Alpha CD13R, CD18R, CD24R Installation and Servicing Instructions
Installation and Servicing
Instructions
Alpha CD13R,18R and 24R
Wall Mounted, Fan Assisted, Room Sealed, Gas Fired,
High Efficiency Condensing Regular Boiler Range
For Technical help or for Service call ...
ALPHA HELPLINE Tel: 0870 3001964
website:www.alpha-innovation.co.uk
Nepicar House, London Road,
Wrotham Heath, Sevenoaks,
Kent TN15 7RS
British Gas
Service Listed
Alpha CD13R G.C. No. 41 532 05
Alpha CD18R G.C. No. 41 532 03
Alpha CD24R G.C. No. 41 532 04
For use with Natural Gas only
Leave these instructions with the User
CONTENTS
1 Introduction ....................................... 2
2 Technical data................................... 3
3 General boiler information..................6
4 Installation......................................... 12
5 Commissioning ................................. 18
6 Boiler operation ................................. 20
7 Routine servicing............................... 21
8 Component replacement ................... 23
9 Wiring diagrams ................................ 27
10 Fault finding ...................................... 29
11 Short parts list ................................... 32
12 Benchmark Checklist ........................ 33
13 Service record ................................... 34
1 INTRODUCTION
The Alpha CD Regular range of high efficiency condensing boilers are wall mounted, fan assisted room-sealed boilers. The
burner is lit electronically and the heat output is controlled by a modulating fan and gas valve.
The boilers provide heating only for open vented systems and with the addition of a sealed system kit for sealed central
heating systems.
The boilers are designed for use with a fully pumped open vented or sealed and pressurised central heating system using only
Natural gas.
The boiler CD13R is suitable for central heating loads of between 5.4 and 13.1 kW (18 400 and 44 700 Btu/h).
The boiler CD18R is suitable for central heating loads of between 5.4 and 19.6 kW (18 400 and 66 800 Btu/h).
The boiler CD24R is suitable for central heating loads of between 6.5 and 25.6 kW (22 200 and 87 300 Btu/h).
The boilers are rated to the SEDBUK efficiency band A and have a NOx class 5 rating.
IMPORTANT
It is the law that all gas appliances are installed by a competent person, ie CORGI registered personnel, in accordance with
the following recommendations:-
Current Gas Safety (Installation and Use) Regulations
All current Building Regulations issued by the Department of the Environment, i.e. Approved Document L1.
Building Standards (Scotland) (Consolidation) Regulations issued by the Scottish Development Department
Health & Safety Document No. 635 (The Electricity At Work Regulations 1989)
The installation should also be in accordance with the following British Standard Codes of Practice:BS 5440:1:2008 Flues
BS 5449:1990 Forced circulation hot water systems
BS 5546:2000 Installation of hot water supplies for domestic purposes
BS 6700:1997 Design, installation, testing and maintenance of services supplying water
BS 6798:2000 Installation of gas fired boilers
BS 6891:1998 Gas installation
BS 7593:2006 Code of Practice for treatment of water in heating systems
BS 7671:2001 Requirements for electrical installations, IEE Wiring Regulations
Reference should also be made to the DEFRA document 'Guide to condensing boiler installation assessment procedure for
dwellings'
If installation is in a timber framed building, refer to the Institute of Gas Engineers document IGE/UP/7.
This appliance meets the requirements of IPX4D, ie degree of protection against moisture.
Failure to install this appliance correctly could lead to prosecution. It is in your own interest and that of safety to ensure that the
law is complied with.
Manufacturer's instructions must NOT be taken in anyway as over-riding statutory obligations.
Notes: 1. Ensure that the Benchmark Checklist has been completed after the boiler has been installed and commissioned.
2. Ensure the appliance has been supplied with an Alpha CD flue system.
Alpha CD13R, 18R, 24R - Contents/Introduction
2
2 TECHNICAL DA T A
2.1 PERFORMANCE - NATURAL GAS (CAT: 12H 2H - G20 - 20 mbar)
Alpha CD13R
Central Heating
Heat Input (H
)kW
s
(Gross) Btu/h
Heat Input (Hi)kW
(Net) Btu/h
Heat Output (Hs condensing) kW
(50°C/30°C) Btu/h
Heat Output (Hi non-condensing) kW
(80°C/60°C) Btu/h
Differential Burner mbar
Pressure in wg
Room sealed
chamber panel
fitted
Gas Rate m³/h
ft³/h
MAX.
