Myson Midas Sfi User guide

404C960 - 02
for the
Midas
Sfi
wall mounted combination gas boiler
G.C. Appliance No.
Midas Sfi 47 494 04
IMPORTANT
FOR USE WITH NATURAL GAS ONLY.
Read these instructionsthoroughly before
working on the boiler.
Leave these instructionsadjacent to the
gas meter.

LIST OF CONTENTS
Section
1
2
- - 3
4
5
6
7
8
9
10
11
12
13
14
Y 15
16
17
18
19
’20
21
22
23
24
25
Subject
Introduction
Method
of operation
Generalrequirements
Delivery
Electricitysupply
Gassupply
Air supply
Fluesystem
Technicaldata
Boilerlocation
Wterandgas connections
Water system
Importantinstallationnotes
Sealedsystemrequirements
Optionalopensystem
Installationprocedure
Commissioning
Balancingthesystem
a
Finalassemblyandhandingover installation
Annualservicing
Replacement of parts
-,
-
Wiringdiagrams
Faultfindingguides
Explodedviews
Shortlistspareparts
Page
3
3
3
3
-
3,
3
4
4
4
5
5
6
6
7
7
7
11
12
13
13
14
20
22
28
30
Page2
If you haveany reasontocomplainof any shortage of components shown inframes 1,2or 8, supplya listof the item@) concerned,
boiler model, your name, addressand any informationwhich may helpus toavoidanyfurther error.
Address
for retum:
Sf” Administration Manager,
CWEon Components Ltd
Earfsway,
Team Valley Trading Estate,
GATESHEAD,Tyne &Wear, NE11
OM. 3 .y- .A
c
-
.”
‘.

1. INTRODUCTION
The Midas Sfi is a fanned balanced flue combination boiler supplying a maximum of 100,OOO Btu/h for domestic hot
centralheating.
The temperatureof domestic hotwater and central heatingare bothadjustablebythe User.
Incorporated
as standard isa programmerfor controlof thecentralheating periodsof operation.
To enable the boiler to be positioned remote from an outside wall the boiler will operate with horizontal flue lengths
3 metres. The Midas Sfi is a little unusual in that it incorporates a micro processor which provides a high level of
control. Itisadvisable to read carefullythefollowing instructionswhich explaintheoperationof the boiler.
water or
of up to
accurate
When the mains electricity supply is first switchedon, the boiler takes 30 seconds to respond whilst the micro processor ‘reads’
the boiler sensors. However, the boiler is equipped with a ‘Purge/Normal’ switch which, in the Purge mode allows either of the
two pumps to operate instantly under the control of the selector switches. This function, which is useful for removing air from
thesystem will notallowthe boilerto fire and, after venting, theswitchshould be retumedto ‘Normal’.
2 METHOD OF OPERATION
The Midas Sfi combination boiler operates in two distinctive modes; Central heating and Domestic hot water, see page 6. It
will not supply heating and hot water at the same time, priority will always be given to hot water. Therefore
if a hot water tap
is tumed on when the boiler is operating to provide central heating, the central heating will be interrupted until the hot water
tap istumed off and the hot water store hasagain reachedtemperature.
Central heating mode
When the central heating is switched on either by the programmer or room thermostat, water from the central heating system
passes into the main heat exchanger and is heated by the burner to a minimum of 50°C and a maximum of 82°C as selected
bythe user control.
For the first
5 minutes of operation the boiler operates on low fan speed and at a fixed low gas rate to provide an output of
35.OOO Btu/h.
If after 5 minutes the central heating control thermostat or room thermostat have not been satisfied the boiler will change to
highfan speed and high gas rate. The gas rate will then modulateto suit the system demand. Should the modulated rate reduce
to
35,OOO Btu/hthe fan will revertto lowspeed, the gas tofixed low rateand a further 5 minute runwill commence.
If during the
5 minute run at low setting the central heating thermostat or room thermostat are satisfied, then the boiler will
remain off for the remainder of the
5 minutes. After that time the boiler will commence a further run for 5 minutes at low fan
speed and lowgas rateand this processwill continue.
This arrangement ensures that the boileroperates for most of the time on the majority of systems at low input thereby preventing
rapid cycling, minimisingnoiseand maximisingefficiency.
After ademandfor central heatingan automatic10 minute central heating pumpoverruntakes place.
Domestic hot water
When a hot water tap is turned on a sensor within the secondary heat exchanger on the mains inlet side activates the hot
water pump and fires the boiler to meet the demand. Water is pumped rapidly throughthe main heat exchanger to the secondary
heat exchanger where ispassesover aseriesof coilsand back tothe main heat exchangerfor reheating.
Cold water enters the boiler and passes through the secondary heat exchanger (where heat is transferred), over another sensor
and onto the hot water tap. The burner pressure is automatically modulated to maintain the desired temperature selected by
the User. The boiler
will always respond to a demand for hot water by running the fan at high speed and initially the gas rate
at maximum input.
