Buderus 500-24C User manual

For the installer
Please read thoroughly
Installation and maintenance
instructions
Gas wall hung Boiler
condensing
7215 3100-00.1TD
Buderus 500-24C
Buderus 500-28C
7215 3100 (05/2009) GB/IE

Contents
Buderus 500-24C/28C - Subject to modifications resulting from technical improvements
2
Contents
Regulations and directives 3
Hazard definitions and abbreviations 5
1 Installation 6
1.1 Technical specifications 6
1.2 Dimensions, connections and assembly 8
1.3 Boiler locations and clearances 9
1.4 Items supplied with unit 10
1.5 Hanging the boiler 11
1.6 Install the wall-spacing frame 12
1.7 Water circulation system 13
1.8 Pipe connections 14
1.9 Flue installation 19
1.10 Electrical connections 25
1.11 External controls 26
1.12 System examples 31
2 Commissioning 34
2.1 Preparing the boiler for operation 35
3 Inspection 46
3.1 General directions 46
3.2 Preparing the boiler for inspection 46
4 Maintenance 47
4.1 Cleaning the heat exchanger and burner 47
4.2 Cleaning the condensate trap and syphon 50
4.3 Cleaning or replacing the plate heat exchanger 51
5Appendix 52
5.1 Fault codes 52
5.2 Wiring diagram 53
5.3 Residual pump lift 54
5.4 Spare parts list 55
Preface
Important general instructions
The appliance is designed exclusively for heating water as
part of a domestic central heating and/or hot water sys-
tem. Do not use the appliance for any other purpose.
Installation, maintenance and repair must be carried out
by a competent engineer (e.g. CORGI registered). Only
use the boiler in conjunction with Buderus accessories
and spares. Other accessories and consumables may 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,
central heating systems ONLY.
BENCHMARK' Log Book
All Buderus gas fired boilers include an installation, com-
missioning 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 leave the log book with the
installed boiler.
Gas Council Aplliance No. :
Buderus 500-24C 47-110-04
Buderus 500-28C 47-110-03
These Installation and maintenance instructions apply to:
Buderus wall-mounted condensing gas combi boilers
models 500-24C and 500-28C.
The boiler type consists of the following components:
Other manuals available for this boiler are:
– user manual;
– service instructions.
Flue type: C13x, C33(x), C53(x), C73(x)
Type: GB/IE II2H3P 20 mbar; 37 mbar
In this document: NG = 2H-G20-20 mbar
LPG = 3P-G31-37 mbar
Electrical rating: 230 VAC, 50 Hz, IP X4D
Fuse rating: 2.5 Ampere slow blow silica filled
– 500 Gas condensing boiler
– 28 Maximum output is 28 kW
– C Combination boiler (Integrated
domestic hot water supply).

