Alpha CD90S User guide

Installation and Servicing
Instructions
Alpha CD90S and 115S
Wall Mounted, Fan Assisted, Gas Fired, High Efficiency
Condensing System Boilers
For use with Natural Gas or Propane Gas (LPG)
Leave these instructions with the User
0051
Nepicar House, London Road,
Wrotham Heath, Sevenoaks,
Kent TN15 7RS
For Technical help or for Service call ...
ALPHA HELPLINE Tel: [phone]
website:www.alpha-innovation.co.uk

2Alpha CD90S/115S - Contents/Introduction
CONTENTS
1 Introduction ....................................... 2
2 Technical data ................................... 3
3 General boiler information .................. 7
4 Installation ......................................... 14
5 Commissioning ................................. 18
6 Routine servicing ............................... 23
7 Wiring diagram .................................. 27
8 Fault finding ...................................... 28
9 Short parts list ................................... 30
10 Benchmark Checklist ......................... 31
11 Service record ................................... 32
The Alpha CD90S and 115S are wall mounted high efficiency condensing, fan assisted system boilers. The burner is lit
electronically and the heat output is controlled by a modulating fan and gas valve.
These are system boilers providing heating only for sealed central heating systems. However, they may be used with an
open central heating system if required - refer to Section 3.8.
The boilers are supplied with type B23 flue configuration (open chamber and forced draught) but can be changed to type C
(room sealed) by using a conversion kit.
The boilers are fitted with a pump, 4 bar pressure relief valve and pressure gauge fully assembled and tested. They are
designed for use with a fully pumped, sealed and pressurised central heating system. If used with an open system refer
to Section 3.8.
The CD90S boiler is suitable for central heating loads of between 22.5 and 90 kW (85 985 and 307 092 Btu/h).
The CD115S boiler is suitable for central heating loads of between 28.8 and 109 kw (98 269 and 371 923 Btu/h).
The boilers can be supplied for use with Natural gas or Propane Gas (LPG).
Note: There are a number of additional controls and accessories available for use with the boilers to enable cascade and
zone installations to be used. Further information is available from Alpha Therm Ltd.
IMPORTANT
It is the law that all gas appliances are installed by a competent person, ie Gas Safe 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
UK Water Regulations/Byelaws (Scotland)
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 5295 Code of practice foe ventilation principles and designing for natural ventilation
BS 5854 Code of practice for flues and flue structures in buildings
BS 5978 Safety and performance of gas fired hot water boilers of rated inputs between 70 kW and 1.8 MW
BS 6644 Specification for installation of gas fired hot water boilers of rated inputs between 70 kW and 1.8 MW
BS 6700 Specification for design, installation, testing and maintenance of services supplying hot water for domestic use
within buildings and their curtilages.
BS 6981 Installation of low pressure gas pipework of up to 28 mm in domestic premises
BS 7074 Application selection and installation of expansion vessels and ancillary equipment for sealed water systems
Part 1 Code of practice for domestic heating and hot water
Part 2 Code of practice for low and medium temperature hot water system
BS 7593 Code of Practice for treatment of water in heating systems
BS 7671 Requirements for electrical installations, IEE Wiring Regulations
BS EN 12828 Design for water based heating systems
DOE Chimney heights, Third edition of the Clean Air Act Memorandum
IGE/UP/1 Soundness testing and purging of industrial and commercial gas installations
IGE/UP/1A Soundness testing and purging of small low pressure industrial and commercial natural gas installations
IGE/UP/4 Commissioning of gas fired plant on industrial and commercial premises
IGE/UP/10 Installation of gas appliances in industrial and commercial premises
Part 1 Flued appliances
IM/11 Flues for commercial and industrial gas fired boilers
Reference should be made to DEFRA document 'Guide to condensing boiler installation assessment procedures for dwellings'.
1 INTRODUCTION

