baxi Duotec 2 24 Combi GA, Duotec 2 28 Combi GA, Duotec 2 33 Combi GA, Duotec 2 40 Combi GA User guide

Installation & Servicing Instructions

Duo-tec 2 Combi GA Range

Gas Fired Wall Mounted Condensing

Combination Boiler

These instructions include the Benchmark Commissioning Checklist

and should be left with the user for safe keeping.

They must be read in conjunction with the Flue Installation Guide.

Model Range

Baxi Duo-tec 2 Combi 24 GA

47-075-54

G.C.N

Baxi Duo-tec 2 Combi 28 GA

G.C.No 47-075-55

Baxi Duo-tec 2 Combi 33 GA

G.C.No 47-075-56

Baxi Duo-tec 2 Combi 40 GA

G.C.No47-075-57

The Benchmark Scheme

Benchmark places responsibilities on both manufacturers and installers. The purpose is to ensure that customers are provided with the correct equipment for their needs, that it is installed, commissioned and serviced in accordance with the manufacturer’s instructions by competent persons and that it meets the requirements of the appropriate Building Regulations. The Benchmark Checklist can be used to demonstrate compliance with Building Regulations and should be provided to the customer for future reference.

Installers are required to carry out installation, commissioning and servicing work in accordance with the Benchmark Code of Practice which is available from the Heating and Hotwater Industry Council who manage and promote the Scheme. Visit www.centralheating.co.uk for more information.

© Baxi Heating UK Ltd 2014 All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, or stored in any retrieval system of any nature (including in any database), in each case whether electronic, mechanical, recording or otherwise, without the prior written permission of the copyright owner, except for permitted fair dealing under Copyrights, Designs and Patents Act 1988.

Applications for the copyright owner’s permission to reproduce or make other use of any part of this publication should be made, giving details of the proposed use, to the following address:

The Company Secretary, Baxi Heating UK Limited, Brooks House, Coventry Road, Warwick. CV34 4LL

Full acknowledgement of author and source must be given.

Building Regulations and the Benchmark Commissioning Checklist

Building Regulations (England & Wales) require notification of the installation of a heating appliance to the relevant Local Authority Building Control Department. This can be achieved via a Competent Persons Self Certification Scheme as an option to notifying the Local Authority directly.

The Health & Safety Executive operates the ‘Gas Safe Register’, a self-certification scheme for gas heating appliances.

These arrangements represent a change from the situation whereby compliance with Building Regulations was accepted as being demonstrated by completion of the Benchmark Logbook (which was then left on site with the customer).

With the introduction of Self Certification Schemes, the Benchmark Logbook is being withdrawn. However, a similar document in the form of a commissioning checklist and service interval record is incorporated at the back of these instructions.

This company is a member of the Benchmark initiative and fully supports the aims of the programme. Its aim is to improve the standards of installation and commissioning of central heating systems in the UK and to encourage the regular servicing of all central heating systems to ensure safety and efficiency.

Building Regulations require that installations should comply with manufacturer's instructions. It is therefore important that the commissioning checklist is completed by the installer. The relevant section of Building Regulations only relates to dwellings. Therefore the checklist only applies if the appliance is being installed in a dwelling or some related structure.

The flowchart opposite gives guidance for installers on the process necessary to ensure compliance with Building Regulations.

WARNING: Any person who does any unauthorised act in relation to a copyright work may be liable to criminal prosecution and civil claims for damages.

0085

ISO 9001

FM 00866

Choose Building

Regulations Notification

Route

Installer Notification Guidelines

Competent Person's

Self Certification Scheme

Install and Commission this appliance to manufacturer's

instructions

Complete the

Benchmark Checklist

If you notify via the ‘Gas Safe

the Building Regulations

certificate on members’ behalf

Building Control

Contact your relevant Local

Authority Building Control

(LABC) who will arrange

an inspection or contact a government approved

inspector

Install and Commission this appliance to manufacturer's

instructions

Scheme Members only

Call ‘Gas Safe Register’ on:

0800 408 5577

or log onto:

www.gassaferegister.co.uk

within 10 days

You must ensure that the

certificate number issued by

the ‘Gas Safe Register’ is written

onto the Benchmark Checklist

‘Gas Safe Register’ will issue a

Building Regulations Compliance

Certificate to the property owner

and inform the relevant LABC

Complete the

Benchmark Checklist

LABC will record the data

and will issue a

certificate of compliance

Legislation

IMPORTANT - Installation, Commissioning, Service & Repair

This appliance must be installed in accordance with the manufacturer’s instructions and the regulations in force. Read the instructions fully before installing or using the appliance.