Regulations and directives
Buderus 500-24C/28C - Subject to modifications resulting from technical improvements 3
Regulations and directives
All gas appliances must be installed by a competent per-
son in accordance with the current Gas Safety (Installa-
tion and Use) regulations.
Failure to install appliances correctly could lead to prose-
cution.
The appliance installation must comply with the current:
Gas Safety Regulations,
IEE Regulations,
Building Regulations,
Building Standards (Scotland) (Consolidation),
Building Regulations (Northern Ireland),
local water by-laws,
Health and Safety Document 635 (The Electricity Work
regulations 1989) and any other local requirements.
The relevant British Standards should be followed,
including:
Where no specific instruction is given, reference should
be made to the relevant British Standard codes of Prac-
tice.
The manufacturer's notes must not be taken, in any way,
as overriding the statutory instrument laws.
The design and construction of the Buderus wall-
mounted condensing gas combi boiler 500-24C and
500-28C 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.
For optimum long term reliable functioning under domes-
tic conditions, the boiler must be inspected and main-
tained as per these instructions, at least once a year by an
officially recognised service engineer.
The term "domestic conditions" means that the boiler is
used to provide central heating and / or hot water to no
more than one single family dwelling.
Failure to comply with these instructions will invalidate the
appliance warranty.
Timer Frame 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 and BS 5440:1.
The appliance must only be installed along with Buderus
flue kits, as these are certified for use with the boiler.
BS7074:1 : Code of practice for domestic and
hot water supply
BS6891 : Installation of low pressure gas
pipework up to 28mm (R1)
BS5546 : Installation of gas hot water sup-
plies for domestic purposes
EN:12828 : Central heating for domestic
premises
BS5440:1 : Flues and ventilation for gas appli-
ances of rated heat input not ex-
ceeding 70 kW (net): Flues
BS5440:2 : Flues and ventilation for gas appli-
ances of rated heat input not ex-
ceeding 70 kW (net): Air Supply
BS5449 : Forced circulation of hot water
systems
BS7593 : Treatment of water in domestic hot
water central heating systems
BS6798 : Installation of gas fired boilers of
rated input up to 70 kW (net).
Warning: 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 informa-
tion about Sentinel call 0151 420 9563.
When using water treatment, only products
suitable for use with Buderus heat exchang-
ers 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 Tech-
nical Product Support Department.
It is most important that the correct concen-
tration of the water treatment product is
maintained in accordance with the manufac-
turer's instructions.
If the boiler is used in an existing system any
unsuitable additives MUST be removed by
thorough cleaning. BS.7593 details the
steps necessary to clean a domestic central
heating system.

Regulations and directives
Buderus 500-24C/28C - Subject to modifications resulting from technical improvements
4
Safe handling of substances
No asbestos, mercury or CFCs are included in any part of
the boiler and its manufacture.
Warning: In hard water areas, treatment to
prevent lime scale may be necessary - how-
ever, 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.
When using plastic pipes, then they must
contain a polymeric barrier.
It is allowed to use copper for the first 600
mm. See also subsection 1.8: “Pipe connec-
tions” in this manual.
Notes related to domestic hot water.
VThe domestic hot water service must be in
accordance with BS 5546 and BS 6700.
VThe boilers are suitable for connection to
most types of washing machine and dish-
washer appliances.
VWhen connecting to suitable showers, en-
sure 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.
VWhere temporary hardness exceeds
150 mg/litre, it is recommended that a
proprietary scale reducing device is fitted
into the boiler cold supply with the require-
ments of the local water company.
Caution
Provision must be made to accommodate
the expansion of DHW contained within the
appliance, where a back flow prevention de-
vice is fitted BS. 67989: §5.4.3.

Hazard definitions and abbreviations
Buderus 500-24C/28C - Subject to modifications resulting from technical improvements 5
Hazard definitions and abbreviations
Hazard definitions Abbreviations
Danger:
Indicates the presence of hazards that will
cause severe personal injury, death or sub-
stantial property damage.
Warning:
Indicates the presence of hazards that can
cause severe personal injury, death or sub-
stantial property damage.
Caution:
Indicates presence of hazards that can
cause minor personal injury or property dam-
age.
NOTICE:
Indicates special instructions on installation,
operation or maintenance that are important
but not related to personal injury or property
damage.
AB = Automatic Bypass
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 = Neutral
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
μ= micro (as μA - micro Amps)
WC = Wiring Centre
ZV = Two Port Zone Valve

