Buderus 24C, 24S, 19S, 11S Servicing Manual
7210 1300 - 02/2006 GB(EN) For trade use
Servicing manual
Gas wall hung boiler condensing
600 Series - 11S / 19S / 24S / 24C
GB122
Please read thoroughly before attempting to diagnose fault
List of contents
Preface
1 Messages – Universal Automatic Burner
(UBA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 UBA status display . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 UBA operating level 1.5 . . . . . . . . . . . . . . . . . . . . . 4
1.3 Service tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.4 Operating messages . . . . . . . . . . . . . . . . . . . . . . . 5
1.5 Fault messages . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2 Faults that the UBA does not display . . . 8
3 Troubleshooting . . . . . . . . . . . . . . . . . . . . . 9
3.1 Troubleshooting tasks . . . . . . . . . . . . . . . . . . . . . 47
3.1.1 Unblocking the 600 Series 11S / 19S / 24S / 24C 47
3.1.2 Chimney-sweep mode . . . . . . . . . . . . . . . . . . . . . 47
3.1.3 Removing and refitting the outer casing . . . . . . . 48
3.1.4 Removing and refitting the combustion-
chamber cover . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
3.1.5 Checking the exhaust-gas sensor . . . . . . . . . . . . 49
3.1.6 Replacing the exhaust-gas sensor . . . . . . . . . . . 49
3.1.7 Checking the air intake and outlet openings . . . . 50
3.1.8 Replacing the UBA . . . . . . . . . . . . . . . . . . . . . . . 50
3.1.9 Checking the fan . . . . . . . . . . . . . . . . . . . . . . . . . 51
3.1.10 Replacing the fan . . . . . . . . . . . . . . . . . . . . . . . . . 51
3.1.11 Checking the wiring connections of the UBA . . . . 53
3.1.12 Checking the miniature fuses . . . . . . . . . . . . . . . 53
3.1.13 Checking the connections for the second
solenoid valve, modulating pump and floor
thermostat switching contact . . . . . . . . . . . . . . . . 53
3.1.14 Checking the circulation pump . . . . . . . . . . . . . . 54
3.1.15 Replacing the circulation pump . . . . . . . . . . . . . . 54
3.1.16 Checking the safety sensor . . . . . . . . . . . . . . . . . 55
3.1.17 Replacing the safety sensor . . . . . . . . . . . . . . . . 55
3.1.18 Checking the safety sensor connection lead . . . . 55
3.1.19 Checking the feed sensor . . . . . . . . . . . . . . . . . . 56
3.1.20 Replacing the feed sensor . . . . . . . . . . . . . . . . . . 56
3.1.21 Checking the feed sensor connection lead . . . . . 56
3.1.22 Checking the domestic hot water /
mains water supply . . . . . . . . . . . . . . . . . . . . . . . 57
3.1.23 Changing the domestic hot water /
mains water supply . . . . . . . . . . . . . . . . . . . . . . . 58
3.1.24 Checking the hot surface ingitor . . . . . . . . . . . . . 59
3.1.25 Replacing the hot surface ingitor . . . . . . . . . . . . . 59
3.1.26 Checking the gas-burner control system for
correct activation . . . . . . . . . . . . . . . . . . . . . . . . . 60
3.1.27 Replacing the gas burner fitting . . . . . . . . . . . . . . 60
3.1.28 Checking and adjusting the gas-to-air ratio . . . . . 62
3.1.29 Measuring the ionisation current . . . . . . . . . . . . . 63
3.1.30 Replacing the ionisation electrode . . . . . . . . . . . . 63
3.1.31 Checking the three-way motorised valve for
correct operation . . . . . . . . . . . . . . . . . . . . . . . . . 64
3.1.32 Replacing the motorised valve body control valve 64
3.1.33 Replacing the three-way valve . . . . . . . . . . . . . . 65
3.1.34 Checking the ERC/RC connections to the UBA . 66
3.1.35 Replacing the terminal strip . . . . . . . . . . . . . . . . . 66
3.1.36 Checking connections at the ERC or RC . . . . . . 67
3.1.37 Replacing the room-temperature control device . 67
Important general instructions for use
This device should only be operated in accordance with its
designated use and the indications given in the servicing
instructions. All maintenance and repair operations must be
carried out by a qualified service technician.
Always operate in conjunction with original accessories, and
use only genuine spare parts. Other combinations of units,
accessories and consumables are only to be used if they
completely fulfil the specifications involved, and if system
performance and safety are not affected in any way.
