→ step 12
→ box 42
→ box 41
No:
→ step 17
→ box 42
step 1 Connect a digital pressure gauge, see box 233 and 234. Open the gas cock and place the boiler into full-load
operation, see box 59 or box 13. Deactivate the heat requirement as per flue-gas test (box 13), and check to
see if the burner remains under pressure after the “heat requirement” symbol on the DBA control panel goes
out.
step 2 Is the burner still under pressure? Yes:
step 3 Check the ionisation electrode, see box 37.
step 4 Close the gas cock, see box 46. Remove the digital pressure gauge and close the burner-pressure
connection nipple. Open the gas cock, see box 59, and run the boiler at full load once more, see box 59 or
box 13. Deactivate heat requirement, see box 13, and check to see if the gas valve is still powered after the
“heat requirement” indicator goes out, see box 165, item 1 and 2.
step 5 Is the gas valve still powered? Yes:
step 6 Replace the gas valve, see box 174.
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 35
→ step 4
No:
→ step 3
→ box 41
No: → step 6
Page 36
box 39
Diagnosis6
[7c]
The power supply was shut off during operation.
Locking boiler-fault code
step 1 Reset the boiler with button "
step 2 Is the error code still displayed? Yes:
step 3 Interpret the fault code now displayed in box 20 and deal with the malfunction.
box 40
The contacts of the gas valve have been broken.
[9f]
Locking boiler-fault code
B", or by turning the operating switch to "OFF" and then "ON" again.
No:
→ step 3
→ box 42
[9l]
step 1 Check the plug-and-socket connection of the gas valve, see box 161.
step 2 Is the plug-and-socket connection in full working order? Yes:
step 3 Reconnect the plug-and-socket connection, see box 161.
step 4 Measure the cable between the gas valve and DBA control panel, see box 164.
step 5 Is the cable correctly connected and free of damage? Yes:
step 6 Replace the cable loom (or the affected part thereof). → box 42
step 7 Measure the resistance of the gas valve coils, see box 171.
step 8 Is the resistance correct? Yes:
step 9 Replace the gas valve, see box 174.
box 41
Bad electrical contacts, circuit board or EEPROM (KIM) of DBA control panel defective.
step 1 Check the contacts on the circuit board of the DBA control panel by pushing fully home the plug-and-socket
connections on the board; check and deal with any other contact problems with plug-and-socket connections.
step 2 Switch the boiler off and then on again at the operating switch.
step 3 Is same fault warning message still displayed? Yes:
step 4 Check the plug-and-socket connection on the EEPROM (KIM), see box 284.
step 5 Has the DBA control panel been replaced? Yes:
step 6 Replace the DBA control panel, see box 281. → step 2
step 7 Contact Buderus (see on the back of this manual).
step 8 Has a new fault occurred? Yes:
step 9 Interpret the fault code now displayed in box 20 and deal with the malfunction.
→ step 4
No:
→ step 3
→ box 42
→ step 7
No:
→ step 6
→ box 41
No: → step 9
→ box 42
→ step 4
No:
→ step 8
→ step 7
No:
→ step 6
→ step 9
No: → box 42
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
36 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 37
Diagnosis 6
box 42
step 1 Fit the casing to the boiler.
step 2 Turn the mains switch on the DBA control panel of the boiler to position “0” (OFF), see box 43.
step 3 Turn the mains switch on the DBA control panel of the boiler to position “1” (ON), see box 55.
The fault is now rectified.
Your Buderus 500 should be working now.
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 37
Page 38
Actions7
7Actions
box 43 Shutting down
1
z Turn the mains switch on the boiler to position “0” (OFF,
item 1).
box 46
1
2
box 44
OFF
permanent
live
z Turn the mains switch to “OFF”.
box 45
z Close the gas cock (item 1).
box 47 Removal of casing
z Use a radiator key to turn the casing lock to “open”, then
remove casing.
box 48 Draining the system
66
2
1
Key to terms (see box 4):
1 = CH flow
2 = DHW outlet (combination boilers only)
3 = Gas connection
4 = MCW inlet (combination boilers only)
5 = CH return
z Close the servicing valves (item 6), if fitted.
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
38 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
3
4
5
z Take the boiler out of operation, see box 43, 44, 45, 46
or 47.
Page 39
Actions 7
box 49
z Loosen by one turn the sealing cap on the automatic air
vent located on the top left-hand part of the boiler.
box 50
6
box 52 Filling the system and venting it of air
z Turn the operating switch on the boiler to position “0”
(OFF), see box 43.
z Remove casing, see box 47.
box 53
DHW
cold
stop
valve
double
check
valve
filling loop
stop
valve
CH
return
z Connect filling loop (accessory), see box 50, item 6.
z Open both stop valves.
z Fill the system to a pressure of approx. 1.5 bar.
z Shut both stop valves.
z Disconnect the filling loop.
z Vent all radiators from air starting with the lowest radiator
and working your way up to the highest point.
z Check the pressure after venting. If the pressure has
dropped under 1.0 bar then top up the system as
described previously.
z Disconnect the filling loop and cap off.
2
1
Key to terms:
1 = CH flow
2 = DHW outlet (combination boilers only)
3 = Gas connection
4 = MCW inlet (combination boilers only)
5 = CH return
3
4
5
z Connect the hose (item 6) to the drain cock of the boiler.
z Open the filling and draining cock and drain the heating
system, see
box 53.
box 51
box 54
ON
permanent
live
z Turn the mains switch to “ON”.
z Fit the casing and use the radiator key to turn the casing
lock to “closed”.
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 39
Page 40
Actions7
box 55
1
z Turn the operating switch on the boiler to position “1”
(ON, item 1).
box 56
z Fill the heating system to a pressure of approximately
1.5 bar, then close the filling loop.
z Vent all the air vent points in the heating system, working
from bottom to top, in order to allow all air in the heating
system to escape.
box 57
box 58
z Vent the pump.
ACAUTION!
Correct venting of the pump will help ensure that it runs
for its specified service life.
The sliding bearing, which is located behind the vent
screw, is lubricated with heating system water.
z Once the heating system has been completely purged of
air, check the pressure at the analogue pressure gauge.
If the pressure is lower than 1.0 bar, the boiler should be
topped up as described above.
z Close the water tap.
In the case of system boilers:
z Close the filling loop of the boiler, see box 50, item 2.
z Remove the hose.
z Fit the sealing cap to the filling and draining cock.
In the case of combination boilers:
z Close the filling loop.
z Remove the hose.
z Fit casing, see box 51.
z Configure target adjustments using the “Settings” menu
on the DBA control panel of the boiler, see box 61
1
z Loosen by two turns the vent screw (item 1) on the front of
the pump.
ACAUTION!
Water will also squirt out!
box 59 Initial startup
1
z Open the gas tap (item 2).
box 60
z Put the boiler into operation, see box 53, 54 or 55.
2
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
40 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 41
Actions 7
box 61
1
z Press the menu button (item 1) on the DBA control panel
of the boiler.
z Configure the menu as required, see box 14.
box 62 Check/replace fuses (1)
HDANGER OF FATAL ACCIDENT
due to electric shock
z Take the boiler out of operation, see box 43, 44 or 47.
box 63
1
2
box 64
z Remove the rear section of the DBA control panel,
see box 70.
z Remove the fuse from the fuse holder.
z Check the fuse with a multimeter. If the fuse possesses
infinitely high electrical resistance, it is defective.
z Replace the defective fuse with a (new) 2.5 AT slow blow
reserve fuse.
box 65
z Refit the DBA control panel, following the above
procedure in reverse order.
z Refit the casing and place the boiler into operation,
see box 51, 53, 54 or 55.
z Remove the casing from the boiler, see box 47.
z Loosen the cap screw on the DBA control panel (item 1).
z Tip the DBA control panel forwards (item 2).
box 66 Check fan – activation 230V AC
HDANGER OF FATAL ACCIDENT
due to electric shock
ACAUTION!
To prevent damage, do not insert the measuring
electrodes of the multimeter too far into the holes of the
plug-and-socket connection.
z Remove the casing and place the boiler out of operation,
see box 47, 43 or 44.
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 41
Page 42
Actions7
box 67
1
z Set the multimeter to VAC. Minimum value: 250 V AC.
z Disconnect the 230V AC plug (item 1) from the fan.
z Attach the multimeter to the two outer contacts (blue and
brown) of the fan connection plug.
z Start system at full load, see box 54, 55 or 13.
z Check whether, with operating code C [0c] active, there
is a voltage of 230 V AC at the two outer contacts (blue
and brown) of the plug.
box 70
1
z Loosen the six screws and remove the rear section.
box 71
Stift 5
Stift 4
JP1
box 68
z Take the electrical system of the boiler out of operation,
box 43 and 44.
see
z Insert the fan connection plug.
z Refit the casing and place the boiler into operation, see
box 51, 53, 54 or 55.
box 69 Check fan – power supply cable (230 V AC)
HDANGER OF FATAL ACCIDENT
due to electric shock
ACAUTION!