1Installation
Buderus 500-24C/28C - Subject to modifications resulting from technical improvements
6
1 Installation
1.1 Technical specifications
Description Unit
500 Series wall-mounted condensing gas
combi-boiler
500-24C 500-28C
Type of gas supply as established in
EN 437 (GB/IE)
GB/IE II2H3P 20 mbar, 37 mbar
(natural gas Hand LPG P)
Rated thermal load for heating
Rated thermal load for preparing hot water
kW
kW
5.7 - 23.0
5.7 - 23.0
5.7 - 23.0
5.7 - 28.5
Rated heating capacity for system temperature
(modulating from 30° to 100°)
Heating curve 75/60 °C
Heating curve 40/30 °C
kW
kW
5.3 - 22.0
6.0 - 24.0
5.3 - 22.0
6.0 - 24.0
Seasonal efficiency (SEDBUK)
for natural gas
for LPG
%
%
90.0
92.3
90.0
92.3
Max. gas rate for heating
Max. gas rate preparing hot water
m3/h
m3/h
2.43
2.43
2.43
3.02
Central heating installation
Heating water temperature °C 30 - 80 30 - 80
ΔT at residual head of 200 mbar °C < 20 < 20
Max. operating pressure of boiler bar 3.0 3.0
Pump over run time min 5 5
Expansion vessel
Capacity of expansion vessel l 7.5 7.5
Admission pressure of expansion vessel bar 1.0 1.0
Plate heat exchanger
DHW flow rate at 35 °C rise l/min 9.4 11.7
Adjustable hot water temperature °C 40 - 60 40 - 60
Minimum connection pressure bar 0.8 0.9
Maximum connection pressure bar 10.0 10.0
Pipe connections
Maximum connection pressure ∅mm 22
CH flow/return (compression fitting) ∅mm 22
MCW inlet / DHW outlet (compression fitting) ∅mm 15
Condensate-water outlet ∅mm 21.5
Pressure relief valve (compression fitting) ∅mm 15 (adapter supplied with boiler)

1
Installation
Buderus 500-24C/28C - Subject to modifications resulting from technical improvements 7
Flue gas values
Condensate water quantity, natural gas, 40/30 °C l/h 1.6 1.6
Exhaust-fume mass-flow rate
Full load
Part-load
g/s
g/s
10.6
4.3
10.6
4.3
Exhaust-fume temperature, full load
Heating curve 75/60 °C
Heating curve 40/30 °C
°C
°C
77
55
77
55
Exhaust-fume temperature, partial load
Heating curve 75/60 °C
Heating curve 40/30 °C
°C
°C
60
35
60
35
CO2 full load, natural gas
standard test gas G20 % 9.2 9.2
CO2 full load, natural gas
standard test gas LPG % 10.3 10.3
Standard emission factor CO mg/kWh < 22 < 22
Standard emission factor NOxmg/kWh < 30 < 30
Flow pressure available for use Pa 75 75
Flue-gas system
Type of exhaust-fume connection C13(X), C33(X), C53(X), C73(X)
Diameter of flue take-off mm Concentric 60/100
Electrical data
Mains connection voltage (50 Hz) V 230
Electrical power consumption
Full/Partial load/Standby W 110/88/4
Electrical protection rating IP X4D
Boiler dimensions and weight
Height x Width x Depth mm 780 x 460 x 330 780 x 460 x 330
Weight (without casing) kg 31 31
Weight (without casing) kg 3 3
Description Unit
500 Series wall-mounted condensing gas
combi-boiler
500-24C 500-28C

1Installation
Buderus 500-24C/28C - Subject to modifications resulting from technical improvements
8
1.2 Dimensions, connections and assembly
A. outside edge frame
1. CH flow = Ø 22 mm (compression fitting)
2. CH return = Ø 22 mm (compression fitting)
3. DHW outlet = Ø 15 mm (compression fitting)
4. MCW inlet = Ø 15 mm (compression fitting)
5. Gas = Gas connection Ø 22 mm (compression fitting)
6. CDO = Condensate drainage outlet Ø 21.5 mm
7. PRV = Pressure relief valve Ø 15 mm (compression fitting)
460 mm
330 mm
150 mm
35 mm
780 mm
(6) 108 mm
Ø100 mm
Ø60 mm
328 mm
376 mm
721 mm
200 mm
(7) 93 mm
(1-2-5) 85 mm
(3-4) 70 mm
1 3 5 4 2 7
A
222 mm
352 mm
403.8 mm
92 mm
6
230 mm
152 mm
282 mm / 287 mm
157 mm / 162 mm
5 mm 5 mm
21 mm
8 mm
21 mm
7215 3100-76.1TD
Note
See wall-mounting template for the neces-
sary clearances.
The wall-spacing frame may not always be
necessary.