13.8
47 000
12.4
42 300
13.1
44 700
12.1
41 300
1.7
0.68
1.31
46.2
21 100
19 100
20 100
18 400
Alpha CD24R
Central Heating
Heat Input (H
)kW
s
(Gross) Btu/h
Heat Input (Hi)kW
(Net) Btu/h
Heat Output (Hs condensing) kW
(50°C/30°C) Btu/h
Heat Output (Hi non-condensing) kW
(80°C/60°C) Btu/h
Differential Burner mbar
Pressure in wg
Room sealed
chamber panel
fitted
Gas Rate m³/h
ft³/h
MAX.
26.6
90 700
24
81 900
25.6
87 300
23.5
80 200
5.6
2.24
2.54
89.7
25 600
23 200
24 600
22 200
MIN.
6.2
5.6
5.9
5.4
0.4
0.16
0.6
21.2
MIN.
7.5
6.8
7.2
6.5
0.6
0.24
0.72
25.4
Alpha CD18R
Central Heating
Heat Input (H
)kW
s
(Gross) Btu/h
Heat Input (Hi)kW
(Net) Btu/h
Heat Output (Hs condensing) k W
(50°C/30°C) Btu/h
Heat Output (Hi non-condensing) kW
(80°C/60°C) Btu/h
Differential Burner mbar
Pressure in wg
Room sealed
chamber panel
fitted
Gas Rate m³/h
ft³/h
MAX.
20.4
69 600
18.4
62 800
19.6
66 800
18.0
61 400
3.54
1.42
1.94
68.5
21 100
19 100
20 100
18 400
MIN.
6.2
5.6
5.9
5.4
0.4
0.16
0.6
21.2
2.2 SEALED SYSTEM
Note: When installed using a sealed heating system, a sealed system kit must be fitted.
Central Heating (Sealed System)
Max. Working System Pressure
Min. System Pressure
Max. System temperature
Pressure Relief Valve Setting
Expansion Vessel Size (pre-charge press.)
Flow Connection
Return Connection
Relief Valve Connection
Recommended System Pressure (cold)
CH Water Temp. (Approx. max.)
2.3 COMPONENTS
Burner
Main Heat exchanger
Main Burner Injector CD13R/18R
CD24R
Flue - Outer Duct
Flue - Inner Duct
2.5 bar
0.5 bar
82°C
3 bar (44 PSI)
8 L at 1.0 bar
22 mm
22 mm
15 mm
1.0 bar
80°C (176°F)
Stainless steel
Stainless steel
5.1 mm
5.25 mm
White
Plastic
Note: Refer to Fig. 5 when using with a fully
pumped open vented system.
2.4 ELECTRICAL
Supply
External Fuse
Power Consumption
Internal Fuse
Electrode Spark Gap
230/240 V ~ 50 Hz
3 A
55 W
F2 A
3 - 4 mm
Alpha CD13R, 18R, 24R - Technical Data
3
2.5 INSTALLATION
2.6 GENERAL
Min. Clearances for Servicing Top
(from casing) Bottom
Sides
Front
Flue Terminal Size
Flue Terminal Protruding
Hole Size Required For Flue Assy.
Lift Weight CD13R/18R
CD24R
235 mm
100 mm
5 mm
450 mm
100 mm Dia.
100 mm
110 mm Dia.
27 kg
28 kg
Case Dimensions Height
Width
Depth
Gas Connection CD13R/18R
CD24R
Primary Water Content
Air Duct Diameter
Flue Duct Diameter
600 mm
390 mm
305 mm
15 mm
22 mm
1.6 L
100 mm
60 mm
2.7 FLUE LENGTHS
CD Easy-Flue 500 mm with terminal and 90° bend. A CD Easy-Flue 1000 mm with terminal and 90° bend is also available.
CD 750 mm and CD 1000 mm flue extensions are available.
Length of Flue Required:-
Rear Flue (includes terminal) = wall thickness + 170 mm (or 140 mm for CD24R)
Side Flue (includes terminal) = wall thickness + distance between wall and side of boiler + 200 mm
Vertical Flue = distance from top of boiler side panel to required roof position minus 1 m for vertical terminal assembly
Maximum horizontal flue length = 12 m.