3
2.1 PERFORMANCE
NATURAL GAS (CAT: I2H 2H - G20 - 20 mbar)
2 TECHNICAL DATA
Alpha CD90S/115S - Technical Data
Alpha CD90S
MAX.
92.8
316 634
90.0
307 080
97.8
333 700
88.4
301 621
5 900
8.9
297
MIN.
23.4
79 841
22.5
76 770
24.9
85 000
22.0
75 064
1 750
2.3
75
Central Heating
Heat Input (Hs)kW
(Gross) Btu/h
Heat Input (Hi)kW
(Net) Btu/h
Heat Output (Hscondensing) kW
(50°C/30°C) Btu/h
Heat Output (Hinon-condensing) kW
(80°C/60°C) Btu/h
Fan Speed rpm
Gas Rate m³/h
ft³/h
Alpha CD115S
Note: The above appliances are fully modulating and are not range rated.
MAX.
110.7
37 771
109.0
371 908
120.5
411 200
109.2
372 590
5 800
10.6
355
MIN.
29.4
100 313
28.8
98 256
32.6
111 200
29.0
98 948
1 750
2.8
94
Central Heating
Heat Input (Hs)kW
(Gross) Btu/h
Heat Input (Hi)kW
(Net) Btu/h
Heat Output (Hscondensing) kW
(50°C/30°C) Btu/h
Heat Output (Hinon-condensing) kW
(80°C/60°C) Btu/h
Fan Speed rpm
Gas Rate m³/h
ft³/h
PROPANE GAS (CAT I3P 3P - G31 - 37 mbar)
Alpha CD90S
MAX.
92.8
31 634
90.0
307 080
95.4
333 700
88.4
301 621
5 900
3.5
117
MIN.
23.4
79 841
22.5
76 770
24.3
85 000
22.0
75 064
1 750
0.9
30
Central Heating
Heat Input (Hs)kW
(Gross) Btu/h
Heat Input (Hi)kW
(Net) Btu/h
Heat Output (Hscondensing) kW
(50°C/30°C) Btu/h
Heat Output (Hinon-condensing) kW
(80°C/60°C) Btu/h
Fan Speed rpm
Gas Rate m³/h
ft³/h
Alpha CD115S
MAX.
110.7
37 771
109.0
371 908
120.5
411 200
109.2
372 590
5 700
4.2
14.0
MIN.
29.4
100 313
28.8
98 256
32.6
111 200
29.0
98 948
1 750
1.1
36.7
Central Heating
Heat Input (Hs)kW
(Gross) Btu/h
Heat Input (Hi)kW
(Net) Btu/h
Heat Output (Hscondensing) kW
(50°C/30°C) Btu/h
Heat Output (Hinon-condensing) kW
(80°C/60°C) Btu/h
Fan Speed rpm
Gas Rate m³/h
ft³/h
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 IPX5D, ie degree of protection against moisture.
This appliance contains no asbestos and no substances have been used in the construction process that contravene the
COSHH Regulations (Control of Substances Hazardous to Health).
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. It is the law that all boiler installations are registered by the installer through the Gas Safe Gas Work
Notification Scheme.
3. The boiler must only be used with the flue components supplied with the boiler.
Propane Gas (LPG) - In addition to the regulations and requirements stated, the boiler must be installed in accordance
with BS 5482:1 - The Installation of Propane Burning Appliances in Permanent Dwellings.

4
2.6 FLUE LENGTHS - See also Section 3.4
CH Max
9.30
9.45
1010 mm
600 mm
610 mm
3/4 "
1 "
9.5 L
11.0 L
Case Dimensions Height
Width
Depth
Gas Connection CD90S
CD115S
Water Content CD90S
CD115S
2.7 GENERAL
Min. Clearances for Servicing Top
(from casing) Bottom
Sides
Front
Flue Diameter Open Flue
Concentric Flue
Flue Protruding Outside Open Flue
Concentric Flue
Hole For Flue Assy. Open Flue
Concentric Flue
Lift Weight CD90S
CD115S
2.5 INSTALLATION
Burner
Main Heat Exchanger
Main Burner Injector CD90S NG
CD115S NG
CD90S LPG
CD115S LPG
Concentric Flue Outer Duct
Concentric Flue Inner Duct
Open Flue Single Flue Pipe
Stainless steel
Stainless steel
12.0 mm
14.0 mm
8.8 mm
10.8 mm
125 mm dia.
80 mm dia.
80 mm dia.
2.3 COMPONENTS
2.4 ELECTRICAL
Supply
External Fuse
Power Consumption CD90S
CD115S
Internal Fuse - Main Terminal
PCB Fuse F1
PCB Fuse F3
Electrode Spark Gap
Electrical Enclosure Degree of Moisture Protection
230/240 V ~ 50 Hz
3 A
370 W
390 W
F2A
T2A
T4A
3 to 4 mm
IPX5D
Alpha CD90S/115S - Technical Data
2.8 PERFORMANCE DATA
%CO2content (± 0.2%)
Natural Gas
Min
9.10
8.95
Boiler model
CD90S
CD115S
350 mm
350 mm
10 mm
450 mm
80 mm
125 mm
80 mm
125 mm
100 mm dia.
127 mm dia.
63 kg
68 kg
CH Max
10.7
10.7
(LPG) Propane Gas
Min
10.2
10.3
Central Heating (Sealed System)
Max. Working System Pressure
Min. System Pressure
Max. System temperature
Pressure Relief Valve Setting
Flow Connection
Return Connection
Relief Valve Connection
Recommended System Pressure (cold)
CH Water Temp. (Approx. max.)
3.5 bar
0.5 bar
85°C
4 bar (58.8 PSI)
1½" BSP
1½" BSP
¾" BSP
1.0 bar
85°C (185°F)
2.2 SYSTEM
Open Flue 80 mm single pipe - B23
Maximum Horizontal
Maximum Vertical
90° bend is equivalent to
45° bend is equivalent to
CD90S
17 m
17 m
2.1 m
1.3 m
CD115S
14 m
14 m
2.1 m
1.3 m
Concentric 80/125 mm room sealed
Maximum Horizontal
Maximum Vertical
90° bend is equivalent to
45° bend is equivalent to
CD90S
10 m
12 m
1.9 m
1.4 m
CD115S
7 m
8 m
1.9 m
1.4 m

