Baxi Boston 2 80 OF User guide

Please leave these Instructions with the User.
Baxi Boston 2 OF
Floor Standing Open Flue
Gas Fired Central Heating Boilers
Natural Gas
Comp N° 235305 - Iss 8 - 4/00
Installation and
Servicing Instructions

Installation Instructions - Page 2
Natural Gas INTRODUCTION
Baxi Boston 2 80 OF
G.C. N° 41 077 84
Baxi Boston 2 70 OF
G.C. N° 41 077 83
Baxi Boston 2 60 OF
G.C. N° 41 077 82
Baxi Boston 2 50 OF
G.C. N° 41 077 81
Baxi Boston 2 40 OF
G.C. N° 41 077 80
Baxi Limited is one of the leading manufacturers of domestic
heating products in the UK.
Our first priority is to give a high quality service to our
customers. Quality is built into every Baxi product - products
which fulfil the demands and needs of customers, offering
choice, efficiency and reliability.
To keep ahead of changing trends, we have made a
commitment to develop new ideas using the latest
technology - with the aim of continuing to make the products
that customers want to buy.
Baxi is also the largest manufacturing partnership in the
country. Everyone who works at the company has a
commitment to quality because, as shareholders, we know
that satisfied customers mean continued success.
We hope you get a satisfactory service from Baxi. If not,
please let us know.
The Boston 2 OF is a range of Floor Standing Open Flue
Boilers. There is a choice of outputs listed below:
The boilers share a common outer case within which there is
adequate space to fit a central heating pump using standard
fittings.
All appliances are designed for use on Gas Type G20
(Natural Gas) only, at supply pressure 20 mb.
Each appliance consists essentially of two components,
namely:
1. COMBUSTION CHAMBER with heat exchanger,
burner and controls.
2. OUTER CASE.
“Benchmark” Log Book
As part of the industry-wide “Benchmark” initiative all
Baxi boilers now include an Installation, Commissioning
and Service Record Log Book. Please read the Log
Book carefully and complete all sections relevant to the
appliance and installation. These include sections on
the type of controls employed, flushing the system,
burner operating pressure etc. The details of the Log
Book will be required in the event of any warranty work.
Also, there is a section to be completed at each
subsequent regular service visit.
The boilers listed below meet requirements of Statutory
Instrument ‘The Boiler (Efficiency) Regulations 1993 No
3083’ and therefore are deemed to meet the requirements of
Directive 92/42/EEc on the efficiency requirements for new
hot water boilers fired with liquid or gaseous fuels.
Boston 2 - 80 OF - G.C.N° 41 077 84
Boston 2 - 70 OF - G.C.N° 41 077 83
Boston 2 - 60 OF - G.C.N° 41 077 82
Boston 2 - 50 OF - G.C.N° 41 077 81
Boston 2 - 40 OF - G.C.N° 41 077 80
Type test for the purposes of Regulation 5 certified by:
NOTIFIED BODY 0086
Baxi is a BS-EN ISO 9001
Accredited Company Product/production certified by:
NOTIFIED BODY 0086

