Vaillant ECOmax VUW 236 EH User guide

ECOmax VUW 236 EH
G.C. No. 47 044 23
ECOmax VUW 286 EH
G.C. No. 47 044 24
Wall hung room sealed fan assisted
condensing combination boilers
INSTRUCTIONS FOR INSTALLATION AND SERVICING
HEATING, CONTROLS, HOT WATER

2
Page
1. Introduction 3
2. Boiler Specification 4
2.1 Technical Data 4
2.2 Dimensions 5
2.3 Boiler connections 5
2.4 Function diagram 6
3. General Requirements 7
3.1 Related documents 7
3.2 Boiler location 8
3.3 Gas supply 9
3.4 Flue system 9
3.5 Air suply 11
3.6 Electricity supply 11
3.7 Guide to system requirements 11
4. Boiler installation sequence 14
4.1 General 14
4.2 Boiler delivery 14
4.3 Preparation of boiler location 15
4.4 Pipework connections 17
4.5 Installing the flue system 18
4.6 Mounting the boiler 18
4.7 Connecting the flue assembly 20
4.8 Electrical installation 22
4.9 Controls 23
5. Commissioning 25
5.1 Preliminary electrical checks 25
5.2 Gas supply 25
5.3 Water supply 25
5.4 Filling the heating system 26
5.5 Initial system flush ('cold') 26
5.6 Filling condensate trap 27
5.7 Initial lighting 27
5.8 Gas inlet working pressure 28
5.9 Adjusting central heating
output (range rating) 28
5.10 Main burner pressure 29
5.11 Functional checks 30
5.12 Checking flame
supervision device 32
5.13 Final system flush ('hot') 33
5.14 Fitting case 33
5.15 Handing over to user 33
Page
6. Servicing 34
6.1 Initial inspection 35
6.2 Routine maintenance 35
6.3 Recommisioning the boiler 37
7. Parts replacement 38
7.1 Initial preparation 38
7.2 Fan 40
7.3 Air pressure sensor 41
7.4 Burner 41
7.5 Electrodes 42
7.6 Condensate sump 43
7.7 Condensate trap 44
7.8 Temperature sensors (NTCs) 44
7.9 Gas valve 44
7.10 Main Heat exchanger 45
7.11 CH expansion vessel 46
7.12 Main safety isolating
transformer 47
7.13 Ignition transformer 48
7.14 Pump 48
7.15 Automatic air release 49
7.16 Automatic bypass 49
7.17 Diverter valve 50
7.18 Pressure gauge 51
7.19 Water section 51
7.20 DHW microswitch 52
7.21 DHW heat exchanger 53
7.22 Circuit boards 53
8. Fault finding 57
8.1 Introduction 57
8.2 Logical fault finding procedure 58
8.3 Fault finding using fault mode 60
8.4 Fault diagnosis using
status mode 62
9. Electrical diagrams 65
9.1 Functional flow diagram 65
9.2 Wiring diagram 66
9.3 Schematic appliance
circuit diagram 67
10. Short parts list 68
11. Supplementary information
for ECOmax 70
THE GAS SAFETY (INSTALLATION AND
USE) REGULATIONS 1994:
`In your own interest, and that of
safety, it is law that all gas appliances
are installed by competent persons, in
accordance with the above regula-
tions. Failure to install appliances
correctly could lead to prosecution.'
Leave these instructions with the user
when the installation is completed.