If the central heating is operating at the time, it will be interrupted whilst the boiler supplies hot water and resume operation
when the hot water tap is turned off. Should the interruption occur during the
5 minute ‘low fan, low gas’ time the boiler will
complete the remainder of the
5 minutes when returning to central heating. However, should the boiler be operating on ‘high
fan, high gas’ to providecentral heatingat the time the interruptionoccurs it will return immediatelyto this setting when retuming
tocentral heating.
To prevent too much water passing through the boiler a flow regulator preset at 10 litreshin has been positioned alongside
afilter inthe inletof the boiler.Too muchwater resultsinwater deliveredtothetap not beinghot enough.
reheat of the secondary heat exchanger is at a low burner pressure and fan speed to minimise noise. The hot water may be
switched off and the cycling stopped by switching the HW switch to the ‘OFF‘ position, if
so desired. The HW selector switch
must be turned back tothe ‘ON’ positionwhen hot water is required.
After a reheat of the secondary heat exchanger a
30 second domestic hot water pump overrun takes place. However, after a
hot water drawoff a 10 minute low fan overrun in conjunction with
30 second domestic hot water pump overrun takes place.
3. GENERAL REQUIREMENTS
The boiler must be installed in accordance with: The
Gas Safety (Installation and Use) Regulations 1990, Building Regulations,
BuildingStandards (Scotland) Regulations,
Local BuildingRegulations,Modeland localWater UndertakingByelawsand thecurrent
IEE Wiring Regulations.
Detailedrecommendationsare stated inthefollowing BritishStandard Codes of Practice: BS6891:1988, BS6798:1987, BS6700:1987,
Bs5546:1990, Bs0440:1:1990, BS5440:2:1989 and B!3449:1990.
NOTE: Gas Safety Installation and Use Regulations 1990: It is law that all gas appliances are installed by competent persons
in accordance with the above regulations. Failure to install appliances correctly could lead to prosecution. It is in your own
interest, and that
of safetyto ensure that the law is compliedwith.
4. DELIVERY
The unit is delivered intwo packages:
(1). The boilerpack which contains the uncased boilerandthecasing kit pack.
5. ELECTRICITYSUPPLY
240V-50Hz via a fused double pole switch with a contact separation of at least 3 mm in both poles or preferably a fused 3
pin plugand shutteredoutlet socket (bothcomplyingwith requirementsof BS1363) adjacenttothe boiler.
Fuse the supply at 3A. The minimum requirement for the power supply cable is that it should be a PVC sheathed flexible cord
at least 0.75 mm2
(24 x 0.2 mm) (codedesignation H05VV - F or H05VVH2 - F) as specified intable 16of BS6500:1984.
All wiringextemal tothe boilershall comply withthe latest IEE Wiring Regulations,and any localregulationswhichapply.
The applii must beearthed.
In the event of an electrical fault after installation of the appliance, preliminary electrical systems checks must be carried out
i.e. EarthContinuity,Polarity, Short Circuitand Resistanceto Earth.
6. GASSUPPLY
The Midas Sfi requires
3.4 mYh (120 ftVh) of natural gas (the input after 10 minutes use at maximum). The meter and supply
pipes must be capable of delivering this quantity of gas in addition to the demand from any other appliances in the house.
Note:
If the gas supply to the boiler is used to supply other appliancesthen use 22 mm pipe. If the last 2 metres to the boiler
The complete installationmust be tested for gas soundnessand purged as described in BS6891.
To deliver hot water ‘instantly’ the secondary heat exhanger is kept hot. To maintain this, the boiler will periodically cycle. This
\
(2).The flue/terminal assembly type, A, B, C, D and E as required.
isfree from junctions then it ispossible to use 15 mm pipe.