In GB, this must be carried out by a competent person as stated in the Gas Safety (Installation & Use) Regulations.

Definition of competence: A person who works for a Gas Safe registered company and holding current certificates in the relevant ACS modules, is deemed competent.

In IE, this must be carried out by a competent person as stated in I.S. 813 “Domestic Gas Installations”.

The addition of anything that may interfere with the normal operation of the appliance without express written permission from the manufacturer or his agent could invalidate the appliance warranty. In GB this could also infringe the Gas Safety (Installation and Use) Regulations.

Warning - Check the information on the data plate is compatible with local supply conditions.

This company declares that no substances harmful to health are contained in the appliance or used during appliance manufacture.

The appliance is suitable only for installation in GB and IE and should be installed in accordance with the rules in force, and only used in a suitably ventilated location.

In GB, the installation must be carried out by a Gas Safe Registered Installer. It must be carried out in accordance with the relevant requirements of the:

• Gas Safety (Installation & Use) Regulations.

• The appropriate Building Regulations either The Building Regulations, The Building Regulations (Scotland), Building Regulations (Northern Ireland).

• The Water Fittings Regulations or Water Byelaws in Scotland.

• The Current I.E.E. Wiring Regulations.

Where no specific instructions are given, reference should be made to the relevant British Standard Code of Practice.

In IE, the installation must be carried out by a competent Person and installed in accordance with the current edition of I.S. 813 ‘Domestic Gas Installations’, the current Building Regulations and reference should be made to the current ETCI rules for electrical installation.

All Gas Safe registered engineers carry an ID card with their licence number and a photograph. You can check your engineer is registered by telephoning 0800 408 5500 or online at www.gassaferegister.co.uk

The boiler meets the requirements of Statutory Instrument “ The Boiler (Efficiency)

Regulations 1993 N

3083” and is deemed to meet the requirements of Directive 92/42/EEC on the energy efficiency requirements for new hot water boilers fired with liquid or gaseous fuels:-

Type test for purpose of Regulation 5 certified by: Notified Body 0085.

Product/Production certified by: Notified Body 0086.

For GB/IE only.

All systems must be thoroughly flushed and treated with inhibitor (see section 6.2).

Codes of Practice - refer to the most recent version

In GB the following Codes of Practice apply: Standard Scope

BS 6891 Gas Installation. BS 5482 Part 1 Butane & Propane Gas Installation BS 5546 Installation of hot water supplies for domestic

purposes. BS EN 12828 Heating systems in buildings. BS EN 12831 Heating systems in buildings - Calculation of load. BS EN 14336 Installation & commissioning of water based

heating systems. BS 6798 Installation of gas fired hot water boilers. BS 5440 Part 1 Flues. BS 5440 Part 2 Ventilation. BS 7074 Expansion vessels and ancillary equipment for

sealed water systems. BS 7593 Treatment of water in domestic hot water

central heating systems.

In IE the following Codes of Practice apply: Standard Scope

I.S. 813 Domestic Gas Installations. The following standards give valuable additional information; BS 5546 Installation of hot water supplies for domestic

purposes. BS EN 12828 Heating systems in buildings. BS EN 12831 Heating systems in buildings - Calculation of load. BS EN 14336 Installation & commissioning of water based

heating systems. BS 7074 Expansion vessels and ancillary equipment for

sealed water systems. BS 7593 Treatment of water in domestic hot water

central heating systems.

Safe Manual Handling

General

The following advice should be adhered to, from when first handling the boiler to the final stages of installation, and also during maintenance.

Most injuries as a result of inappropriate handling and lifting are to the back, but all other parts of the body are vulnerable, particularly shoulders, arms and hands. Health & Safety is the responsibility of EVERYONE.

There is no ‘safe’ limit for one man - each person has different capabilities. The boiler should be handled and lifted by TWO PEOPLE.

Do not handle or lift unless you feel physically able.

Wear appropriate Personal Protection Equipment e.g. protective gloves, safety footwear etc.

Preparation

Co-ordinate movements - know where, and when, you are both going.

Minimise the number of times needed to move the boiler - plan ahead.

Always ensure when handling or lifting the route is clear and unobstructed. If possible avoid steps, wet or slippery surfaces, unlit areas etc. and take special care on ladders/into lofts.

Technique

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. See the ‘Installation’ section of these instructions for recommended lift points.

Remember

The circumstances of each installation are different. Always asses the risks associated with handling and lifting according to the individual conditions.

