Alpha CD25C Installation And Servicing Instructions
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Alpha CD25C Installation And Servicing Instructions

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

Alpha CD25C/28C/35C
Range of Wall Mounted, Fan Assisted, Room Sealed,
Gas Fired, High Efficiency Condensing Combination Boilers
0051
Instructions
For Technical help or for Service call ...
ALPHA HELPLINE
Tel: 0870 3001964
Nepicar House, London Road,
Wrotham Heath, Sevenoaks,
Kent TN15 7RS
British Gas
Alpha CD25C
Alpha CD28C
Alpha CD35C
For use with Natural Gas only
Leave these instructions with the User
Service Listed
G.C. No. 47 532 31
G.C. No. 47 532 33
G.C. No. 47 532 35

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Summary of Contents for Alpha Alpha CD25C

  • Page 1: Installation And Servicing

    Installation and Servicing Instructions Alpha CD25C/28C/35C Range of Wall Mounted, Fan Assisted, Room Sealed, Gas Fired, High Efficiency Condensing Combination Boilers For Technical help or for Service call ... ALPHA HELPLINE Tel: 0870 3001964 Nepicar House, London Road, Wrotham Heath, Sevenoaks,...

  • Page 2: Table Of Contents

    The CD35C boiler is suitable for central heating loads of between 7.8 and 30.3 kw (26 614 and 103 400 Btu/h). The maximum output available for domestic hot water is 24.3 kW (84 800 Btu/h), capable of providing 9.6 litres/min for the Alpha CD25C boiler, 28.7 kW (97 900 Btu/h), providing 11.4 litres/min for the Alpha CD28C boiler and 34.6 kW (118 100 Btu/h), providing...

  • Page 3: Technical Data

    14.2 ft³/h 106.6 30.4 gal/min 3.13 Specific Flow Rate (D) at 30°C Rise L/min 15.6 Note: The above appliances are fully modulating and are not range rated. (Flow rate @ 30K to EN625) gal/min 3.44 Alpha CD25C/28C/35C - Technical Data...
  • Page 4 Air Duct Diameter 100 mm CD35C 45 kg Flue Duct Diameter 60 mm PERFORMANCE SEDBUK Rating Band 'A' NOx Classification content (± 0.2%) Boiler Model Natural Gas Min. CH Max. DHW Max. CD25C CD28C CD35C Alpha CD25C/28C/35C - Technical Data...
  • Page 5 Note: For outputs upto 28 kW refer to Section 3.7. 2.10 ELECTRICAL CONNECTIONS Note: This Appliance Must Be Earthed An optional integral single channel Clock kit is available if required. Note: Only use the Alpha single channel clock. Do not fit any two channel clocks. Brown Blue Used...

  • Page 6: Boiler Schematic

    22 - DHW temperature sensor 34 - Flue thermostat 11 - Pressure differential test points 23 - Flue sampling point 35 - Diverter valve motor 12 - Flue hood 24 - Gas service cock Fig. 2 Alpha CD25C/28C/35C - 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 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.
  • Page 8 L = B + C + 225 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 CD25C/28C/35C - General Boiler Information...
  • Page 9 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. BOILER LOCATION The boiler is not suitable for external installation unless it is installed within a purpose designed weatherproof building.
  • Page 10 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. 6 Fig. 7 Alpha CD25C/28C/35C - General Boiler Information...
  • Page 11 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 12 A supply of direct mains fed hot and cold water is permitted provided the appliance is of the over- rim flushing type. Before the mains water supply pipe is connected to the boiler, it should be thoroughly flushed out to avoid the danger of dirt or foreign matter entering the boiler. Alpha CD25C/28C/35C - General Boiler Information...

  • Page 13: Installation

    140 mm, 180 mm if the wall jig is used (ensure the Template lines are horizontal). This will give the position of the centre of the hole for the flue. Fig. 11 Alpha CD25C/28C/35C - Installation...
  • Page 14 E - Heating return (22 mm) F - Pressure relief valve (15 mm) G - Heating drain point H - Cold water inlet filter I - Condensate discharge pipe Fig. 13a - Without wall jig Alpha CD25C/28C/35C - Installation...
  • Page 15 FIT THE FLUE - Figs. 14, 15 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 16 Comments Up to maximum:- 11.86 m 11.775 m Alpha CD 750 mm or 1000 mm flue extension (Part No. 6.2000750 or 6.2001050) is required to extend the range of telescopic flue. Refer to Section 4.7 paragraph 2 for instructions on how to extend the flue.
  • Page 17 (use a 127 mm core drill). The size of the hole provides sufficient clearance for the clamps on the flue extension to pass through the hole. Determine the overall flue length as described in Section 4.6, paragraph 2 to determine the number of Alpha CD 750/1000 mm flue extensions required.
  • Page 18 FIT THE CLOCK KIT - Fig. 21 Ensure the electrical supply to the boiler is isolated. Important: Only use an Alpha single channel clock. Do not fit a two channel clock. Remove the two screws securing the clock cover at the rear of the control panel.