Page 3

Maximumcentral heatinginput
Minimumcentral heating input (m-on)
Maximumcentral heatina output
36.6 kW (125,000 Btdh)
13.2 kW (45,000 Btu/h)
29.3 kW (100.OOO Btu/h)
I Maximumburner pressure I 16.0 mbar (6.4in wa) I
Minimumcentral heatingoutput (modulation)
Maximumhot water input
Maximumhotwater output
I Minimum bumertxessure Imodulation) I 1.8 mbar f 0.2 10.7in wa f 0.1) I
9.5 kW (32,500 Btu/h)
36.6 kW (125,000 Btu/h)
29.3 kW (l00,OOO Btu/h)
Bumertype
Bumer injector
Pilot injector
I Pilotflame I 35 to 40 mm Iona I
Furigas 175-500424 or Bray AB24016M
Furigas 515-001-136 marked 470
Honeywell 4500-41o8-005 marked 56142A
spark gap
Ignition
Weight (empty)
Liftingweight (installing)
I Watercontent I 4.0 litre 10.8 aal) I
~
3.0 to 4.0 mm
Intermittent Pilot
64 kg (140 Ib)
56 ka (123 Ib)
Max. heatingsystemtemperature
Max. domestichotwater temperature
Max. nominal domestic hotwater flow
'Domestic hotwater performance
~~
82°C f 2°C
65°C f 2°C
10.0 litreshin (2.2 gal/min)
9.3 litres/min 12.06 aal/min) raised45°C 12.0 litreshin (2.65 aal/min) raised35°C
I Max. heatina system water cawcitv I 200 litres 144 aal) I
Max. mainswater inletpressure
Min. mainswater inletpressure
Max. heatingsystemwater pressure
Min.heatingsystemwater pressure
10 bar (145 Ibf/in2)
0.9 bar (13.0 Ibf/in2) (seenoteinframe 22)
3 bar (44 Ibf/in2) (seesection 14)
0.5 bar (7 Ibf/in2)
I Clearancerequired:top I 50 mm (2 in) I
Height (case)
Width (case)
Depth
900 mm (35Vz in)
480 mm (18% in)
350 mm (13% in)
I water connections I 15 mm and 22 mm com~ressionfittinas I
Clearancerequired: bottom
Clearancerequired:front
Clearancerequired:sides
Flueterminalsize
150 mm (6 in)
610 mm (24 in)
10 mm (3% in)
100 mm dia x 65 mm deep (4 india x 2% indeep)
Gas connection
Page4
Rc%
Dataplate position Behindcasefront, rightof centre
80,000
gQ000
loo,o0o
- -
- - 15.93 21
0 2.0 6.6 23.4
- - -
-
17.92 235 1.6 5.3 26.4
- - - -
19.91 265
1 .o 3.3 29.3

10. BOILER LOCATION
The boiler is notsuitable for external installation.
The boiler must bemountedon aflat wall which is sufficiently robust
to take the weight of theboiler.
The boiler is suitable for installation to a combustible wall e.g. wood cladding, provided that the aidflue tube assembly is
not closer than 25” (lin) to combustible material.
A metal sleeve should be installedto surround the air/flue tube assembly
to providea25” (lin)annular space. Furtherguidanceisgiven in BS5440:1:1990, sub
- clauses 3.3 and 4.2.5.
If the boiler is to be installedinatimber framed buildingitshouldbefittedinaccordancewiththe BritishGaspublication - “Guide for
Gas InstallationinTimber FramedHousing” reference DM2.
If indoubt advice must besought from the localregion of BritishGasor
from MysonHeating.
The boiler may be installed in any room, although particular attention is drawn
to the requirements of the latest IEE Wiring
Regulations and, in Scotland, the electrical provisions of the building regulations applicable in Scotland, with respect to the
installationof the boiler inaroomcontainingabathor shower.
Wherearoom
- sealedapplianceisinstalledina roomcontaininga bathor shower, any electricalswitchor appliancecontrolutilising
mainselectricityshouldbe
so situatedthatitcannot betouched by a personusingthe bathor shower.
Where the installationof the boilerwill be inan unusualposition,special procedures may be necessary and BS6798 and 885546
givedetailedguidanceonthis aspect.
A cupboard or compartment used to enclosethe boiler must be designed and constructed spcificallyfor this purpose. An existing
cupboard or compartment may be used provided that it is modified for the purpose. Details of essential features of
cupboard/compartment design including airing cupboard installations are given in BS6798 itnd BS5546 and should be complied
with.
If theboileris to be installedina runof kitchenunitsitisrecommendedthatthe boileris fitted Ccst or the adjacentunitsremoved.
The boiler must be installed
so that the flue terminal is exposed to the externalair. It is imprrrtant that the positionof the terminal
allowsthefree passageof air across it at alltimes.
TerminalPosition
Directlybelowan openablewindow,airvent or any otherventilationopening
Belowgutters, soilpipesor drainpipes
Beloweaves
or balconies
Aboveadjacentgroundor balconylevel
Fromvertical soil pipesor drain pipes
Froman externalor internalcorner
Fromasurfacefacingthe terminal
Fromaterminalfacingtheterminal
Verticallyfromaterminalonthesame
wall
Horizontallyfrom aterminal onthesame wall
Adjacent toanopeningwindow
Froman openinginacar porti.e. door or window intothe house
MinimumSpacing
300 mm (1 2 in)
75 mm (3 in)*
200 mm(8in)*
300 mm (1 2 in)t
75 mm (3 in)
25 mm (1 in)
600 mm (24 in)
1200 mm (48 in)
1500 mm (60 in)
300 mm (1 2 in)
150
mm (6 in)
1200
mm (48 in)
* If the terminal isfitted within 850 mm (34 in) of a plasticor painted gutter/pipeor 450 mm (le in) of paintedeaves, an aluminium
shieldof at least750mm (30 in) inlengthshould befitted
to theundersideof thegutter/pipe or painted surface.
t If theterminal isfitted lessthan2 m (6.6 ft) aboveabalcony, abovegroundor above a flat roof to whichpeoplehaveaccessthen a
suitableterminalguardmust be providedandfitted.
A type KI protective guard is available from Tower Flue Components Ltd. at: Vale Rise, Tonbridge, Kent TN9 1TB. Tel: 0732
351555. The guard must be securely fitted to the wall and centrally located over the flue ‘terminal. Refer to the Manufacturers
instructions.