1
Installation
Buderus 500-24C/28C - Subject to modifications resulting from technical improvements 9
1.3 Boiler locations and clearances
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
Scotland, the electrical provisions of the building regula-
tions applicable in Scotland, with respect to the installa-
tion of the boiler in a room or internal space containing a
bath or shower. If the appliance is to be installed in a room
containing a bath or shower then, providing water jets are
not going to be used for cleaning purposes (as in commu-
nal baths/showers), the appliance can be installed 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). Fig. 1 Bathroom Installations
A= Radius
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 compart-
ment in which the boiler is installed, due to the low surface
temperatures of the boiler casing during operation; there-
fore the requirements of BS 6798, Clause 12, and
BS 5440:2 may be disregarded.
The permanent clearances required are:
The position selected for installation MUST allow ade-
quate space for servicing:
In addition, sufficient space may be required to allow lift-
ing access to the wall-mounting bracket. Fig. 2 Compartment Installations
600mm
750mm
2250mm
1123
600mm A
600mm
600mm
750mm
2250mm
323
112
7215 3100-01.1TD
A = in front 8 mm
B=below 21mm
C=rightside 5mm
D = left side 5 mm
E = above 21 mm
A = in front 350 mm
B=below 180mm
C=rightside 5mm
D = left side 5 mm
E=above 200mm
A
B
C
D
E
7215 3100-02.1TD

1Installation
Buderus 500-24C/28C - Subject to modifications resulting from technical improvements
10
1.4 Items supplied with unit
VCheck the contents against the packing list to ensure
that nothing is missing.
Fig. 3 Items supplied with unit
Key to fig. 3:
1: Wall-mounted condensing gas boiler
2: Wall bracket
3: Manifold Assembly
4: Wall-spacing frame
5: Bracket for ModuLink 250 RF
6: Technical documents:
1 x Installation and maintenance manual
1 x User manual
1 x Wall-mounting template
1 x Benchmark Logbook
1 x Warranty card
1 x Envelope for Warranty card
7: Plastic bag containing the following accessories:
4 x wall fixing screws
4 x wall plugs
4 x washers
4 x push fit rivet for wall-spacing frame
2 x rubber stops for wall-spacing frame
3 x cable clamp - top part
6 x cable clamp - fixing screw
Seals (1 x G½“ - 1“, 2 x ¾“ - 22 mm, 2 x ½“ - 15 mm)
1 x MCW inlet filter
Initial start-up sticker
Second identification plate
Pressure Relief Valve compression fitting + brass insert
Radiator key
7
1
2
6
5
3
4
7215 3100-03.1TD

1
Installation
Buderus 500-24C/28C - Subject to modifications resulting from technical improvements 11
1.5 Hanging the boiler
Fig. 4 Installation
VAttach the wall-mounting template.
VDrill the necessary holes.
VAttach the manifold assembly to the wall (Æfig. 4,
item 1).
VMake the pipework connections to the manifold.
VAttach the wall bracket (Æfig. 4, item 2).
VOpen the locking mechanism using a radiator key
(Æfig. 5, item 1). The radiator key is included in the
delivery of the boiler in the accessories bag.
VDetach the casing of the condensing gas boiler
(Æfig. 5).
VRemove the polystyrene foam piece from the top of the
boiler.
VHang the condensing gas boiler onto the wall bracket
(Æfig. 4).
Fig. 5 Remove casing
VConnect manifold unions to the boiler using supplied
seals.
Note
Pipework from the boiler is routed down-
wards as standard, but may be routed up-
wards behind the boiler using the wall-
spacing frame (supplied with the boiler).
If using the supplied wall-spacing frame, fol-
low the procedure in section 1.6.
CAUTION!
DO NOT remove the polystyrene foam bot-
tom slab until lifted into position.
During installation work, cover the condens-
ing boiler and flue connection to prevent site
dirt from entering.
7215 3100-04.1TD
1
2
7215 3100-05.1TD
Note
If the boiler isn't connected to the pipework
immediately, place caps on the pipe connec-
tions.