33
1. Introduction Note: This boiler must be installed and
serviced by a competent person in
accordance with the Gas Safety
(Installation and Use) Regulations
1994. In the U.K. `CORGI' Registered
Installers undertake the work to a safe
and satisfactory standard.
ECOmax is a fully automatic, wall
mounted, room sealed, condensing
(high efficiency) combination boiler
for central heating and domestic hot
water. Domestic hot water is supplied
directly from the boiler, and has priority
over the central heating. (This has the
advantage that no copper cylinder,
cold water tank, feed and expansion
tank and associ-ated pipework are
required).
The boiler has been designed for use
with sealed systems, and comes fully
tested and assembled with built-in
circulating pump, bypass, expansion
vessel and diverter valve.
The boiler, because it has a larger
heat exchanger, extracts more heat
from the flue gases. The conversion of
this otherwise wasted heat into usable
warmth means the boiler has a higher
efficiency. Because the flue gases are
reduced to such a low temperature,
the water vapour contained in them
can condense. To discharge this con-
densate a drain is provided on the
boiler, and this must be connected to
a drainage point on site.
The boiler features a comprehensive
diagnostic system, which gives de-
tailed information on the boiler status
when operating and performance of
key components to aid in commis-
sioning and fault finding.
ECOmax range consists of models
with outputs for domestic hot water
of 22.7 and 28.3 kW. The boiler is
easily sited on any internal wall
and can be installed with either a
horizontal or vertical RSF (Room
Sealed Fan assisted) flue. Flue
extensions and additional bends and
elbows are available for increased
siting flexibility. (The boiler is not
suitable for external installation).
If desired, an inhibitor may be used
in the system. Guidance on the use
of inhibitors is contained in these
instructions. (The boiler does not utilise
aluminium in the water system and
does not require a special inhibitor).
The boiler is designed to operate on
Natural Gas only.
The boiler contains a domestic hot
water heat exchanger. The temperatu-
re in the heat exchanger is limited by
the boiler control system and it is not
normally necessary to install a scale
reducer on the cold mains inlet to the
boiler. However, in exceptionally hard
water areas to prevent scale formation
in the property hot water system pipe-
work a scale reducer may be fitted.
The data badge is fitted on the com-
bustion chamber cover.
ECOmax boilers carry the „CE” Mark.
This demonstrates that the boilers fulfill
the essential requirements of the Gas
Appliance Directive (90/396/EEC)
and the Gas Appliance (Safety)
Regulations 1992.
The „CE” Mark also demonstrates
that the boilers comply with the
requirements of the Electromagnetic
Compatibility Drective
(89/336/EEC), the Low Voltage
Directive (73/23/EEC), the Boiler
Efficiency Directive (92/42/EEC)
and the Boiler (Efficiency) Regulations
1993.

44
ECOmax VUW 236 EH VUW 286 EH units
Countries of Destination GB, IE
Maximum CH heat input 19.5 (66,500) 24.2 (82,600) kW (Btu/h)
CH heat output range
80 °C flow/60 °C return 9.9-17.2 12.3-21.3 kW
(33,800-58,700) 42,000-72,700) (Btu/h)
50 °C flow/30 °C return 10.5-18.0 13.1-22.3 kW
(35,800-61,400) (44,700-76,100) (Btu/h)
Maximum DHW heat input 25.0 (85,300) 31.1 (106,100) kW (Btu/h)
Maximum DHW heat output 22.7 (77,500) 28.3 (96,600) kW (Btu/h)
DHW flow rate @ 35 °C rise 9.3 11.6 l/min
Mains water pressure required for max. flow rate 1.0 1.0 bar
Minimum water flow rate 2 2 l/min
Mains water pressure required for min flow rate 0.2 0.2 bar
Maximum inlet water pressure 10 10 bar
Inlet gas working pressure required (Natural Gas) 20 20 mbar
Gas supply (G20) Gross C.V. (s.t.) 37.8 37.8 MJ/m3
Gas burner pressure max (DHW) 3.0 3.0 mbar
Gas rate max (DHW) 2.38 2.96 m3/h
CH flow temperature range 35-90 35-90 °C
Minimum CH water flow (for 20 °C rise) 770 960 l/h
Pump pressure available 0.25 0.25 bar
12 l expansion vessel pre-charge pressure 0.8 0.8 bar
Maximum CH system pressure 3.0 3.0 bar
Connections
Heating flow / return 3/43/4in. BSP
Cold water inlet 15 15 mm
DHW outlet 15 15 mm
Gas inlet 15 15 mm
Condensate drain (internal diameter, min) 19 19 mm
Pressure relief discharge pipework (min) 15 15 mm
Weight 56 57 kg
Boiler water content 1.5 1.6 litres
Volume of condensate (max.) 0.5 0.6 l/h
Maximum flue gas temperature 70 70 °C
Electrical supply
Voltage 230/50 230/50 V~/Hz
Fuses internal/external 2/3 2/3 A
Power input 130 130 W
2. Boiler specification
2.1 Technical data