11. WATER AND GASCONNECTIONS
All water connections are centred 40 mm from the wall. Compression fittings are supplied
to accept 22 mm and 15mm copper
tubing
to 882871.
Note:All water connections (5) atthe bottomof the boilerhavebeentemporarily sealedwith plasticplugs. RemoveALL FIVE plugs
’
beforeanyfittingsare connected.
heating
return water valve
inlet discharge
- -
Page 5

12. WATER SYSTEM
CentralHeatingOn
/
b' radiators
Pump isolation
t valves
From
radiators
e
Domestic HotWater On
Mains inlet
isolationvalve
Hotwater
sensors
4
+ out
Hot
water
Mainswater in,
lnlinefilter and
flow regulator
housing
13. IMPORTANT INSTALLATIONNOTES
1. A system by - passisincluded in the MidasSfi boiler.
2. Ensurethat the isolatingvalves are open.
3. Mainselectricitymustalways beconnectedto the boiler.
4.
5.
6.
7.
8.
9.
10.
11.
Thewater connectionsmust beconnected as shown in thewater system schematics.
The maximum working pressure of the Midas
Sfi is 10 bar (145 Ibfhn2). If the mains water pressure is likely to exceed
this, a pressure reducingvalve must befitted to the
cold water inlet.
When Commissioning, the system and boiler must beventedandthe pump runningbeforethe mainbumerislit.
Thesystem must beflushed
twice; initiallycoldwithallvalves open, andthen after the first heating.
In areas with hard or aggressive water we recommend that an inhibitor should be used for example Femox CP3.
See CommissioningInstructionsfor detailsof use.
Ifused
on opensystem alink must beconnectedbetween L1 & P1onterminal Mock
If there is a device which prevents the expansion of domestic water or if the domestic water supply is metered then a
device must be fittedwhichwill allow for theexpansionof water.
If the domestic water inlet pressure is less than 1.3 bar, the flow regulator can be removed to achieve the full flow rate
I__- 1 __-.. CL.

14. SEALED SYSTEM REQUIREMENTS
1. Theinstallation mustcomply with the requirementsof BS6798and BS5449.
2. A safety valve set to operate at 3 bar (45 Ibf/in2) and a pressure gauge covering the range 0-4 bar (0 to 60 Ibf/in2 are
incorporated within the boiler.
3. A 12 litre expansion vessel to BS4814 is fitted and pre - charged to 0.5 bar (7.5 Ibf/in2) is suitable for a system with a
maximum water content of 120 litres (27 gal). An additional expansion vessel can be installed
in the central heating system
if required, refer to
835449 Table 3 to calculatethesize of thevessel.
4. Water lost from the system shall be replaced from a make - up vessel, and non return valve, mounted higher than the
top of the sytem and connected as shown
in fig. A. Where access to a make - up vessel would be difficult, make - up CE~
beprovided bypre - pressurising thesystem to 1.5 bar (22.5 Ibf/in2) cold - seefig. B.
Note: Stopvalves mustcomplywith therequirementsof BS1010:2.
1 Heating - ~ ~ '"%~~I~l I Heating cM ch:Ft
system system
Stopvalve Non - return Non - return Test t-7-
valve valve cock Hose unions
Fig A Fig. 6
15. OPTIONALOPEN SYSTEM
Thisunitcanbeinstalled inan opensystem
if required, inwhichcaserefertoframe 4 inthefollowing installation procedure.
16. INSTALLATIONPROCEDURE
OPENTHE MAINBOILER PACK
The MidasSfi is receivedintwo packs.unpackthe larger of
thetwo. Removethe outer panels packand placeto one
side, and checkfor thefollowingcontents.
Bt3
22 mm isolationvalves (2)
15 mm isolationvalve
filter and flow regulator
1
22 mm nut andolive
0 0
Opensystemplate I.0.l
M6 screwsandwashers 9 9 3 9
(4 of each) Q Q
Fluegasket
Template
Fluesleeve Wallmountingplate
BOILER DIMENSIONS
Clearances
requiredfor
servicing:
Top:
50mm
Bottom: 150 mm
Front: 610 mm
Side: 10mm
All dimensionsin
mm.
- 480 -4
Note: If theboileristo beinstalledinarunof kitchenunits it is
recommendedthat the boilerisfittedfirst or theadjacentunits
removed.
CHECKTHE OUTER PANELSPACK
Theouter panelpackcontainstheouterfront andside
panelstogetherwith thefaciacover and bottompanel.
Keepthesetoone side intheir packinguntilrequired.
The illustrationshowshowthey willeventuallybefittedto
RH SideDane1
ilerchassis.
theboi
DONOT ASSEMBLE NOW.
, (3 screws -t
G
LHSide
panel
+ 2 studs)
Bottomoanel
OPTIONALOPENSYSTEM
1. Removeinnercasefront andfan assembly,seeframe 6.
2. Removecover plate (2 screws),takingcarenotto damage
gasket.Discardplateonly.