Note that all the servicing tasks described here must be carried
out by a qualified maintenance firm. Work on gas pipes and
fittings must only be carried out by a CORGI registered
engineer.
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.
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.
BENCHMARK' Log Book
All Buderus gas boilers now include an Installation, 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 section at each service visit.
REMEMBER: Please hand the log book back to the user.
Subject to modifications resulting from technical improvements! Buderus Ltd. • http://www.buderus-domestic.co.uk
2 Servicing manual for wall-mounted condensing gas boiler 600 Series 11S/19S/24S/24C • Issued 02/2006
Messages – Universal Automatic Burner (UBA) 1
Buderus
U122 K
1 Messages – Universal Automatic Burner (UBA)
1.1 UBA status display
Operational condition and error messages appear on the
display of the Universal Automatic Burner (UBA).
The message consists of two characters.
The first character is displayed automatically.
Fig. 1 600 Series 11S / 19S / 24S / 24C: Display
To display the second character:
z Hinge the control panel cover to the left to open.
z Press the "Service" button.
Fig. 2 600 Series 11S / 19S / 24S / 24C:
Open the control panel cover
Fig. 3 "Service" button
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Servicing manual for wall-mounted condensing gas boiler 600 Series 11S/19S/24S/24C • Issued 02/2006 3
Messages – Universal Automatic Burner (UBA)1
1.2 UBA operating level 1.5
UBA operating level 1.5 (fig. 4).
Key:
Item 1: Display
Item 2: Service button
Item 3: Reset button
Item 4: Boiler flow temperature
Item 5: Hot-water temperature
Item 6: Power adjustment
Item 7: Pump overrun switch
Item 8: Chimney-sweep switch
Item 9: 11 kW jumper
1
2
3
4
5
Fig. 4 UBA operating level 1.5
9
8
7
6
1.3 Service tool
The service tool allows you to determine the operating status
of the boiler, check components and carry out fast fault diagnosis.
z Open the cover at the front of the boiler unit and insert the
twin plug connector of the service tool into the sockets
provided (fig. 5, item 1).
1
11
KW
I
0
Fig. 5 Service tool connection
01
12
1
10
1
10
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4 Servicing manual for wall-mounted condensing gas boiler 600 Series 11S/19S/24S/24C • Issued 02/2006
Messages – Universal Automatic Burner (UBA) 1
1.4 Operating messages
Display after
Display
pressing the
service button
Meaning
-.
=.
0
A
C
H
L
U
y
A
H
y
600 Series 11S / 19S / 24S / 24C is ready for operation
Burner interval circuit, 10 min from burner start-up
Waiting for the three-way valve and/or pump to switch
Standby activated, 600 Series 11S / 19S / 24S / 24C ready to provide heat or hot water
Initial safety period: self-testing of UBA during burner start-up
Post- or pre-flushing period of fan unit
Flow temperature at adjustment setting
600 Series 11S / 19S / 24S / 24C running in heating mode
“Chimney-sweep” mode, flow-temperature controller bypassed,
600 Series 11S / 19S / 24S / 24C heating to previously-entered flow temperature
Normal heating mode
Service mode
600 Series 11S / 19S / 24S / 24C running in hot-water mode
H
r
Table 1 Displayed UBA operating messages
Normal hot water mode
Reset
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Servicing manual for wall-mounted condensing gas boiler 600 Series 11S/19S/24S/24C • Issued 02/2006 5
Messages – Universal Automatic Burner (UBA)1
1.5 Fault messages
Display
2
3
4
Display after
pressing the
service button
C
P
C
A
C
F
H
Trouble-
Meaning
Water flow
Safety sensor exceeds 100 °C page 10
Excessive temperature increase at safety sensor page 11
Air volume flow
Bad plug-in connection at cable loom, or damaged wiring page 12
Temperatures
Feed sensor above 100 °C page 13
F2 fuse malfunction, or exhaust-gas sensor tripped
Safety sensor exceeds 100 °C page 17
Dripping tap page 18
shooting
flow diagram
page 15
L
P
U
y
5
C
6
A
C
H
L
Short circuit in safety sensor page 19
Safety sensor, loose contact or defective page 20
Short circuit in feed sensor page 21
Feed sensor, loose contact or defective page 22
Communication
600 series has switched off after disconnection of diagnosis plug
Flame monitoring
F1 fuse defective, or no ionisation message after ignition page 24
Ionisation message, but no flame page 28
Flame dies out after gas valve is opened page 29
Flame goes out during warm-up phase page 30
page 23
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6 Servicing manual for wall-mounted condensing gas boiler 600 Series 11S/19S/24S/24C • Issued 02/2006
