Baxi Combi Instant 80e, Combi Instant 105e Quick Start Manual

Baxi Combi Instant 80e & 105e

Gas Fired Wall Mounted Combination Boiler

Installation & Servicing Instructions

Please leave these instructions with the user

Natural Gas

Baxi Combi Instant 80e

G.C.No47 075 13

Baxi Combi Instant 105e

G.C.No47 075 09

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 0051.

Product/Production certified by:

Notified Body 0051.

For GB/IE only.

Baxi is a BS-EN ISO 9001

Accredited Company

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. From 1 April 2005 this

can be achieved via a Competent Persons Self Certification

Scheme as an option to notifying the Local Authority directly.

Similar arrangements will follow for Scotland and will apply in

Northern Ireland from 1 January 2006.

CORGI operate 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Benchmark Logbook is being withdrawn.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.

Potterton 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.

Installer Notification Guidelines

Choose Building

Regulations Notification

Route

Contact your relevant Local

Authority Building Control

(LABC) who will arrange

an inspection or contact a government approved

inspector

LABC will record the data

and will issue a

certificate of compliance

CORGI will record the data and

will send a certificate of

compliance to the property

You must ensure that the

notification number issued by

CORGI is writen onto the

Benchmark Checklist

Scheme Members only

Call CORGI on: 0870 88 88 777

or log onto:

www.corgi-notify.com

within 10 days

If you notify via CORGI Scheme,

CORGI will then notify the

relevant Local Authority

Building Control Scheme

on member's behalf

Complete the

Benchmark Checklist

Install and Commission this appliance to manufacturer's

instructions

Competent Person's

Self Certification Scheme

Building Control

Legislation

Codes of Practice, most recent version should be used

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 CORGI 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”.

Lifting - This product should be lifted and handled by two people. Stooping should be

avoided and protective equipment worn where necessary. Carrying & lifting equipment

should be used as required e.g. when installing in a loft space.

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.

All CORGI registered installers carry a CORGI identification card and have a

registration number. You can check your installer is registered by telephoning

0870 4012300 or writing to:-

1 Elmwood,

Chineham Business Park,

Crockford Lane,

Basingstoke. RG24 8WG

or check online at www.corgi-gas-safety.com

Baxi declare 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 CORGI 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 systems must be thoroughly flushed and treated with inhibitor (see section 6.2).

In GB the following Codes of Practice apply: Standard Scope

BS 6891 Gas Installation. BS 5546 Installation of hot water supplies for

domestic purposes. BS 5449 Forced circulation hot water 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 BS standards give valuable additional information; BS 5546 Installation of hot water supplies for

domestic purposes. BS 5449 Forced circulation hot water systems. BS 7074 Expansion vessels and ancillary equipment

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

central heating systems.

1.0 Introduction 6

2.0 General Layout 7

3.0 Appliance Operation 8

4.0 Technical Data 10

5.0 Dimensions and Fixings 12

6.0 System Details 13

7.0 Site Requirements 16

8.0 Installation 21

9.0 Commissioning the Boiler 26

10.0 Completion 28

11.0 Servicing the Boiler 29

12.0 Changing Components 31

13.0 Illustrated Wiring Diagram 40

14.0 Fault Finding 41

15.0 Short Parts List 48

Benchmark Checklist 50

Section Page

Contents

1.0 Introduction

1.1 Description

1. The Baxi Combi Instant 80e or 105e is a fully automatic gas fired wall mounted combination boiler. It is room sealed and fan assisted, and will serve central heating and mains fed domestic hot water.

2.The unit incorporates a small storage cylinder built into the boiler providing hot water the moment the tap is turned on.

3. The boiler is set to give a maximum output of 24.0 kW (Instant 80e) or 31.0 kW (Instant 105e).

4. It is designed for use on Natural Gas (G20) and can be converted to use Propane (Instant 80e and 105e) or Butane (Instant 80e only).

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

6. The boiler data badge gives details of the model, serial number and Gas Council number and is situated on the control box. It is visible when the case front panel is removed (Fig. 1).

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 the standard horizontal flue kit, part no. 247719.

All systems must be thoroughly flushed and treated with

inhibitor (see section 6.2).