To prevent damage, do not insert the measuring
electrodes of the multimeter too far into the holes of the
plug-and-socket connection.
z Take the boiler out of service and tip the DBA control panel
forwards, see
box 43, 44, 47 or 63.
z Disconnect the 230V AC plug (item 1) from the fan.
z Set multimeter to “measure resistance”.
z Check the power supply cable of the fan for breaks.
The electrical resistance measured at each individual wire
must be approximately 0
z Check the power supply cable of the fan for internal short
circuits. The level of electrical resistance, measured
between two wires chosen at random, must be infinitely
high. See also
box 72
z Insert the fan connection plug.
z Refit the DBA control panel, following the above
procedure in reverse order.
z Refit the casing and place the boiler into operation,
see box 51, 53, 54 or 55.
box 287.
Ω.
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
42 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 43
Actions 7
box 73 Check fan – tacho cable
HDANGER OF FATAL ACCIDENT
due to electric shock
ACAUTION!
To prevent damage, do not insert the measuring
electrodes of the multimeter too far into the holes of the
plug-and-socket connection.
z Take the boiler out of service and tip the DBA control panel
forwards, see box 43, 44, 47 or 63.
z Loosen the six screws and remove the rear section,
see box 70.
box 74
1
box 76 Check fan and/or replace
HDANGER OF FATAL ACCIDENT
due to electric shock
ADANGER OF FATAL ACCIDENT
All work on gas pipework and gas-fitting components
must be carried out by a company registered and
authorised for this purpose.
INOTE:
Please observe the fitting instructions supplied with the
fan.
z Take the boiler out of operation and close the gas tap,
see box 43, 44, 46 or 47.
box 77
5
6
JP4
z Pull out the tacho cable plug (item 1).
z Set multimeter to “measure resistance”.
z Attach the multimeter.
z Check the tacho cable of the fan for breaks.
The electrical resistance measured at each individual wire
must be approximately 0
z Check the tacho cable of the fan for internal short circuits.
The level of electrical resistance, measured between two
wires chosen at random, must be infinitely high.
box 75
z Connect the tacho cable plug.
z Refit the DBA control panel, following the above
procedure in reverse order.
z Refit the casing and place the boiler into operation,
see box 51, 53, 54 or 55.
Ω.
17
15
JP3
1
2
3
z Pull out the power supply plug of the gas valve (item 1).
z Loosen the union nut (item 2).
z Detach the air silencer tube (item 3).
box 78
1
2
3
z Pull out both fan plugs (item 2).
z Pull out the glow ignitor plug (item 3).
z Pull out the ionisation electrode plug (item 1).
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 43
Page 44
Actions7
box 79
1
2
box 81
1
z Remove the Venturi (item 1).
box 82
z Fit the Venturi to the new fan.
box 83
z Twist (drawing 1) the fan in the direction of the arrow to
remove (drawing 2).
z Check to see if the fan is soiled or wet.
z Check to see if the fan impeller has come loose at the
motor spindle.
box 80
1
2
z Loosen the three screws (item 1) on the gas valve.
z Remove the gas valve (item 2).
1
z Fit the gas valve to the new fan. When doing so, ensure
that the gas injector (item
box 84
z Fit the fan to the boiler. Remember to fit the new flat rubber
sealing ring (supplied) when doing so.
z Fit the air silencer tube to the fan.
z Fit the gas supply pipe to the gas valve. Ensure when
doing so that the flat rubber sealing ring is correctly fitted.
z Insert the power supply plug into the gas valve, then insert
the power supply plug and tacho cable plug into the fan.
z Open the gas cock and place the electrical system of the
boiler into operation, see box 59, 54 or 55.
z Carry out a gas-leak check. Check the tightness of all
components that were loosened in the course of
component removal. Use an authorised foam-type leak
detection product for this purpose. If you detect a gas leak,
refer to
z Remedy the cause of the gas leak.
z Open the gas cock, place the electrical system of the
boiler into operation and fit the casing, see box 59, 54, 55
or 51.
box 46, 43 or 44.
1) is correctly fitted.
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
44 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 45
Actions 7
box 85 Check the non return valve
A
6
5
4
3
7
2
1
z Remove the fan, see box 76 to box 79.
z Check to see if the non return valve (item 5 and 6, if fitted)
is soiled or defective.
z Loosen the upper nut (item 2).
z Loosen the two lower nuts (item 1).
z Turn the securing plate 180° counterclockwise (item 3).
z Remove the fan part (item 7).
z Bend the silicon seal (item 4).
z Remove the plastic valvehousing (item 5).
z Check the silicon valve (item 6) and replace when
necessary.
z After checking, refit all components in reverse order.
Make sure that the cam (item A) of the silicon valve is
mounted in the correct manner (A).
z First tighten the upper nut (item 2), then tighten the lower
two nuts (item
1).
z Refit all other components in reverse order, then put the
boiler into service, see box 51, 54 or 55.
box 86 Check the Venturi
box 87
1
1
z Check the article number of the Venturi against those
listed in the table in
z Check to ensure that the correct Venturi has been fitted.
This is done by comparing the article numbers listed
against the number on the Venturi (item 1), see box 5.
z Check the Venturi for soiling.
box 88
z Refit the Venturi and fan by following the above procedure
in reverse order.
z Refit the air silencer tube.
z Refit the casing and place the boiler into operation,
see box 51, 53, 54 or 55.
box 89 Check the pump – mechanical restrictions
z Remove casing, see box 47.
z Remove the vent screw on the front of the pump,
see box 57.
ACAUTION!
Note that water will squirt out when the vent screw is
removed. Have a bucket and a supply of dry cloths to
hand.
box 5.
z Take the boiler out of operation, see box 43, 44 or 47.
z Remove the air intake duct, see box 77.
z Remove the Venturi, see box 81, item 1.
box 90
z Put the electrical system of the boiler into operation,
see box 54 and 55.
z Check to see if the pump is running. The pump may
become mechanically blocked if the heating system has
been out of use for an extended period.
z Insert a screwdriver and attempt to make the pump turn.
Use the screwdriver to turn the fan wheel in the direction
of rotation shown on the identification plate of the pump.
z Refit the vent screw to the pump.
z Fit casing, see box 51.
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 45
Page 46
Actions7
box 91 Check the pump – activation
HDANGER OF FATAL ACCIDENT
due to electric shock
ACAUTION!
To prevent damage, do not insert the measuring
electrodes of the multimeter too far into the holes of the
plug-and-socket connection.
ACAUTION!
Close gas valve during pump test.
z Take the boiler out of operation, see box 43, 44 or 47.
box 92
box 94
z Insert the power supply plug of the pump.
z Fit casing, see box 51.
box 95 Check the pump – power supply cable
HDANGER OF FATAL ACCIDENT
due to electric shock
z Take the boiler out of serve and tip the DBA control panel
forwards, see box 43, 44, 47 or 63.
z Loosen the six screws and remove the rear section,
see box 70.
z Remove the power supply plug of the pump, see box 92.
box 96
2
3
JP1
z Pull out the power supply plug of the pump.
box 93
z Set the multimeter to “measure AC voltage”.
Minimum measuring range: 250V AC.
z Put the boiler into operation, see box 54 and 55.
z Carry out a multimeter check to verify whether 230V AC is
present at both outer contacts (L and N) of the power
supply plug of the pump during locking fault code
[2l] .
z Check the power supply cable of the pump for breaks.
The electrical resistance measured at each individual wire
must be approximately 0
z Check the power supply cable of the pump for internal
short circuits. The level of electrical resistance, measured
between two wires chosen at random, must be infinitely
high.
z Fit the power supply plug of the pump, fit the DBA control
panel and place the boiler into operation, see
or 55.
box 97 Check the pump – soiling
z Take the boiler out of operation and drain the heating
system, see box 43, 44, 47, 45, 49 or 50.
Ω.
box 53, 54
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
46 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 47
Actions 7
box 98
z Loosen the four Allen screws on the pump.
z Remove the top section of the pump.
box 99
box 102
1
1
z Loosen the union nuts (item 1) at the top and side of the
pump.
z Remove the pump.
box 103
ACAUTION!
