Alpha CD12S Installation And Servicing Instructions
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Alpha CD12S Installation And Servicing Instructions

Range of wall mounted, fan assisted, room sealed, gas fired, high efficiency condensing system boilers
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Installation and Servicing

Alpha CD12S/20S/28S
Range of Wall Mounted, Fan Assisted, Room Sealed,
Gas Fired, High Efficiency Condensing System Boilers
0051
Instructions
For Technical help or for Service call ...
ALPHA HELPLINE Tel: 0844 8718764
website: www.alpha-innovation.co.uk
Nepicar House, London Road,
Wrotham Heath, Sevenoaks,
Kent TN15 7RS
British Gas
Alpha CD12S
Alpha CD20S
Alpha CD28S
For use with Natural Gas only
Leave these instructions with the User
Service Listed
G.C. No. 41 532 16
G.C. No. 41 532 18
G.C. No. 41 532 20

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Summary of Contents for Alpha CD12S

  • Page 1: Installation And Servicing

    Alpha CD12S/20S/28S Range of Wall Mounted, Fan Assisted, Room Sealed, Gas Fired, High Efficiency Condensing System Boilers For Technical help or for Service call ... ALPHA HELPLINE Tel: 0844 8718764 website: www.alpha-innovation.co.uk Nepicar House, London Road, Wrotham Heath, Sevenoaks, Kent TN15 7RS...

  • Page 2: Table Of Contents

    They are designed for use with a fully pumped, sealed and pressurised central heating system using only Natural gas. The CD12S boiler is suitable for central heating loads of between 2.4 and 12.8 kW (8 200 and 43 650 Btu/h).

  • Page 3: Technical Data

    18 420 Differential Burner mbar 0.25 Room sealed chamber panel Pressure in wg 2.52 0.10 fitted Gas Rate m³/h 3.04 ft³/h 107.3 21.2 Note: The above appliances are fully modulating and are not range rated. Alpha CD12S/20S/28S - Technical Data...

  • Page 4: Technical Data

    SAP efficiency NOx class CH Max band CD12S 90.1 CD20S 90.1 CD28S 90.1 Note: The differential burner pressure and the combustion performance value of %CO content have been factory preset and do not require adjusting. Alpha CD12S/20S/28S - Technical Data...
  • Page 5 Note: This Appliance Must Be Earthed An optional integral two channel Clock kit is available if required. Note: Only use an Alpha two channel clock. Do not fit any single channel clocks. Fuse - Always fit fast blow 2 A...

  • Page 6: Boiler Schematic

    Drain point Condensate trap Main burner Pressure relief valve Heat exchanger thermal fuse Primary/condensing heat exchanger Primary pressure switch Room sealed chamber Ignition electrodes Flame sensing electrode Pressure differential test points Venturi negative point Fig. 2 Alpha CD12S/20S/28S - Technical Data...

  • Page 7: General Boiler Information

    2. Under no circumstances must the flue length (including allowances for extra bends) exceed 12 metres horizontally and 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.
  • Page 8 L = B + C + 245 mm + (2 x 45° bends = 1.8 metre) VERTICAL FLUE OPTIONS Not less than 300 mm Not less than 300 mm Not less than 300 mm Not less than 300 mm Hmax = 15 m Hmax = 13.2 m Fig. 3 Alpha CD12S/20S/28S - General Boiler Information...
  • Page 9 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. Alpha CD12S/20S/28S - General Boiler Information...
  • Page 10 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 CD12S/20S/28S - General Boiler Information...
  • Page 11 Heating circuit water Feed cistern to be Stop return Stop supply located above highest valve valve Stop point in the system Test cock valve Test cock Filling loop temporarily connected Fig. 7 Fig. 8 Alpha CD12S/20S/28S - General Boiler Information...
  • Page 12 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 condensing heat exchanger is constructed in stainless steel and therefore is compatible with most materials used in a heating system.
  • Page 13 Two rows of 3 x 12mm holes at 25mm centres, 50mm from the bottom Soakaway depth 400mm of the tube. Holes to face filled with limestone chippings away from house. Fig. 10 - External soakaway Alpha CD12S/20S/28S - General Boiler Information...