If at any time when installing the boiler you feel that you may have injured yourself STOP !! DO NOT ‘work through’ the pain - you may cause further injury.

IF IN ANY DOUBT DO NOT HANDLE OR LIFT THE BOILER - OBTAIN ADVICE OR ASSISTANCE BEFORE PROCEEDING !!

CONTENTS

Section Page

1.0 Introduction 7

2.0 General Layout 8

3.0 Appliance Operation 9

4.0 Technical Data 10

5.0 Dimensions and Fixings 11

6.0 System Details 12

7.0 Site Requirements 15

8.0 Flue Options 20

9.0 Installation 22

10.0 Commissioning 27

11.0 Completion 31

12.0 Servicing 32

13.0 Changing Components 34

14.0 Combustion & Calibration 42

15.0 Electrical 43

16.0 Short Parts List 44

17.0 Fault Finding 45

18.0 External Low Voltage Controls 51

Benchmark Checklist 54

Information Label

1.0 Introduction

1.1 Description

1. The Baxi Duo-tec 2 Combi GA Range are fully automatic gas fired wall mounted condensing combination boilers. It is room sealed and fan assisted, and will serve central heating and mains fed domestic hot water.

2. The boiler is set to give a maximum output of :-

24 models - 24 kW DHW

21.2 kW CH (Condensing)

28 models - 28 kW DHW

25.3 kW CH (Condensing)

33 models - 33 kW DHW

29.6 kW CH (Condensing)

40 models - 40 kW DHW

33.8 kW CH (Condensing)

3. The boiler is factory set for use on Natural Gas (G20). It can be converted to operate on Propane (G31) - see Section 10.1 ‘Gas Type Check’.

4. The boiler is suitable for use only on fully pumped sealed heating systems. Priority is given to domestic hot water.

Fig. 1

Control Flap

5. The boiler data badge gives details of the model, serial number and Gas Council number and is situated on the inner door panel. It is visible when the case front panel is removed (Fig. 2).

6. The boiler model, serial number and Gas Council number are also shown on the information label behind the boiler control flap (Fig. 1). This is for user reference.

7. The boiler is intended to be installed in residential / commercial / light industrial E.M.C. environments on a governed meter supply only.

8. The boiler must be installed with one of the purpose designed flues such as one of the standard horizontal telescopic flue kits detailed in the Flue Installation Guide .

9. All systems must be thoroughly cleansed, flushed and

treated with inhibitor (see section 6.2).

1.2 Optional Extras

Various timers, external controls, etc. are available as optional extras. Full details are contained in the relevant sales literature.

Gas Type Label

Fig. 2

Data Badge

1.3 Contents of Pack

The pack contains:-

• Boiler

• Wall Plate inc. Taps

• Template

• Fittings & Literature Pack

NOTE: These Installation & Servicing Instructions MUST be read in conjunction with the Flue Installation Guide supplied in the Literature Pack.

2.0 General Layout

2.1 Layout

1. Expansion Vessel

2. Expansion Vessel Valve

3. Primary Heat Exchanger

4. DHW Plate Heat Exchanger

5. Pump with Automatic Air Vent

6. Central Heating System Pressure Gauge

7. Fan Assembly

8. Air/Gas Collector

9. Flue Se nsor

10. Flame Sensing Electrode

11. Spark Ignition Electrode

12. Combustion Box Cover & Burner

13. Control Box Display

14. Condensate Trap

15. Safety Pressure Relief Valve

16. Drain Off Point

17. Gas Valve

18. Diverter Valve Motor

19. Boiler Controls

20. Boiler Adaptor

21. Heating Flow Sensor

22. Safety Thermostat

3.0 Appliance Operation

3.1 Central Heating Mode

1. With a demand for heating, the pump circulates water through the primary circuit.

2. Once main burner ignites the fan speed controls the gas rate to maintain the heating temperature measured by the temperature sensor.

3. When the flow temperature exceeds the setting temperature, a 3 minute delay occurs before the burner relights automatically (anti-cycling). The pump continues to run during this period.

4. When the demand is satisfied the burner is extinguished and the pump continues to run for a period of 3 minutes (Pump Overrun).

3.2 Domestic Hot Water Mode

1. Priority is given to the domestic hot water supply. A demand at a tap or shower will override any central heating requirement.

2. The flow of water will operate the Hall Effect Sensor which requests the 3 way valve to change position. This will allow the pump to circulate the primary water through the DHW plate heat exchanger.

3. The burner will light automatically and the temperature of the domestic hot water is controlled by the temperature sensor.