Installation Requirements - Page 3
GENERAL
The installation must be carried out by a Corgi Registered
Installer or other competent person and be in accordance
with relevant BS Codes of Practice, I.E.E. Regulations, Gas
Safety Regulations, Building Regulations and by-laws of the
Local Water Undertaking. References should be made to BS
6891, BS 6798, BS 5440 Pt 1 & 2, BS 5449, BS 5546 and
BS 1363.
IMPORTANT INFORMATION
VENTILATION
Detailed recommendations for air supply are given in BS
5440:2.
The following notes are intended to give general guidance.
The room in which the open flue unit is situated requires an
air vent which should be direct to outside or to a room which
itself has an air vent direct to outside. Where the boiler is in
a compartment with air vents direct to outside, the room
containing the compartment does not require the provisions
This product contains Refractory Ceramic Fibres (R.C.F.)
which are man-made vitreous silicate fibres. Excessive
exposure to these materials may cause temporary irritation
to eyes, skin and respiratory tract. Care must be taken when
handling these articles to ensure the release of dust or fibres
is kept to a minimum. To ensure that the release of fibres
from these articles is kept to a minimum, during installation
and servicing it is recommended that a H.E.P.A. filtered
vacuum is used to remove any dust, soot or other debris
accumulated in and around the appliance. This should be
of additional ventilation.
The actual minimum
effective area
requirements of
cupboard/compartment
air vents are based
upon the rated input of
the appliance.
performed before and after working on the installation. It is
recommended that any replaced item(s) are not broken up
but sealed within heavy duty polythene bags and clearly
labelled “R.C.F. waste”. This is not classified as “hazardous
waste” and may be disposed of at a tipping site licensed for
the disposal of industrial waste. Protective clothing is not
required when handling these articles but it is recommended
that gloves are worn and the normal hygiene rules of not
smoking, eating or drinking in the work area are followed and
always wash hands before eating or drinking.
SITING
The boiler must be fitted on a suitable outside or inside wall
with due considerations of the open flue requirements.
It should not be installed in a bathroom, bedroom or bed
sitting room.
A new or existing cupboard or compartment used to enclose
the boiler must be constructed specifically for this purpose.
Details of essential features of Cupboard / compartment
design are given in BS 5440:2.
CLEARANCES
The minimum vertical areas required for the appliances
depend on the appliance rating and its application. The
details are given in Fig 5.
We recommend the use of the Stadium BM729 “Black Hole”
ventilator which is available from your local merchant.
Ventilation areas required:
FLUE ARRANGEMENT
The 80, 70 OF are intended for connection with 125mm (5
in) flue tube. The 60, 50 and 40 OF are intended for
connection with 100mm (4 in) flue tube.
For full information on flues refer to BS 5440, but the general
requirements are as follows:
1) The flue should be kept as short and as warm as
possible.
2) Give maximum possible vertical rise from the appliance
before using any bends (preferably at least 600mm (24
in)). Avoid the use of right angled bends.
3) Terminate in an approved terminal preferably above
ridge height but at least above the eaves of a pitched
roof.
4) If Twin-wall type flue tubing is to be used the inner
tubing of the boiler adaptor must not project into the
draught diverter of the boiler. A boiler adaptor which
meets this requirement is obtainable.
5) An existing brick chimney should be lined with acid and
moisture resistant materials such as stainless steel
flexible flue pipe. This is particularly important if the flue
is above 6.5 metres (20 ft) in height and not wholly
internal.
WHETHER OR NOT THE CHIMNEY IS TO BE LINED
IT MUST BE SWEPT THOROUGHLY BEFORE THE
INSTALLATION.
6) Whatever type of flue is used it must be properly
supported and not simply supported on the boiler.

Water Circulation Systems - Page 4
(see page 8)
The appliances are only suitable for connection to a cistern
supply and can be used with:-
1) Open vented pumped domestic hot water and pumped
central heating systems.
2) Gravity flow domestic hot water and pumped central
heating systems.
(a) With 28mm pipes the minimum circulating head
for gravity domestic hot water should not be less
than 1m (3ft 3in) measured vertically from the flow
connection on the boiler to the flow connection on
the cylinder. At this head, the maximum horizontal
distance measured along the run of the pipe
should not exceed 3m (10ft). Greater horizontal
distances and smaller pipe sizes are acceptable
with suitably increased heads. Allowances must
be made for pipe bends where necessary.
(b) If the above conditions are not easily met then
pumped primaries should be used.
(c) Gravity flow and return pipes should be laid to
maximum fall to avoid air locks.
The following points are of particular importance:
1) THE WATER SPREADER MUST BE FITTED TO THE
PUMPED RETURN CONNECTION ON ALL
SYSTEMS.
2) The appliances must not be used on sealed systems.
3) The system must be designed to avoid reverse
circulation.
4) The static head must not exceed 30m (100ft) of water.
5) The boilers must only be used with an indirect cylinder
when domestic hot water is required.
6) Drain points should be fitted at the lowest points in the
system.
7) The system must be designed such that gravity
circulation in the heating system does not take place
when the pump is not running.
8) In systems using non-metallic pipework it is necessary
to use copper pipe for the boiler Flow and Return. The
copper must extend at least 1 metre from the boiler and
include any branches.
GAS SUPPLY
The gas connection is located at the bottom left hand side of
the appliance and is Rc½ (½ in B.S.P.T. internal). Ensure
that the pipework from the meter to the appliance is of
adequate size. Do not use pipes of a smaller size than the
appliance gas connection.
ELECTRICAL SUPPLY
External wiring must be correctly earthed and polarised and
in accordance with I.E.E. Regulations.
For wiring instructions see ‘Electrical Connections’.
Treatment of Water Circulating Systems
For optimum performance after installation, this boiler and its
associated central heating system must be flushed in
accordance with the guidelines given in BS7593:1992
“Treatment of water in domestic hot water central heating
systems”.
This must involve the use of a proprietry cleanser, such as
BetzDearborn’s Sentinel X300 or X400, or Fernox’s
Superfloc. Full instructions are supplied with the products but
for immediate information please contact BetzDearborn on
0151 420 9563, or Fernox on 01799 550811.
For long term protection against corrosion and scale, after
flushing it is recommended that an inhibitor such as
BetzDearborn’s Sentinel X100, or Fernox’s MB-1 or Copal is
dosed in accordance with the guidelines given in
BS7593:1992.
Failure to flush and add inhibitor to the system may
invalidate the appliance warranty.
APPLIANCE DETAILS (all models)
HEIGHT 900mm (35½ in)
WIDTH 395mm (15½ in)
FORWARD PROJECTION
FROM THE WALL 535mm (21 in).
BOILER TAPPINGS 4 x Rp1 (1 in BSP internal) and
1 x Rp¾ (¾ in BSP internal)
ELECTRICAL SUPPLY 230V~50Hz - 3 amp fuse
GAS CONNECTION RC½ (½ in BSPT internal)
MAX. WORKING HEAD 30m (100ft)
THERMOCOUPLE OUTPUT 10 - 15mv
HYDRAULIC RESISTANCE CHARTS