55
GW 398/0
fig. 1
2.3 Boiler connections
1 Connection support bracket
2 Service valve (flow of heating
system)
3 Domestic hot water connection
4 Compression Union (gas)
5 Gas service valve (supplied with
the boiler)
6 Cold water connection with
shut-off walve
7 Service valve (return of heating
system)
8 Discharge pipe
9 Pressure relief valve
10 Compression union (return of
heating system)
11 Compression union (flow of
heating system)
14 Boiler condensate drain
23 Frame of appliance (lower
connection)
GW 399/1
fig. 2
2.2 Dimensions
(All dimensions in mm)
1a Air/flue duct to the rear
1b Air/flue duct to the side
2 Appliance bracket
3 Heating system return 3/4” Rp
(3/4” B.S.P.)
4 Cold water connection (15 mm)
5 Gas connection (15 mm)
6 Hot water connection (15 mm)
11 Heating system flow 3/4” Rp
(3/4” B.S.P.)
12 Pre-assembled connection set
with service valves (flow and
return) pressure relief valve,
cold and hot water connection
13 Pressure relief valve 3/4” Rp
(3/4” B-S.P.)
14 Boiler condensate drain
(18 mm O. D.)
* with standard horizontal flue
accessory.
(max. = 6880 mm with extensions)

66
GW 512/1
fig. 3
2.4 Function diagram
1 Air duct
2 Flue gas duct
3 Fully modulating automatic gas
valve
4 Fully modulating fan
5 Fully modulating low NOx burner
6 Combustion chamber
7 Flame sensing electrode
8 High efficiency heat exchanger
9 Condensate trap
10 DHW heat exchanger
11 Boiler display
12 User control panel
13 DHW outlet
14 CH flow service valve
15 Gas service valve
16 Air pressure sensor
17 Ignition electrodes
18 Temperature sensors (NTCs)
19 Expansion vessel charging valve
20 Expansion vessel
21 Automatic bypass valve
22 Automatic air vent
23 Circulating pump
24 Diverter valve
25 Pressure gauge
26 Water section
27 Pressure relief valve
28 CH return service valve
29 Cold water shut off valve

7
3. General requirements 3.1 Related documents
The installation of the boiler must be in
accordance with the relevant require-
ments of Gas Safety (Installation and
Use) Regulations 1994, Health and
Safety Document No. 635 (The Elec-
tricity at Work Regulations 1989),
BS7671 (IEE Wiring Regulations) and
the bylaws of the local Water Under-
taking. It should be in accordance
with any relevant requirements of the
Local Authority, Building Regulations,
Building Standards (Scotland) Regu-
lations and the relevant recommen-
dations of the following British
Standards:-
BS 5440: Flues and ventilation of gas
fired boilers not exceeding 60 kW:
- Part 1: Flues
- Part 2: Ventilation
BS 5449: Specification for forced
circulation hot water for domestic
premises.
BS 5546: Specification for gas hot
water supplies for domestic premises.
BS 6700: Services supplying water
for domestic use within buildings and
their curtilages.
BS 6798: Specification for installation
of gas fired boilers not exceeding
60 kW input.
BS 6891: Specification for installation
of low pressure gas pipework up to
28 mm (R1) in domestic premises
(2nd family gas).
BS 7593: Treatment of water in dome-
stic hot water central heating systems.
BRITISH GAS PUBLICATION DM2:
Guide for Installation in Timber
Framed Housing
Important
The appliance must be installed and
serviced by a competent person as
stated in the Gas Safety (Installation
and Use) Regulations 1994