1Installation
Buderus 500-24C/28C - Subject to modifications resulting from technical improvements
12
1.6 Install the wall-spacing frame
VAttach the wall-mounting template.
VDrill the necessary holes.
VAttach the wall bracket (Æfig. 4, item 2).
VMount the rubber stops in one of the wall-spacing
brackets and hang this on the wall bracket (Æfig. 6).
Fig. 6 Hanging the wall-spacing bracket
VMount the two strips on the upper and lower wall-spac-
ing brackets using the snap rivets (Æfig. 7).
The lower wall-spacing bracket is fitted upside down
compared to the upper wall-spacing bracket, ie. with
the hooks facing down.
VAttach this lower wall-spacing bracket to the wall.
Fig. 7 Mounting the lower bracket
7215 3100-06.1TD
7215 3100-07.1TD

1
Installation
Buderus 500-24C/28C - Subject to modifications resulting from technical improvements 13
VMount the lower bracket on the wall and attach the
manifold assembly. If the manifold does not sit flat,
check the orientation of the lower wall-spacing bracket
(Æfig. 8).
VMake the pipework connections to the manifold.
See also subsection 1.8.
VOpen the case locking mechanism, using a radiator key
(Æfig. 5, item 1). The radiator key is included in the
delivery of the boiler, in the accessory bag.
VRemove the boiler case.
VRemove the polystyrene foam piece from the top of the
boiler.
VConnect the manifold unions to the boiler, using the
seals supplied. Fig. 8 Mounting the manifold
VHang the boiler (Æfig. 9) onto the upper wall-spacing
frame bracket.
Fig. 9 Hanging the boiler
1.7 Water circulation system
The central heating system should be installed in accord-
ance with BS.6798 and, in addition, for smallbore and
microbore systems, BS.5449 or EN 12823.
Note
If the boiler is not to be connected the pipe-
work immediately, then place caps on the
pipe connections.
7215 3100-08.1TD
7215 3100-09.1TD

1Installation
Buderus 500-24C/28C - Subject to modifications resulting from technical improvements
14
1.8 Pipe connections
VConnect pipes as shown in fig. 10. Ensure that all pipe-
work is routed so as to minimise any strain on the boiler
fittings.
The first 600 mm of pipework must be in copper, then
another approved material type can be used.
1.8.1 Gas supply
The gas installation must be installed in accordance with
BS.6891.
The complete installation MUST be tested for gas tight-
ness and purged as described in IGE/UP/1b.
Fig. 10 Pipe connections
Key to fig. 6
1: CH flow
2: DHW outlet
3: Gas
4: MCW inlet
5: CH return
1.8.2 Gas connection
VConnect to gas supply according to relevant stand-
ards.
1.8.3 Compression fitting pressure relief valve
outlet
VInsert the small piece of pipe (Æfig. 11).
VAttach the compression fitting (Æfig. 12).
Fig. 11 Insert pipe
CAUTION!
Do not use galvanised radiators or pipes.
CAUTION!
Pipework from the meter to the boiler MUST
be of adequate size, generally Ø22 mm.
7215 3100-10.1TD
21345
7215 3100-11.1TD

1
Installation
Buderus 500-24C/28C - Subject to modifications resulting from technical improvements 15
1.8.4 Hot-water temperature
Fig. 12 Compression fitting
1.8.5 Condensate removal
Positioning and termination of the condensate
drain pipe
The condensate pipe should be run and terminate inter-
nally to the house soil and vent stack or waste pipe. Alter-
natively, the condensate can be discharged into the
rainwater system if connected to a foul water draining sys-
tem, or into a purpose-made soak away (condensate
absorption point).
All connecting drainage pipework should generally have a
fall of at least 2.5° to the horizontal, or approximately 50
mm per metre of pipe run. If this is can not be achieved,
consider the use of a condens pump.
If an external pipe run is unavoidable then the run should
be limited to 3 m in length. Should this be exceeded then
the pipework diameter should be increased to 32 mm.
It should be noted that the connection of a condensate
pipe to a drain may be subject to local building controls.
CAUTION!
DO NOT use galvanised pipes or fittings.
The hot water heat exchanger contains cop-
per and can suffer from electrolytic corro-
sion.
Note
When using plastic pipes, observe the sup-
plier’s instructions - especially those referring
to recommended jointing techniques and the
notes relating to the heating system water on
page 3.
7215 3100-12.1TD
Warning:
Any external run must be insulated with water
proof insulation.