Fitting the Appliance - Page 5
PREPARATION
1) A sound and level floor which conforms to the
requirements of the Local Authorities and Building
Regulations must be provided.
2) Select the most suitable position for the boiler taking
due account of any clearances required for the safe
and proper functions of the boiler and its associated
controls.
3) Manoeuvre the boiler into position so that the two
spacer pips on the rear of the draught diverter touch the
wall.
4) Connect the water flow and return pipes (see Boiler
Connections).
5) Connect the flue pipe, making sure that the flue trim is
placed in position before the final connection is made.
6) Complete the gas connection to the boiler.
7) Partially fit the outer case.
8) Connect the electrical supply
(see Electrical Connections).
9) Complete the installation (see Commissioning the Unit).
10) Complete the assembly of the outer case.
BOILER CONNECTIONS (Fig 3)
The boilers have 5 water connections:
2 x Rp1 (1 in BSP internal) return connections.
2 x Rp1 (1 in BSP internal) flow connections.
1 x Rp¾ (¾ in BSP internal) flow connection.
The 1 x Rp¾ (¾ in BSP internal) flow connection is for use
when the pump is fitted inside the outer case. For other
installations this connection must be plugged.
THE WATER SPREADER MUST BE FITTED TO THE
PUMPED RETURN CONNECTION ON ALL
INSTALLATIONS. THE MARKS ON THE SPREADER
MUST BE BETWEEN THE TWO MARKERS ON THE
COMBUSTION CHAMBER (Fig 4).
WARNING: Overtightening of the water spreader may
damage the heat exchanger. Do not apply excessive
amounts of sealing tape to the thread of the spreader.
The spreader has one mark on the 80, 70 and has two
marks on the 60, 50, 40.
When installing the pipework ensure that:
a) Suitable union fittings are used at the first joint of all
boiler connections.
b) The pipework will run through the cutouts provided in
the outer case (Fig 2).
c) Drain off points are provided as appropriate.
d) Pipe sizes are suitable for the system design.
Pump (Fig 1)
A suitable pump e.g. Grundfos UPS 15-50, 15-60 or
equivalent Myson or Wilo with ball type isolating valves and
22mm compression fittings may be fitted inside the outer
case.
The pump should be connected to the ¾ in flow connection
on the front of the heat exchanger using the following
standard fittings.
A - 1 off - Elbow 3/4 BSP male x 3/4 BSP female
B - 1 off - Conex straight connector 3/4 BSP male
x 22mm copper
C - 3 off - 22mm Yorkshire elbows
D - 1 off - when installing the 60, 50 and 40
60mm long - 22mm copper tube
D - 1 off - when installing the 80 and 70
92mm long - 22mm copper tube
E - 1 off - 100mm long - 22mm copper tube
F - 1 off - 145mm long - 22mm copper tube
G - 1 off - 42mm long - 22mm copper tube
The redundant flow connection(s) must be plugged.
Accuracy is important to avoid the pump and or pipework
obstructing removal of the top panel of the combustion
chamber, or fouling the top panel of the outer case.
OUTER CASE (Fig 6)
Assemble the outer case in the following manner:
1) Locate the RH side panel over the pegs at the RH side
of the base and press downwards to secure. When
fitting the panels if access is restricted the cutouts at
the top of the back edge of the panels can be used to
pass the case fixing brackets.
2) Secure the panel to the case fixing brackets with two of
the six screws provided.
3) Repeat 1 & 2 with the LH side panel.
4) Secure the hinges of the facia panel to the two side
panels using two of the six screws provided.
5) At this point the electrical connections to the facia panel
can be made and the appliance can be commissioned.
(See ‘Electrical Connections’ and ‘Commissioning the
Appliance’).
6) Swing the facia panel upwards and secure to the side
panels using the two screws retained to the control
facia.
7) Lift trim clear of flue connection on the boiler and locate
the top panel on the top of the side panels and press
down to secure. Re-position the trim in the cutout on
the top panel.
8) Hook the bottom edge of the front panel over the lugs
on the base and swing the top edge back till the pegs at
the top of the panel locate in the corresponding holes.
Press to secure.
GAS CONNECTION (Fig 3)
Adapt the gas supply 15mm (½ in BSP) within the outer case
making the gas connection to the service tap provided.