5
2.9 AVAILABLE PUMP HEAD FOR CENTRAL HEATING
Alpha CD90S/115S - Technical Data
Fig. 1
2.10 ELECTRICAL CONNECTIONS
Note: This Appliance Must Be Earthed
Fig. 2
GJ MORHF E TS K VUY Z
X86
X85
LNNL
Fuse F2A
230V ~ 50Hz
Fused at 3A
External Pump
Max 1A
(Optional)
External sensor
(Optional)
Zone
manager
(Optional)
37
A
38
B
DHW
temp sensor
(Optional)
Diverter valve
motor
(Optional)
Summer switch
(Optional)
Analog
input
0 - 10 Volt
(Optional)
PQN
L
6
2
3
LINK
Room
thermostat
(Optional)
230/240 V ~ 50 Hz only Maximum 24 V connection only
Note: Do not connect 230/240 V ~ 50 Hz
BA
Total Head
(m water)
10
9
8
7
6
5
4
3
2
1
0
Flow Rate (l/h)
CD
11
A = CD90S - Available head with pump at maximum speed
B = CD90S - Available head with pump at speed two
C = CD115S - Available head with pump at maximum speed
D = CD115S - Available head with pump at speed two
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000

6
2.11 BOILER SCHEMATIC
Alpha CD90S/115S - Technical Data
1 Tundish
2 Pressure relief valve (4 bar)
3 Drain point
4 Primary pressure switch
5 Gas valve
6 Fan
7 Injector
8 Air inlet pipe
9 Ignition electrodes
10 Combustion chamber cover
11 Heat exchanger
12 Flue hood
13 Air inlet sampling point
14 Flue sampling point
Fig. 3
15 Automatic air vent
16 Primary flow temperature sensor
17 Primary return temperature sensor
18 Overheat thermostat
19 Flue overheat thermostat
20 Burner
21 Flame sensing electrode
22 Venturi
23 Venturi positive point (P2)
24 Pump
25 Condensate trap
1
2
3
4
5
6
7
8
9
10
11
12
13 14
15
16
17
18
19
20
21
22
23
24
25
Return
Gas
Flow
Condensate
discharge

7
Alpha CD90S/115S - General Boiler Information
3.1 GAS SUPPLY
Natural Gas:
The Alpha CD90S boiler requires a gas rate of 8.9 m³/h (297 ft³/h).
The Alpha CD115S boiler requires a gas rate of 10.6 m³/h (355 ft³/h).
Propane Gas (LPG):
The Alpha CD90S boiler requires a gas rate of 7.17 kg/h or 14 litres/h of liquid gas.
The Alpha CD115S boiler requires a gas rate of 8.76 kg/h or 17.2 litres/h of liquid gas.
The local Propane Gas supplier should be consulted, at the installation planning stage, in order to establish the
availability of an adequate supply of gas.
The meter and supply pipes must be capable of delivering this quantity of gas in addition to the demand from any other
appliances. The boiler requires at least a 35 mm gas supply pipe and ensure the inlet supply pressure is at least 20 mbar
for Natural Gas or 37 mbar for Propane Gas (LPG).
The complete installation, including the meter, must be tested for gas tightness 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
Note: 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).
3.3 AIR SUPPLY
Open flued (Type B23 flue)
Alpha CD90S and CD115S boilers leave the factory with 'B23' type configuration (open chamber and forced draught -
single flue pipe) and receive the air for combustion from openings in the rear of the boiler, therefore air supply for
combustion and ventilation must be provided in accordance with BS6644.
Note: Where a boiler installation is to operate in summer months (e.g. DHW) additional ventilation requirements are
required if operating more than 50% of the time (refer to BS 6644).
Room sealed (Type C flue)
If the boilers are converted to a 'C' type configuration (sealed chamber and forced draught - concentric flue pipe) as
described in Section 3.4 only air for ventilation is required.
A minimum of 2 cm² free area per kW of net heat input at both high and low level is required for boiler rooms. For
enclosures refer to BS 6644.
The minimum clearances for servicing must always be maintained.
3 GENERAL BOILER INFORMATION

8
3.4 FLUE SYSTEM
The flue system must be installed in accordance with BS 5854, BS 6644, IM/11.
For horizontal flues ensure the flue assembly slopes downwards towards the boiler by a minimum of 25 - 30 mm per
metre of flue.
It is recommended that horizontal and vertical flue assemblies should be supported approximately every 1.5 m with access
provided to the joints.
Alpha CD90S and CD115S boilers leave the factory with 'B23' type flue configuration (open chamber and forced draught -
single flue pipe). To change the configuration to 'C' type (sealed chamber and forced draught - concentric flue pipe),
remove the 80 mm dia. adapter, the bracket and gasket from the top of the boiler and fit the concentric flue adaptor, see
Section 4.5.
Note: 1. Under no circumstances must the flue length (including allowances for extra bends) exceed the maximum flue
lengths stated for each type of flue.
2. Failure to use the correct Alpha flue components with the boiler will invalidate the boilers CE approval, guarantee
and may be unsafe.
Seals for flue elements - If lubrication of components (already performed by the manufacturer) is not sufficient, remove
the residual lubricant using a dry cloth, then to ease fitting apply a small amount of common or industrial talc to the seal.
Ensure that the seals are correctly located in the elbows and extensions as shown in Fig. 4.
Alpha CD90S/115S - General Boiler Information
Fig. 4
Seal Seal
Flue components are available as follows:-
Open flue - 80 mm dia. single pipe
Horizontal terminal kit 80 mm dia. (includes 1 m straight with terminal, one 90° bend and two collars)
Vertical terminal kit 80 mm dia.
Extension pipe 1 m x 80 mm dia.
90° bend 80 mm dia.
45° bend 80 mm dia.
Concentric flue - 80/125 mm dia.
Horizontal terminal kit 80/125 mm dia. (includes 1 m straight with terminal, one 90° bend, two collars and adaptor)
Vertical terminal kit 80/125 mm dia. (includes adaptor)
Extension kit 1 m x 80/125 mm dia.
90° bend 80/125 mm dia.
45° bend 80/125 mm dia.