1Installation
Buderus 500-24C/28C - Subject to modifications resulting from technical improvements
16
Materials for condensate
The condensate drainage pipe should be run in a stand-
ard drain pipe material, e.g. PVC (polyvinyl-chloride),
PVC-u (unplasticized polyvinyl-chloride), ABS (acryloni-
trile-butadienestyrene), PP (polypropylene) or PVC-C
(cross-linked polyvinyl-chloride).
The condensate drain can be attached to the syphon.
Ensure that the black rubberised olive (Æfig. 13) is cor-
rectly aligned.
Any internal pipework should be of a diameter to match
the requirements of the condensate exit pipe on the appli-
ance.
Fig. 13 Condensate outlet
Internal termination to internal stack
The condensate drainage pipe should have a minimum
outside diameter of 21.5 mm with no length restriction.
It should incorporate a trap with a 75 mm condensate seal
and be connected to the stack at a point at least 450 mm
above the invert of the stack. The trap built into the
boiler will provide this 75 mm (Æfig. 14) conden-
sate seal.
Fig. 14 Internal termination of condensate drainage pipe
to internal stack
1. Boiler
2. Ø21.5 mm min.
3. internal soil and vent stack
4. No length restriction
5. 450 mm min.
6. invert
Note
Ensure that the condensate trap is filled with
water.
7215 3100-13.1TD
4
2
3
6
1
7215 3100-14.1TD
5

1
Installation
Buderus 500-24C/28C - Subject to modifications resulting from technical improvements 17
External termination via internal branche (e.g. sink
waste)
The condensate drainage pipe should have a minimum
outside diameter of 21.5 mm with no length restriction.
The connection should preferably be made downstream
of the sink waste trap. If the connection is only possible
upstream, then the air break is needed between the two
traps. This can be provided by the sink waste pipe
(Æfig. 14 and fig. 15).
Fig. 15 External termination of condensate drainage
pipe via internal discharge branch (e.g. sink
waste) and condensate syphon
1. Sink
2. Boiler
3. No length restriction
4. Ø21.5 mm min.
5. open end of pipe direct into gully, below ground but above
water level
Fig. 16 External termination of condensate drainage
pipe via internal discharge branch (e.g. sink
waste) and condensate syphon
1. Sink
2. Boiler
3. No length restriction
4. Ø21.5 mm min.
5. open end of pipe direct into gully, below ground but above
water level
7215 3100-15.1TD
1
5
24
3
3
2
4
1
7215 3100-16.1TD
5

1Installation
Buderus 500-24C/28C - Subject to modifications resulting from technical improvements
18
Condensate absorption point
The condensate drainage pipe should have a minimum
outside diameter of 21.5 mm and the external pipe length
should not be more than 3 m. The condensate absorption
point should be sited in a convenient position as close as
possible to the boiler but not in the vicinity of other serv-
ices. For information Æfig. 17.
Fig. 17 External termination of condensate drainage
pipe to absorption point
1. External length of pipe 3 m max.
2. Ø21.5 mm min.
3. Ø1000 mm min.
4. Ø100 mm min. plastic tube
5. bottom of tube sealed
6. limestone chippings
7. Two rows of three 12 mm holes at 25 mm centres 50 mm
from bottom of tube and facing away from house
8. Ground (either/or)
9. 25 mm min.
10. 300 mm min.
11 hole depth 400 mm min.
Note
When discharging condensate to an outside
drain caution must be taken to ensure block-
age cannot occur during freezing conditions.
If this is likely to occur, the use of a syphon
trap is recommended.
7215 3100-17.1TD
1
2
3
4
5
6
7
8
11
910