1.2 Instant Domestic Hot Water

(Expansion Vessel & Pre-Heat Store)

1. The boiler expansion vessel incorporates a small volume of stored primary hot water.

2. When the boiler has been off and there is then a demand for domestic hot water the stored primary hot water ensures that domestic hot water is supplied instantly at temperature.

3. The stored hot water is part of the primary circuit. This is not supplied as domestic hot water, which is fresh mains water heated by a heat exchanger within the boiler.

4. The stored primary hot water temperature is maintained whilst the boiler is in operation. During a period when there is no demand for heating or hot water the temperature of the stored primary hot water will eventually fall. The boiler will operate occasionally in order to maintain the temperature. This is indicated by the domestic hot water mode neon flashing.

1.3 Optional Extras

Various flue extensions, bends, vertical flue kits,control accessories etc. are available as optional extras. These are detailed in a separate publication.

Data Badge

Fig. 1

Control Box

Case Front Panel

2.0 General Layout

2.1 Layout

1. Air Pressure Switch

2. Expansion Vessel & Pre-Heat Store

3. Burner Manifold

4. Automatic Air Vent

5. DHW Plate Heat Exchanger

6. Circulation Pump

7. Drain Off Point

8. Pressure Relief Valve

9. Position for Optional Integral Timer

10. Central Heating System Pressure Gauge

11. PCB

12. Control Box

13. 3-Way Valve Assembly

14. Spark Generator

15. Flame Sensing Electrode

16. Spark Electrode

17. Burner

18. Primary Heat Exchanger

19. Fan Assembly

20. On/Off/Reset Selector Switch

21. Central Heating Temperature Control

22. Domestic Hot Water Pre-Heat Control

23. Flame Failure

24. Safety Thermostat

25. Fault on Fan or Flue

26. Fault on Pump or Low System Pressure

27. Fault on Hot Water Sensor

28. Fault on Central Heating Sensor

29. Power On

30. Domestic Hot Water Mode

31. Central Heating Mode

32. Burner On

When neons 23 to 28 are constantly illuminated, they

indicate the temperature of the central heating water.

30° 40° 50° 60° 70° 80°

bar

OFF

PREHEAT

30° 40° 50° 60° 70° 80°

23 24

26 27

30 31 32

3.0 Appliance Operation

NOTE: All delay timers mentioned in 3.1 and 3.2 are

overridden by domestic hot water demand.

3.1 Central Heating Mode (Fig. 2)

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

through the primary circuit. At a pre-determined flow

rate the central heating flow switch operates, initiating

the ignition sequence.

2. The main burner ignites at low rate, then the gas valve

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 30 minutes (Pump Overrun).

5. If there is no other demand the pre-heat function will

operate if switched on (see Section 3.2).

3.2 Domestic Hot Water - Preheat Mode

(Fig. 3)

1. With the pre-heat function switched on (pre-heat

control fully clockwise), priority is given to the

replenishment of the pre-heat store. The DHW mode

neon ( ) will flash during this function.

2. The diverter valve remains in the DHW priority

position. This allows the pump to circulate hot water to

the store and back to the primary heat exchanger via the

bypass pipe.

3. The automatic ignition sequence commences after

approximately 25 seconds and the burner will light.

4. When the store reaches the desired temperature the

burner is extinguished. The pump continues to run for a

period of 30 seconds.

5. Following a demand for domestic hot water or the

end of a central heating ON period, the pre-heat

function restarts.

16 15 14 13 12

1 Primary Heat Exchanger 2 Burner 3 Ignition Electrode 4 Flame Sensing Electrode 5 Gas Valve 6 Pump 7 Automatic Air Vent 8 Plate Heat Exchanger 9 Flow Sensor with Filter 10 Pressure Relief Valve 11 Boiler Drain Point 12 Heating Return 13 Cold Water Inlet On/Off Valve and Filter

14 Gas Inlet 15 Domestic Hot Water Outlet 16 Heating Flow 17 Pressure Gauge 18 Hydraulic Pressure Sensor Microswitch 19 Automatic By-Pass 20 Hydraulic Pressure Sensor 21 Diverter Valve Assembly 22 Domestic Hot Water Flow Priority Assembly 23 Domestic Hot Water Flow Priority Microswitch 24 Safety Thermostat 25 Central Heating Temperature Sensor 26 Expansion Vessel & Pre-Heat Store 27 Domestic Hot Water Temperature Sensor

Key

Central Heating Mode

Fig. 2

16 15 14 13 12

Domestic Hot Water - Preheat Mode

Fig. 3

3.0 Appliance Operation

3.3 Domestic Hot Water Mode (Fig. 3A)

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 DHW flow switch

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 and take the

stored water to give instant hot water.