Maximum vertical flue length including terminal is 15 m.
Each additional CD 90° Bend is equivalent to 1.3 m of flue length.
Each CD 45° Bend is equivalent to 0.9 m of flue length.
The CD Vertical Flue terminal assembly is equivalent to 1 m of flue length.
2.8 PRESSURE LOSS ACROSS BOILER
2.5
2.0
Pressure loss
(metres head of water)
1.5
1.0
0.5
0
0 200 300100 400 500 600 700 800 900 1000
Flow rate (litres/hr)
2.9 ELECTRICAL CONNECTIONS
Note: This Appliance Must Be Earthed
An optional integral two channel Clock kit (Part No. 6.1000220) is available if required.
Note: Only use the Alpha two channel clock. Do not fit any single channel clocks.
Fuse - Always fit fast blow 2 A
Live (Brown wire)
Neutral (Blue wire)
Earth (Green/Yellow wire)
Switched Live
230/240 V (Ch1 ON)
Ch1 OFF
Ch2 ON
Live (Brown wire)
Neutral (Blue wire)
Earth (Green/Yellow wire)
Fig. 1
Use only when internal
clock is fitted
Boiler terminal block
White
Grey
Black
Blue
wire
wire
wire
Internal 2 Channel Clock Terminals
wire
Brown
wire
12345
WARNING
1. Ensure wires are connected
correctly
2. Only fit the Alpha recommended
2 channel clock. Other clocks
could cause damage.
Clock connections
F2A
L
N
1
2
3
4
L
N
230/240 V ~ 50 Hz
Fuse supply 3 A
Note: To connect external
control, remove link from
terminals 1 and 2 and
connect a 230/240 V
switched live to terminal 1
External Pump
20°C System design
temperature difference
Note: The pump must
always be connected
to this terminal block
Alpha CD13R, 18R, 24R - Technical Data
4
2.10 BOILER SCHEMATIC
12
10
Primary
Heating
return
2
8
Primary
Heating
flow
5
15
1
+
-
11
13
14
16
9
7
-
17
18
6
+
3
19
4
20
Gas Condensate
discharge
1 - Flue sampling point
2 - Flue thermostat
3 - Injector
4 - Gas valve
5 - Primary return temperature sensor
6 - Venturi
7 - Main burner
8 - Primary/condensing heat exchanger
9 - Room sealed chamber
10 - Fan
11 - Pressure differential test points
21
12 - Flue hood
13 - Overheat thermostat
14 - Primary flow temperature sensor
15 - Drain point
16 - Ignition electrodes
17 - Flame sensing electrode
18 - Venturi negative point
19 - Venturi positive point
20 - Gas service cock
21 - Condensate trap
Fig. 2
Alpha CD13R, 18R, 24R - Technical Data
5
3 GENERAL BOILER INFORMATION
3.1 GAS SUPPLY
The CD13R boiler requires a gas rate of 1.31 m³/h (46.2 ft³/h).
The CD18R boiler requires a gas rate of 1.94 m³/h (68.5 ft³/h).
The CD24R boiler requires a gas rate of 2.54 m³/h (89.7 ft³/h).
The meter and supply pipes must be capable of delivering this quantity of gas in addition to the demand from any other
appliances in the house. The CD13R and CD18R require at least a 15 mm gas supply pipe and the CD24R requires a 22 mm
gas supply pipe.
The complete installation, including the meter, must be tested for gas soundness and purged as described in BS 6891.
3.2 ELECTRICAL SUPPLY
The boiler requires a 230/240 V ~ 50 Hz mains supply, fused at 3 A
The boiler must be earthed.
There must only be one common isolator, providing complete electrical isolation, for the boiler and any external controls.
This boiler has been fitted with a supply cable, however, if it is necessary to fit a cable use PVC insulated cable not less than
0.75 mm² (24 x 0.2 mm) to BS 6500 Table 16. The boiler should be connected to a fused three pin plug and unswitched
shuttered socket outlet (both complying with BS 1363), or a fused double pole switch with a contact separation of at least 3 mm
in both poles.
Wiring external to the boiler must be in accordance with the current IEE Wiring Regulations (BS 7671).