4. When the domestic hot water demand ceases the burner will extinguish and the diverter valve will remain in the domestic hot water mode, unless there is a demand for central heating.

Key

1. Pump with Automatic Air Vent

2. Boiler Drain Tap

3. Pressure Gauge

4. Safety Pressure Relief Valve

5. DHW Flow Sensor/Filter/Restrictor

6. Domestic Hot Water Priority Sensor

7. Domestic Hot Water NTC Sensor

8. Hydraulic Pressure Switch

9. Three Way Valve & Motor

10. Plate Heat Exchanger

11. Gas Valve

13. Heating Flow Sensor

14. Flue Sensor

15. Boiler Adaptor

16. Primary Heat Exchanger

17. Spark Ignition Electrode

18. Burner

19. Flame Sensing Electrode

20. Air/Gas Collector

21. Heating Return Sensor

22. Fan

23. Air/Gas Venturi

24. Expansion Vessel

12. Safety Thermostat (105° C)

Connections:A – Condensate Drain B – Heating Flow C – Domestic Hot Water Outlet D – Gas Inlet E – Cold Water Inlet On/Off Valve and filter F – Heating Return

Fig. 3

1. The frost protection mode is integral to the appliance and functions as long as there is power to the boiler, as indicated by the standby signal .

2. With CH & DHW or CH only selected, when the boiler temperature falls below 5°C the boiler will fire until a temperature of 30°C is reached.

3. If DHW only is selected, when the boiler CH temperature falls below 5°C the boiler will fire until a temperature of 30°C is reached. When the boiler DHW temperature falls below 5°C the boiler will fire until a temperature of 7°C is reached.

4. Further protection can be incorporated by using a system frost thermostat.

3.4 Pump Protection

1. If the boiler has been inactive for a period of 24 hours the pump will automatically operate for 1 minute to prevent sticking.

3.3 Boiler Frost Protection Mode

4.0 Technical Data

4.1

Appliance Type C

13 C33 C43 C53

Appliance Category CAT I

Heat Input CH (Net) Max Min

24 model kW 20 3.5 28 model kW 24 3.9 33 model kW 28 4.8 40 model kW 32 5.9

Heat Output CH (Non-Condensing)

Max Min 24 model kW 20 3.4 28 model kW 24 3.8 33 model kW 28 4.7 40 model kW 32 5.7

Heat Output CH (Condensing)

Max Min 24 model kW 21.2 3.7 28 model kW 25.3 4.1 33 model kW 29.6 5.1 40 model kW 33.8 6.2

Heat Input DHW (Net) Max 24 model kW 24.7 28 model kW 28.9 33 model kW 34 40 model kW 41.2

Heat Output DHW Max 24 model kW 24 28 model kW 28 33 model kW 33 40 model kW 40

Injector

24 model mm 4.4 28 model mm 4.6 33 model mm 4.9 40 model mm 5.8

NATURAL GAS ONLY !

Max Gas Rate (Natural Gas - G20)

(After 10 mins)

24 model m3/h 2.54

28 model m 33 model m

/h 2.96

/h 3.49

40 model m3/h 4.23

Inlet Pressure (Natural Gas - G20)

mbar 20

PROPANE ONLY !

Max Gas Rate (Propane - G31)

(After 10 mins) 24 model kg/h 1.92 28 model kg/h 2.25 33 model kg/h 2.64 40 model kg/h 3.2

Inlet Pressure (Propane - G31)

mbar 37

NOTE: All data in this section are nominal values and subject to normal production tolerances.

2H 3P

Electrical Supply 230V~ 50H

(Appliance must be connected to an

earthed supply)

Power Consumption

24 model W 104 28 model W 116 33 model W 132 40 model W 142

Electrical Protection

IPX5D

External Fuse Rating 3A

Internal Fuse Rating F2L

Condensate Drain

To accept 21.5mm (3/4in) plastic waste pipe

Flue Terminal Diameter 100mm Dimensions Projection 125mm

Connections copper tails

Gas Inlet - 22mm Heating Flow - 22mm Heating Return - 22mm Cold Water Inlet - 15mm Hot Water Outlet - 15mm Pressure Relief Discharge - 15mm

Outercase Dimensions

Casing Height - 763mm Overall Height Inc Flue Elbow - 923mm Casing Width - 450mm Casing Depth - 355mm

Clearances

Above Casing 175 mm Min Below Casing 150 mm* Min Front 450 mm Min (For Servicing) Front 5 mm Min (In Operation) L.H. Side 5 mm Min R.H. Side 5 mm Min

*This is MINIMUM recommended dimension. Greater clearance will aid installation and maintenance.