Page 6

Electrical Connections - Page 7
THIS APPLIANCE MUST BE EARTHED
GENERAL
The mains supply required is 230V ~ 50 Hz fused at 3 amps.
A double pole switch of contact separation of 3mm in all
poles should be provided in the installation or an unswitched
socket outlet should be used. All external wiring shall be
correctly earthed and polarised and be in accordance with
I.E.E. Regulations.
Electrical supply to controls
The recommended cable for connection to the appliance is
0.5mm216/.20 PVC to IEC 53 Code 227 (heat resistant).
The input cable should be secured with the cable clips
provided and be laid to avoid contact with hot surfaces.
The length of the supply conductors between the cable grip
and the terminals must be such that the current carrying
conductors become taut before the earthing conductor if the
cable should slip out of the cable grip.
1) With the outer case assembled as in ‘Outer Case’ 1-4
remove the 2 screws securing the thermostat cover to
the facia panel.
2) Fit the input cable to the terminal strip and clamp using
the cable grip provided and clamp the incoming cable
into the cable clips provided on the outer case side
panel so as to avoid contact with the hot combustion
box surfaces.
3) Connect the 2 green and yellow earth wires halfway
down the appliance wiring harness to the combustion
chamber earth point on the outer case support bracket.
4) Fit the socket at the end of the wiring harness to the
plug attached to the burner feed pipe and clip the wire
to the cable clips provided.
5) Refit the thermostat cover to the facia panel.
6) Push the thermostat phial into the thermostat pocket
and clip the capillary behind the retaining clip (Fig. 8).
INTERNAL WIRING

Notes for Guidance - Page 8
PIPE SIZING
a) The sizes of flow and return pipes from the boiler
should be determined by normal methods
according to the requirements of the system.
Normally the pump should be set to give a 11°C
(52°F) drop across the system with the gas rate of
the boiler adjusted to the output required.
b) The open vent pipe must be a minimum of 22mm
and must rise continuously to above the feed tank.
The flow pipe from the boiler may form part of the
open vent. No part of the open vent should contain
a valve.
c) The 15mm cold feed pipe should not include a
valve unless required by the local water authority.
DOMESTIC HOT WATER
An indirect cylinder must be used. If a self priming indirect
type is employed it must be of adequate size and applied
strictly in accordance with the cylinder manufacturers’
instructions.
FUEL ECONOMY
Better fuel economy is achieved by exercising control of the
boiler by means of a room thermostat and or a cylinder
thermostat as appropriate.
ALLOWING THE BOILER TO CYCLE ON THE BOILER
THERMOSTAT DOES NOT PRODUCE THE BEST
RESULTS. SIMILARLY FOR ECONOMY AND BOILER
PERFORMANCE THE SYSTEM SHOULD BE DESIGNED
SO THAT GRAVITY CIRCULATION IN THE HEATING
CIRCUIT DOES NOT TAKE PLACE WHEN THE PUMP IS
NOT RUNNING.
IMPORTANT: Gravity Flow and Return connections
must be taken from the same side of the boiler.
In both cases the cold feed pipe which is the neutral
point of the system is shown directly behind the pump
to avoid sub atmospheric pressure (air entrainment) in
the system.