9
3.4.1 Horizontal Flue Options
Alpha CD90S/115S - General Boiler Information
3.4.2 Vertical Flue Options
Open flue: 80 mm dia. single pipe
Hmax = 17 m (CD90S), 14 m (CD115S)
Concentric flue: 80/125 mm dia.
Hmax = 12 m (CD90S), 8 m (CD115S)
Open flue: 80 mm dia. single pipe
Hmax = 14.4 m (CD90S), 11.4 m (CD115S)
Concentric flue: 80/125 mm dia.
Hmax = 9.2 m (CD90S), 5.2 m (CD115S)
Open flue: 80 mm dia. single pipe Lmax = 17 m (CD90S), 14 m (CD115S)
90° bend is equivalent to 2.1 m of flue length
45° bend is equivalent to 1.3 m of flue length
Concentric flue: 80/125 mm dia. Lmax = 10 m (CD90S), 7 m (CD115S)
90° bend is equivalent to 1.9 m of flue length
45° bend is equivalent to 1.4 m of flue length
Open flue: 80 mm dia. single pipe
Lmax = 14.9 m (CD90S), 11.9 (CD115S)
Concentric flue: 80/125 mm dia.
Lmax = 8.1 m (CD90S), 5.1 m (CD115S) Open flue: 80 mm dia. single pipe
Lmax = 14.4 m (CD90S), 11.4 m (CD115S)
Concentric flue: 80/125 mm dia.
Lmax = 7.2 m (CD90S), 4.2 m (CD115S)
Fig. 5 - Horizontal flues
Fig. 6 - Vertical flues
Not less than
300 mm
H
Not less than
300 mm
Not less than
300 mm
H
Not less than
300 mm
L max L max
L max
L max

10 Alpha CD90S/115S - General Boiler Information
3.5 FLUE TERMINAL LOCATION - Fig. 7
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.
A terminal must not be sited below 2.1 m where people have access to, such as public footpaths, access routes, patios
etc. However, If the terminal is fitted less than 2.1 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.
Notes: 1. In addition, the terminal should not be nearer
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
can be extended beyond gutters, pipes, eaves,
balconies etc. by upto 500 mm. If the flue is
extended more than 500 mm outside, it should
be boxed and insulated.
4. To reduce the possibility of nuisance to
neighbouring buildings etc. it is
recommended the terminal shouild not be
less than 2500 mm from car parking spaces,
building boundary walls, fences etc.
Note: A terminal must not be sited under a car port roof
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 or boundary 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.
N Minimum protrusion through a roof
O From a vertical obstruction
P From an openable window
Q From an adjacent vertical terminal
Min. distance (mm)Terminal position
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)
1200 mm
300 (See Note 1)
1500 mm
300 mm
300 mm (See Note 1)
300 mm
300 mm
600 mm
600 mm
J
D
G
HI
Q
Boundary
OP
N
Fig. 7
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 room-
sealed 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 6644.

11
Alpha CD90S/115S - General Boiler Information
Propane Gas (LPG): Installation pipes, cylinders and pressure regulators should be fitted in accordance with BS 5482:1.
Bulk tank installation must comply with the requirements of the Home Office code of practice for the storage of liquefied
petroleum gas at fixed installations. The boiler must not be installed in a room or internal space below ground level, e.g.
in a basement or cellar, except where at least one side is open to ground level.
3.7 FROST PROTECTION
The boiler is fitted with a frost thermostat that activates the pump and burner when the system water temperature in the
boiler falls below 3°C.
The electrical supply to the boiler must be left on for the thermostat to operate and the selector switch must be set to ON .
3.8 CENTRAL HEATING SYSTEM - Fig. 8
The boiler is designed for use in a sealed central heating system in accordance with the requirements of BS 5449 and BS 6798.
The system should be designed to operate with flow temperatures of up to 85°C. When designing the system, the pump head,
expansion vessel size, mean radiator temperature, etc. must all be taken into account. Refer to the pump performance graph
for guidelines (see Fig. 1).
To ensure the boiler heat exchanger is protected from contamination, we strongly recommend the use of a barrier heat
exchanger when installing these boilers. Barrier heat exchangers are available from Alpha Therm Ltd..
If the boiler is to be used with an open central heating system refer to Fig. 8 and use a barrier heat exchanger (i.e. separates
the boiler primary circuit from the open heating circuit).
Sealed system volume - An expansion vessel is not incorporated into the boiler. An expansion vessel must be fitted in
the position shown in Fig. 8. To check correct operation of the expansion vessel the system pressure should not be more
than 3.5 bar when the system is at maximum operating temperature (for further guidance refer to BS 7074:1), For
example an 8 litre expansion vessel is suitable for a sealed system of 80 litres.
The boiler is supplied with the following components built in:-
Pressure relief valve - complying with BS 6759 and set to operate at 4 bar. The discharge pipe must be routed clear of
the boiler and terminated in such a manner that it can be seen, but cannot cause injury to persons or property.
Pressure gauge - To indicate the system pressure to be maintained.
By-pass - The boiler has no built-in by-pass, therefore an automatic by-pass is required for the system.
Fig. 8
Installation on a low temperature heating system.
The boiler can directly feed a low temperature system, varying the maximum delivery temperature of the boiler and
setting a value of between 20 and 85°C. To vary the boiler maximum delivery temperature, modify the boiler maximum
delivery temperature of parameter No. 4 as described in Section 5.7 and Table 3.
In this mode it is advisable to include a safety limit thermostat set at 55°C in series with the boiler circulating pump. The
thermostat must be positioned in the system flow pipe at more than 2 metres from the boiler.
Make up vessel
(sealed system only)
Automatic
air vent
Expansion vessel
(sealed system only)
Double check valve assy.
(sealed system only)
Filling point
(sealed system only)
Static head of system
Heating return
System
drain tap
Heating flow
Note: A drain tap should be installed at the lowest
point of the heating circuit and beneath the appliance.
Boiler
Heating return
Fit pump if Barrier
heat exchanger used
Heating flow
Barrier heat exchanger used on
open or old/dirty systems
Return
Flow
Flow
Return
Drain
tap