Fit new flat sealing rings when installing the new pump.
z Install the new pump.
z Insert the power supply plug of the pump, fill and vent the
heating system of air and put the boiler into operation,
see box 57 to 60.
z Fit casing, see box 51.
z Clean the pump impeller wheel.
box 100
z Refit the top section of the pump.
z Fill and vent the heating system, see box 52 to 58.
z Fit casing, see box 51.
box 101 Replace the pump
HDANGER OF FATAL ACCIDENT
due to electric shock
z Take the boiler out of operation and drain the heating
system, see box 43, 44, 47, 45, 49 or 50.
z Remove the power supply plug of the pump, see box 92.
box 104 Check the flow, safety and DHW temp. sensors
(applies to external cylinder only)
z Put the boiler into operation, see box 54 or 55.
z Open the hot water tap and wait for the boiler to start up,
then gradually close the hot water tap to bring the CH flow
temperature to over 80
z Take the boiler out of operation and remove the casing,
see box 43, 44 or 47.
°C.
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 47
Page 48
Actions7
box 105
z Pull out the plug of the safety sensor.
box 107
z Pull out the plug of the flow NTC sensor.
box 108
box 106
z Set multimeter to “measure resistance”.
z Measure the resistance of the safety sensor.
z Set multimeter to “measure resistance”.
z Measure the resistance of the flow NTC sensor.
box 109
z Measure the electrical resistance of the flow NTC sensor
and safety sensor.
z Measure the electrical resistance of the flow NTC sensor
and check the earth (ground) connection of the safety
sensor. This must be infinitely high.
The measured resistance of the flow NTC sensor is
virtually identical to that of the safety sensor.
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
48 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 49
Actions 7
box 110
z Use a digital contact-type thermometer to measure the
temperature in the vicinity of the corresponding sensor.
z Compare the resistance readings with the values listed in
box 111.
z Replace the corresponding sensor if the reading fluctuates
by more than 10% with respect to the reference value (e.g.
infinitely high resistance in the event of a line break or
resistance of 0
Ω in the case of a short circuit).
z Reinsert the plug.
z Refit the casing and place the boiler into operation,
see box 51, 53, 54 or 55.
box 111
Resistance readings (approximate values) for the sensor
Temperature
in °C
0 29,490
5 23, 462 55 3,271
10 18,787 60 2, 760
15 15,136 65 2, 339
20 12, 268 70 1, 990
Resistance in ΩTemperature
in °C
Resistance in
Ω
box 113
1) 2)
13
121110
JP3
25 10,000 75 1, 700
30 8,197 80 1,458
35 6,754 85 1,255
40 5,594 90 1,084
45 4, 656 95 940
50 3 ,893 100 817
box 112 Check the flow, safety and DHW temperature
sensors – cables
HDANGER OF FATAL ACCIDENT
due to electric shock
ACAUTION!
To prevent damage, do not insert the measuring
electrodes of the multimeter too far into the holes of the
plug-and-socket connection.
z Take the boiler out of service and tip the DBA control panel
forwards, see box 43, 44, 47 or 63.
z Loosen the six screws and remove the rear section,
see box 70.
z Pull out the plugs of the flow NTC sensor and safety
sensor, see
box 105.
Key to terms:
1) Flow NTC sensor
2) Safety sensor
z Set multimeter to “measure resistance”.
z Check the cables of the flow NTC sensor and safety
sensor for breaks. The electrical resistance measured at
each individual wire must be approximately 0
Ω.
z Check the cables of the flow NTC sensor and safety
sensor for internal short circuits. The level of electrical
resistance, measured between two wires, must be
infinitely high.
z Measure the electrical resistance of the flow NTC sensor
and check the earth (ground) connection of the safety
sensor. This must be infinitely high.
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 49
Page 50
Actions7
box 114
Room Controller
Hot water tank sensor
24 VAC
3-way valve
Hot water tank sensor
1
2
3
4
5
6
7
Room Controller
24 VAC
3-way valve
z Set multimeter to “measure resistance”.
z Detach the cables of the DHW temperature sensor (item 3
and 4) from the DBA control panel.
z Measure the resistance of the cable of the DHW
temperature sensor and check it for short circuits and
breaks. See box 112.
z Fit the cables of the DHW temperature sensor to the DBA
control panel (item 3 and 4).
box 117
2
3
1
ACAUTION!
Note that water will squirt out when the sensor is
removed. Have a bucket and a supply of dry cloths to
hand.
z Pull out the plug of the safety sensor (item 1).
z Detach the stop spring of the safety sensor by pulling in
the direction of the arrow (item 2).
z Remove the safety sensor (item 3).
box 118
box 115
z Insert the cables of the corresponding DHW temperature
or outside air-temperature sensor.
z Fit the DBA control panel and place the boiler into
operation, see
box 54, 55 or 51.
box 116 Replace the flow NTC sensor and/or safety
sensor
z Take the boiler out of operation, drain the heating system
and pull out the plug of the corresponding sensor,
see box 43, 44, 47, 45, 47, 49 or 50.
ACAUTION!
Note that water will squirt out when the sensor is
removed. Have a bucket and a supply of dry cloths to
hand.
z Detach the stop spring of the flow NTC sensor by pulling
in the direction of the arrow.
z Remove the flow NTC sensor.
box 119
z Fit the corresponding new sensor.
z Fill the heating system, vent it of air and place the boiler
into operation, see box 52 to 58.
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
50 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 51
Actions 7
box 120 Check the flue-gas STL
z Take the boiler out of operation, see box 43, 44 or 47.
box 121
z Remove both plugs of the flue-gas STL.
box 122
box 126 Check the flue-gas STL - cable
HDANGER OF FATAL ACCIDENT
due to electric shock
z Take the boiler out of service and tip the DBA control panel
forwards, see
z Loosen the six screws and remove the rear section,
see box 70.
z Remove both plugs of the flue-gas STL, see box 121.
box 127
box 43, 44, 47 or 63.
11
1
JP4
z Set multimeter to “measure resistance”.
z Check the electrical resistance of the flue-gas STL.
box 123
z Check the temperature of the flue gas at the test point on
the flue pipe.
z Compare the flue-gas temperature reading with the
measured electrical resistance, see
box 124
Flue-gas STL
Temperature Status Resistance in Ω
box 124.
≤ 105 °C closed 0
>105 °C open infinitely high
box 125
z Insert both plugs at the flue-gas STL and fit the cover on
the test point of the flue pipe. Put the boiler into operation,
box 51, 54 or 55.
see
z Set multimeter to “measure resistance”.
z Check the cables of the flue-gas STL for breaks.
z The electrical resistance measured at each individual wire
must be approximately 0
z Check the cables of the flue-gas STL for internal short
circuits. The level of electrical resistance, measured
between two wires chosen at random, must be infinitely
high.
box 128
z Insert both plugs at the flue-gas STL, fit the DBA control
panel, attach the casing and place the boiler into
operation, see
box 129 Replace the flue-gas STL
z Take the boiler out of operation, see box 43, 44 or 47.
z Remove both plugs of the flue-gas STL, see box 121.
z Twist the flue-gas STL anticlockwise to remove.
z Fit the new flue-gas STL. Use a new seal when doing so.
z Insert both plugs at the flue-gas STL and place the boiler
into operation, see box 51, 54 or 55.
box 51, 54 or 55.
Ω.
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 51
Page 52
Actions7
box 130 Check the glow ignitor – activation
HDANGER OF FATAL ACCIDENT
due to electric shock
z Take the boiler out of operation, see box 43, 44 or 47.
box 131
1
z Pull out the plug of the glow ignitor (item 1).
box 132
box 134 Check the glow ignitor – resistance
HDANGER OF FATAL ACCIDENT
due to electric shock
z Take the boiler out of operation, see box 43, 44 or 47.
z Remove the plug of the glow ignitor, see box 131.
box 135
z Set multimeter to “measure resistance”.
z Check to see if the electrical resistance of the glow ignitor
lies between 50 and 300 Ω.
z Set the multimeter to “measure AC voltage”.
Minimum measuring range: 230V AC.
z Put the boiler into partial-load or full-load operation,
see box 13.
z Check to see whether, with the operating code C [0c]
110 - 230 V AC is measured at the plug.
box 133
z Take the boiler out of operation, see box 43.
z Connect the plug of the glow ignitor.
z Put the boiler into operation, see box 54, 55 or 51.
box 136
z Connect the plug of the glow ignitor.
z Fit the casing and place the boiler into operation,
see box 51, 54 or 55.
box 137 Check the glow ignitor – power supply cable
HDANGER OF FATAL ACCIDENT
due to electric shock
ACAUTION!
To prevent damage, do not insert the measuring
electrodes of the multimeter too far into the holes of the
plug-and-socket connection.
z Take the boiler out of serve and tip the DBA control panel
forwards, see
box 43, 44, 47 or 63.
z Loosen the six screws and remove the rear section,
see box 70.
z Remove the plug of the glow ignitor, see box 131.