Commissioning the Unit - Page 9
Reference should be made to BS 5449: section 5 when
commissioning the boiler and system.
Flush the whole system in accordance with BS 7593:1992.
(See Treatment of Water Circulating Systems on page 4).
Check the system for leaks.
Turn the gas service cock fully anti-clockwise.
Purge the air from the gas service pipe in accordance with
BS 6891 and test for gas soundness.
Turn the boiler thermostat to the OFF position.
Ensure that all external controls e.g. room thermostat, timer,
etc., are calling for heat and turn on the mains electrical
supply.
Remove the test point sealing screw and connect a pressure
gauge.
Hold in the ON/OFF button on the gas control valve.
Press the piezo igniter button and release. Repeat until pilot
lights. Hold in the grey ON/OFF button for a further 20
seconds and then release. The pilot light should then remain
alight. If not, turn the grey button clockwise and wait 3
minutes before repeating the sequence.
The pilot flame should be without a yellow tip and be
approximately 25mm (1 in) long.
Operate the burner by turning the boiler thermostat knob to
the HIGH setting and check the operation of the flame failure
device by turning the grey ON/OFF button clockwise. The
burner and the pilot should extinguish.
Turn the boiler thermostat to the OFF position. Wait 3
minutes and re-light the pilot as previously described.
Operate the burner and allow the system to reach normal
operating temperature. Make further checks for leaks and
check the burner setting pressure, adjusting if necessary.
This is done by adjusting the throttle screw (red plastic
surround) in either direction as required.
Remove the pressure gauge and tighten the pressure test
point sealing screw.
The boiler and system should be run and then flushed and
treated in accordance with BS 7593:1992 and the flushing
agent/inhibitor manufacturers instructions. When all the air
has been removed from the water circuit, the pump and
radiators should be balanced to achieve the design
temperature drop across the system.
Recheck the system for leaks.
Turn the boiler thermostat to the required setting.
Complete the assembly of the outer case as described in
‘Outer Case’ (Fig. 6).
9. Carefully read and complete all sections of the
“Benchmark” Installation, Commissioning and Service
Record Log Book that are relevant to the appliance and
installation. The details of the Log Book will be required in
the event of any warranty work. The Log Book must be
handed to the user for safe keeping and each subsequent
regular service visit recorded.
Instruct the user in the use of the unit. Please leave these
instructions, the users instructions and the log book with the
user.
NOTE: In the event of an electrical fault after the installation
of the appliance, preliminary electrical system checks must
be carried out (i.e. Earth continuity, polarity and resistance to
earth).