12 Alpha CD90S/115S - General Boiler Information
3.9 FILLING THE SEALED CENTRAL HEATING SYSTEM - Figs. 9
The system design pressure (cold) should be set to 1.0 bar. This pressure is equivalent to a static head (see Fig. 8) 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
Fig. 9. The position for connecting an automatic make-up vessel is indicated in Fig. 8. A double check valve assembly
must be used.
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. 9. 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 4 bar.
Drain taps (to BS 2879) must be used to allow the system to be completely drained.
3.10 FLUSHING THE HEATING SYSTEM
It is essential that the central heating system is thoroughly cleaned and flushed when fitting an Alpha CD50S or CD70S
boiler. Failure to do so will invalidate the warranty. If this is difficult because the system is old/dirty refer to Section 3.8,
Fig. 8 gives consideration to using a barrier heat exchanger.
The primary 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 CD90S or CD115S boilers. Further information
can be obtained from Fernox (Tel: [phone]) or Sentinel (Tel: [phone]).
The system should be flushed in accordance with BS 7593 . 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.
Fig. 9
Filling loop
temporarily connected
Heating circuit
return Mains
water
supply
Stop
valve
Hose
unions
Stop
valve
Double check
valve assembly
Test cock

13
Alpha CD90S/115S - General Boiler Information
3.11 DISPOSAL OF CONDENSATE
Provision must be made for the safe disposal of condensate produced by the flue gases of the Alpha CD90S or CD115S
boilers and reference should be made to BS 6644 for the requirements on the disposal of condensate.
The boilers incorporate a condensate trap, therefore no additional trap is required.
The condensate should ideally be discharged internally into an internal waste pipe 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 at least 32 mm and protected from
the risk of freezing with a waterproof insulation and the length should be kept to a maximum of 3 m. Termination should
be into an external gulley or soakaway as shown in Figs. 10 and 11.
Note: All pipework must have a continuous fall (see Figs. 10 and 11) 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.
Fig. 11 - External soakaway
Ground level (either/or)
22mm termination
from boiler
2½ fall
O
25mm
300mm
Two rows of 3 x 12mm
holes at 25mm centres,
50mm from the bottom
of the tube. Holes to face
away from house.
Cement mortar
sealing
100mm plastic tube
Bottom of tube sealed
Soakaway depth 400mm
filled with limestone chippings
500 mm min.
Fig. 10 - External gully
Open end of pipe
diverted into gully
below grid but above
water level
Use waterproof
pipework insulation
in very exposed
positions
Ensure pipe is
adequately supported
Plastic pipe
Minimum gradient 2½°

14 Alpha CD90S/115S - Installation
4.1 UNPACKING
1. The basic boiler is supplied in a single box, containing the following:-
Cased boiler with:-
Mounting hooks and wall plugs
Tundish for pressure relief valve outlet
Condensate discharge pipe
Gas service cock - 3/4" BSP (CD90S) or 1" BSP (CD115S)
Literature pack and Wall template
Other parts of the flue system are supplied in separate packs as ordered.
2. Unpack boiler and remove the loose items.
4.2 DIMENSIONS and CONNECTIONS- Fig. 12
4 INSTALLATION
Fig. 12
4.3 PREPARE THE WALL - Fig. 13
1. Decide upon the position of the boiler taking into account the clearances
required for servicing (refer to Section 2.5) and the flue terminal position.
2. Tape the template to the wall (ensure it is level and the right way up).
Mark the position of the two holes for the boiler mounting hooks, and
the centres of the flow, return, gas and discharge connections.
3. Drill the fixing holes (12 mm dia.) to accept the No.12 plugs supplied.
Screw the boiler mounting hooks fully into the plugs.
4. Cut suitable holes in the wall/roof 100 mm dia for open flue 80 mm dia.
pipe or 127 mm dia. for concentric flue. Use the centre line positions
given on the flue template.
5. Lift the boiler and locate it on the mounting hooks.
Note: When handling or lifting always use safe techniques - keep your
back straight, bend your knees, don't twist - move your feet, avoid bending
forwards and sideways and keep the load as close to your body as
possible.
Where possible transport the boiler using a sack truck or other suitable
trolley.
Always grip the boiler firmly, and before lifting feel where the weight is
concentrated to establish the centre of gravity, repositioning yourself as
necessary.
Centre line for
vertical flues
Centre line
for horizontal
concentric flue
Centre line
for horizontal
open flue
Alpha
HEATING
FLOW
(11/2" BSP)
BOTTOM OF CASING
MINIMUM SIDE
CLEARANCE 10 mm
TOP OF CASING
WITH COVER
BOILER MOUNTING
HOOK FIXING HOLE
MINIMUM TOP CLEARANCE 350 mm
BOILER MOUNTING
HOOK FIXING HOLE
MINIMUM SIDE
CLEARANCE 10 mm
SAFETY
VALVE
(3/4" BSP)
GAS
(28 mm)
HEATING
RETURN
(11/2" BSP)
MINIMUM BOTTOM CLEARANCE 250 mm
WITHOUT HYDRAULIC OPTIONAL KIT
FOR USE WITH ALPHA CD50 - 70S
200 mm
170 mm
Fig. 13
Heating flow B
Heating return B
Gas D
D
Pressure relief valve discharge C A
B
C
300 300
140
80 Dia.
1086
1010
982
905
495
600
300
445
170 134
253
315
340
610
Condensate drain A
105