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.

5. If there is no other demand the pre-heat function will

operate if switched on (see Section 3.2)

IMPORTANT: When the selector switch is in the ‘0’ (Off) position the electrical supply to the boiler is isolated. The boiler will not operate and the integral timer (if fitted) will require resetting once the selector switch is set to either Position (i) or Position (ii).

3.4 Frost Protection Mode

1. The frost protection mode is integral to the appliance

and functions only with the selector switch (see Section

2.1) in the domestic hot water and central heating

position. If the system temperature falls below 5° C then

the boiler will fire on its minimum setting until a flow

temperature of 30° C is reached. Further protection can

be incorporated by using a system frost thermostat.

3.5 Pump Protection

1. With the selector switch (see Section 2.1) in either the

central heating or central heating and hot water position

the pump will automatically operate for 1 minute in

every 24 hours to prevent sticking.

16 15 14 13 12

Key

Fig. 3A

Domestic Hot Water Mode

4.0 Technical Data

4.2 Combi Instant 80e

Flue Terminal Diameter 100mm Dimensions Projection 95mm

Outercase Dimensions

Casing Height - 780mm Overall Height Inc Flue Elbow - 980mm Casing Width - 450mm Casing Depth - 345mm

Clearances

Both Sides 5 mm Min Above Casing 200 mm Min Below Casing 200 mm Min Front 450 mm Min (For Servicing) Front 5 mm Min (In Operation)

Weights kg Packaged Boiler Carton 48.5 Packaged Flue Kit 3 Installation Lift Weight 42

Central Heating Primary Circuit Pressures

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

DHW Circuit bar Pressures

Max Operating 8 Min Operating 0.2

Min Operating Pressure at 12.7 l/min 0.96

Flow Rates l/min DHW Flow Rate @ 30o C Rise 13.7

DHW Flow Rate @ 35o C Rise 9.8

Min Working DHW Flow Rate 2.5

Pump - Grundfos UP 15-50

Available Head See graph below

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

bar

Min Pre-charge Pressure 0.5

litre Max Capacity of CH System 80

Primary Water Content of Boiler (unpressurised) 3.0

Connections copper tails Gas Supply - 22mm Central Heating Flow - 22mm Central Heating Return - 22mm Cold Water Mains Inlet - 15mm DHW Flow - 15mm Pressure Relief Discharge - 15mm

Temperatures

C.H. Flow Temp (adjustable)

35°C to 85°C max (± 5°C)

D.H.W. Flow Temp

35°C to 65°C max (± 5°C) dependent upon flow rate 50°C Pre-heat OFF 65°C Pre-heat ON ± 5°C dependent upon flow rate

Heat Input C/H & DHW (Net)

Max Min

kW 26.3 10.6

Btu/h 89,739 36,168

Heat Output Max Min

kW 24.0 9.3

Btu/h 81,819 31,738

Electrical Supply 230V~ 50H

(Appliance must be connected to an earthed supply)

Power Consumption 170W

External Fuse Rating 3A

Internal Fuse Rating

Fuse 2A Fast Blow to BS 4265

Appliance Category CAT II

2H 3+

Max Gas Rate (Natural Gas - G20)

(After 10 Mins)

m3/h 2.78

ft3/h 98.12

Inlet Pressure (Natural Gas - G20)

mbar 20

in wg 8

Burner Injector (Natural Gas - G20)

12 x 1.28mm Diameter

Burner Pressure (Natural Gas - G20)

Max Rate Min Rate

mbar 12.2 ± 0.5 2.5 ± 0.2

in wg 4.88 ± 0.2 1.0 ± 0.2

Appliance Type C

NOxClass 3

Electrical Protection

IPX5D

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 have been certified by 0051.