Weights

(24/28)

Packaged Boiler Carton 41.5kg Installation Lift Weight 36kg

(33)

Packaged Boiler Carton 43.5kg Installation Lift Weight 38kg

(40)

Packaged Boiler Carton 44.5kg Installation Lift Weight 39kg

SEDBUK Declaration

SAP 2005 Seasonal Efficiency for N. G.

models is 91.1%

SAP 2005 Seasonal Efficiency for L.P.G.

models is 93.2%

SAP 2009 Annual Efficiency for N. G.

models is 89%

SAP 2009 Annual Efficiency for L.P.G.

models is 91%

This value is used in the UK Government’s Standard

Assessment Procedure (SAP) for energy rating of

dwellings. The test data from which it has been calculated

has been certified by 0087.

NOxClass 5

Central Heating Primary Circuit Pressures

bar Safety Discharge 3 Max Operating 2.5 Min Operating 0.5 Recommended Operating Range 1-2

DHW Circuit bar Pressures

Max Operating 8 Min Operating 0.15

Flow Rates (24) (28) (33) (40)

l/min l/min l/min l/min DHW Flow Rate @ 30o C Rise 10.9 12.9 15.3 18.3

DHW Flow Rate @ 35o C Rise 9.8 11.5 13.5 16.4

Min Working DHW Flow Rate 2 2 2 2

IMPORTANT: Where Low Flow Taps or Fittings are intended to be used in the DHW system connected it is strongly recommended that the DHW flow rate DOES NOT fall below 2.5l/min. This will ensure reliable operation of the DHW function.

Expansion Vessel - (For Central Heating only. Integral with appliance)

bar

Min Pre-charge Pressure 0.5

(24 & 28) (33 & 40)

litre litre Max Capacity of CH System 125 155

Primary Water Content of Boiler (unpressurised) 2.5 2.8

Temperatures

C.H. Flow Temp (adjustable)

25°C to 80°C max (± 5°C)

D.H.W. Flow Temp (adjustable)

35°C to 60°C max (± 5°C) dependent upon flow rate

Pump

Available Head See graph below

Pump - Available Head

5.5

4.5

3.5

2.5

Metre (wg)

1.5

0.5

200 400 600 800 1000 1200

Flow Rate (l/h)

Dimensions

5.0 Dimensions and Fixings

At least 1.5°

A 763mm

B 355mm*

*This can be reduced to 345mm by removing the boiler control access flap

C 450mm

D 116mm Ø Min.

E 160mm

(207mm for 80/125mm flue systems)

360° Orientation

F 150mm

G 106mm

H 170mm

J 280mm

Boiler Side

Condensate

Drain

Flue Ø 100mm

Pressure

Relief Valve

(15mm)

Tap Rail

Boiler Side

50 mm

192 mm

Heating

Flow

(22mm)

65 mm 65 mm 65 mm 65 mm 95 mm45 mm

Hot Water

Outlet

(15mm)

Gas Inlet

(22mm)

Cold Water

Inlet

(15mm)

Heating

Return

(22mm)

6.0 System Details

6.1 Information

1. The Baxi Duo-tec Combi HE GA Condensing Combination Boiler is a ‘Water Byelaws Scheme - Approved Product’. To comply with the Water Byelaws your attention is drawn to the following installation requirements and notes (IRN).

a) IRN 001 - See text of entry for installation

requirements and notes.

b) IRN 302 - Byelaw 14.

2. Reference to the WRc publications, ‘Water fittings and materials directory’ and ‘Water supply byelaws guide’ give full details of byelaws and the IRNs.

6.2 Treatment of Water Circulating Systems

1. All recirculatory water systems will be subject to corrosion unless they are flushed and an appropriate water treatment is applied. To prevent this, follow the guidelines given in BS 7593 “Treatment of Water in Domestic Hot Water Central Heating Systems” and the treatment manufacturers instructions.

2. Treatment must involve the use of a proprietary cleanser, such as Sentinel X300 or X400, or Fernox F3 and an inhibitor such as Sentinel X100 or Fernox MB-1.

3. Full instructions are supplied with the products, for further information contact Sentinel (0800 389 4670) or Fernox (0870 870 0362).

Failure to flush and add inhibitor to the system will invalidate the appliance warranty.

4. It is important to check the inhibitor concentration after installation, system modification and at every service in accordance with the inhibitor manufacturer’s instructions. (Test kits are available from inhibitor stockists.)