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
52 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 53
Actions 7
box 138
1
6
JP1
z Set multimeter to “measure resistance”.
z Check the mains cable of the glow ignitor for breaks.
The electrical resistance measured at each individual wire
must be approximately 0
z Check the mains cable of the glow ignitor for internal short
circuits. The level of electrical resistance, measured
between any two wires, must be infinitely high.
Ω.
box 142
ACAUTION!
The filament of the glow ignitor consists of sintered
material and is highly breakable.
z Fit a new glow ignitor.
z Connect the plug of the glow ignitor.
z Put the boiler into operation, see box 51, 54 or 55.
box 143 Measure the ionisation current
z Take the boiler out of operation, see box 43, 44 or 47.
box 144
1
box 139
z Connect the plug of the glow ignitor.
z Fit the DBA control panel and place the boiler into
operation, see box 51, 54 or 55.
box 140 Replace the glow ignitor
HDANGER OF FATAL ACCIDENT
due to electric shock
z Take the boiler out of operation, see box 43, 44 or 47.
z Remove the plug of the glow ignitor, see box 131.
box 141
z Pull out the ionisation electrode plug (item 1).
box 145
1
2
z Use a multimeter that is specially designed to measure the
3
ionisation current.
z Loosen the fixing nut of the glow ignitor (item 1).
z Remove the mounting plate (item 2).
z Detach the glow ignitor (item 3).
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 53
Page 54
Actions7
box 146
z Set the multimeter to “measure direct current”.
Measuring range: Microamperes [µA].
z Connect the multimeter in series the ionisation circuit.
z Put the boiler into service mode, see box 54, 55 or 13.
z Check to see if the ionisation current, during service mode,
operating code C [lo] , > 5 µA (micro amperes) and,
with operating code
The value is 0 (zero), or between 1.3 and 50 µA.
box 147
z Take the boiler out of operation, see box 43 or 44.
z Detach the multimeter.
z Connect the plug of the ionisation electrode.
z Turn the operating switch on the boiler to position “0”,
see box 55.
z Put the boiler into operation, see box 51, 54 or 55.
C [hi] , > 25 µA.
box 150
z Connect the plug of the ionisation electrode.
z Put the boiler into operation, see box 51, 54 or 55.
box 151 Check the ionisation electrode – cable
HDANGER OF FATAL ACCIDENT
due to electric shock
z Take the boiler out of service and tip the DBA control panel
forwards, see box 43, 44, 47 or 63.
z Loosen the six screws and remove the rear section,
see box 70.
z Remove the plug of the ionisation electrode, see box 144.
box 152
15
JP4
box 148 Check the ionisation electrode – short circuits
z Take the boiler out of operation, see box 43, 44 or 47.
z Loosen the plug-in connection of the ionisation electrode,
see box 144.
box 149
z Set multimeter to “measure resistance”.
z Take a reading at the electrode to check whether there is
a possible short circuit between the ionisation electrode
and earth (ground). The electrical resistance between the
ionisation electrode and earth (ground) must be infinitely
high.
z Set the multimeter to “measure resistance”.
z Take a reading at the ionisation electrode to check
whether there is a possible break in the cable of the
electrode. The electrical resistance of the cable must be
approximately 0
box 153
z Take an earth (ground) reading check whether there is a
possible short circuit between the cable of the ionisation
electrode and earth (ground). The electrical resistance
between the ionisation electrode cable and earth (ground)
must be infinitely high.
Ω.
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
54 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 55
Actions 7
box 154
z Connect the plug of the ionisation electrode.
z Refit the DBA control panel, by following the above
procedure in reverse order, and place the boiler into
operation, see box 51, 54 or 55.
box 155 Check and replace the ionisation electrode
z Take the boiler out of operation, see box 43, 44 or 47.
z Remove the plug of the ionisation electrode, see box 144.
box 156
1
2
3
box 158
12
34
z Check the ionisation electrode for signs of wear (item 2),
damage (item 3) or soiling (item 4).
box 159
z Replace the ionisation electrode if required.
z Fit the ionisation electrode.
z Connect the plug of the ionisation electrode.
z Put the boiler into operation, see box 51, 54 or 55.
z Loosen the fixing nut on the ionisation electrode (item 1).
z Remove the mounting plate (item 2).
z Detach the ionisation electrode (item 3).
box 157
z Set multimeter to “measure resistance”.
z Take a reading at the ionisation electrode to check
whether there is a possible break in the electrode cable.
The electrical resistance of the ionisation electrode cable
must be approximately 0
Ω.
box 160 Check the ionisation circuit – earth (ground)
lead
1
z Check to ensure that the earth (ground) lead of the
ionisation circuit (item
1) has been correctly fitted.
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 55
Page 56
Actions7
box 161 Check the gas valve – power supply plug
z Take the boiler out of operation, see box 43, 44 or 47.
box 162
1
z Check to ensure that the power supply plug (item 1) has
been inserted correctly into the gas valve.
box 163
z Put the boiler into operation, see box 51, 54 or 55.
box 164 Check the gas valve – activation
box 168
1
z Remove the plug from the gas valve (item 1).
box 169
JP4
2
3
z Take the boiler out of operation, see box 43, 44 or 47.
box 165
12
z Run the boiler at full load, see box 54, 55 and
box 13, step 14.
z Set the multimeter to “measure DC voltage”.
Minimum measuring range: 40V DC.
z Check to see if the gas valve has been activated. During
operating code
must be detectable at both the centre and upper contacts
(item 1 and 2).
box 166
z Put the boiler into operation, see box 51, 54 or 55.
box 167 Check gas valve – electrical resistance of
power supply cable
z Take the boiler out of operation and remove the DBA
control panel, see box 43, 44, 47, 63 or 70.
C [0l], or somewhat later, 20 – 24V DC
z Set multimeter to “measure resistance”.
z Check the power supply cable of the gas valve for breaks.
The electrical resistance measured at each individual wire
must be approximately 0 Ω.
z Check the power supply cable of the gas valve for internal
short circuits. The level of electrical resistance, measured
between two wires, must be infinitely high.
box 170
z Insert the gas valve plug.
z Fit the DBA control panel and place the boiler into
operation, see
box 171 Check the gas valve – internal electrical
z Take the boiler out of operation, see box 43, 44 or 47.
z Remove the power supply plug of the gas valve,
see box 168.
box 51, 54 or 55.
resistance
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
56 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 57
Actions 7
box 172
±70 - 110 Ω ±180 - 250 Ω
12
z Set multimeter to “measure resistance”.
z Take a reading at the coils to check the internal electrical
resistance of the two gas valve coils. The electrical
resistance between the middle and lower contact must be
approx. 70 – 110
between the middle and upper contact must be approx.
180 – 250 Ω (item 2).
box 173
z Fit the power supply plug to the gas valve.
z Put the boiler into operation, see box 51, 54 or 55.
box 174 Replace the gas valve
ADANGER OF FATAL ACCIDENT!
All work on gas pipework and gas-fitting components
must be carried out by a company registered and
authorised for this purpose.
z Take the boiler out of operation and close the gas tap,
see box 43, 44, 46 or 47.
z Remove the fan, see box 77, 78, 79 or 80.
Ω (item 1). The electrical resistance
box 176
z Fit the gas injector to the new gas valve.
z Fit the new gas valve to the fan.
z Fit the fan to the boiler, insert the air silencer tube into the
fan, fit the gas supply pipe to the gas valve and insert the
plugs into the fan and gas valve.
z Fit the air silencer tube to the fan.
ACAUTION!
When attaching the gas supply pipe to the gas valve,
ensure that the flat rubber seal is fitted correctly
between the gas supply pipe and gas valve.
z Fit the gas supply pipe to the gas valve.
z Insert the power supply plug into the gas valve, then insert
the power supply plug and tacho cable plug into the fan.
z Open the gas cock and place the boiler into full-load
operation, see box 59, 54, 55 or 13.
z Carry out a gas-leak check. Check the tightness of all
components that were loosened during removal of the gas
valve. Use an authorised foam-type leak detection product
for this purpose.
z Remedy the cause of the gas leak.
z Put the boiler into operation, see box 51, 54 or 55.
box 177 Check the ON/OFF or modulating control
function
z Take the boiler out of service and tip the DBA control panel
forwards, see
box 43, 44, 47 or 63.
z Loosen the six screws and remove the rear section,
see box 70.
box 178
box 175
1
z Pull the gas injector (item 1) out of the gas valve.
Room Controller
Hot water tank sensor
24 VAC
3-way valve
Hot water tank sensor
1
2
3
4
5
6
7
Room Controller
24 VAC
3-way valve
z Bridge the two contacts, terminal 1 and 2.
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 57
Page 58
Actions7
box 179
z Put the boiler into full-load operation, see box 54, 55 or 61.