SEDBUK Declaration For Combi Instant 80e

The seasonal efficiency (SEDBUK) is 78.6 %

200 400 600 800 1000 1200

0.5

1.5

2.5

3.5

Metre wg

l/h

Pump - Available Head

4.5

5.5

LPG Gases Propane - G31 and

Butane - G30

Burner Injector

12 x 0.77mm diameter

Burner Pressure

Propane mbar

in wg

Butane mbar

in wg

Inlet Pressures

mbar in wg

Max Rate

36.2

14.5

28.3

11.3

Min Rate

6.4

2.6

5.3

2.1

Propane

14.8

Butane

11.2

4.0 Technical Data

4.2 Combi Instant 105e

Flue Terminal Diameter 100mm Dimensions Projection 95mm

Outercase Dimensions

Casing Height - 780mm Overall Height Inc Flue Elbow - 980mm Casing Width - 450mm Casing Depth - 345mm

Clearances

Both Sides 5 mm Min Above Casing 200 mm Min Below Casing 200 mm Min Front 450 mm Min (For Servicing) Front 5 mm Min (In Operation)

Weights kg Packaged Boiler Carton 50.5 Packaged Flue Kit 3 Installation Lift Weight 44

Central Heating Primary Circuit Pressures

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

DHW Circuit bar Pressures

Max Operating 8 Min Operating 0.2

Min Operating Pressure at 12.7 l/min 0.96

Flow Rates l/min DHW Flow Rate @ 30o C Rise 14.7

DHW Flow Rate @ 35o C Rise 12.7

Min Working DHW Flow Rate 2.5

Pump - Grundfos UP 15-60

Available Head See graph below

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

bar

Min Pre-charge Pressure 0.5

litre Max Capacity of CH System 80

Primary Water Content of Boiler (unpressurised) 3.2

Connections copper tails Gas Supply - 22mm Central Heating Flow - 22mm Central Heating Return - 22mm Cold Water Mains Inlet - 15mm DHW Flow - 15mm Pressure Relief Discharge - 15mm

Temperatures

C.H. Flow Temp (adjustable)

35°C to 85°C max (± 5°C)

D.H.W. Flow Temp

35°C to 65°C max (± 5°C) dependent upon flow rate 50°C Pre-heat OFF 65°C Pre-heat ON ± 5°C dependent upon flow rate

Heat Input C/H & DHW (Net)

Max Min

kW 34.3 11.9

Btu/h 117,036 40,610

Heat Output Max Min

kW 31.0 10.4

Btu/h 105,776 35,490

Electrical Supply 230V~ 50H

(Appliance must be connected to an earthed supply)

Power Consumption 190W

External Fuse Rating 3A

Internal Fuse Rating

Fuse 2A Fast Blow to BS 4265

Appliance Category CAT II

2H 3P

Max Gas Rate (Natural Gas - G20)

(After 10 Mins)

m3/h 3.63

ft3/h 128.12

Inlet Pressure (Natural Gas - G20)

mbar 20

in wg 8

Burner Injector (Natural Gas - G20)

15 x 1.28mm Diameter

Burner Pressure (Natural Gas - G20)

Max Rate Min Rate

mbar 13.4 ± 0.5 1.8 ± 0.2

in wg 5.36 ± 0.2 0.72 ± 0.2

Appliance Type C

NOxClass 3

Electrical Protection

IPX5D

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 have been certified by 0051.

SEDBUK Declaration For Combi Instant 105e

The seasonal efficiency (SEDBUK) is 78.5 %

200 400 600 800 1000 1200

0.5

1.5

2.5

3.5

Metre wg

l/h

Pump - Available Head

4.5

5.5

LPG Gases Propane - G31

Burner Injector 15 x 0.77mm diameter

Burner Pressure

Propane mbar

in wg

Inlet Pressures

mbar in wg

Max Rate

35.8 ±0.5

14.3 ±0.2

Min Rate

4.9 ±0.2 2 ±0.2

14.8

5.0 Dimensions and Fixings

Dimensions

A 780mm

B 345mm

C 450mm

D 107mm Ø Min.