5. For information or advice regarding any of the above contact Technical Enquiries 0844 871 1555.

6.3 Bypass

1. The boiler is fitted with an automatic integral bypass. Some systems may require an additional external bypass.

6.4 System Control

1. Further external controls (e.g. room thermostat sensors) MUST be fitted to optimise the economical operation of the boiler in accordance with Part L of the Building Regulations (2010). A range of optional controls is available. Full details are contained in the relevant Sales Literature.

6.0 System Details

6.5 System Filling and Pressurising

Fig. 4

Stop Valve

DHW Mains Inlet

Double Check Valve

Temporary Loop

Stop Valve

1. A filling point connection on the central heating return pipework must be provided to facilitate initial filling and pressurising and also any subsequent water loss replacement/refilling.

2. A filling loop is supplied with the boiler. Follow the instructions provided with it.

3. The filling method adopted must be in accordance with all

Return

relevant water supply regulations and use approved equipment.

4. Your attention is drawn to: for GB: Guidance G24.2 and recommendation R24.2 of the Water Regulations Guide. for IE: the current edition of I.S. 813 “Domestic Gas Installations”.

5. The sealed primary circuits may be filled or replenished by means of a temporary connection between the circuit and a supply pipe, provided a ‘Listed’ double check valve or some other no less effective backflow prevention device is permanently connected at the inlet to the circuit and the temporary connection is removed after use.

6.6 Expansion Vessel (Central Heating only)

The end of the pipe should

terminate facing down and towards the wall

Fig. 6a

Filling Loop Connections

Fig. 5

1. The appliance expansion vessel is pre-charged to 0.5 bar. Therefore, the minimum cold fill pressure is 0.5 bar. The vessel is suitable for correct operation for system capacities up to 125 litres (24/28) or 155 litres (33/40). For greater system capacities an additional expansion vessel must be fitted. For GB refer to BS 7074 Pt 1. For IE, the current edition of I.S. 813 “Domestic Gas Installations”.

6.7 Safety Pressure Relief Valve (Fig. 6)

1. The pressure relief valve is set at 3 bar, therefore all pipework, fittings, etc. should be suitable for pressures in excess of 3 bar and temperature in excess of 100°C.

2. The pressure relief discharge pipe should be not less than 15mm dia, run continuously downward, and discharge outside the building, preferably over a drain. It should be routed in such a manner that no hazard occurs to occupants or causes damage to wiring or electrical components. The end of the pipe should terminate facing down and towards the wall (Fig. 6a).

3. The discharge must not be above a window, entrance or other public access. Consideration must be given to the possibility that boiling water/steam could discharge from the pipe.

Pressure Relief Valve

Fig. 6

Discharge Pipe

Control Box removed for clarity

4. A remote relief valve kit is available to enable the boiler to be installed in cellars or similar locations below outside ground level (kit no. 5121379).

5. A boiler discharge pump is available, part no. 720648301. This pump will dispose of both condensate & high temperature water from the relief valve. It has a maximum head of 5 metres.

Other Tap Outlets

Expansion Vessel*

Boiler

6.0 System Details

6.8 Domestic Hot Water Circuit (Fig. 7)

1. All DHW circuits, connections, fittings, etc. should be fully in accordance with relevant standards and water supply regulations.

2. Your attention is drawn to: for GB: Guidance G17 to G24 and recommendation R17 to R24 of the Water Regulations Guide. for IE: the current edition of I.S. 813 “Domestic Gas Installations”.

Fig. 7

Check Valve*

Pressure Reducer Valve*

Stop Tap

*See 6.8 for instances when these items may be required

To Hot Taps

IMPORTANT: Where Low Flow Taps or Fittings are intended to be used in the DHW system connected to a Baxi Duo-tec Combi GA it is strongly recommended that the DHW flow rate DOES NOT fall below 2.5l/min. This will ensure reliable operation of the DHW function.

3. The Water Regulations recommendations for England and Wales prohibits backflow from appliances into the wholesome water supply due to thermal expansion. However this type of instantaneous combination boiler, with less than 15 litres of stored capacity, does not require any backflow prevention device as any thermal expansion is accommodated within the appliance. It is possible in certain circumstances that other cold water demands (e.g. washing machines, flushing of W.C.s) may affect the DHW function of the boiler. In these instances the fitting of a backflow prevention device and expansion vessel is recommended.

4. Also if there is an existing check valve, loose jumpered stop cock, water meter or water treatment device already fitted to the wholesome water supply connected to the boiler domestic hot water (DHW) inlet supply then a suitable expansion device may be required.