3. Replacewithopensystem platesupplied.
4. Loosennut retainingtheair vent Dsicard.
5. The unitwill now accept a 22 mm pipe,the roomsealpointbeing
maintainedby the plategasket.Suppliedwiththe boilerisan
extra
22 mm nutand oliveto connectthe 22 mm combinedcold
feedand vent.
Page7

I REAR EXIT FLUE - use Frames 5 to 12. For Side Exit Flueuse Frames 13 to 18.
holeandthe5fixingholesfor
thewall mountingplate.
3. Cutthe 115 mm (4% in)dia.
holeinthewall anddrilland
plugthe fixingholestoaccept
2%” lg. No. 12woodscrews.
THE WALL
All dimensions in mm
1-310-1
Flue
hole
dia.
Q Wail mounting
plate I
SECURETHE BOILER TO THE WALL
PLATE
1 1. The boilerhas two flanges
I
2.
3.
4.
onthebackof the chassis
at thetop. These aretobe
hookedoverthetopof the
wall mountingplatetotake
theboiler’sweight.
Withamaneitherside
lift
the boilerontothewallplate.
Securetowall plateusing
the 4screwsandwashers
supplied.
Removetheprotective
bottomplate(4screws)and
discardplate,retainingthe
screws.
ADJUST THE LENGTHOFTHE FLUE/
TERMINAL ASSEMBLY
Sealthis joint
with tapesupplied Pilot holes (3 off) Air tubs
Flue
tube
I
Keepseams inline
Finishedwall thickness + 25mm (1 in)
1. Adjustthe lengthof thefluehermina1assembly so that itis 25 mm
(1 in) plusthefinishedwallthickness,from the back of the
terminalflangetotheendof theOUTER airtubeas shown.
Note: Ensurethattheseamsinthe outer airtubes areinline.
2. Drillthroughthethree pilotholes,shownabove,with a2.8 mm
drillandsecurethe two tubestogether usingthethree No. 8x
10lgscrewssuppliedwith theflue/terminalassembly.
Note: Whendrillingthroughtheouterair tube take carenotto
damagethe innerfluetube withthedrill.
3. Sealthe centrejoint withthetapesupplied.
PREPARETHE BOILER
1. Removeinner case front (4 screws).
2. Disconnectthe%way plugfromthe airflow Sensor and the
3. Remove2screwssecuringfan assembly base platetofluehood.
4. Remove4
screws securingflue hoodto the combustionchamber.
5. Carefullyslideflue hood out from underthefan assembly (take
care nottodamagethegasket onthe base of thefan assembly,
renew if necessary beforereassembly),then removefan
Sway plugand socket for thefan motor leads.
assembly. Fan
Fluetube sleeve
(rearexitshown)
\
UNPACKTHE FLUETERMINAL
ASSEMBLY
Carefullyunpacktheflueterminalassembly. Do notdiscardthe
packinguntilallthe itemsarefound.
‘0’ Qcn ring
Clampingring
(2 off)
Outer wall plate
M4 x 25 mm lgscrews
No. 8 x 1” lgstainless
screws (4off)
(4 off)
Outersealingplate
Qkk
No. 8 x 10 mm lgscrews
Sealingtape (3 off)
FITTHE FLUUTERMINAL
ASSEMBLY (1)
Note: Ifthewallisto bemadegoodupto theterminaltheouterwall
plateneednot beused.
1. Fittheouterwall plateoverthefluehermina1assembly.
2. Fromoutsidethe buildinginserttheflue/terminalassemblyinto
thewall. Ensurethattheslotsintheend of theterminalare
vertical.
Mer

FITTHE FLUWERMINAL RE
- ASSEMBLETHE BOILER
tubeand infront of theswagedsection.
4. Securetheflue/terminalassemblytothe boilerusingthe
two
halvesof theclampingringasshownbelow. Ensurethat the
of theair tube.
1. Decideuponthepositionof theboiler.Notethatthemaximum
distance(usingthelongestflue/terminalassemblyand two flue
extensions)from thesideof thewhitecase
to theOUTSIDEwall
is3012mm(li81/~in.)
mountingfixing holes,thesideof the boilerandthehorizontal
centre lineof theflue. Seeframe
5.
3. Continuethe horizontalflue centrelineacrossthe wall and
aroundontothesidewall. Ensuretheselinesare level.
4. Onthesidewall, marktheverticalcentreof theflue exit hole.This
2. Usingthetemplateprovided,markthepositionsof thewall
5. Checkthattheterminal positionwill meettherequirementsgiven
6. Drilland plugthefivewall mountingplatefixing holestoaccept
2%’’ lgNo. 12woodscrews.
7. Cutthe 115mm (4% in) dia. holeinthe sidewallfor the
flue/terminalassembly inthe positionpreviouslymarked.
8. Makea noteof thefinishedwallthicknessandthedistancefrom
thesidewalltothe sideof thewhitecase.Thesemeasurements
are very importantand arerequiredinframe 15when adjustingthe
flue/terminalassembly.
woodscrews (notsupplied).Ensureitislevelandthe rightway up.