  • Page 14: Installation

    140 mm, 185 mm if the wall jig is used (ensure the lines are horizontal). Template This will give the position of the centre of the hole for the flue. Fig. 12 Alpha CD12S/20S/28S - Installation...
  • Page 15 B - Gas inlet (22 mm) Heating flow C - Heating return (22 mm) valve D - Pressure relief valve (15 mm) Heating drain Condensate point discharge pipe Fig. 14a - Without wall jig Alpha CD12S/20S/28S - Installation...
  • Page 16 FIT THE FLUE - Figs. 15, 16 The following procedure applies to fitting an Alpha CD Easy-Flue to both rear or side exit flue - horizontally only. The CD Easy-Flues are suitable for use in the flue length ranges shown in the tables below.
  • Page 17 Note: Ensure that all cuts are square and free from burrs. Once assembled with the components pushed home, the flue is fully sealed. Allow 20 mm 30 mm Do not cut past this point Fig. 20 Alpha CD12S/20S/28S - Installation...
  • Page 18 Use the template (supplied with the boiler) to mark the required flue position, ensure the slope towards the boiler is correct. Determine the overall flue length as described in Section 4.6, paragraph 2 to determine the number of Alpha CD 750 or 1000 mm flue extensions required.
  • Page 19 Plume Management 45° bend 60 mm dia. (each 45° bend equivalent to 0.9 m flue length) Plume Management 1000 mm extension 60 mm dia. (equivalent to 1 m flue length) 60 mm dia. wall bracket Fig. 22 Alpha CD12S/20S/28S - Installation...
  • Page 20 Note: The equivalent horizontal flue assembly length + the equivalent plume management length (PM length) must not exceed the maximum flue length stated for each boiler, i.e. Alpha CD boiler maximum equivalent flue length must not exceed 12 metres. Alpha CD12S/20S/28S - Installation...
  • Page 21 Ensure the electrical supply to the boiler is isolated. IMPORTANT - Only use an Alpha two channel clock. Do not fit a single channel clock. Remove the two screws securing the clock cover at the rear of the control panel.

  • Page 22: Commissioning

    Set the selector switch to (CH). 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. Alpha CD12S/20S/28S - Commissioning...
  • Page 23 Section 8.2). It is recommended that a label is attached to the boiler drawing attention to the fact that the system has been drained. Complete the details of the installation in the Benchmark Checklist in Section 12. Alpha CD12S/20S/28S - Commissioning...
  • Page 24 12. Leave these Installation and Servicing instructions with the User for use on future calls. The boiler operating mode is controlled by the selector switch on the facia panel, when set to ON the boiler will provide central heating. Alpha CD12S/20S/28S - Commissioning...

  • Page 25: Boiler Operation

    A and B Flashing on and off alternatively - System pressure is very low and re-pressurisation is required. A Flashing and B Illuminated continuously - Pump fault or restricted flow. Note: Do not hold the selector switch in the reset position (3) for more than 2 to 3 seconds. Alpha CD12S/20S/28S - Boiler Operation...

  • Page 26: Routine Servicing

    2. The expansion vessel pressure test point is accessible from inside the boiler at the top. Check that the condensate trap drain pipe is connected and all joints are sound. Record details of the service in the Service Record in Section 12. Alpha CD12S/20S/28S - Routine Servicing...

  • Page 27: Component Replacement

    Note: Before removing the cap, ensure that the water released from the trap can be contained to avoid spillage. The trap will contain no more than 200 cc of condensate water. Replace the drain cap. Alpha CD12S/20S/28S - Routine Servicing...
  • Page 28 Place the front case panel in position and secure in position with the four screws previously removed, see Fig. 30. Raise the control panel and secure in position with the two screws provided. Check the operation of the boiler. (Refer to Boiler Operation, Section 6). Return all controls to their original settings. Alpha CD12S/20S/28S - Routine Servicing...