5. The boiler’s maximum working mains pressure is 8 bar, therefore all pipework, connections, fittings, etc. should be suitable for pressures in excess of 8 bar. A pressure reducing valve must be fitted for pressures in excess of 8 bar. The manufacturer of any outlet fittings, such as a shower valve, may require a lower maximum pressure. The pressure reduction must take account of all fittings connected to the DHW system.

6.9 Showers

1. If a shower control is supplied from the appliance it should be of the thermostatic or pressure balanced type. Thermostatic type shower valves provide the best comfort and guard against water at too high a temperature. Existing controls may not be suitable - refer to the shower valve manufacturer.

6.10 Hard Water Areas

1. If the area of the installation is recognised as a HARD WATER AREA then a suitable device should be fitted to treat the mains water supply to the boiler. Contact your Water Distribution Company for advice on suitable devices.

5mm Min

450mm

5mm Min

175 mm Min (300mm

Min if using 80/125mm

flueing system)

763mm

7.0 Site Requirements

7.1 Location

1. The boiler may be fitted to any suitable wall with the flue passing through an outside wall or roof and discharging to atmosphere in a position permitting satisfactory removal of combustion products and providing an adequate air supply. The boiler should be fitted within the building unless otherwise protected by a suitable enclosure i.e. garage or outhouse. (The boiler may be fitted inside a cupboard-see Section 7.3).

2. Where the boiler is sited in an unheated enclosure and during periods when the heating system is to be unused it is recommended that the permanent live is left on to give BOILER frost protection. NOTE: THIS WILL NOT PROTECT THE SYSTEM !

3. If the boiler is fitted in a room containing a bath or shower reference must be made to the relevant requirements. In GB this is the current I.E.E. Wiring Regulations and Building Regulations. In IE reference should be made to the current edition of I.S. 813 “Domestic Gas Installations” and the current ETCI rules.

Fig. 8

450mm Min

For Servicing

Purposes

150mm* Min

At least 1.5°

4. If the boiler is to be fitted into a building of timber frame construction then reference must be made to the current edition of Institute of Gas Engineers Publication IGE/UP/7 (Gas Installations in Timber Framed Housing).

7.2 Clearances (Figs. 8 & 9)

1. A flat vertical area is required for the installation of the boiler.

2. These dimensions include the necessary clearances around the boiler for case removal, spanner access and air movement. Additional clearances may be required for the passage of pipes around local obstructions such as joists running parallel to the front face of the boiler.

*This is MINIMUM recommended dimension. Greater clearance will aid installation and maintenance.

7.3 Ventilation of Compartments

1. Where the appliance is installed in a cupboard or compartment, no air vents are required.

5mm Min

In Operation

Fig. 9

2. BS 5440: Part 2 refers to room sealed appliances installed in compartments. The appliance will run sufficiently cool without ventilation.

355mm

(345mm with flap removed)

7.0 Site Requirement

7.4 Gas Supply

1. The gas installation should be in accordance with the relevant standards. In GB this is BS 6891 (NG) or BS 5482 Pt. 1 (LPG). In IE this is the current edition of I.S. 813 “Domestic Gas Installations”.

2. The connection to the appliance is a 22mm copper tail located at the rear of the gas service cock (Fig. 10).

3. Ensure that the pipework from the meter to the appliance is of adequate size, and the demands of any other gas appliances in the property are taken into consideration. Do not use pipes of a smaller diameter than the boiler gas connection (22mm).

Fig. 10

Zone 1

Zone 0

Window Recess

Zone 2

Fig. A

Zone 2

Window Recess

Zone 2

0.6 m

In GB Only

Window Recess Zone 2

Gas Service Cock

Outside Zones

Ceiling

7.5 Electrical Supply

1. External wiring must be correctly earthed, polarised and in accordance with relevant regulations/rules. In GB this is the current I.E.E. Wiring Regulations. In IE reference should be made to the current edition of ETCI rules.

2. The mains supply is 230V ~ 50Hzfused at 3A.

NOTE: The method of connection to the electricity supply must facilitate complete electrical isolation of the appliance.

Connection may be via a fused double-pole isolator with a contact separation of at least 3mm in all poles and servicing the boiler and system controls only.

7.6 Bath & Shower Rooms

1. If the boiler is fitted in a room containing a bath or shower it can be fitted in zone 2, (Figs. A & B shows zone dimensions for a bathtub. For other examples refer to the Current I.E.E. Wiring Regulations) reference must be made to the relevant requirements. In GB this is the current I.E.E. Wiring Regulations and Building Regulations. In IE reference should be made to the current edition of I.S. 813 “Domestic Gas Installations” and the current ETCI rules.