Servicing the Unit - Page 10
(See ‘BOILER SERVICING GUIDE’ label on the boiler)
Before servicing the appliance please read the
Important Information section on page 3.
After servicing, complete the relevant section of the
“Benchmark” Installation, Commissioning and Service
Record Log Book. This should be in the possession of the
user.
For economy and safety reasons, it is important to
service the appliance regularly.
1) Turn off the electrical supply to the boiler.
2) Remove the front panel of the outer case by pulling
forwards at the top and lifting upwards.
3) Lift trim on flue pipe connection clear of the top panel
and remove the top panel of the outer case by pulling
upwards.
4) Turn off the gas supply at the service tap and
disconnect the union (Fig 7).
5) Disconnect the electrical socket by pulling upwards (Fig
7).
6) Remove the four wing nuts and carefully withdraw the
burner and controls assembly. Remove the terminals
from the thermocouple interrupter (Fig 12).
7) Release the two screws securing the front insulation
assembly and remove the assembly (Fig 9).
8) Remove the four thumb screws securing the top
inspection panel (Fig 10). Remove the retaining bracket
and remove the casting baffles.
9) Clean the fins of the heat exchanger with a stiff bristle
brush. Clean out any deposits that have collected in the
bottom of the combustion box ensuring that the two air
openings in the base are clear.
10) Remove any debris that may have collected under the
combustion box.
11) Check all the insulation panels for damage, replace if
necessary. Refit the front insulation panel, casting
baffles and retaining bracket the top inspection panel.
12) Clean the burner as follows:
a) Pull and release the lint arrester from the front of
the combustion box panel held in position by two
spring clips. This can be cleaned by thoroughly
washing and then allowed to dry.
b) Disconnect the burner by removing the 3 securing
screws (Fig 11).
c) Brush any deposits from the blades and ensure
none of the ports are blocked. Clean any deposits
from the venturi.
d) Remove the injector from the inlet manifold, clean
carefully and replace.
13) Clean the pilot as follows: Unscrew the pilot tubing nuts
at both ends and remove the pilot
tube. Remove and clean the pilot injector and clean the
pilot shroud (Fig 12).
14) Re-assemble the pilot components and then the burner
in reverse order of dismantling.
15) Refit the burner and controls assembly checking that
the door seal is undamaged. Replace if necessary.
Reconnect the T.T.B. terminals.
16) Reconnect the gas union at the service tap. Turn on the
tap and check for gas soundness.
17) Refit the electrical socket and turn the thermostat to the
OFF position.
18) Refit the outer case top panel.
19) Hold in the grey on/off button on the gas control valve
(Fig 7). Press in the igniter button and release. Repeat
until the pilot lights. Hold in the on/off button for a
further 20 seconds and then release. The pilot should
then stay alight.
(IF THE PILOT FAILS TO REMAIN ALIGHT, TURN
THE GREY ON/OFF BUTTON FULLY CLOCKWISE
AND RELEASE, WAIT 3 MINUTES AND START
AGAIN FROM 19.) The flame should be without a
yellow tip and be approximately 25mm (1 in) long. No
adjustment of the pilot flame is necessary as the pilot
jet is sized to give the correct flame length at 20 mbar
(8 in wg) inlet pressure.
20) Turn on the electricity supply to the boiler.
21) Remove the pressure test point screw (Fig 7). Connect
a pressure gauge and operate the burner by turning the
thermostat knob to its highest setting.
22) Check that the pressure corresponding to the range
rated output is correct for the installation (see data
label). If necessary adjust the appliance throttle (Fig 7).
23) Turn the boiler thermostat to the OFF position and refit
the pressure test point screw.
24) Turn the boiler thermostat to its original setting.
25) Replace the outer case front panel.
26) Complete the relevant section of the “Benchmark”
Installation, Commissioning and Service Record Log
and hand it back to the user.