Messages – Universal Automatic Burner (UBA) 1
Display
7
8
9
Display after
pressing the
service button
A
C
F
H
L
y
A
Trouble-
Meaning
Mains voltage
Voltage in UBA too low or too high page 31
Mains voltage interrupted following a fault warning message page 32
F3 fuse defect, or UBA system error page 33
Voltage peaks in UBA page 34
UBA timer error page 35
General fault/gas-pressure
External switching contact, e.g. temperature monitor for floor heating, has
been tripped
System error
System error page 37
shooting
flow diagram
page 36
C
F, H, P
L
U
E
Any indication,
except
Incorrect cable connection at KIM, or KIM defective page 38
System error (UBA defective) page 39
Wiring to gas-burner assembly incorrect, or loose wiring connections
in UBA
KIM defective page 41
UBA system fault
UBA system fault
P
P
Table 2 Displayed UBA fault warning messages
Non-compatible UBA fitted page 42
page 40
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Servicing manual for wall-mounted condensing gas boiler 600 Series 11S/19S/24S/24C • Issued 02/2006 7
Faults that the UBA does not display2
2 Faults that the UBA does not display
Hot-water mode
Although the UBA is apparently ready for use, situations may
arise where a hot-water tap is opened and no hot water flows
out, or flows out for only a short period.
Troubleshooting flow diagram:
page 43/44.
Heating mode
Although the UBA is apparently ready for use, and the room
temperature has not yet reached the preset level, the
600 Series 11S / 19S / 24S / 24C wall-mounted condensing
gas boiler fails to go into heating mode.
Troubleshooting flow diagram:
page 45.
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8 Servicing manual for wall-mounted condensing gas boiler 600 Series 11S/19S/24S/24C • Issued 02/2006
Troubleshooting 3
3 Troubleshooting
The following flow diagrams are provided for the purpose of
systematic troubleshooting.
Take the opportunity, while carrying out fault diagnosis, to
check that all that plugs and wiring terminals on the UBA are
connected correctly.
WARNING
Switch off the 600 Series 11S / 19S / 24S / 24C
BEFORE checking the connections.
Each time a fault has been rectified, push the “reset”
button " " to unblock the UBA and return it to standby mode.
NOTE
The system cannot be reset by disconnecting
at the master switch.
Certain troubleshooting tasks must be carried out with the
600 Series 11S / 19S / 24S / 24C in heating mode.
When doing so, the chimney-sweep switch should be set to "1"
(fig. 6).
Remember to return the chimney-sweep switch to “0” once
work is complete.
01
Fig. 6 Chimney sweeper switch on UBA
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Servicing manual for wall-mounted condensing gas boiler 600 Series 11S/19S/24S/24C • Issued 02/2006 9
Troubleshooting3
2
Safety sensor temp. exceeds
100 °C
Wait approx. 30 sec for the boiler to return
automatically to normal operation
New fault warning message
2C?
Check system and heat exchanger, as
indicated in the installation and servicing
instructions, for signs of airlocks and dirt -
purge and/or clean as required
Are all
maintenance shutoff
valves open?
Is the water
pressure in the system at
least 1 bar?
C
Yes
Yes
No
No
No
Open maintenance shutoff valves
Fill up with water as indicated in the
installation and servicing instruc-
tions, and purge the system of air
Yes
Is at least one
thermostatic valve open (to
control the amount of water
circulating)?
Yes
Remove the casing (page 48)
Check safety sensor and wiring
(page 55)
Safety sensor OK?
Yes
Check circulation pump (page 54)
Circulation pump OK?
Yes
Filter to catch dirt fitted?
If yes, is it unclogged?
No
No
No
Open one thermostatic valve
Replace safety sensor (page 55)
Replace circulation pump (page 54)
Fit the casing (page 48)
"reset"
A
page 46
Fig. 7 Fault warning message 2C: Safety sensor temp. exceeds 100 °C
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10 Servicing manual for wall-mounted condensing gas boiler 600 Series 11S/19S/24S/24C • Issued 02/2006
600 Series 11S / 19S / 24S / 24C
OK
Troubleshooting 3
2
Excessive temperature
increase at safety sensor
Wait approx. 30 sec for the boiler to return
automatically to normal operation
New fault warning message
Check system and heat exchanger, as
indicated in the installation and servicing
instructions, for signs of airlocks and dirt -
purge and/or clean as required
Are all
maintenance shutoff
valves open?
Is the water
pressure in the system at
least 1 bar?