  • Page 19: Commissioning

    Loosen the gas inlet pressure test point screw on the gas valve (see Fig. 23). Ensure the gas supply is on and open the boiler service cock to purge in accordance with BS 6891. Retighten the test point screw and test for gas soundness. Close the boiler gas service cock. Alpha CD25C/28C/35C - Commissioning...
  • Page 20 Thoroughly flush out the water pipework (refer to Section 3.9) and with no pressure in the boiler heating circuit, empty the cyclone (if applicable) at it's drain point (see Fig. 13) of any debris. Clean the mains water inlet filter (see Fig. 13). Re-pressurise the system as described in Section 5.1. Alpha CD25C/28C/35C - Commissioning...
  • Page 21 Note: It is a requirement that the installation is registered by the installer through the CORGI Gas Work Notification Scheme. 12. Leave these Installation and Servicing instructions with the User for use on future calls. Alpha CD25C/28C/35C - Commissioning...

  • Page 22: 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 CD25C/28C/35C - Boiler Operation...

  • Page 23: Routine Servicing

    Front case locating pins Combustion Six nuts and washers chamber front securing combustion assembly chamber front assembly Gas pipe Viewing window union assembly Pressure tube connections Fan assembly fixing screws Front case fixing screws Ignition generator Fig. 26 Alpha CD25C/28C/35C - Routine Servicing...
  • Page 24 Place the front case panel in position and secure in position with the four screws previously removed, see Fig. 26. 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 CD25C/28C/35C - Routine Servicing...

  • Page 25: 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 CD25C/28C/35C - Component Replacement...
  • Page 26 Fit the new assembly and re-assemble in reverse order and test for gas soundness. Light the boiler. (Refer to Commissioning, Section 5.4) and the instructions supplied with the replacement valve for adjustment of the valve. Complete re-assembly as described in Routine Servicing, Section 7.4 paragraphs 5 to 9. Alpha CD25C/28C/35C - Component Replacement...
  • Page 27 Re-assemble in reverse order with a new motor. 8.15 CLOCK (if fitted) - Refer to Fig. 21 Note: For replacement only use an Alpha single channel clock. Do not fit a two channel clock. Gain access behind the control panel as described in Section 8.1.
  • Page 28 Fit the new gauge using a new 'O' ring on the manifold connection if necessary. Refill and pressurise the system. (Refer to Commissioning, Section 5.1). Primary pressure switch Automatic air vent DHW sensor Pump Diverter valve Pressure relief valve Pressure gauge Fig. 32 Alpha CD25C/28C/35C - Component Replacement...
  • Page 29 Re-assemble in reverse order making sure that the words on the heat exchanger are at the top when fitted and that the seals are in position in the manifold. Refill and pressurise the system. (Refer to Commissioning, Section 5.1). Alpha CD25C/28C/35C - Component Replacement...
  • Page 30 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 CD25C/28C/35C - Component Replacement...

  • Page 31: Wiring Diagrams

    REMOVE LINK FROM TERMINALS 1 & 2 - Green AND CONNECT 230/240 V SWITCHED LIVE TO G/Y - Green/Yellow TERMINAL1. - White Gy - Grey A FROST THERMOSTAT IS INCORPORATED Pk - Pink WITHIN THE MAIN PCB - Purple Alpha CD25C/28C/35C - Wiring Diagrams...
  • Page 32 Valve Motor Primary DHW Switch Temperature Sensor Primary Pressure Switch Transformer 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 CD25C/28C/35C - Wiring Diagrams...

  • Page 33: Fault Finding

    Check gas valve adjustment Go to section ' ', page 35 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 CD25C/28C/35C - Fault Finding...
  • Page 34 DHW flow valve senses no flow. Primary water diverted Diverter valve/DHW switch fault to CH system. DHW flow switch released (off) Burner goes out Pump stops Fan stops after 50 seconds Operation sequence successful Alpha CD25C/28C/35C - Fault Finding...
  • Page 35 Does the piston move in and out when operating the boiler between CH and DHW Ensure by-pass slot is in horizontal position Is diverter valve spindle sticking and that the valve is not stuck open Replace diverter valve Alpha CD25C/28C/35C - Fault Finding...
  • Page 36 Remove the diverter valve motor, is the brass piston Replace lead motor plug and lead fully extended (flush with plastic housing) Replace motor Replace valve Diverter valve spindle operating Check by-pass valve is not stuck open Check DHW heat exchanger for blockage Alpha CD25C/28C/35C - Fault Finding...

  • Page 37: Short Parts List

    Diverter valve motor assembly 1.018064 Fig. 30 Diverter valve assembly 3.015562 Fig. 2, item 27 By-pass assembly 3.017174 Fig. 27 Combustion chamber insulation panel front E94-420 1.014732 Fig. 2, item 29 Condensate trap 3.017281 Alpha CD25C/28C/35C - Short Parts List...

  • Page 38: 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 ..............CORGI ID No........... Sign ..............Date ..............Alpha CD25C/28C/35C - Benchmark Checklist...

  • Page 39: 13 Service Record

    Engineers Name ................. Company Name ................Company Name ................Telephone No................Telephone No................CORGI ID card serial No............CORGI ID card serial No............Comments ................... Comments ..........................................................Signature ..................Signature ..................Alpha CD25C/28C/35C - Service Record...
  • Page 40 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 2006. Tel: 0870 3001964 email: info@alphatherm.co.uk website: www.alpha-boilers.com Part No.

This manual is also suitable for:

Cd28cCd35c

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