Page 11

Changing Components - Page 12
When changing components ensure that electrical and
gas supplies are isolated.
Before changing any components please read the
Important Information section on page 3
THERMOCOUPLE
1) Remove the outer case front panel by pulling forwards
at the top and lifting upwards.
2) Turn off the gas supply at the service tap or at the
ON/OFF button on the gas valve.
3) Release the thermocouple nut at the side of the gas
valve from the interrupter adaptor (Fig. 12).
4) Release the thermocouple nut at the pilot bracket.
5) Re-assemble in reverse order of dismantling.
THERMOCOUPLE RE-ROUTE DEVICE
1) Remove the burner and controls assembly as
described in steps 1 to 6 - Servicing the Unit.
2) Remove valve heat shield.
3) Release thermocouple nut and interrupter device from
the valve (Fig 12).
4) Disconnect the re-route nut.
5) Remove terminal cover and re-route device.
6) Re-assemble in reverse order of dismantling.
INJECTOR
1) Remove the burner and controls assembly.
2) Remove the burner securing screws and remove the
burner (Fig 11).
3) Unscrew the injector from the feed pipe.
4) Re-assemble in reverse order of dismantling.
BURNER
1) Remove the burner and controls assembly.
2) Remove the burner securing screws and remove the
burner (Fig 11).
3) Re-assemble in reverse order.
T.T.B. ASSEMBLY (Fig 12)
1) Disconnect the two terminals from the thermocouple
interrupter on the valve.
2) Remove the leads from their clips on the boiler.
3) Remove the four screws securing the top inspection
panel.
4) Slacken the R.H. baffle securing screw. There is no
baffle on 80 & 60 models.
5) Lift the T.T.B. bracket upwards to disengage it from the
screw.
6) Withdraw the complete assembly out through the
combustion box.
7) Reassemble in reverse order of dismantling.
BOILER THERMOSTAT
1) Remove the outer case front panel by pulling forwards
at the top and lifting upwards.
2) Remove the outer case top panel by pulling upwards.
3) Remove the two facia retaining screws (Fig 8) taking
care not to lose the two spacer washers and allow the
facia to swing forwards on its hinges.
4) Release the thermostat capillary from behind its
retaining clip and remove the thermostat phial from the
boiler (Fig 8).
5) Remove the screws securing the thermostat cover to
the facia.
6) Disconnect the three spade electrical terminals from the
thermostat.
7) Pull off the thermostat knob and remove the locknut
securing the thermostat to the facia panel.
8) Re-assemble in reverse order of dismantling ensuring
that the thermostat phial is replaced into the thermostat
pocket.
GAS VALVE (Fig 12)
1) Remove the burner and controls assembly as
described in steps 1 to 6 - Servicing the Unit.
2) Disconnect the thermocouple nuts at the valve and at
the pilot bracket.
3) Disconnect interrupter adaptor.
4) Disconnect the pilot feed pipe at the valve and at the
pilot bracket ensuring that the pilot injector is not
misplaced.
5) Disconnect the electrode lead and remove the piezo
unit.
6) Remove the screw securing the electrical terminal
cover to the gas valve. Disconnect the electrical
connections.
7) Remove the valve complete with the heat shield and
inlet pipe by disconnecting the flanged burner feed pipe
(Fig 7).
8) Disconnect the flanged inlet pipe. Retain the O rings for
re-assembly but replace if damaged.
9) Remove the heat shield by undoing the retaining
screws.
10) Release the thermocouple re-route nut and remove the
re-route.
11) Individual sub components of the valve may be
replaced as outlined by Honeywell instructions.
12) Re-assemble in reverse order of dismantling.
INSULATION IN COMBUSTION BOX
1) Remove the burner and controls assembly as
described in steps 1 to 6 - Servicing the Unit.
2) Release the 2 screws securing the front insulation
assembly and remove the assembly (Fig 9).
3) Remove the two screws and air guides securing the
two side insulation panels (Fig 13) and carefully remove
diagonally through the door opening.
4) Remove the two screws and washers securing the back
panel insulation (Fig 13).
5) Remove the ceramic insulation pad from the front
insulation assembly by bending the securing tabs.
6) 60, 50, 40 OF only - Remove the two sloping panels of
insulation adjacent to the heat exchanger by removing
four screws and washers. Ease out the bottom edge of
the insulation panel and slide down (Fig 13).
7) Replace insulation as necessary and bend down
securing tabs where applicable.
8) Re-assemble in reverse order of dismantling taking
care not to damage the new insulation.
PIEZO UNIT (Fig 12)
1) Remove the burner and controls assembly as
described in steps 1 to 6 - Servicing the Unit.
2) Disconnect the electrode lead at the piezo unit.
3) Remove the nut securing the piezo unit to the heat
shield and remove the piezo unit.
4) Re-assemble in reverse order of dismantling.
SPARK ELECTRODE (Fig 12)
1) Remove the burner and controls assembly as
described in steps 1 to 6 - Servicing the Unit.
2) Disconnect the electrode lead at the electrode.
3) Remove the nut securing the electrode and remove the
electrode.
4) Re-assemble in reverse order of dismantling.

Page 13

Short Parts List - Page 14
BAXI BOSTON 2 - 80/70/60/50/40 OF
B.G.C. No 41 077 84/83/82/81/80
Model
60
50
40
Key N°
A
B
D
E
E
E
F
G
H
I
J
K
L
M
N
O
P(40,50)
P(60,70,80)
80
70
A
B
C
E
E
F
G
H
I
J
K
L
M
N
O
Description
Seal - Panel Door
Kit - Sight Window
Burner - Boiler (70-80)
Burner - Boiler (40-50-60)
Injector - Stereomatic
(80 OF)
Injector - Stereomatic
(70 OF)
Injector - Stereomatic
(60 OF)
Injector - Stereomatic
(50 OF)
Injector - Stereomatic
(40 OF)
Valve - Control
Honeywell V4600 T1037
Burner - Pilot
Honeywell Q349A 1059
Injector - Pilot
Honeywell 56/42 A
Electrode - Pilot ignition
Kigass E3356
Lead - Electrode
Thermocouple - 18”
Honeywell Q3909 A
Kit - Piezo Unit
Thermostat – Kit
Ranco
Knob Thermostat
Arrester Lint
T.T.B. Assembly (Black Sleeve)
T.T.B. Assembly (Red Sleeve)
G.C.
N°
364 260
364 719
378 898
378 899
378 901
378 902
364 330
364 331
364 332
379 810
170 580
381 702
387 852
183 628
390 131
183 936
382 387
378 903
364 340
170 560
170 561
Manufact’rs
Part N°
112057
226114
235262
234721
236246
236245
112040
112060
112051
233359
236667
236107
102024
042740
102005
040456
112025
235303
110069
236346
236547
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