If the boiler goes into heating mode within approx.
3 minutes :-h. , the cause of the fault lies outside the
boiler.
z Take the boiler out of operation, see box 43 or 44.
z Remove the bridge connection.
z Connect the ON/OFF or modulating control element to the
boiler.
z Put the boiler into operation, see box 51, 54 or 55.
box 180 Adjust the output flow rate (applies to
combination boilers only)
box 182
1
ADANGER OF DAMAGE TO THE SYSTEM!
Before removing the servomotor, check to see if the
3-way valve is in its "heating mode" position, and wait
for the boiler display code C [0h] to appear. This
prevents sudden pressure surges occurring in the
heating circuit while the removal operation is taking
place, and the resultant accidental opening of the
pressure relief valve.
z Remove the stop spring (item 1).
z Remove the servomotor.
ACAUTION!
As the water pressure and pipework resistance in the
plumbing system can vary widely with each situation, it
is important to adjust correctly the DHW flow rate at the
boiler. Take a DHW flow rate reading, see
box 12.
Adjust the DHW flow rate at the flow regulator for hot water.
To check the DHW flow rate press and hold the down "D"
arrow and read off the display in ltrs/m.
– To increase the DHW flow rate:
turn the flow regulator in direction “+”.
– To reduce the DHW flow rate:
turn the flow regulator in direction “–”.
z Adjust the flow rate of hot water at one of taps where the
user is likely to require hot water at an ideal temperature.
Factory default setting: see factory settings in the
installation instruction.
This assumes a cold water input temperature of 10 °C.
box 181 Check the internal 3-way valve – movement of
the servomotor
z Take the boiler out of operation, see box 43, 44 or 47.
box 183
z Put the boiler into operation, see box 54 and 55.
z Use the "Settings" menu on the boiler DBA control panel
to adjust the temperature to 60
°C, see box 14 or 18.
z Open a hot water tap.
z Check to see if the servomotor of the internal 3-way valve,
during operating code
C [0c], rotates through a full
revolution.
z Close the hot water tap.
z Check to see if the servomotor runs back again.
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
58 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 59
Actions 7
box 184
z Fit the servomotor to the 3-way valve.
z Insert the stop spring.
z Adjust the DBA control panel, see box 61.
z Fit casing, see box 51.
box 185 Check the internal 3-way valve – activation
ACAUTION!
To prevent damage, do not insert the measuring
electrodes of the multimeter too far into the holes of the
plug-and-socket connection.
z Take the boiler out of operation, see box 43, 44 or 47.
box 186
z Pull out the power supply plug of the servomotor.
box 187
z Put the boiler into operation, see box 54 and 55.
box 188
box 189
z Insert the power supply plug of the 3-way valve.
z Put the boiler into operation, see box 51 or 61.
box 190 Internal 3-way valve – replace the servomotor
z Take the boiler out of operation, see box 43, 44 or 47.
z Remove the power supply plug of the servomotor,
see box 186.
z Remove the servomotor, see box 182.
z Fit the new servomotor by following the above procedure
in reverse order.
z Put the boiler into operation, see box 51, 54 or 55.
box 191 Check the internal 3-way valve – power supply
cable
HDANGER OF FATAL ACCIDENT
due to electric shock
ACAUTION!
To prevent damage, do not insert the measuring
electrodes of the multimeter too far into the holes of the
plug-and-socket connection.
z Take the boiler out of operation and remove the DBA
control panel, see
box 43, 44, 47, 63 or 70.
z Remove the power supply plug of the servomotor of the
3-way valve, see box 186.
box 192
8
9
10
1 ~
0
2
3 0
z Set the multimeter to “measure AC voltage”.
Minimum measuring range: 40V AC.
z Use the "Settings" menu on the boiler DBA control panel
to adjust the temperature to 60
°C, see box 14 or 18.
z Open a hot water tap.
z Check to see if, during operating code C [0c] at plug-in
contacts “1” and “3”, 24
V AC is detected between plug-in
contacts “1” and “2” .
z Close the hot water tap.
z Check to see if, during operating code C [0h], 24 V AC
is detected at plug-in contacts “1” and “2” .
JP4
z Set multimeter to “measure resistance”.
z Check the power supply cable of the 3-way valve for
breaks. The electrical resistance measured at each
individual wire must be approximately 0 Ω.
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 59
Page 60
Actions7
box 193
z Check the power supply cable of the 3-way valve for
internal short circuits. The level of electrical resistance,
measured between two wires chosen at random, must be
infinitely high.
box 194
z Insert the power supply plug of the 3-way valve, fit the
DBA control panel and place the boiler into operation,
see box 51, 54 or 55.
box 198 Replace the internal 3-way valve – drive
mechanism
z Take the boiler out of operation and drain the heating
system, see
z Remove the servomotor of the 3-way valve, see box 182.
box 199
box 48 to 51.
1
2
z Remove the stop spring (item 1) by pulling it in the
direction of the arrow.
box 200
box 195 Check the internal 3-way valve – drive
mechanism
z Take the boiler out of operation, see box 43, 44 or 47.
z Remove the servomotor of the 3-way valve, see box 182.
box 196
z Check to ensure that the drive mechanism of the 3-way
valve is running smoothly. This is done by gradually
pushing the spring fully home by hand and allowing the
spring to return gradually to its home position.
1
z Remove the drive mechanism (item 1) of the 3-way valve.
ACAUTION!
Note that water will squirt out when the drive
mechanism is removed.
Have a bucket and a supply of dry cloths to hand.
box 197
z Refit the servomotor, following the above procedure in
reverse order.
z Put the boiler into operation, see box 51, 54 or 55.
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
60 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 61
Actions 7
box 201
z Fit the new drive mechanism on the internal 3-way valve.
Ensure that the flat side faces upwards.
box 205
z Remove the stop spring and 3-way valve-motor.
box 206
123
box 202
z Connect the servomotor of the 3-way valve by following
the above procedure in reverse order.
z Fill the heating system, vent it of air and place the boiler
into operation, see box 52 to 58.
box 203 Replace the internal 3-way valve
z Take the boiler out of operation and drain the heating
system, see box 48 to 51.
box 204
1
2
3
45
z Pull the plug (item 1) out of the pump.
z Loosen the four screws (item 3) on the pump.
z Remove the return pipe with spring (item 4).
z Remove the pipe to the expansion vessel with spring
(item 5).
z Pull out the pump (item 2).
z Disconnect the cable from the main switch, see box 54.
z Pull the spring off the flow NTC sensor lead (item 1).
z Pull out the flow NTC sensor plug (item 2).
z Pull the main switch cable out of the nut (item 3).
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 61
Page 62
Actions7
box 207
3 3 H3 3
122 12
z Remove all pipes beneath the boiler.
ACAUTION!
Note that water will squirt out when the internal 3-way
valve is removed. Have a bucket and a supply of dry
cloths to hand.
z Loosen the gas pipe at the gas valve.
z Remove the two screws (item 1).
z Remove the complete hydraulic assembly.
z Remove the four M8 nuts (item 2).
z Remove the five screws (item 3).
z Remove the plastic block (H3).
box 209
z Replace the housing of the 3-way valve.
box 210
z Refit all components, following the above procedure in
reverse order.
z Fill the heating system, vent it of air and place the boiler
into operation, see box 52 to 58.
box 211 Check the Buderus 24V AC external
3-way valve – movement of the servomotor
box 208
1
2
z Loosen the screw in the plastic block (item 2).
z Remove the pressure relief valve (item 1), see box 276
or 277.
z Remove the drive mechanism on the internal 3-way valve,
see box 200.
ACAUTION!
Note that water will squirt out when the internal 3-way
valve is removed. Have a bucket and a supply of dry
cloths to hand.
z Put the boiler into operation, see box 54 and 55.
z Adjust the hot water in the "Settings" menu on the DBA
control panel of the boiler to 60
z Open a hot water tap.
z Check to see if the servomotor of the Buderus
24V AC external 3-way valve, during the operating
code C [0c] rotates from the setting for heating mode
(position “
(position “2”).
z Close the hot water tap.
z Check to see if the servomotor runs back again.
z Adjust the hot water in the “Settings” menu on the DBA
control panel of the boiler, see
1”) to the position for hot water mode
°C, see box 61.
box 61.
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
62 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 63
Actions 7
box 212 Check the Buderus 24V AC external
3-way valve – activation (1)
ACAUTION!