15
Alpha CD90S/115S - Installation
4.4 CONNECT THE PIPEWORK - Fig. 12
1. Thoroughly flush out all the water pipework. Refer to Section 3.10.
2. Connect the system flow and return pipework to the boiler using suitable
isolating valves.
Note: Do not forget that the pressure relief valve discharge pipe must be
routed clear of the boiler to a drain in such a manner that it may be seen, but
cannot cause injury to persons or property.
3. Connect the 22 mm condensate trap drain pipe to the condensate discharge
pipe using the clip supplied.
Ensure that the condensate discharge pipe is as required in Section 3.11.
Pour at least 0.5 litre of water into the flue duct, as shown in Fig. 14, and
check the condensate discharge pipe for soundness
4. Ensure that all the valves are closed and do not turn on the water or gas supplies at
this stage.
4.5 'B23' TYPE SINGLE PIPE 80 mm FLUE KITS
Vertical kit - see Figs. 15 and 16, and refer to Section 3.4.
Fig. 17 shows the vertical flue kit parts.
To assemble the kit to the boiler - Slide the flue pipe down through the roof seal and place the seal over the flue duct. Push
the flue duct into the flue socket on top of the boiler up to the stop. Ensure the seal is pushed in position against the ceiling.
The maximum vertical length (without bends) for flue pipe is 17 m (CD90S) or 14 m (CD115S) (see Figs. 15 and 16).
To install extensions or other flue components, proceed as follows: fit the male end of the pipe or elbow up to the stop on
the female socket (with lip seals) of the previously installed component, this will ensure a secure fit and seal of the joints.
Ensure all joints have the seal located correctly and the tape supplied is applied around each joint to ensure the flue
ducts cannot be pulled apart.
It is recommended that the flue should be supported approximately every 1.5 m with access provided to the joints.
Fig. 15 Fig. 16
Horizontal through the wall kit - see Figs. 17 and 18, and refer to Section 3.4.
Fig. 17 shows the horizontal through the wall kit parts.
To assemble the kit to the boiler - Fit the male end of the flue elbow into central flue outlet on the top of the boiler to the stop.
Place the outer seal over the flue duct and slide it throught the wall from the outside. Place the inner seal over the flue duct
then insert the duct into the elbow up to the stop. Slide the seals along the duct to seal it to the inside and outside of the wall.
To install extensions or other flue components, proceed as follows: fit the male end (smooth) of the pipe or elbow up to
the stop on the female socket (with lip seals) of the previously installed component, this will ensure a secure fit and seal
of the joints.
Extensions for flue kit - The maximum vertical/horizontal straight length (without flue bend) is 17 m (CD90S) or 14 m (CD115S)
(refer to Section 3.4).
Note: To prevent condensate lying in the flue pipe, slope the pipe towards the boilers with a minimum slope of 2.5° - 3°
(25 - 30 mm per metre). When installing the extensions, a wall/ceiling mounted clamp must be installed every 1.5 metres.
Fig. 14
Maximum length
17 m (CD90S)
14 m (CD115S)
430 mm
minimum
Seal
Flue pipe
Seal
Ver tical terminal