P
2P?
Yes
Yes
No
No
No
Open maintenance shutoff valves
Fill up with water as indicated in the
installation and servicing instruc-
tions, and purge the system of air
Yes
Is at least one
thermostatic valve open (to
control the amount of water
circulating)?
Yes
Remove the casing (page 48)
Check safety sensor and wiring
(page 55)
Safety sensor OK?
Yes
Check circulation pump (page 54)
Circulation pump OK?
Yes
Filter to catch dirt fitted?
If yes, is it unclogged?
No
No
No
Open one thermostatic valve
Replace safety sensor
(page 55)
Replace circulation pump (page 54)
Fit the casing (page 48)
"reset"
A
page 46
Fig. 8 Fault warning message 2P: Excessive temperature increase at safety sensor
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Servicing manual for wall-mounted condensing gas boiler 600 Series 11S/19S/24S/24C • Issued 02/2006 11
600 Series 11S / 19S / 24S / 24C
OK
Troubleshooting3
Flashing
3
C
Bad plug-in connection at cable loom,
or damaged wiring
"reset"
New fault warning
message 3C?
Yes
Remove the casing (page 48)
Check for a damaged or broken
connection lead between plugs
03-20 and 04-20 of the 20-core
lead to the UBA
No
Wiring OK?
Yes
Use the corresponding flow diagram
to diagnose and deal with the fault.
No
Replace cable
"reset"
Yes
600 Series 11S / 19S / 24S / 24C
New fault warning
message?
No
Fit the casing (page 48)
OK
Fig. 9 Fault warning message 3C: Bad plug-in connection at cable loom, or damaged wiring
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12 Servicing manual for wall-mounted condensing gas boiler 600 Series 11S/19S/24S/24C • Issued 02/2006
Troubleshooting 3
Flashing
4
Feed sensor above 100 °C
"reset"
New fault warning message
4A?
Yes
Check system and heat exchanger, as
indicated in the installation and servicing
instructions, for signs of airlocks and
dirt - purge and/or clean as required.
Are all
maintenance shutoff
valves open?
Yes
Is the water
pressure in the system at
least 1 bar?
Yes
A
No
No
No
Open maintenance shutoff valves
Fill up with water as indicated in the
installation and servicing instruc-
tions, and purge the system of air
Is at least one
thermostatic valve open (to control
the amount of water cir-
culating)?
Yes
Remove the casing (page 48)
Check circulation pump (page 54)
Circulation pump OK?
Yes
Filter to catch dirt fitted?
If yes, is it unclogged?
No
No
Open one thermostatic valve
Replace circulation pump (page 54)
16
page 14
Fig. 10 Fault warning message 4A: Feed sensor above 100 °C
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Servicing manual for wall-mounted condensing gas boiler 600 Series 11S/19S/24S/24C • Issued 02/2006 13
17
page 14
Troubleshooting3
page 13
16
Check feed sensor and feed-sensor
connection wiring (page 56)
Flow sensor
and wiring
OK?
Yes
A
No
page 13
17
Replace feed sensor or cable
(page 56)
"reset"
page 46
Fit the casing (page 48)
600 Series
11S / 19S / 24S / 24C
OK
Fig. 11 Continuation of fault warning message 4A: Feed sensor above 100 °C
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14 Servicing manual for wall-mounted condensing gas boiler 600 Series 11S/19S/24S/24C • Issued 02/2006
Troubleshooting 3
Flashing
4
F2 fuse malfunction, or exhaust-gas
sensor tripped
"reset"
New fault
warning message
4C?
Yes
Remove the casing (page 48)
Check miniature fuse F2 (page 53)
Miniature fuse F2 OK?
C
No
No
Fuse (1.25 AT) should be
replaced
Yes
Check wiring connection of UBA
(page 53)
Wiring connection
OK?
Yes
Check exhaust-gas sensor
(page 49)
Exhaust-gas
sensor OK?
Yes
18
No
No
Connect lead correctly
Replace exhaust-gas sensor
(page 49)
19
20
page 16
Fig. 12 Fault warning message 4C: F2 fuse malfunction, or exhaust-gas sensor tripped
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Servicing manual for wall-mounted condensing gas boiler 600 Series 11S/19S/24S/24C • Issued 02/2006 15
page 16
page 16
Troubleshooting3
page 15
18
Open the heat exchanger and
burner, as indicated in the installation
and servicing instructions, and check
for dirt
Are the heat exchang-
er and burner soiled?