E 200mm

F 190mm

G 143mm

360° Orientation

Tube Ø 100mm

Domestic Hot

Water Outlet

(15mm)

Cold Water

Inlet

(15mm)

Heating

Return

(22mm)

Heating

Flow

(22mm)

Pressure Relief

Valve

(15mm)

Gas

Inlet

(22mm)

65 mm

65 mm 65 mm

65 mm

Tap Rail

6.0 System Details

6.1 Information

1. The Baxi Combi Instant 80e and 105e Combination Boilers are ‘Water Byelaws Scheme - Approved Products’. 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 116 - Byelaw 90 and 91. c) 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 Central Heating Circuit

1. The appliance is suitable for fully pumped SEALED SYSTEMS ONLY.

Treatment of Water Circulating Systems

• All recirculatory water systems will be subject to corrosion

unless an appropriate water treatment is applied. This means that the efficiency of the system will deteriorate as corrosion sludge accumulates within the system, risking damage to pump and valves, boiler noise and circulation problems.

• For optimum performance after installation this boiler and

its associated central heating system must be flushed. A means of achieving this is by following the guidelines given in BS 7593 “Treatment of water in domestic hot water central heating systems”.

• This must involve the use of a proprietary cleanser, such as

BetzDearborn Sentinel X300 or X400, or Fernox Superfloc. Full instructions are supplied with the products, but for immediate information please contact BetzDearborn (+44 (0)151 420 9563) or Fernox (+44 (0)1799 550 811) directly.

• For long term protection against corrosion and scale, after

flushing it is recommended that an inhibitor such as BetzDearborn Sentinel X100, or Fernox MB-1 or Copa used. The correct dosing is obtained by following the guidelines given in BS 7593.

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

• 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.)

• For information or advice regarding any of the above

contact the Technical Enquiries.

6.3 Bypass

1. The boiler is fitted with an automatic integral bypass.

6.4 System Control

1. The boiler is designed for use in a heating system that

incorporates external controls, i.e. a minimum of a timer

device.

2. Suitable timer kits are available as optional extras.

3. For optimum operating conditions and maximum

economy the fitting of a programmable room thermostat,

such as the Baxi Combi Controller, is recommended.

6.0 System Details

6.5 System Filling and Pressurising

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. There are connection points on the mains cold water

inlet and central heating return isolating taps (Fig. 4a) to

which the optional filling loop kit (Part No. 248221) can

be assembled.

3. The filling method adopted must be in accordance

with al relevant water supply regulations and use

approved equipment.

4. Your attention is drawn to: for GB: Guidance G24.2

and recommendation R24.2 of 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)

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 80 litres. For greater system capacities

an additional expansion vessel must be fitted - refer to

BS 7074 Pt 1.

6.7 Pressure Relief Valve (Fig. 5)

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.

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.

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.

Fig. 5

Stop Valve

Double Check Valve

DHW Mains Inlet

CH Return

Temporary Hose

Pressure Relief Valve

Filling Loop

Discharge Pipe

Fig. 4

Fig. 4A

Stop Valve

6.0 System Details

6.8 Domestic Hot Water Circuit (Fig. 6)

1. All DHW circuits, connections, fittings, etc. should be

fully in accordance with relevant standards, the 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”.

3. A single check valve must be fitted as shown in Fig. 6

to prevent backflow to the supply pipe and to ensure

the efficient operation of the expansion vessel which is

required to accommodate the thermal expansion of the

water.

4. When the domestic water system includes any device

which prevents water expanding back towards the

supply (check valve, loose jumpered stopcock, water

meter, water treatment device), then an expansion

vessel must be fitted (e.g. Zilmet 160ml, R

/215bar).

5. If the hot water expansion is not provided for, then

high pressures can develop which may result in damage

to fittings and devices on the system.

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.

Boiler

Other Tap Outlets

Expansion Vessel

To Hot Taps

Check Valve

Pressure Reducer Valve

Stop Tap

Fig. 6

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. If the boiler is sited in an unheated enclosure then it is

recommended to leave the ON/OFF Selector Switch in

the domestic hot water and central heating position to

give frost protection.

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.

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. 7 & 8)

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.

200mm Min

780mm

450mm

200mm Min

5mm Min

450mm Min

For Servicing

Purposes

Fig. 7

Fig. 8

In Operation

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Baxi Combi Instant 80e, Combi Instant 105e Quick Start Manual

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