16 Alpha CD90S/115S - Installation
4.6 'C' TYPE CONCENTRIC FLUE KITS
Convert the boiler from the factory supplied 'B23' type configuration to 'C' type, i.e. room sealed concentric flue by
removing the 80 mm dia. adaptor and four screws securing the fixing plate and gasket from the top of the boiler.
Horizontal through the wall concentric flue kit - see Figs. 19 and 20.
Fig. 19 shows the flue kit parts that need to be fitted to
the boiler to ensure the room sealed concentric flue
can be used.
To assemble the kit to the boiler - Fit the adapter into
the central flue outlet on the top of the boiler up to the
stop. Slide the square gasket over the adapter up to
the groove, then fix it to the cover by means of the
previously removed fixing plate and four screws. Fit the
male end of the flue elbow up to the stop on the
adapter. Place the outer seal over the concentric flue
pipe and slide it throught the wall from the outside.
Place the inner seal over the concentric flue pipe then
insert the pipe into the elbow up to the stop. Slide the
seals along the duct to seal it to the inside and outside
of the wall.
To install extensions or other flue components,
proceed as follows: fit the male end (smooth) of the
concentric pipe or concentric elbow up to the stop on
the female socket (with lip seals) of the previously
installed component, this will ensure a secure fit and seal of the joints.
Extensions for horizontal kit - The horizontal kit can be extended up to a maximum horizontal distance of 10 m (CD90S)
or 14 m (CD115S) (Fig. 20), including the flue terminal and excluding the flue bend on the boiler (refer to Section 3.4).
Note: To prevent condensate lying in the flue pipe, slope the pipe towards the boilers with a minimum slope of 3° (25 - 30 mm
per metre). When installing the extensions, a wall/ceiling mounted clamp must be installed every 1.5 metres.
Fig. 20
Fig. 19
Fig. 17 Fig. 18
Flue elbow
Flue pipe Inner seal
Outer seal
160 mm
100 mm
80 mm
Note: Ensure the flue slopes downwards towards
the boiler by a minimum of 25 to 30 mm per metre (2.5° to 3°)
Flue elbow
Fixing plate
Square gasket
Adaptor
Concentric flue pipe
Inner seal Outer seal
190 mm
136 mm 9820 mm (CD90S), 6820 mm (CD115S)
Maximum 10 m (CD90S), 7 m (CD115S)
180 mm
Inner seal
Outer seal
Note: Ensure the flue slopes downwards towards
the boiler by a minimum of 25 to 30 mm per metre (2.5° - 3°)

17
Alpha CD90S/115S - Installation
4.7 CONNECT THE MAINS SUPPLY - Fig. 2
1. Remove the four screws securing the plastic top cover so that it can be lifted slightly at the front edge.
2. Remove the two fixing screws (one each side at the bottom) securing the case front panel (refer to Fig. 23). Pull the bottom
of the panel outwards while pushing up at the same time and remove the panel then remove the two screws securing the
control panel and lower the panel to gain access to the terminal block. Refer to Technical Data, Section 2.10 for
connection details.
3. Note: This boiler has been fitted with a mains supply cable. However, if it is necessary to fit an alternative supply cable,
ensure the cable clamp that has been fitted is removed and connect as follows:-
Pass the mains supply cable through the cable clamp and connect as follows:- Brown to L, Blue to N and Green/Yellow
to . Ensure correct polarity.
Note: Ensure that the length of the earth wire is such that if the supply cable is pulled out of its clamp the live and
neutral wires become taut before the earth wire.
Do not switch on the electrical supply at this stage.
4. If any external control, i.e. room thermostat etc. is to be fitted, refer to Fig. 2.
Note: All external control connections are less than 24 volts.
Do not connect 230/240 volts to any of the terminals G to Z on the X86 terminal block or to the X84 terminal block.
5. Ensure that there is sufficient free cable to allow the control panel to be raised and lowered then tighten the cable clamp
screws.
6. Leave the control panel open until commissioning procedures have been completed.
7. Carry out electrical system checks - Short circuit, Polarity, Earth continuity and Resistance to earth with a suitable
multimeter.

18 Alpha CD90S/115S - Commissioning
When commissioning the boiler, ensure the Benchmark Checklist is completed.
5.1 FILL THE SYSTEM
1. The boiler is fitted with an automatic air vent positioned as shown in Fig. 3, ensure that the vent is always open.
2. Open any central heating flow and return valves.
3. Open the fill point valve on the filling loop until water is heard to flow.
4. To remove the air - Vent each radiator in turn, starting with the lowest in the system.
5. It is important that the pump is properly vented to avoid it running dry and damaging its bearings. Unscrew and
remove the cap from the centre of the pump. Using a suitable screwdriver rotate the exposed spindle about half a
turn, then replace the cap.
6. Check the operation of the pressure relief valve (see Fig. 3) by turning the head anti-clockwise until it clicks. The
click is the valve lifting off its seat allowing water to escape from the system - check that this is actually happening.
7. Continue to fill the system until the pressure gauge indicates 1.0 bar. Close the fill point valve and check the system for
water soundness, rectifying where necessary. Disconnect the filling loop from the mains supply. If the system has been
over pressurised water may be released from the system by manually operating the drain point (see Fig. 3) until the
system design pressure is obtained. The system design pressure (cold) should be between 0.75 and 1.25 bar.
Refer to Sections 3.9 and 3.10. Filling and Flushing the system.
5.2 TEST FOR GAS TIGHTNESS AND PURGE THE SUPPLY
1. With the boiler gas service cock
closed. Pressure test the gas supply
and inlet pipework connection to the
boiler gas service cock for tightness
in accordance with BS 6891.
2. Loosen the gas inlet pressure test
point screw on the gas valve (see
Fig. 21). Ensure the gas supply is
on and open the boiler service cock
to purge in accordance with BS
6891.
3. Retighten the test point screw and
test for gas tightness. Close the
boiler gas service cock.
5 COMMISSIONING
Fig. 22
On/Off switch Pressure gaugeDisplay panel
ON
MODE STEP STORE
+
-
RESET
Alpha
5.3 BOILER CONTROLS - Fig. 22
Fig. 21
5.4 INITIAL LIGHTING - Refer to Fig. 22
1. Ensure that the gas and electrical supplies to the boiler are off and that any heating flow and return valves are open.
2. Turn on the gas and electrical supplies to the boiler.
3. Ensure any external controls are calling for heat.
4. Set the On/Off switch to ON. The boiler will now run in the central heating mode. The pump will start, the fan will start
and the main gas valve solenoid will open allowing the main burner to light.
Inlet gas
pressure
test point
Outlet gas
pressure
test point
Outlet flow
regulator
Off-set
adjustment
screw
P1
P3