No
Shut the heat exchanger and burner
Yes
Clean the heat exchanger
and burner, as indicated in
the installation and servicing
instructions
page 15
19
"reset"
page 15
20
A
page 46
Fit the casing
(page 48)
600 Series
11S / 19S / 24S / 24C
OK
Fig. 13 Continuation of fault warning message 4C: F2 fuse malfunction, or exhaust-gas sensor tripped
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16 Servicing manual for wall-mounted condensing gas boiler 600 Series 11S/19S/24S/24C • Issued 02/2006
Troubleshooting 3
Flashing
4
Safety sensor temp. exceeds 100 °C
"reset"
New fault
warning message 4F?
Yes
Check system and heat exchanger, as
indicated in the installation and servicing
instructions, for signs of airlocks and
dirt - purge and/or clean as required
Are all
maintenance shutoff
valves open?
Yes
Is the water
pressure in the system at
least 1 bar?
F
No
No
No
Open maintenance shutoff valves
Fill up with water as indicated in the
installation and servicing instruc-
tions, and purge the system of air
Yes
Is at least one
thermostatic valve open (to
control the amount of water
circulating)?
Yes
Remove the casing (page 48)
Check circulation pump (page 54)
Circulation pump OK?
Yes
Check safety sensor
(page 55)
Safety sensor
OK?
Yes
No
No
No
Open one thermostatic valve
Replace circulation pump (page 54)
Replace safety sensor
(page 55)
Fit the casing (page 48)
"reset"
A
600 Series 11S / 19S / 24S / 24C
page 46
Fig. 14 Fault warning message 4F: Safety sensor temp. exceeds 100 °C
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Servicing manual for wall-mounted condensing gas boiler 600 Series 11S/19S/24S/24C • Issued 02/2006 17
OK
Troubleshooting3
Flashing
4
Dripping tap
There is constant heat monitoring
over a period of 4 hours, but the
boiler has been heating up for less
than 20 minutes. The hot water
requirement is now blocked for one
hour, or the restriction lifted if a heat
requirement arises.
Is there a
dripping tap somewhere in
the hot-water system?
Yes
H
No
Please deal with this item
Yes
"reset"
New fault warning
message 4H?
No
600 Series
11S / 19S / 24S / 24C
OK
Fig. 15 Fault warning message 4H: Dripping tap
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18 Servicing manual for wall-mounted condensing gas boiler 600 Series 11S/19S/24S/24C • Issued 02/2006
Troubleshooting 3
Flashing
4
Short circuit at safety sensor
"reset"
New fault warning
message 4L?
Yes
Remove the casing (page 48)
Check wiring to safety sensor for short
circuits (page 55)
L
No
Wiring OK?
Yes
Check safety sensor (page 55)
Safety sensor
OK?
Yes
A
page 46
No
No
Replace cable
Replace safety sensor
(page 55)
"reset"
Fit the casing
(page 48)
600 Series
11S / 19S / 24S / 24C
OK
Fig. 16 Fault warning message 4L: Short circuit in safety sensor
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Servicing manual for wall-mounted condensing gas boiler 600 Series 11S/19S/24S/24C • Issued 02/2006 19
Troubleshooting3
Flashing
4
Safety sensor, loose contact
or defect
"reset"
New fault warning
message 4P?
Yes
Remove the casing (page 48)
Check wiring to safety sensor for loose
contacts (page 55)
P
No
Wiring OK?
Yes
Check safety sensor (page 55)
Safety sensor
OK?
Yes
A
page 46
No
No
Replace cable (page 55)
Replace safety sensor (page 55)
"reset"
Fit the casing
(page 48)
600 Series
11S / 19S / 24S / 24C
OK
Fig. 17 Fault warning message 4P: Safety sensor, loose contact or defect
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20 Servicing manual for wall-mounted condensing gas boiler 600 Series 11S/19S/24S/24C • Issued 02/2006
Troubleshooting 3
Flashing
4
Short circuit in feed sensor
"reset"
New fault warning
message 4U?
Yes
Remove the casing (page 48)
Check wiring to feed sensor for short
circuits (page 56)
U
No
Wiring OK?
Yes
Check feed sensor (page 56)
Feed sensor
OK?
Yes
A
page 46
No
No
Replace cable
Replace feed sensor
(page 56)
"reset"
Fit the casing
(page 48)
600 Series
11S / 19S / 24S / 24C
OK
Fig. 18 Fault warning message 4U: Short circuit in feed sensor
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Servicing manual for wall-mounted condensing gas boiler 600 Series 11S/19S/24S/24C • Issued 02/2006 21
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