Note: If a room thermostat is fitted, it must be suitable for 230/240 V switching.
3.3 AIR SUPPLY
The boiler does not require any air vents for cooling in the room in which it is installed or when installed in a cupboard or
compartment. The minimum clearances for servicing must always be maintained.
Note: A cupboard or compartment used to enclose the boiler must be designed and constructed specifically for the purpose,
i.e. comply with the Building Regulations.
3.4 FLUE SYSTEM - Fig. 3
The flue system must be installed in accordance with BS 5440:1.
For horizontal flues ensure the flue assembly is horizontal and the inner duct is sloping downwards towards the boiler.
Flue components are available as follows:CD Easy-Flue 500 mm (includes 90° bend and terminal) - Part No. 6.2000510.
CD Easy-Flue 1000 mm (includes 90° bend and terminal) - Part No. 6.2001010.
CD 750 mm flue extension - Part No. 6.2000750.
CD 1000 mm flue extension - Part No. 6.2001050.
CD 90° bend - Part No. 6.2000590.
CD 45° bend - Part No. 6.2000545.
CD Vertical flue terminal assembly. Refer to the separate installation instructions supplied with the assembly.
The following methods determine the correct length of flue required.
For rear exit flue (including terminal) L = B + 170 mm (or 140 mm for CD24R)
For side exit flue (including terminal) L = B + C + 200 mm (min. side clearance required is 5 mm)
For vertical flue L = H minus 1000 mm for vertical terminal assembly
Where L = Required flue length
B = Finished wall thickness
C = Distance from the inside wall to the side of the boiler
H = Distance from top of boiler side panel to roof position
Note: 1. If an extra 90° bend is used, this reduces the maximum flue length by 1.3 m. Each 45° bend used reduces the maximum
flue length by 0.9 m.
2. Under no circumstances must the flue length (including allowances for extra bends) exceed 12 metres horizontally and
only 15 metres vertically.
3. Failure to use Alpha CD flue components with the boiler will invalidate the boilers CE approval, guarantee and may be
unsafe.
4. Further Plume management flue accessories are available - Refer to the Easy-Flue installation instructions.
Alpha CD13R, 18R, 24R - General Boiler Information
6
HORIZONTAL FLUE OPTIONS - Lmax = 12 metres
L = B + C + 200 mm
C
B
B
F
E
L = B + E + F + 200 mm + (90° bend = 1.3 metre)
L = B + C + E + 200 mm
C
B
E
C
B
VERTICAL FLUE OPTIONS
Not less than
300 mm
H
L = B + C + 200 mm + (2 x 45° bends = 1.8 metre)
Not less than
300 mm
Not less than
300 mm
Not less than
300 mm
H
Hmax=15m
Hmax = 13.2 m
Fig. 3
Alpha CD13R, 18R, 24R - General Boiler Information
7
3.5 FLUE TERMINAL LOCATION - Fig. 4
Fig. 4
Notes: 1.In addition, the terminal should not be nearer
Min. distance (mm)Terminal position
A Directly below an opening, air brick, windows, etc.
B Below gutters, soil pipes or drain pipes
C Below eaves
D Below balconies
E From a vertical drain pipe or soil pipe
F From an internal or external corner
G Above ground, roof or balcony level
H From a surface facing the terminal
I From a terminal facing the terminal
J Above an opening, air brick, window etc.
K Vertically from a terminal on the same wall
L Horizontally from a terminal on the same wall
M Horizontally from an opening, air brick, window etc.
300 (See Note 1)
75 (See Note 3)
200 (See Note 3)
200 (See Note 3)
150 (See Note 3)
300 (See Note 2)
300
600 (See Note 4 & 5)
1200 mm
300 (See Note 1)
1500 mm
300 mm
300 mm (See Note 1)
Note: A terminal must not be sited under a car port roof
Note: In certain weather conditions the terminal will emit a plume of steam. If possible avoid positioning the terminal where this may cause
a nuisance, i.e. positions A, D, G, H, J or M.
The flue terminal must be exposed to the external air and the position must allow the free passage of air across it at all times.