9. Securethewall mountingplateinpositionwith five 2W‘lgNo. 12
I
175
inwallfor flue
(1
15 mm (4% in)dia.)
/
(LHflue illustrated)
Wallmountingplate
Spiritlevel I
PREPAREAND FITTHE BOILER
El
1. Preparethe boiler and
securetothewallmounting Edgeclips
plateasdescribedin
frames
6 and7.
2. Unpackthefluekerminal
assemblyasframe 8.
3. Openthe outer panelspack
andtake thesidepanel
appropriatefor a LH or RH
exitflue.
4. Pushoutthe roundinfill
panelafter removingthree
edgeclips.
5. Fitthetop edgeof the side
panelintopositionas
shown.
6. Securesidepanelwithtop
screwatthisstage.
sideparL hail
(LHflue exit illustrated.)
ADJUST THE LENGTHOFTHE FLUE/
TERMINALASSEMBLY
Sealthisjoint
withtapesupplied Pilotholes
(3 off) Air tube
\/ Flue
‘\If
tube
Y
I
I
Keepseams inline
I
I- Finishedwall thickness + B + 28 mm (1 ’/a in) I
(B=distance betweenthewall andthesideof the boilercase)
1. Usingthemeasurementsnotedinframe 13,adjustthelengthof
theflue/terminal assemblyas shownabove. Measurements
shouldbetaken from thebackof theterminalflangetotheendof
theOUTER air tube as shown.
Note: Ensurethat the seamsinthe outerair tubesareinline.
2. Drillthroughthethreepilot holesshown above,with a 2.8 mmdrill
andsecurethe
two tubestogether usingthethree No. 8 x 10lg
screwssuppliedwiththefluekerminalassembly.
Note: When drillingthroughtheouter air tubetake care not to
damagetheinnerfluetube with thedrill.
3. Sealthecentrejoint withthetape supplied.
~
Page 9

FLUEEXTENSION Theflueextensionkitallows
thestandardflue/terminalassembly tobeextendedby965
-mm (38in)withone kit.1930mm(76 in)with two kits.
Amaximumof
two flueextensionsmay beused, if required.
Sealthisjoint 5 mm
with tapesupplied -7 p- , Drill 3 holes(2.8mm dia.)
Extension ' Keepseams ' Standardflue/terminal
inline assembly
1. If theflue extensionkitisused,connecttheplainendof the
extensiontotheswagedend of thestandardflue/terminal. Ensure
that the innerflue tubeof thestandardflue/terminalfits INSIDE
theinnerfluetubeof theextensionandtheouterair tubefits
OVERtheair tubeof theextension.Pushfully home.
Note: Ensurethat theseams intheouterair tubesareinline.
2. Drillthree equally spaced holesusinga2.8 mm drillinthe
positionshown,throughboththestandardflue/terminalandthe
extensiontubesleeve. Securethetwotubestogetherusingthe
three No. 8x
10 lgscrewssuppliedwith theflue extension.
Note: Whendrillingthroughtheouter air tubetakecarenot to
damagethe innerfluetubewith thedrill.
3. Sealthejoints with thetapesuppliedwiththeflue extension.
4. AdjusttheOVERALLlengthas describedinframe 15. Secure
andsealthejoints.
REASSEMBLETHE BOILER
For bothside exits thefan base platehas to be rotated
90" anticlockwiserelativetothe fan (viewedfrom below).
Turnoverthefan assemblyand undothe
4 fixingscrews holdingthe
fan to thefan mounting plate, takingcare not to damage either of
thetwogaskets,turnthefan mountingplate
90" anticlockwiseand
secureto the fan with the
4 screws.
For Right Hand Exit
1. Positionfan assembly Over heatexchangerwith itsoutlet pointing
towardstheflue exit hole.
2. Pushflue tubesleeve ontofan outlet.
3. Carefullyslideflue hood under thefan assembly, takingcare not
todamagethegasket on the baseof thefan assembly,with the
air flowsensor left of thefan.
FITTHE FLUE/TERMINAL
ASSEMBLY
1. Removethe 4 screws, sealingplateandgasketfrom the side
throughwhich theflueisto exitand useto seal the rearexit.
2. Theflueisfittedinthesameway asdescribedinframes 10 and
11 butissecuredtothe chassissidefrom insidethefan
compartment.(Forease of installationfit the lowerhalffirst.)
Note: Ensurethat thegasket hastheedgewiththecorners
removedtowardsthefront of theboiler.
Sealingplateandgasket
11 '
(LH flue illustrated)
Fluegasket
Fanassembly RIGHT HAND FLUE
I
LEFTHANDFLUE
4. Fitthefree end of theflue tube sleeve over terminal innertube and secure
Note: Theoutersealingplateneednot beused if thewall
ismadegoodup
to theterminal.
1. Connectgassupplyvia a straightconnectortothe
servicecock. (Itwill benecessarytolowerthecontrol
1. Placetheouter sealing
plateovertheterminaland
markthe positionof thefour
fixingholes.