  • Page 29: Component Replacement

    Gain access to the room sealed chamber as described in Section 8.1. Undo the gas inlet union to the combustion chamber front to gain access. Unscrew the damaged injector and screw in a replacement. Re-assemble in reverse order. Alpha CD12S/20S/28S - Component Replacement...
  • Page 30 Light the boiler. (Refer to Commissioning, Section 5.4) and adjust the gas valve as described in the instructions supplied with the replacement valve. Complete re-assembly as described in Routine Servicing, Section 7.4 paragraphs 5 to 9. Alpha CD12S/20S/28S - Component Replacement...
  • Page 31 Fig. 32 8.14 CLOCK (if fitted) - Fig. 21 Note: For replacement only use an Alpha two channel clock. Do not fit a single channel clock. Gain access behind the control panel as described in Section 8.1. Remove the two screws securing the clock cover at the rear of the control panel.
  • Page 32 Fit the new gauge using a new 'O' ring on the connection if necessary. Refill and pressurise the system. (Refer to Commissioning, Section 5.1). Automatic air vent Primary temperature sensor Primary pressure switch Cable grommet Pump Pressure relief valve Pressure gauge Fig. 34 Alpha CD12S/20S/28S - Component Replacement...
  • Page 33 Remove the bottom tray and close the isolating valves either side of the cyclone. Disconnect the unions from the cyclone. Remove the two screws securing the support bracket and remove the cyclone. Re-assemble with a new cyclone. Pressurise the system. (Refer to Commissioning, Section 5.1). Alpha CD12S/20S/28S - Component Replacement...
  • Page 34 Remove the screw securing the trap to the bottom of the boiler casing and lift out the trap. Fit the new trap in reverse order. Note: Fill the new trap with water once installed. Alpha CD12S/20S/28S - Component Replacement...

  • Page 35: Wiring Diagrams

    AND CONNECT 230/240 V SWITCHED LIVE TO Gy - Grey - Blue TERMINAL1. - Pink - Red - Purple - Orange A FROST THERMOSTAT IS INCORPORATED W/Bl - White/Blue - Green WITHIN THE MAIN PCB Alpha CD12S/20S/28S - Wiring Diagrams...
  • Page 36 Switch Flue Temperature Transformer Sensor Heat Exchanger Overheat Thermal Fuse Thermostat Note: Main Terminal Block TO CONNECT EXTERNAL CONTROL REMOVE LINK FROM TERMINALS 1 AND 2 AND CONNECT 240 V SWITCHED LIVE TO TERMINAL 1. Alpha CD12S/20S/28S - Wiring Diagrams...

  • Page 37: Fault Finding

    Check gas valve adjustment Go to section ' ', page 34 set temperature is reached Pump continues to run until temperature Burner goes out Fan stops after 50 seconds reduces to set temperature Operation sequence successful Alpha CD12S/20S/28S - Fault Finding...
  • Page 38 Replace PCB Fan connections correct at fan and PCB connector X13 Fan jammed or faulty winding Replace fan PCB connector, is 36 V dc across terminals 5 and 3 or 4 Replace PCB Alpha CD12S/20S/28S - Fault Finding...
  • Page 39 1 and N Unplug leads from primary pressure Continuity across primary Replace PCB switch, is there 5V DC at PCB across pressure switch terminals X9 connector terminals 1 and 3 Replace primary pressure switch Alpha CD12S/20S/28S - Fault Finding...

  • Page 40: Short Parts List

    1.023999 Fig. 27 H50-444 Burner - CD28S 1.023979 Fig. 2, item 3 Main injector 3.5 mm - CD12S 1.025585 Fig. 2, item 3 Main injector 4.2 mm - CD20S 1.024872 Fig. 2, item 3 Main injector 5.4 mm - CD28S 1.024388...

  • Page 41: Benchmark Checklist

    The operation of the appliance and system controls have been demonstrated to the customer The manufacturer's literature has been left with the customer COMMISSIONING ENG'S NAME: Print ...............Gas Safe ID No..........Sign ................Date ..............Alpha CD12S/20S/28S - Benchmark Checklist...

  • Page 42: Service Record

    Gas Safe ID card serial No.............. CO/CO Initial ratio ......Final ratio ....... CO/CO Initial ratio ......Final ratio ....... Faults/Repairs carried out ............... Faults/Repairs carried out ................................................................................................... Engineers signature ................. Engineers signature ................. Alpha CD12S/20S/28S - Service Record...
  • Page 43 Alpha CD12S/20S/28S...
  • Page 44 These instructions have been carefully prepared but we reserve the right to Nepicar House, London Road, Wrotham Heath, alter the specification at any time in the interest of product improvement. Sevenoaks, Kent TN15 7RS © Alpha Therm Limited 2011. Tel: 0844 8718764 email: info@alpha-innovation.co.uk website: www.alpha-innovation.co.uk Part No.

This manual is also suitable for:

Cd20sCd28s

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