If the terminal is fitted within 850 mm of a plastic or painted gutter or 450 mm of painted eaves, an aluminium shield at least 1 m
long should be fitted to the underside of the gutter or painted surface. A terminal must not be sited below 2 m where people
have access to, such as public footpaths, access routes, patios etc. However, If the terminal is fitted less than 2 m above a
surface where there is no public access, the terminal must be protected by a terminal guard.
A suitable guard is available from Alpha Therm Ltd.
For further information refer to BS 5440 Pt1:2008.
than 150 mm to the framework of an
opening into the buiding, i.e. a window
surround or door surround.
2.This clearance may be reduced to 25 mm
without effecting the performance of the
boiler. However, to ensure the condensate
plume does not affect adjacent surfaces a
clearance of 300 mm is preferable.
3.These clearances may be reduced to 25 mm
without effecting the performance of the
boiler. However, to ensure the condensate
plume does not affect adjacent surfaces the
terminal should be extended beyond gutters,
pipes, eaves, balconies etc.
4.It is recommended the terminal should not
be less than 2000 mm from boundary walls,
fences etc. if the plume is likely to cause a
nuisance.
5.This distance may be reduced to 300 mm if
terminal is not facing the boundary.
3.6 BOILER LOCATION
The boiler is not suitable for external installation, unless it is installed within a purpose designed weatherproof building.
The boiler must be installed on a flat vertical wall which is capable of supporting the weight of the boiler. The boiler can be fitted
to or adjacent to a wall comprising of a combustible material without the need for a special thermal insulation barrier.
If the boiler is to be fitted in a timber framed building, it should be fitted in accordance with the Institute of Gas Engineers 'Guide
for Gas Installations in Timber Frame Housing', reference IGE/UP/7.
The boiler may be installed in any room or internal space, although particular attention is drawn to the requirements of the
current IEE Wiring (BS7671) Regulations, and in Scotland, 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. Where a roomsealed boiler is installed in a room containing a bath or shower, it must not be possible for a person using the bath or shower
to touch any electrical switch or boiler control utilising mains electricity.
The boiler may be installed in a cupboard or compartment, provided it is correctly designed for that purpose, i.e. complies with
the Building Regulations and the requirements of BS 6798.
Alpha CD13R, 18R, 24R - General Boiler Information
8
3.7 CENTRAL HEATING SYSTEM - Fig. 5 and 5a
The boiler is designed for use in an open or (if the alpha sealed system kit is used) sealed central heating system in accordance
with the requirements of BS 5449 and BS 6798.
Vent (22mm min)
Cold feed
(15mm min)
150mm max
Pump
Boiler
Mid position
3-port valve
Automatic
by-pass valve
Fig. 5 - Open system with Y-Plan
Make-up
vessel
Manual air vents
450mm min height
Feed and
expansion tank
1000mm min height
DHW storage
cylinder
Balancing
valve
Above highest
point of system
Double
Pump
Boiler
Mid position
3-port valve
Automatic
by-pass valve
check valve
Pressure
gauge
Expansion
vessel
Balancing
valve
Filling point
Discharge
pipe
DHW storage
cylinder
Fig. 5a - Sealed system with Y-Plan
3.8 FILLING THE OPEN VENTED CENTRAL HEATING SYSTEM
A minimum head of 1 m is required between the boiler/pump and the feed and expansion tank.
The boiler must be supplied from an unrestricted water supply taken from a feed and expansion cistern situated at a maximum
height of 27 m above the boiler.
The cold feed must be 15 mm minimum size. The vent should be 22 mm in size, rise continuously and be unrestricted.
It is important that the relative positions of the pump, cold feed and open vents are as shown in Fig. 5.
The domestict hot water cylinder must be of the fully indirect coil type.
Alpha CD13R, 18R, 24R - General Boiler Information
9
3.9 FILLING THE SEALED CENTRAL HEATING SYSTEM - Figs. 6, 7
The system design pressure (cold) should be set to 1.0 bar. This pressure is equivalent to a static head (see Fig. 5) of 10.2 metres of water.
Provision should be made to replace water lost from the system. This can be by manual or automatic means, as shown in Figs.
6 and 7. The position for connecting an automatic make-up vessel is indicated in Fig. 5a. A double check valve assembly must
be used, as shown in Fig. 7.
Filling of the system must be carried out in a manner approved by the local Water Undertaking. Where allowed, the system
may be filled via a temporary connection as shown in Fig. 6. After filling, always disconnect the flexible hose of the filling loop.