2. Removethesealingplate
and drilland plugthefixing
holes,suitablefor 1
" lg
No. 8woodscrews.
Note: Theterminalshould
becoveredbeforedrillingto
preventdebrisenteringthe
terminal.
3. Removeany coveringfrom
theterminal.Positionthe
sealingplateover the

I
CONNECTTHE POWER SUPPLY
CABLE Referalsoto page 3, section 5.
1. Remove theelectricscover (4 screws)and remove thefacia panel
2. Slackenthecableclamp (2 screws) andfeedthepowersupply
(4screws) and carefullypullforward (seeframe 42).
cablethroughitto connectwiththeterminal blockas
follows: Brownleadto ‘L’ (Live)
Bluelead to ‘N’(Neutral)
Green/yellowlead to = (Earth)
andclamp,thentightenthecableclampscrews.
3. Take upexcess slack inthepowersupplycablebetweenblock
Note: Whenwiringinexternalcontrols,refertowiring diagram on
page 20. Ensureallcablesare secured.
4. Leaveenoughcablefor the controlbox to hingefreely.
5. Whenconnectingthepower supplycable, ensurethatthe length
of earth leadissuch,that ifthepowersupplycableslips out of the
cableclamp, theliveand neutralleadsbecometaut beforethe
earthlead.
6. Replaceelectricscover.
Terminal
block
Powersupply
cable
Cableclamp
IMPORTANT NOTE When a room thermostat is to be fitted
remove link R I N to R OUT and connect the room thermostat as
shown on the back page of this booklet.
CONNECTTHE WATER SUPPLY
1. Makeconnectionsas shown below. For dimensionssee page 5,
section 12.
2. Fillthe central heatingsystem and open mainswater supply.
Ensureallvalvesare openand thoroughlyflush thesystem
through.
Refillthesystemand pressuriseto 1.5 bar (sealedsystems only).
Check for leaksand rectifywhere necessary.
Note: Any discharge from the safety valve must bedirected clear of
the boilertoa drain in such a mannerthat it may beseen but
cannot cause injuryto persons
or property.
8 0
Q Drain
Domestic Discharge
hotwater
Isolation
__..
22” 15” valves 22 mm
From Mainswater To
radiators in radiators
Do not forget to remove the five plastic plugs from the pipe ends.
Note:
Ifthe mainspressureis liableto exceed 10 bar (145 lbf/inz)
then a pressurereducing valve must befitted. For domestic water
inlet pressuresof betweenthe minimum pressureof 0.4 bar and
1.3 bar theflow regulatorshould breremoved
so that the maximum
flow ratecan beobtained (seeframe 58). The filter should beleft in
placeinorderto protectcomponentswithin the appliance.Above
1.3 bar theflow regulatormust be left inplace.
17. COMMISSIONING
To vent the primary water circuit of air it is necessary to interrupt the normal procedure of the boiler. This will prevent the
boilerfrom attemptingto ignitethe
gas andfromfunctioning normally.
By using the switch marked ‘Normal/Purge’ situated on top of the control box and the programme select switches on the front
facia the system can be purgedof air.
Finally,ensurethat thesystem is pre
- pressurisedto 1.5 bar (sealedsystems only).
Proceedas follows:
PURGETHE BOILER OF AIR
1. Ensuregas cock is closed (thecock is closedwhen the operating
2. Ensureelectricitysupply is switchedoff.
3. Set purgeswitchat ‘PURGE’.
4. Set programmeselector switchesto ‘HW off and ‘CH off.
5. For sealedsystems loosentheairvent bleedscrew 2 to3 turns.
Refertodiagram on page 6 for the positionof the air vent.
6. Switchon theelectricitysupply.
7. By switchingthe hotwater selector switchtothe ‘ON’position
and back it is possibleto pulsethe hot water pump. Similarly,
switchingthe CH selector switchtothe ‘CONT positionwill start
the CH pump (providedthe DW switch is in the OFF position).
8. Oncetheair has beeneliminatedclosetheair vent bleedscrews.
Set bothselector switchesto‘OFF‘ and the purgeswitch to
NORMAL.
Note: When theelectricityisfirst switchedon there isa delay of
approximately
30 secondswhilst theelectronics‘warm up’before
the boiler respondsto any commandswith the switch set to
NORMAL. Duringthis ‘warm up’periodthe pumpswill operate
providedtheswitch is inthe PURGEposition.
slot ishorizontal).
Inspection
\ I window I
I
Centralheatingcontrol
Hot water control
Programme
selector switches
Page 11

PURGETHE SUPPLY AND CHECK
THE PILOTFLAME
Purgethegassupply
1. Loosenthegasvalve inlet pressuretest pointscrewone turn.
2. Turnonthegassupplyandopentheboilerservicecockto purge
inaccordancewith BS6891 (thecock isopenwhentheoperating
slot isvertical). Retightentest pointscrew andtest for gas soundness.