To prevent damage, do not insert the measuring
electrodes of the multimeter too far into the holes of the
plug-and-socket connection.
z Take the boiler out of operation, see box 43, 44 or 47.
box 213
z Remove the power supply plug of the servomotor of the
Buderus 24V AC external 3-way valve.
box 214
z Put the boiler into operation, see box 51, 54 or 55.
box 215
6
3
2
Plug-in contacts
of Buderus 24V
AC external 3-
way valve
2 24V AC 5
3 0V AC 6
6 _ \ __ 7
Purpose Plug-in contacts
on DBA control
panel
box 216
z Insert the power supply plug of the Buderus
24V AC external 3-way valve.
z Put the boiler into operation, see box 51, 54 or 55.
box 217 Replace the Buderus 24V AC external 3-way
valve – servomotor
z Take the boiler out of operation, see box 43, 44 or 47.
z Remove the power supply plug of the servomotor of the
Buderus 24V AC external 3-way valve, see
box 218
z Remove the servomotor of the Buderus 24V AC external
3-way valve. To release the servomotor press the release
catch (item 1) and twist the servomotor.
ADANGER OF DAMAGE TO THE SYSTEM!
Before removing the servomotor, check to see if the
Buderus 24V AC external 3-way valve is in its "heating
mode" position, and wait for the boiler display code
[0h] to appear. This prevents sudden pressure surges
occurring in the heating circuit while the removal
operation is taking place, and the resultant accidental
opening of the pressure relief valve.
box 219
z Fit the new servomotor by following the above procedure
in reverse order.
z Put the boiler into operation, see box 51, 54 or 55.
box 213.
C
z Set the multimeter to “measure AC voltage”.
Minimum measuring range: 40V AC.
z Open a hot water tap.
z Adjust the hot water in the "Settings" menu on the DBA
control panel of the boiler to 60 °C, see box 61.
z Check to see if, during operating code C [0c], 24 V AC
is detected at plug-in contacts “2” and “6”.
z Close the hot water tap.
z Check to see if, during operating code C [0h] , 24 V AC
is detected at plug-in contacts “2” and “3”.
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 63
Page 64
Actions7
box 220 Check the Buderus 24V AC external
3-way valve – power supply cable
ACAUTION!
To prevent damage, do not insert the measuring
electrodes of the multimeter too far into the holes of the
plug-and-socket connection.
z Take the boiler out of operation, see box 43 or 44.
z Remove the power supply plug of the servomotor of the
Buderus 24V AC external 3-way valve, see box 213.
z Remove the connection of the power supply cable of the
Buderus 24V AC external 3-way valve at the boiler.
z Set multimeter to “measure resistance”.
z Check the power supply cable of the Buderus
24V AC external 3-way valve for breaks. The electrical
resistance measured at each individual wire must be
approximately 0
Ω.
z Check the power supply cable of the Buderus
24V AC external 3-way valve for internal short circuits. The
level of electrical resistance, measured between two wires
chosen at random, must be infinitely high.
z Insert the power supply plug of the Buderus
24V AC external 3-way valve.
z Connect the power supply cable of the Buderus 24V AC
external 3-way valve at the boiler.
z Put the boiler into operation, see box 54 or 55.
box 221 Check the Buderus 24V AC external
3-way valve – drive mechanism
z Take the boiler out of operation, see box 43 or 44.
z Remove the servomotor of the Buderus 24V AC external
3-way valve, see
box 218.
box 222
box 224 Replace the Buderus 24V AC external 3-way
valve – drive mechanism
z Take the boiler out of operation and drain the heating
system, see
box 48 to 51.
z Remove the servomotor of the Buderus 24V AC external
3-way valve, see box 213 or 218.
box 225
z Remove the drive mechanism of the Buderus
24V AC external 3-way valve using the wrench supplied
with the drive mechanism.
ACAUTION!
Note that water will squirt out when the drive
mechanism is removed.
Have a bucket and a supply of dry cloths to hand.
box 226
z Fit the new drive mechanism to the Buderus
24V AC external 3-way valve.
z Connect the servomotor of the Buderus 24V AC external
3-way valve by following the above procedure in reverse
order.
z Fill the heating system, vent it of air and place the boiler
into operation, see box 52 to 58.
box 227 Check the Buderus 24V AC external
3-way valve – installation
z Check to ensure that the drive mechanism of the Buderus
24V AC external 3-way valve is running smoothly. This is
done by gradually pushing the spring fully home by hand
and allowing the spring to return gradually to its home
position.
box 223
z Refit the servomotor, following the above procedure in
reverse order.
z Put the boiler into operation, see box 54 or 55.
z Use the letters marked on the 3-way valve to check
whether the Buderus 24V AC external 3-way valve is
correctly fitted:
A = flow of storage-type water heater
B = CH flow
AB= boiler flow
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
64 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 65
Actions 7
box 228 Check the Buderus 24V AC external
3-way valve – activation (2)
Room Controller
Hot water tank sensor
24 VAC
3-way valve
Plug-in contacts
on DBA control
panel
1
2
3
4
5
6
7
Room Controller
Hot water tank sensor
24 VAC
3-way valve
Purpose Plug-in contacts
of Buderus 24V
AC external 3-
way valve
5 24V AC 2
6 0V AC 3
7_ \ __ 6
box 230 Measure the gas input pressure – static and
dynamic
ADANGER OF FATAL ACCIDENT!
All work on gas supply pipes and gas-fitting
components must be carried out by a company
registered and authorised for this purpose.
z Take the boiler out of operation and close the gas tap,
see box 43, 44, 46 or 47.
z Open some of the radiator valves.
box 231
1
2
z Take the boiler out of operation and remove the DBA
control panel, see box 43, 44, 47, 63 or 70.
z Put the boiler into operation, see box 54 and 55.
z Open hot water tap.
z Adjust the hot water in the "Settings" menu on the DBA
control panel of the boiler to 60 °C, see
box 61 and box 14.
z Set the multimeter to “measure AC voltage”.
Minimum measuring range: 40V AC.
Plug-and-socket connection DBA control panel conn.
67
36
25
z Check whether, with operating code C [0c] active,
there is a voltage of 24 V AC at the plug-in contacts item 6
and item 7.
z Close the hot water tap.
z Check whether, with operating code C [0h] active,
there is a voltage of 24 V AC at the plug-in contacts item 5
and item
6.
box 229
z Fit the DBA control panel and place the boiler into
operation, see
box 51, 54 or 55.
ACAUTION!
The pressure gauge should be accurate to 2 decimal
places (X.00).
z Reset the digital pressure gauge to zero.
ACAUTION!
Throughout the measuring operation, keep the
pressure gauge in the same position (horizontal or
vertical) in which it was reset to zero.
z Loosen by two turns the screw on the gas connection
pressure measuring nipple (item
1).
z Fit the pressure gauge to the gas connection pressure
measurement nipple (item
2).
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 65
Page 66
Actions7
box 232
z Open the gas tap, see box 59.
z Put all other gas-fired devices (e.g. gas ovens and stoves,
etc.) out of use.
z Check to see if static gas input pressure does not rise
slowly for 2
minutes.
z Run all other gas-fired appliances (e.g. gas ovens and
stoves, etc.) at full capacity, but do not operate the boiler.
z The static gas input pressure must be:
for natural gas minimum 20 mbar and
for propane minimum 37 mbar.
z Open the gas cock and place the boiler into service mode,
see box 59, 54, 55 or 13.
z Press the service button “A" twice.
z Capacity during service mode is at "C" [hi] = 100 %
(max. heating capacity).
z Wait for 1 minute, until the boiler starts at full load.
z Measure the working gas pressure at the appliance.
z Measure the difference between the static and working
gas input pressure.
The working pressure may be:
for natural gas minimum 17 mbar and
for propane minimum 30 mbar.
z Take the boiler out of operation and close the gas tap, see
box 43, 44 or 46.
z Remove the pressure gauge.
z Tighten the screw on the gas connection pressure
measurement nipple.
z Open the gas tap, see box 59.
z Use a detection product to check the gas connection
pressure measurement nipple for leaks. Use an
authorised foam-type leak detection product for this
purpose.
z Fit the casing and place the boiler into operation,
see box 51, 54 or 55.
box 233 Measure and adjust the gas/air ratio
ADANGER OF FATAL ACCIDENT!
All work on gas pipework and gas-fitting components
must be carried out by a company registered and
authorised for this purpose.
z Take the boiler out of operation and close the gas tap,
see box 43, 44, 46 or 47.
z Open some of the radiator valves.
box 234
1
2
z Reset the digital pressure gauge to zero.
ACAUTION!