All fittings used in the system must be able to withstand pressures up to 3 bar.
Drain taps (to BS 2879) must be used to allow the system to be completely drained.
Mains
water
supply
Feed cistern to be
located above highest
point in the system
Heating circuit
return
Stop
valve
temporarily connected
Hose
unions
Filling loop
Double check
valve assembly
Test cock
Stop
valve
Mains
water
supply
Heating circuit
return
Double check
valve assembly
Test cock
Overflow
Stop
valve
Fig. 6 Fig. 7
3.10 FLUSHING THE HEATING SYSTEM
It is essential that the central heating system is thoroughly cleaned and flushed when fitting an Alpha CD boiler. Failure to do so
will invalidate the warranty.
The primary and condensing heat exchanger is constructed in stainless steel and therefore is compatible with most materials
used in a heating system.
If a cleaning agent and inhibitor are used, they must be applied in accordance with their manufacturers instructions. Only
products from Fernox and Sentinel are acceptable for use with the Alpha CD boilers. Further information can be obtained from
Fernox (Tel: 0179 9521133) or Sentinel (Tel: 0151 4209563).
The system should be flushed in accordance with BS 7593 and BS 5449. The following procedures are recommended:
1. Installing onto a new system:a.Fill the system, vent at high points, at pump and radiators.
b.Check for leaks.
c.Rapidly drain the system.
d.If required, chemically clean the system as instructed by the recommended cleaner manufacturer.
Note: Ensure that the system is flushed to remove any remains of the cleaner.
e.If chemical cleaner is not used to clean the system:-
i) Refill the system.
ii) Switch on the boiler and allow the system to heat up to the normal operating temperature.
iii) Rapidly drain the system while the water is still hot.
iv) Refill the system.
f. As required, add the recommended inhibitor to the system as instructed by the inhibitor manufacturer.
g.Recheck for leaks.
2. Installing onto an existing system, clean the system before fitting the new boiler:a.If the old boiler is still working:-
i) Switch on the boiler and allow the system to heat up to the normal operating temperature.
ii) Rapidly drain the system while the water is still hot.
iii) Refill and chemically clean the system as instructed by the recommended cleaner manufacturer.
iv) Ensure the system is flushed to remove any remains of the cleaner.
v) Fit the new boiler.
b.If the old boiler is not working:-
i) Rapidly drain the system.
ii) Remove the old boiler.
iii) Flush the system through.
iv) Fit the new boiler.
v) Refill and chemically clean the system as instructed by the recommended cleaner manufacturer.
vi) Ensure the system is flushed to remove any remains of the cleaner.
c.As required, add the recommended inhibitor to the system as instructed by the inhibitor manufacturer.
d.Check for leaks.
Alpha CD13R, 18R, 24R - General Boiler Information
10
3.11 DISPOSAL OF CONDENSATE
Provision must be made for the safe disposal of condensate produced by the flue gases of the Alpha CD boilers and reference
should be made to BS 6798: 2000 for the requirements on the disposal of condensate.
The boilers incorporate a condensate trap which has a seal of 75 mm, therefore no additional trap is required.
The condensate should ideally be discharged internally into an internal waste pipe (washing machine/sink waste) or soil pipe to
avoid the possible risk of freezing. The pipework must be in 22 mm pipe.
External pipe runs should be avoided, but if it is necessary, the pipework should be protected from the risk of freezing with
waterproof insulation and the length should be kept to a maximum of 3 m. Alternatively the condensate pipework could be
increased to a minimum of 32 mm diameter without the requirement to insulate the pipework. Termination should be into an
external gulley or soakaway as shown in Figs. 8 and 9.
Note: All pipework must have a continuous fall (see Figs. 8 and 9) from the boiler and must be of an acid resistant material
such as plastic waste pipe. (copper or steel is not suitable).
It should be noted that the connection of a condensate pipe to a drain may be subject to local building control requirements.
Use waterproof
pipework insulation
Plastic pipe
in very exposed
positions
Ensure pipe is
adequately supported
Minimum gradient 2½°
Fig. 8 - External gully
Open end of pipe
divertedinto gully
below grid butabove
water level
Fig. 9 - External soakaway
Alpha CD13R, 18R, 24R - General Boiler Information
11
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