8
3.2 Boiler location
The location chosen for the boiler must
permit the provision of a satisfactory
flue termination. The location must
also provide adequate space for servi-
cing and air circulation around the
boiler. The boiler may be installed in
any room, although particular atten-
tion is drawn to the requirements of
the I.E.E. Regulations and, in Scot-
land, the electrical provisions of the
Building Regulations, in respect of the
installation of the boiler in a room
containing a bath or shower.
(Note: Where a room sealed boiler is
installed in a room containing a bath
or shower, any electrical switch or
boiler control utilising mains electricity
should be so situated that it cannot be
touched by a person using the bath or
shower).
Where the installation of the boiler
will be in an unusual location, special
procedures may be necessary and BS
5546 and BS 6798 give detailed gui-
dance on this aspect.
The boiler must be mounted on a flat,
vertical wall, which must be sufficient-
ly robust to take the weight of the boi-
ler. The boiler may be installed on a
combustible wall, subject to the
requirements of the Local Authorities
and Building Regulations.
A compartment used to enclose the
boiler must be designed and construc-
ted specifically for this purpose.
(An existing cupboard or compartment
may be used provided that it is modi-
fied for the purpose). Details of essen-
tial features of cupboard/compart-
ment design including airing cup-
board installations are given in
BS 6798.
If the boiler is to be fitted in a timber
framed building, it should be fitted in
accordance with British Gas Publica-
tion DM2 `Guide for Gas Installations
in Timber Framed Housing'.

9
GW 319/0
fig. 4
3.3 Gas supply
The gas supplier should ensure the
availability of an adequate supply of
gas.
A gas meter may only be connected
to the service pipe by the supplier of
gas or their contractor.
An existing meter should be checked
to ensure that it is capable of passing
the rate of gas supply required.
Installation pipes should be fitted in
accordance with BS 6891.
Pipework from the meter to the boiler
must be of an adequate size. Do not
use pipes of a smaller size than the
boiler gas connection (15mm).
The complete installation must be
tested for soundness and purged as
described in BS 6891.
3.4 Flue system
The standard horizontal flue system
(Accy No 300931) is suitable for
installations up to 1 metre measured
from the centre of the boiler flue outlet
to the outside face of the wall
(A, fig. 4). One metre flue extensions
(Accy No 300923) are available to
extend this length up to 6880 mm.
90 ° elbows (Accy No 300934) and
45 ° bends (Accy No 300949) are
also available to increase siting flexi-
bility.
A vertical flue system is also available
(Accy No 300945).
Refer to the flue installation instructions
for full details.

3.4.1 Flue Termination
1. The terminal must be positioned
such that the combustion products can
disperse freely at all times.
2. Flue gases from high efficiency con-
densing boilers are emitted at relative-
ly low temperatures, leading to a ten-
dency for a plume of water vapour to
be visible at or near the terminal.
More care should therefore be taken
when choosing the site for a terminal
of a condensing boiler. If possible
avoid placing the terminal below a
window, next to a door or close to
opposing walls. It is also recommen-
ded that the flue is not terminated
beneath a car port roof.
3. If the terminal is fitted less than 2m
above a balcony, above ground or
above a flat roof to which people
have access then a suitable guard
must be provided and fitted (available
from Tower Flue Components,
Tonbridge, TN9 1TB: reference
CGDK3BL).
Table 1:
Terminal position for fan-assisted flue.
(minimum distance - see fig. 5) mm
A- Directly below an openable
window or other opening
(e.g. air brick) 300
B- Below gutters, soil pipes
or drain pipes 751
C- Below eaves 2001
D- Below balconies 2001
E- From vertical drain pipes
and soil pipes 25
F- From internal or external
corners 3002
G-Above ground or balcony
level 300
H- From a surface facing a
terminal 600
I- From a terminal facing a
terminal 1200
K- Vertically from a terminal
on the same wall 1500
L- Horizontally from a
terminal on the same wall 300
M-Distance from adjacent
wall for Vertical Flue 500
10
2Dimension F: This clearance may be
reduced to 25mm without affecting
the performance of the boiler.
However, in order to ensure that the
condensate plume does not affect
adjacent surfaces a clearance of
300 mm is preferred.
fig. 5
GW 524/0
1 Dimensions B, C and D: These clear-
ances may be reduced to 25mm with-
out affecting the performance of the
boiler. In order to ensure that the con-
densate plume does not affect adja-
cent surfaces the terminal should be
extended as shown in fig. 6.
fig. 6
GW 445/0
Note: Vertical flues must not terminate
within 600 mm of an openable win-
dow, air vent or any other ventilation
opening.