Throughout the measuring operation, keep the
pressure gauge in the same position (horizontal or
vertical) in which it was reset to zero.
z Loosen by two turns the screw on the burner pressure
measurement nipple (item 1).
z Connect the pressure gauge to the burner pressure
measurement nipple (item 2).
box 235
z Open the gas cock and place the boiler into service mode,
box 59, 54, 55 or 13.
see
z Press the service button “A" once.
z Capacity during service mode is at C [lo] = 25%
(max. heating circuit capacity).
z Wait a short time for the boiler to be adjusted downwards.
box 236
ABB
–15 –10 –5 0 5 (Pa)
–0,15 –0,10 –0,05 0,00 0,05 (mbar)
DC
Key to terms:
A = correct; B = false; C = turn anticlockwise;
D = turn clockwise
z Check the gas/air ratio during service mode operation.
The differential pressure (p
must be –5 Pa (±5 Pa) (as indicated by the measuring
device: –10 to 0
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
66 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
– p
gas
air
)
Pa).
Page 67
Actions 7
box 237
1
z Use the adjustment screw to readjust the gas/air ratio if
necessary (item 1).
INOTE:
The adjustment screw (4mm Allen screw) is located
behind the screw-on cover.
box 238
z Take the boiler out of operation and close the gas tap,
see box 43, 44 or 46.
z Remove the pressure gauge.
z Tighten the screw on the burner pressure measurement
nipple.
z Open the gas cock and place the boiler into full-load
operation, see box 59, 54, 55 and 13.
z Wait for the boiler to start.
z Use a detection product to check the burner pressure
measurement nipple for leaks. Use an authorised foamtype leak detection product for this purpose.
z Take the boiler out of operation, see box 43 or 44.
z Fit the casing and place the boiler into operation,
see box 51, 54 or 55.
box 239 Vent the gas flow pipe.
box 240
1
2
z Loosen by two turns the screw on the gas connection
pressure measuring nipple (item
z Connect a long hose (item 2) to the gas connection
pressure measurement nipple and then run this hose out
of the building.
box 241
z Leave the gas cock open until no further air escapes from
the hose, see box 59.
z Close the gas cock, see box 46.
z Remove the hose from the gas connection pressure
measurement nipple.
z Tighten the screw on the gas connection pressure
measurement nipple.
z Open the gas tap, see box 59.
z Use a detection product to check the gas connection
pressure measurement nipple for leaks. Use an
authorised foam-type leak detection product for this
purpose.
z Fit the casing and place the boiler into operation,
see box 51, 54 or 55.
box 242 Replace the automatic air vent
z Take the boiler out of operation and drain the heating
system, see
box 48 to 50.
1).
ADANGER OF FATAL ACCIDENT!
All work on gas supply pipes and gas-fitting
components must be carried out by a company
registered and authorised for this purpose.
z Take the boiler out of operation and close the gas tap,
see box 43, 44, 46 or 47.
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 67
Page 68
Actions7
box 243
z Twist the automatic air vent in the direction of the arrow to
remove.
box 244
z Fit the new automatic air vent by following the above
procedure in reverse order.
z Fill the heating system, vent it of air and place the boiler
into operation, see
box 245 Replace the burner
box 52 to 58.
box 247
1
z Turn the gas/air unit clockwise by about 10°.
box 248
HDANGER OF FATAL ACCIDENT
due to electric shock
ADANGER OF FATAL ACCIDENT!
All work on gas supply pipes and gas-fitting
components must be carried out by a company
registered and authorised for this purpose.
z Take the boiler out of operation and close the gas tap,
see box 43, 44, 46 or 47.
z Remove the power supply plug of the glow ignitor,
see box 131.
z Remove the plug of the ionisation electrode, see box 144.
z Remove the power supply plug of the gas valve, union nut
and air silencer tube, see
box 246
box 77.
1
z Remove the gas/air unit along with the burner.
box 249
1
z Pull out both fan plugs (item 1).
z Loosen both screws (item 1).
z Remove the burner.
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
68 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 69
Actions 7
box 250
z Fit the new burner to the gas/air unit. Note that a new seal
must be fitted between the burner and gas/air unit.
box 251
z Remove the heat exchanger-gas/air seal.
box 252
z Check the heat exchanger-gas/air seal for signs of ageing.
z Replace the heat exchanger-gas/air seal if required.
z Refit all components, following the above procedure in
reverse order.
z Open the gas cock and place the boiler into full-load
operation, see box 59, 54, 55 and 13.
z Carry out a gas-leak check. Check the tightness of all
components that were loosened in the course of removal
of the burner. Use an authorised foam-type leak detection
product for this purpose.
z Remedy the cause of the gas leak.
z Open the gas cock and place the boiler into operation,
see box 59, 54, 55 or 51.
box 255
z Install the new sight glass. Use a new seal when doing so.
z Put the boiler into operation, see box 51, 54 or 55.
box 256 Replace/clean condensate trap and syphon
z Take the boiler out of operation, see box 43, 44 or 47.
box 257
1
2
z Remove the condensate trap (item 1) and syphon
(item 2).
box 253 Replace the sight glass
z Take the boiler out of operation, see box 43, 44 or 47.
box 254
box 258
z Clean the condensate trap and syphon.
z Fit the new or cleaned syphon.
z Put the boiler into operation, see box 51, 54 or 55.
1
z Loosen both screws (item 1).
z Remove the sight glass along with the seals.
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 69
Page 70
Actions7
box 259 Replace/clean the heat exchanger
HDANGER OF FATAL ACCIDENT
due to electric shock
ADANGER OF FATAL ACCIDENT!
All work on gas supply pipes and gas-fitting
components must be carried out by a company
registered and authorised for this purpose.
z Take the boiler out of operation, close the gas cock and
drain the heating system, see box 46 or 48 to 50.
z Remove the power supply plug of the glow ignitor,
see box 131.
z Remove the plug of the ionisation electrode, see box 144.
z Remove the power supply plug of the gas valve, union nut
and air silencer tube, see
z Pull out both fan plugs, see box 78, item 1.
z Remove the gas/air unit along with the burner,
see box 247 and 248.
z Remove the heat exchanger-gas/air seal, see box 251.
box 260
box 77.
box 261
1
z Remove the restrictor baffle (item 1).
box 262
1
1
z Open the four clip fastenings(item 1).
z Clean the heat exchanger with a brush and compressed
air or with TAB2.
In the event of serious restriction, continue with box 261.
1
1
z Remove the stop spring on the top left-hand side of the
heat exchanger by turning it towards the arrow.
box 263
z Remove the stop spring on the bottom right-hand side of
the heat exchanger by turning it towards the arrow.
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
70 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 71
Actions 7
box 264
z Pull the heat exchanger towards the arrow to remove.
box 265
box 266
z Clean the heat exchanger with compressed air, a high-
pressure hose or with water and a soft brush.
ACAUTION!
When cleaning the heat exchanger never use a steel
brush.
ACAUTION!
When using compressed air:
Use eye protection, inhalation protection and hearing
1
protection.
box 267
2
z Check the seal on the heat exchanger casing (item 1) for
signs of ageing and replace if required.
z Replace the four O-rings (item 2), two on each side.
1
ACAUTION!
Observe the position of the heat exchanger during
fitting. Insert the upper section of the heat exchanger at
the top.
z Fit the new or cleaned heat exchanger and all other
components by following the above procedure in reverse.
ACAUTION!
The released coil (item 1) touches the underside.
ACAUTION!
Insert a new heat exchanger-gas/air seal before fitting
the gas/air unit.
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 71
Page 72
Actions7
box 268
z Fill the heating system, vent it of air, open the gas tap and
place the boiler into operation, see
box 269 Replace plate heat exchanger
z Take the boiler out of operation, see box 43, 44 or 47.
z Close the cold water tap.
z Drain the heating system, see box 48 to 51.
z Open hot water tap.
box 270
box 59 or 52 to 58.
box 272
z Remove condensate trap.
box 271
z Remove both screws from the plate heat exchanger.
box 273
z Remove the plate heat exchanger.
z Remove syphon.
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
72 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 73
Actions 7
box 274
z Fit new plate heat exchanger.
z Renew the four O-rings if necessary.
z Refit the plate heat exchanger and secure with the two
screws.
z Open the cold water service valve.
z Open the hot water tap in order to clean the new plate heat
exchanger (inside).
z Close the hot water tap.
z Fill the heating system, see box 52.
z Fit the casing and place the boiler into operation,
see box 51, 54 or 55.
box 275 Replace the pressure relief valve
z Take the boiler out of operation and drain the heating
system, see
box 276
box 48 to 50.
1
box 278
z Fit the new pressure relief valve and all other components
by following the above procedure in reverse.
z Fill the heating system, vent it of air and place the boiler
into operation, see box 52 to 58.
box 279 Replace the turbine flowmeter
2
z Remove the stop spring (item 2) of the pressure relief
valve.
z Remove the pressure relief valve (item 1) in the direction
of the arrow.
box 277
z Remove the stop spring.
box 280
z Use a screwdriver to lever out the turbine flowmeter.
box 281 Replace the DBA control panel
z Release the pressure relief valve from the section of
condendsate outlet pipework by pulling in the direction of
the arrow.