19
Alpha CD90S/115S - Commissioning
5.5 BOILER DISPLAY PANEL AND FUNCTION MODES
The boiler display panel (see Fig. 22), is composed of a 4-character display and 6 keys. By using these keys it is possible
to adjust the boiler as it would be by using traditional selector switches and knobs.
Table 1 gives the function of each key.
When the boiler is operating, the 4-figure display indicates the mode code (by means of the first 2 figures on the left) and
the boiler flow temperature (by means of the other two figures on the right).
For example if these values are shown on the display it means that the boiler is operating in
heating mode with a flow temperature of 60°C.
The boiler function modes are given in Table 2:
Table 1
RESET
MODE
STEP
STORE
+
-
Manual reset for possible boiler block
Display menu selection key
Selection of parameter to be displayed or edited
Data and storage confirmation key
Increase set value
Decrease set value
03 60
Table 2
5.6 BOILER FUNCTIONING PARAMETERS
PARAMETER Mode - Press the MODE key once to enter Parameter mode. In this mode the preset operational values
can be changed. The first two figures indicate the parameter number, the last two give the setting value. To change the
boiler settings proceed as follows:
1. Press the MODE key once to enter parameter mode, using the STEP key select the parameter to be changed.
2. Change the value using the + or - keys, press the STORE key to store the new value.
3. Press MODE to make the new value effective.
Parameters that can be modified are given in Table 3.
Table 3
0
1
85°C
20°C
20°C
1
2
3
4
Description
Domestic hot water setting value *
Domestic hot water functioning mode
Heating function mode
Max. heating flow temperature
Lower limit value Upper limit value New value
20°C
0 = disabled
1 = enabled
2 = disabled + continuous pump
3 = enabled + continuous pump
0 = disabled
1 = enabled
2 = disabled + continuous pump
3 = enabled + continuous pump
70°C
85°C
Parameter Factory set
*Only active with hot water function enabled when external accessories are fitted.
Mode code
0
1
2
3
4
5
6
7
8
9 (flashing)
A
Mode description
Stand - by, no operation demand
Pre-ventilation
Burner ignition
Burner lit (system heating)
Burner lit (domestic hot water)
Fan check
Burner off, requested temperature reached
Pump over-run in system heating mode
Pump over-run in domestic hot water mode
Burner off for one of the reasons given in Table 8 in Section 8
3 - way valve check

20 Alpha CD90S/115S - Installation
Parameter 1: Allows domestic hot water temperature to be set if controlled with NTC probe.
Parameter 2: Allows domestic hot water production to be activated or cut out. With factory settings domestic hot water
production is cut out.
Parameter 3: Allows system heating function (Summer) to be cut out, or enabled (Winter). With factory settings system
heating is on.
Parameter 4: Allows heating flow temperature to be set. If the external temperature probe is connected to the boiler, the
electronics automatically determine the ideal system water temperature. This parameter represents the
maximum temperature that the system delivery water can reach.
INFO Mode - Press the MODE key twice to enter INFO mode. In this mode the instantaneous operational values can be
displayed and checked, but without making changes. The first two figures indicate the step number; the last two give the
setting value.
For example if these values are shown on the display it means that the boiler is operating in
heating mode with a return temperature of 40°C.
5.7 BOILER FUNCTIONING PARAMETERS
Tables 5 and 6 gives the boiler adjustment parameters with factory settings. To modify the parameters reserved for the
Installer, it is necessary to enter an access code, which can be supplied on request.
To enter the code:
1. Press the MODE and STEP keys at the same time for 2 seconds; the display will show the wording CODE and
subsequently a random number on the last two digits.
2. Change the value by operating the + or - keys until reaching the correct code.
3. Press the STORE key to confirm.
02 40
Table 4
Step
1
2
3
4
6
7, 8, 9
E
Visulisation
Flow temperature
Return temperature
Not active (Domestic temp., if domestic circuit probe is present)
Not active (External temp., if probe is installed)
Flow temperature set point
Temperature gradients (cannot be modified)
Flame current value
Value
Value in °C
Value in °C
-36 (value in °C)
-36 (value in °C)
Value in °C
°C/S
µA
Possible settings for the Installer and User (without entering an access code)
Table 5
Parameter
1
2
3
4
Description
Domestic hot water set point value
Domestic hot water functioning mode
Central heating functioning mode
Max, central heating flow temperature
Lower limit value
20°C
0 = disabled
1 = enabled
2 = disabled + continuous pump
3 = enabled + continuous pump
0 = disabled
1 = enabled
2 = disabled + continuous pump
3 = enabled + continuous pump
20°C
Upper limit value
70°C
85°C
Factory set
20°C
0
1
85°C
New value