11
3.5 Air supply
Detailed recommendations for air sup-
ply are given in BS 5440: Part 2.
It is not necessary to have an air vent
in the room or internal space in which
the boiler is installed.
3.5.1 Cupboard or compart-
ment air supply
ECOmax Room Sealed Condensing
Combination Boilers are very high
efficiency appliances. As a conse-
quence the heat loss from the
appliance casing during operation
is very low. For cupboard and
compartment installations it is there-
fore not necessary to provide any high
or low level permanent air vents for
cooling purposes.
3.6 Electricity supply
A 230 volts~ 50Hz single phase elec-
tricity supply fused to 3 amps must be
provided in accordance with the latest
edition of the I.E.E. Wiring Regulati-
ons and any other local regulations
that may apply.
THIS APPLIANCE MUST BE EARTHED.
The method of connection to the mains
electricity supply must provide a
means of completely isolating the boi-
ler and its ancillary controls. Isolation
is preferably by the use of a fused
three-pin plug and unswitched shut-
tered socket outlet, both complying
with the requirements of BS 1363.
Alternatively, a 3 Amp fused double-
pole switch with a 3mm contact sepa-
ration on both poles may be used.
3.7 Guide to system
requirements
3.7.1 Water circulation system
Detailed recommendations for the
water circulation system are given in
BS 6798 and BS 5449: Part 1 (for
small bore and micro bore central
heating systems).

12
fig. 7
GW 400/0
Pipework not forming part of the use-
ful heating surface should be insulated
to help prevent heat loss and possible
freezing, particularly where pipes are
run through roof spaces and venti-
lated underfloor spaces.
Draining taps must be located in
accessible positions which permit the
draining of the whole system including
the boiler and the hot water system.
Draining taps should be at least
1/2in. BSP nominal size and be in
accordance with BS 2879.
The boiler is suitable for use with mini-
bore or microbore systems. Copper
tubing to BS 2871: Part 1 should be
used for water carrying pipework. All
capillary joints in the DHW pipework
must be made with lead free solder.
Particularly where a new boiler is to
be fitted to an existing system, it is
good practice that the system is
thoroughly cleansed. This cleansing
should take place prior to the fitting of
the new boiler and be in accordance
with BS 7593.
For advice on the application of
system cleansers contact sentinel,
Grace Dearbom Ltd.
Widnes., Cheshire, WA8 8 UD.
Tel.: [phone]
3.7.2 Filling and make up
The system should be filled with water
via a separate filling point fitted at a
convenient point on the heating cir-
cuit. Where local Water Authority
Regulation allows, a temporary con-
nection to the mains may be used
(fig. 7). The connection must be
removed when filling is completed.
Where local Water Authority Regula-
tion does not allow temporary connec-
tion, a sealed system filler pump with
break tank must be used. The heating
system will not be filled automatically
from the domestic side.
(Alternative methods of filling sealed
systems are given in BS 5449).
Heating
circuit
return Double check
valve assembly
Stop
valve
Test
valve
Hose
unions
Mains
water
supply
Temporary
Hose
fig. 8
GW 401/0
3.7.3 Pressure relief valve
A pressure relief valve is provided rea-
dy-assembled to the return C.H. ser-
vice valve (4, fig. 8). This safety devi-
ce is required on all sealed C.H.
systems and is pre-set at 3 bar and
provided with a 3/4 in. BSP connec-
tion for a discharge pipe (minimum
size 15mm).