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 73
HDANGER OF FATAL ACCIDENT
due to electric shock
z Take the boiler out of operation and remove the DBA
control panel, see
box 43, 44, 47, 63 or 70.
Page 74
Actions7
box 282
1
JP1 JP2 JP4 JP3
z Disconnect the five plugs (harness - item 1, JP1, JP2, JP4
and JP3) from the DBA control panel.
box 283
box 284 Check the EEPROM (KIM)
z Check the plug-and-socket connection on the EEPROM
(KIM).
box 285 Check the junction box – 230V room-
temperature connection
1
z Remove the DBA control panel.
z Fit the new DBA control panel, following the above
procedure in reverse order.
ACAUTION!
Please ensure that the new DBA control panel is fitted
with the correct KIM (see box 284). The coloured stripe
on the new KIM should match that of the old KIM.
Otherwise, refit the old KIM to the new DBA control
panel.
z Fit the casing and place the boiler into operation,
see box 51, 54 or 55.
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
74 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
2
3
z Remove the casing lock and lower the DBA.
z Remove the cover from the RTH converter/Junction box
(item 1).
z Run the 230V power supply cable through the cable
pipework.
z Connect the 230V cable to item 1. The switch live should
be connected to terminal 1 and the Neutral to terminal 2 of
the 230V connection (item 2).
Page 75
box 286 Check the junction box – 0 Volt room-
temperature connection
z Remove the casing lock and lower the DBA, see box 285.
z Remove the cover from the RTH converter/junction box,
see box 285, item 1.
z Run the volt free power supply cable through the cable
pipework.
z Connect the volt free cable at position 1 and 2 of the volt
free connection, see box 285, item 3.
Actions 7
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 75
Page 76
Appendix8
8 Appendix
box 287 Wiring diagram
Buderus controller,
RTH converter or
ON/OFF-controller
pin 1
pin 17
pin 1
Low voltage
pin 17
pin 4
JP2 JP4 JP3JP1
pin 1
pin 6
pin1
High voltage
hot-water tank sensor
24 VAC
earth
3-way valve
DBA
1
2
1)
3
4
5
6
7
Mains
230 VAC,
50 Hz
24 VAC
0 VAC
switch contact
DBA
1) only for Buderus 500-24/S:
remove the link at the connection of the hot water tank sensor
2) only for Buderus 500-24/C and 500-28/C
safety sensor
10
JP3
11
12
13
2
16
1
6
15
7
17
7
4
10
8
9
2
3
11
1
ionisation electrode
15
14
6
5
flow sensor
23
1
1
2
3
5
4
1
flue gas thermostat
5
241
JP4
231
LN
5
4
M
LPEN
~
2)
Turbine
2)
Buderus
gas valve
fan
sensor
hot-water
3-way valve
24V AC external
LPEN
231
glow ignitor
M
~
pump
JP1 JP2 JP4 JP3
LN
3
2
1
3
Mains
LN
4
3
2
4
1
JP2
120 VAC
230 VAC, 50 Hz
JP1
6
1
Mains switch
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
76 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 77
9 Index
box 288 Index
Index
9
A
Adjust the output flow rate (applies to combination
boilers only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 180
C
Check and replace the ionisation electrode . . . . . . . . . . . . . . .box 155
Check fan – activation 230V AC . . . . . . . . . . . . . . . . . . . . . . . . .box 66
Check fan – power supply cable (230 V AC) . . . . . . . . . . . . . . .box 69
Check fan – tacho cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 73
Check fan and/or replace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 76
Check gas valve – electrical resistance of power
supply cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 167
Check the Buderus 24V AC external 3-way
valve – activation (1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 212
Check the Buderus 24V AC external 3-way
valve – activation (2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 228
Check the Buderus 24V AC external 3-way
valve – drive mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . .box 221
Check the Buderus 24V AC external 3-way
valve – installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 227
Check the Buderus 24V AC external 3-way
valve – movement of the servomotor . . . . . . . . . . . . . . . . .box 211
Check the Buderus 24V AC external 3-way
valve – power supply cable . . . . . . . . . . . . . . . . . . . . . . . . .box 220
Check the by-pass valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 14
Check the flow, safety and DHW temperature sensors –
cables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 112
Check the flow, safety and DHW temperature sensors
(applies to external cylinder only) . . . . . . . . . . . . . . . . . . . .box 104
Check the flue-gas STL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 120
Check the flue-gas STL – cable . . . . . . . . . . . . . . . . . . . . . . . . .box 126
Check the gas valve – activation . . . . . . . . . . . . . . . . . . . . . . . .box 164
Check the gas valve – internal electrical resistance . . . . . . . .box 171
Check the gas valve – power supply plug . . . . . . . . . . . . . . . . .box 161
Check the glow ignitor – activation . . . . . . . . . . . . . . . . . . . . . .box 130
Check the glow ignitor – power supply cable . . . . . . . . . . . . . .box 137
Check the glow ignitor – resistance . . . . . . . . . . . . . . . . . . . . . .box 134
Check the internal 3-way valve – activation . . . . . . . . . . . . . . .box 185
Check the internal 3-way valve – drive mechanism . . . . . . . . . box 195
Check the internal 3-way valve – movement of the servomotor box 181
Check the internal 3-way valve – power supply cable . . . . . . .box 191
Check the ionisation circuit – earth (ground) lead . . . . . . . . . .box 160
Check the ionisation electrode – cable . . . . . . . . . . . . . . . . . . .box 151
Check the ionisation electrode – short circuits . . . . . . . . . . . . .box 148
Check the pressure control valve . . . . . . . . . . . . . . . . . . . . . . . . .box 85
Check the pump – activation . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 91
Check the pump – mechanical restrictions . . . . . . . . . . . . . . . . .box 89
Check the pump – power supply cable . . . . . . . . . . . . . . . . . . . .box 95
Check the pump – soiling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 97
Check/replace fuses (1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 62
R
Removal of casing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 47
Replace plate heat exchanger . . . . . . . . . . . . . . . . . . . . . . . . . .box 269
Replace the automatic air vent . . . . . . . . . . . . . . . . . . . . . . . . . .box 242
Replace the Buderus 24V AC external 3-way
valve – drive mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . .box 224
Replace the Buderus 24V AC external 3-way
valve – servomotor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 217
Replace the burner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 245
Replace the DBA control panel . . . . . . . . . . . . . . . . . . . . . . . . .box 281
Replace the flow NTC sensor and/or safety sensor . . . . . . . . .box 116
Replace the flue-gas STL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 129
Replace the gas valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 174
Replace the glow ignitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 140
Replace the internal 3-way valve . . . . . . . . . . . . . . . . . . . . . . . .box 203
Replace the internal 3-way valve – drive mechanism . . . . . . .box 198
Replace the pressure relief valve . . . . . . . . . . . . . . . . . . . . . . . .box 275
Replace the pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 101
Replace the sight glass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 253
Replace/clean condensate trap and syphon . . . . . . . . . . . . . . .box 256
Replace/clean the heat exchanger . . . . . . . . . . . . . . . . . . . . . .box 259
S
Shutting down . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 43
T
Technical specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 5
V
Vent the gas flow pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 239
W
Wiring diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 287
D
Draining the system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 48
F
Filling the system and venting it of air . . . . . . . . . . . . . . . . . . . . .box 52
I
Initial startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .box 59
Internal 3-way valve – replace the servomotor . . . . . . . . . . . . .box 190
M
Measure and adjust the gas/air ratio . . . . . . . . . . . . . . . . . . . . .box 233
Measure the gas input pressure – static and dynamic . . . . . .box 230
Measure the ionisation current . . . . . . . . . . . . . . . . . . . . . . . . . .box 143
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 77
Page 78
Notes
We reserve the right to make technical modifications Buderus Ltd. • http://www.buderus-domestic.co.uk
78 Servicing manual Gas condensing boiler Buderus 500-24/S, 500-24/C and 500-28/C • Issued 02/2006
Page 79
Notes
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 79
Page 80
Heating system specialist:
Buderus
Cotswold Way
Warndon
Worcester
WR4 9SW
Telephone: 01905 - 752 936
Fax: 01905 - 753 130
Customer Services:
Technical Product Support:
Sales:
Returns:
Spares:
Tel: 0870 - 421 5933
Tel: 0870 - 421 5944
Tel: 01905 - 752 640
Tel: 01905 - 752 531
Tel: 01905 - 752 576
Fax: 01905 - 456 445 / 455 394
Fax: 01905 - 455 392
Fax: 01905 - 754 620
www.buderus-domestic.co.uk
721.489A – 4612 – 02/2006
Loading...