1
Installation
Buderus 500-24C/28C - Subject to modifications resulting from technical improvements 19
1.9 Flue installation
1.9.1 Siting the flue terminal
Fig. 18 Flue terminal position
1under carport
The flue must be installed in accordance with the recom-
mendations of BS.5440-1:2000.
Pluming will occur at the terminal so terminal positions
where this could cause a nuisance should be avoided.
The air supply and the flue gas exhaust must meet the
applicable general regulations. Please consult the instruc-
tions provided with the flue terminal kits prior to installa-
tion.
The boiler MUST be installed so that the terminal is
exposed to external air.
It is important that the position of the terminal allows the
free passage of air at all times.
Minimum acceptable spacing from the terminal to
obstructions and ventilation openings are specified in
table 1.
If the lowest part of the terminal is less than 2 metres
above the level of the ground, balcony, flat roof or place to
which any person has access, the terminal must be pro-
tected by a guard.
Ensure that the guard is fitted centrally.
The flue assembly shall be so placed or shielded as to
prevent ignition or damage to any part of the building.
The air inlet/products outlet duct and the terminal of the
boiler MUST NOT be closer than 25 mm to combustible
material. Detailed recommendations on the protection of
combustible material are given in BS.5440-1:2000.
Danger:
Only use Buderus flue gas systems.
As other flue gas systems are not tested with
this appliance.
A
FM
G
M
B,C
FF
B,C
K
G
K
K
G
C
LL
A
N
N
O
E
FJ
K
G
D
H, I
1
7215 3100-18.1TD
Terminal position Maximum
Spacing
A. Directly below, above or alongside an
opening window, air vent or other venti-
lation opening
300 mm
B. Below guttering, drain pipes or soil
pipes
200 mm
C. Below eaves 200 mm
D. Below balconies or a car port roof
Not recommended!
200 mm
E. From vertical drain pipes or soil pipes 150 mm
F. From internal or external corners 300 mm
G. Above adjacent ground, roof or balcony
level
300 mm
H. From a surface facing the terminal 600 mm
I. From a terminal facing a terminal 1200 mm
J. From an opening in a car port (e.g.
door or window) into dwelling.
Not recommended!
1200 mm
K. Vertically from a terminal on the same
wall
1500 mm
L. Horizontally from a terminal on the wall 300 mm
M. Adjacent to opening 300 mm
N. Above intersection with roof 300 mm
O. From a vertical structure on the roof 500 mm
Tab. 1 Balanced flue terminal position

1Installation
Buderus 500-24C/28C - Subject to modifications resulting from technical improvements
20
If this could occur the appliance MUST be turned off (with
the owners permission), and labelled as unsafe until cor-
rective action can be taken.
1.9.2 Air supply and flue gas exhaust in a closed
installation
The boiler case incorporates the seal for the air supply
system. It is important that the case is fitted correctly.
To ensure optimal operation, the 500 Series appliances
must be connected to a Buderus horizontal or vertical flue
terminal. These terminals have been developed specifi-
cally for Buderus condensing gas boilers and have been
comprehensively tested for trouble free operation when
correctly installed.
Fig. 19 Standard horizontal flue pack
Standard horizontal flue pack (Æfig 19):
–item 1: Flue turret 60/100;
–item 2: Horizontal flue terminal 60/100;
–item 3: Flue finishing kit.
Fig. 20 Side flue and rear flue installation
NOTE
It is absolutely essential to ensure, in prac-
tice, that products of combustion discharg-
ing from the terminal cannot re-enter the
building or any other adjacent building
through ventilators, windows, doors, other
sources of natural air infiltration, or forced
ventilation/air-conditioning.
1
2
3
7215 3100-19.1TD
415 mm
5 mm
L
7215 3100-20.1TD