Safety valve setting (bar) 3.0
Initial system pressure (bar) 1.0 1.5
Total water content of system VESSEL VOLUME (L)
litres
25 2.7 3.9
50 5.4 7.8
100 10.9 15.6
125 13.6 19.5
150 16.3 23.4
175 19.1 27.3
200 21.8 31.2
225 24.5 35.1
250 27.2 39.0
275 30.0 42.9
300 32.7 46.8
325 35.7 50.7
350 38.1 54.6
375 40.9 58.5
400 43.6 62.4
425 46.3 66.3
450 49.0 70.2
475 51.8 74.1
500 54.5 78.0
For system volumes other than
those given above, multiply 0.109 0.156
the system volume by the factor
across
13
fig. 9
GW 402/0
3.7.4 Pressure gauge
This is factory fitted to the boiler and
indicates the primary circuit pressure
to facilitate filling and testing.
3.7.5 Expansion vessel
An expansion vessel is incorporated
into the boiler suitable for a sealed
heating system with a maximum water
contents of 135 litres.
If the nominal capacity of the built-in
expansion vessel is not sufficient for
the heating system (for instance in
case of modernization of old open
systems) an additional expansion ves-
sel can be installed external to the boi-
ler in the return pipe as close as pos-
sible to the boiler in accordance with
BS 5449: Part 1.
Guidance on the sizing of an addi-
tional expansion vessel is given in
Table 2.
3.7.6 Circulating pump
The circulating pump is included in the
boiler. The pump head available for
the heating system is shown in fig. 9.
3.7.7 System by-pass
An automatic system by-pass is inclu-
ded within the boiler. The boiler is
suitable for use in systems with
thermostatic radiator valves and no
additional by-pass is required.
3.7.8 Venting
The boiler is fitted with an automatic
air vent. Additional provision should
be made to enable the heating system
to be vented during filling and com-
missioning either by automatic air
vents or manually.
3.7.9 DHW expansion vessel
accessory
A DHW expansion vessel kit (Accy.
No. 8070) is available as an optional
extra from Vaillant Ltd. This expansion
vessel kit should be fitted to the boiler
whenever either a stop valve of the
loose jumper type or a non return
valve are present in the cold water
mains supply to the boiler (fig. 10).
Table 2: Sizing of Additional Expansion Vessel
fig. 10
GW 494/0

14
fig. 11
GW 403/0
4. Boiler installation
sequence
4.1 General
The boiler should be mounted on a
flat and vertical area of wall of suf-
ficient area for the boiler plus the
required minimum clearances for
installation and servicing (fig. 11).
These are shown on the installation
template supplied with the boiler and
are:-
5 mm either side of the boiler
150 mm below the boiler
165 mm on top of the boiler
500 mm in front of the boiler *
* This clearance is only required to
enable easier access to the boiler for
servicing and may be provided by an
openable door, etc.
NOTE: If the boiler is to be fitted in a
timber framed building, it should be
fitted in accordance with British Gas
publication reference DM2 'Guide for
gas installations in timber framed hou-
sing.'
4.2 Boiler delivery
ECOmax is delivered in three packs:
a. the carton containing the boiler
b. separately boxed connection group
(Accy No.9313)
c. separately boxed flue accessory,
either:
•1m horizontal flue accessory
(Accy No. 300931); or
•vertical flue accessory
(Accy No. 300945)

15
4.2.1 Installation accessories
Table 3 lists the standard and optional
accessories which are available for
ECOmax.
4.2.2 Unpack the boiler
(fig. 12)
Open the boiler carton and remove:
a. protective cardboard sheet
b. top and bottom decorative panels
c. polystyrene packaging
NOTE: Care should be taken not to
scratch the white powder coated sur-
face of the boiler casing.
Packed in the boiler carton are the
following:
•boiler installation template
•boiler hanging bracket
•gas service valve and adaptor
•fixing screws and wallplugs
•installation and user instructions
4.3 Preparation of boiler
location
4.3.1 Select position of boiler.
Refer to Section 3.2 `Boiler Location'
for information regarding siting the
boiler. In general the boiler must be
positioned such that:
•there is adequate space around the
boiler for service and maintenance
•the boiler can be correctly flued,
i.e. the flue terminal position is sited
in accordance with Section 3.4.1
and the air / flue duct can be
installed in accordance with the
flue installation instructions
supplied.
•all necessary pipework can be
connected, including the pressure
relief valve discharge pipe and the
condensate drain.
fig. 12
GW 405/0
Table 3: Installation Accessories
Standard Accessories Accy. No.
1)Pre-assembled connection group 9313
incl. isolating valves
(flow and return), pressure
relief valve, cold and hot
water connections
2)Air/flue duct assembly 300931
incl. terminal (horizontal)
Optional Accessories Accy. No.
3)Air/flue duct assembly 300945
incl. terminal (vertical)
4)Pitched roof adjustable roof tile 9076
5)Flat roof penetration collar 9056
6)Extension: (1 m) for the 300923
standard air/flue duct
assembly (optional extra)
7)Additional 90 ° elbow 300934
8)Additional 45 ° bends (pair) 300949
9)Internal flue fixing kit 8098
10) Pipe cover accessory 8099