Zone 1

Zone 0

Fig. B

Zone 2

0.6 m

2.25 m

In GB Only

Examples are shown of the following methods of termination:i) to an internal soil & vent pipe ii) via an internal discharge branch (e.g. sink waste) downstream of the trap iii) to a drain or gully iv) to a purpose made soakaway v) pumped into an internal discharge branch (e.g. sink waste) downstream of the trap vi) pumped into an external soil & vent pipe vii) to a drain or gully with extended external run & trace heating

It is strongly recommended to discharge internally into the household drainage system. If connecting to a rain water drain, that drain MUST discharge into a foul drain.

50mm per metre of pipe run

2.5° Minimum fall

Boiler

Sink

Boiler

50mm per metre of pipe run

2.5° Minimum fall

50mm per metre of pipe run

2.5° Minimum fall

21.5mm

i) Termination to an internal soil and vent pipe

450mm min*

ii) External termination via internal discharge branch

iii) Termination to a drain or gully

32mm

*450mm is applicable to properties up to 3 storeys. For multi-storey building installations consult BS 6798.

e.g sink waste - downstream*

Pipe must terminate above water level but below surrounding surface. Cut end at 45°

Insulation

Pipe must terminate above water level but below surrounding surface. Cut end at 45°

*It is NOT RECOMMENDED to connect upstream of the sink or other waste water receptacle !

7.0 Site Requirements

7.7 Condensate Drain

FAILURE TO INSTALL THE CONDENSATE DISCHARGE PIPEWORK CORRECTLY WILL AFFECT THE RELIABLE OPERATION OF THE BOILER.

CAREFUL CONSIDERATION MUST BE GIVEN TO THE POSSIBILITY OF THE PIPEWORK BEING SUBJECT TO FREEZING CONDITIONS AND APPROPRIATE MEASURES TAKEN TO PREVENT BLOCKAGE. CORRECT INSTALLATION IN ACCORDANCE WITH THIS SECTION WILL CONSIDERABLY MINIMISE THE LIKELIHOOD OF BLOCKAGE AND SUBSEQUENT BOILER LOCK-OUT.

A CONDENSATE DISCHARGE PUMP AND PIPE ‘TRACE HEATING’ ARE AVAILABLE AS ACCESSORIES - see paragraphs 7.7.12 to 7.715 for further details.

The condensate discharge pipe MUST NOT RISE at any point along its length. There MUST be a fall of AT LEAST

2.5° (50mm per metre) along the entire run EXCEPT when employing a suitable condensate pump in basement and cellar or similar applications.

The boiler condensate trap incorporates a seal of 75mm, therefore it is unnecessary to install an air break and trap in the discharge pipework.

1. The condensate outlet will accept 21.5mm ( overflow pipe. It is strongly recommended that this discharges internally into the household drainage system. Where this is not possible, discharge into an outside drain is permissible providing every possible precaution is taken to prevent freezing.

2. Ensure the discharge of condensate complies with any national or local regulations in force. BS 6798 & Part H1 of the

Building Regulations give further detailed guidance.

3. The discharge pipe should be run in a proprietary drain pipe material e.g. PVC, PVC-U, ABS, PVC-C or PP.

4. Metal pipework is NOT suitable for use in condensate discharge systems.

5. The pipe should be a minimum of 21.5mm diameter and must be supported using suitably spaced clips of the correct design to prevent sagging.

6. It is advisable that the full length of condensate pipe is run

internally and preferably be less than 3 metres.

/4in) plastic

Boiler

50mm per metre of pipe run

2.5° Minimum fall

iv) Termination to a purpose made soakaway

Further specific requirements for soakaway design are referred to in BS 6798.

500mm min

Holes in the soak-away must face away from the building

7. Internal runs greater than 3 metres or runs in cold areas

should use 32mm waste pipe.

8. External runs MUST be a MINIMUM of 32mm and fully insulated with material suitable for external use.

9. If the boiler is fitted in an unheated location the entire condensate discharge pipe should be treated as an external run and sized and insulated accordingly.

10. In all cases discharge pipe must be installed to aid disposal of the condensate. To reduce the risk of condensate being trapped, as few bends and fittings as possible should be used and any burrs on cut pipe removed.

11. When discharging condensate into a soil stack or waste pipe the effects of existing plumbing must be considered. If soil pipes or waste pipes are subjected to internal pressure fluctuations when WC's are flushed or sinks emptied then back-pressure may force water out of the boiler trap and cause appliance lockout.

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