16
4.3.2 Using the boiler template
(fig. 13)
4.3.2.1 Once a suitable location has
been chosen, fix the paper installation
template on the wall ensuring that the
centerline of the template is vertical
using a spirit level or plumb line.
The template shows the positions of
the fixing holes for the boiler hanging
bracket and connection group. The
template also shows the position of
the flue exit hole, for use where the
air flue duct is to be installed directly
to the rear of the boiler, e.g. where
the boiler is installed on an outside
wall and the flue terminates directly
behind.
4.3.2.2 Mark on the wall the positi-
ons of the hanging bracket (2) and
connection group fixing holes (3). Drill
two holes Ø 10 mm for the hanging
bracket, and similarly drill three holes
Ø 8 mm for the connection group.
(Note: Use the alternative fixing holes
where necessary).
4.3.2.3 Rear exit flue.
Mark the position of the centre of the
flue duct and its circumference, e.g.
by drilling through the template (1).
4.3.2.4 Other flue options.
Refer to the installation instructions
supplied with the flue accessory for
detailed instructions on other flue op-
tions such as vertical RSF flues, flue
runs to the side of the boiler and the
use of additional flue elbows and
bends etc.
4.3.2.5 Remove the template from the
wall and plug the drilled holes using
the wallplugs supplied.
4.3.3 Fitting the boiler hanging
bracket and connection
group.
Secure the hanging bracket and
connection group securely to the wall
using the screws supplied. (If the con-
dition of the wall is poor it may be
necessary to use additional or alterna-
tive fixings to ensure adequate sup-
port).
NOTE: If the boiler is to be fitted in a
timber framed building ensure that the
brackets are secured to a substantial
part of the timber frame capable of
taking the weight of the boiler.
fig. 13
GW 426/0

17
fig. 14
GW 406/0
4.4 Pipework connections
(fig. 14)
Figure 14 shows the central heating,
domestic hot water, mains cold water
and pressure relief valve connections.
4.4.1 Central heating flow
and return
Before connecting the heating circuit
to the connection group, all pipework
and radiators must be thoroughly
flushed to remove any installation
debris. Connect the flow and return
pipes to the central heating service
valves (8) and (9) on the connection
group using compression adaptors.
4.4.2 Cold mains water inlet
and hot water outlet
Flush out all foreign matter from the
mains supply pipe before connecting
to the boiler.
Connect the mains water supply (3)
and hot water outlet pipes (4) to the
15 mm compression connections pro-
vided.
Note: The boiler has a maximum
domestic water working pressure of
10 Bar. If the cold mains supply pres-
sure exceeds 10 Bar, a pressure red-
ucing valve must be fitted to the cold
water inlet.
4.4.3 Pressure relief valve
discharge
The connection group contains the
pressure relief valve required for a
sealed system (5). Connect a dis-
charge pipe not less than 15 mm dia-
meter to the Rc 3/4outlet of this valve
using a compression adaptor.
This discharge pipework should be as
short as possible and installed with a
continuous fall away from the boiler.
The pipe should terminate in a posi-
tion which ensures that any discharge
of water or steam from the valve can-
not create a hazard to persons in or
about the premises, or damage to any
electrical components or external
wiring, and the point of discharge
should be clearly visible. The dis-
charge must not terminate above a
window, an entrance or any type of
public access. The installer must con-
sider that the pipe could discharge
boiling water.
Key:
1 CH Flow pipe
2 CH Return pipe
3 Cold Mains water supply
4 DHW outlet
5 CH Pressure relief valve (PRV)
6 PRV discharge pipe
7 Cold Mains water service valve
8 CH Flow service valve
9 CH Return service valve

18
fig. 15
VC/VCW 442/2
fig. 16
GW 424/0
4.5 Installing the flue system
At this stage install the flue system
(refer to separate air/flue duct installa-
tion instructions).
4.6 Mounting the boiler
4.6.1 Preparation (fig. 15)
Remove the boiler from the carton.
Lay the boiler on its back and remove
the four plastic sealing caps from
boiler flow and return and domestic
water connections.
On the connection group close the CH
service valves (8), unscrew the union
nuts (6) and remove plastic sealing
plugs.
Close cold mains water service valve,
unscrew union nuts (4), remove and
discard plastic sealing plug. (Take
care not to lose sealing washers!)
Slide the 22 mm nuts (6) and olives
(5) over the flow and return tails of the
boiler as far as possible. Fix these
temporarily in this position using tape
or similar.
4.6.2 Fitting the boiler (fig. 16)
Lift the boiler up to the wall so that it is
slightly above the connection group.
Lower the boiler slowly onto the
connection group so that:
•the flow and return tails of the boi-
ler engage into the top of the CH
service valves
AND
•the cross member at the top rear of
the boiler slots into the hanging
bracket.
Remove the tape (or similar) used to
secure the nuts and olives on the flow
and return tails, slide these down onto
the CH service valves and tighten.
Align the cold and hot water connec-
tions with the boiler, fit the sealing
washers and tighten. (If necessary
adjust the position of the hot and
cold water connection pipes by loose-
ning the locking nuts on the connec-
tion group).

19
fig. 17
GW 407/1
fig. 18
GW 525/0
4.6.3 Gas supply (fig. 17)
The boiler is supplied with a 20 mm x
15 mm gas service valve (7). Fit the
20 mm compression fitting to the
boiler gas inlet (3) and tighten. Install
a gas supply pipe not less than 15 mm
diameter and connect to the gas service
valve. (Ensure the gas supply pipework
is adequately sized such that a 20 mbar
- 8" w.g. – gas pressure is available
at the boiler inlet at full flow rate).
Tighten all union connections.
4.6.4 Condensate discharge
(fig. 18)
Insert the boiler condensate drain (1)
by at least 50 mm into a condensate
discharge pipe (2). The condensate
discharge pipe should be minimum
19 mm internal diameter and be
made of an acid resistant material
(e.g. plastic overflow pipe).
The discharge pipe from the boiler
condensate drain must have a conti-
nous fall and preferably be installed
and terminated within the building to
prevent freezing.
The discharge pipe must terminate in
a suitable position, e.g.:-
connecting into the internal stackpi-
pe of the property (at least 450 mm
above the invert of the stack). A
trap giving a water seal of at least
75 mm (3) should be incorporated
into the pipe run, and there must be
an air break (4) in the discharge
pipe upstream of the trap.
connecting into the internal dischar-
ge system of the property such as a
sink or washing machine waste.
The connection should be upstream
of the sink / washing machine
waste trap. (If the connection is
downstream of the waste trap then
an additional trap giving a water
seal of at least 75 mm (3) and an
air break (4) must be incorporated
into the pipe run, as (a)).
terminating in a gulley (5) below
grid level (6) and above the water
level.
at a condensate absorption point
('soakaway')-7.
O
a
O
b
O
c
O
d

20
fig. 19
GW 411/1
fig. 20
GW 333/0
fig. 21
GW 334/0
fig. 22
GW 335/0
Note:
If it is necessary to install any conden-
sate pipework externally, then it
should be kept as short as possible,
be insulated with waterproof insu-
lation and have a continuous fall of at
least 2.5 ° (i.e. 45mm fall for every
metre length).
Refer to the British Gas publication
`Guidance notes for the installation of
domestic condensing boilers' for
further information.
Before operating the boiler the con-
densate trap on the boiler (1, fig. 19)
must be filled with water as described
in Section 5.6 `Filling condensate
trap'.
4.7 Connecting the flue
assembly to the boiler
(Note: Refer to the air/flue duct instal-
lation instructions for full details of
installation of the air flue duct. This
Section is included for further refer-
ence only, e.g. in case the boiler has
to be removed from the wall.)
4.7.1 Horizontal Flue
Place a 95 mm diameter x 88 mm
long air duct clamp (1, fig. 20) over
the air duct.
Push the sliding sleeve (1, fig. 21)
over the cut end of the flue duct.
Fit the flue elbow to the boiler by
inserting the spigot of the flue elbow
into the flue outlet socket of the boiler.
When correctly fitted the air duct of
the flue elbow should butt up to the
boiler air duct.
Line up the flue elbow socket with the
air/flue duct and pull back the sliding
sleeve so that it engages into the
socket of the flue elbow (fig. 22). The
sliding sleeve must penetrate the flue
elbow socket such that there is at least
20 mm engagement at both ends of
the sliding sleeve (fig. 23)