Checkthe pilotflame
1. Removecombustionchamberfront platetogetherwithfront
insulationpanel
(4 screws).Seeillustration,frame 26.
2. Removepilotshield(2screws).Seeillustration,frame32.
3. Disconnectone of theviolet leadsfromthegas valve modulatingicoil.
4. Switchontheelectricitysupply and set the hotwaterandcentral
heatingcontrols
to position 8.
5. Open a hotwater tap fully and set programmerswitches to ‘HW on’,
‘CH
off. The unitwill go throughthe ignitionsequenceand the
pilotwill light,asecond or so afterthe pilot is lit the maingas
solenoidwill open and the mainburner will light (at a low rate).
Note: The pilotburner isturned off whenever the mainburner is off.
flame is35to 40 mm long, envelopstheelectrodeandextends
10 mm pastit.Adjust if necessary(clockwiseto reducethe flame).
Gas service
cock
6. The pilotthrottleisfactorysetfully open.Checkthat thepilot
/
10. Replacecombustionchamber
front plateandfront insulation
panel
(4 screws).
Proceedto frame 25.
7. Testthepilotsupplyconnectionsfor gassoundness.
8. Turn off thehotwater tapandselectprogramme‘CHoff/HW off’.
9. Replacethe pilotshield.
CHECKTHE BURNER SETTING
PRESSURES Followingonfrom frame 24:
1. Ensurethat the programmer switches are set to ‘CHoff, ’HW off.
Loosenthe burnersetting pressuretest pointscrew on the gas
valve and connecta pressuregauge.
2. Open a hotwater tap fully and select ‘CH off, ‘HW on’. The main
burnerwill lightat the minimuminput.Check that thesetting
pressureis
1.8 mbar +0.2 (0.7 inwg *0.1). To adjustthe minimum
settingpressureremovethegas valve modulatingcoil cover and
adjustthe brass nut, ensuringthat the red plastic nut does not
move (anticlockwisetodecreasethe pressure).
3. Turnoff thehotwater tap, switchoff theelectricitysupplyand
reconnecttheviolet lead
to thegasvalve.
4. Switchontheelectricitysupply and opena hotwatertapfully.The
mainburnerwilllightatthemaximuminput.Checkthatthesetting
pressureis 16.0 mbar
(6.4 inwg). To adjustthe maximumsetting
pressureadjustthe redplasticnut,ensuringthat the brassnut
doesnot move(anticlockwiseto decreasethepressure).
Note: If either the minimumor maximumsetting pressureare
adjustedalwaysrechecktheother oneand alwaysswitch
off
theelectricitysupply when removingand replacingthe
modulatingcoillead.
5. Turn off the hot water tap and select programme ‘CHoff, ‘HW off.
6. Disconnectthe pressuregauge, retightenthe test pointscrewand
replacethe modulatingcoilcover.
Brassnut -
minimumburner
pressureadjustment
h 611 1 I I
Redplasticnut -
maximumburner
Lover Modulatingcoil ‘I/
7. Select programme‘CHoff, ‘HW on: if the main burner does not
lightopena hotwater tap fully. With the mainburneralighttest th,
pressuretest pointscrew for gas soundness.
8. Select programme‘CHoff, ‘HW off andturn off the hotwater tap
itwas opened.
9. Replacethe inner casefront
(4 screws) ensuringthe case seal is
intact.Tightensufficientlytoform aseal.
18. BALANCINGTHE SYSTEM
It is recommended that the system is balanced with the central heating output at minimum. This fixed low rate output may be
maintainedlongerthan
5 minutesprovidedthefollowingprocedureisadopted.
1. Switch off the electricitysupply and disconnect aviolet leadfromthegas valve modulatingcoil.
2. Switch on the electricity supply, select programme ‘CH cont’, ‘HW off, and turn the central heating control to position 8.
3. Balancethe system.
4. Switchoff the electricity supply and reconnectthe violet leadto thegas valve modulatingcoil.
5. Switchon the electricity supply and check that the boileroperates correctly.
6. Select programme‘CHcont: ‘HW
off and check that the boileroperates correctly.
Note: Duringthe
5 minutes heatingoperationat low fan and low gas rate the boiler may be turned off by usingthe central heating
control. However
if during this periodthe central heatingcontrol is restoredto the original positionthe boilerwill not restart untilthe
remainderof the
5 minuteshaselapsed.
The boilercan be restartedimmediatelyfor afurther
5 minutesoperationon lowfan and low gas rate by switchingthe Purge/Normal
switch to Purge,wait afew secondsandthen set itback to Normal.
When the systemhas beentested, drainthe water while it isstill hot inorder
to completethe flushing process. Where an inhibitoris
added to the system, for example Fernox CP3 for use with copper tube boilers, it should be used in accordance with their
instructions. Where the boiler is used on an old system, special care is required.The system should be drained and flushed out,
ensuringthat allthe radiatorsare drained. When filling, add the correct quantity of inhibitor for the system volume. As a guide a
3
radiatorsystemwillon average require about 2’14 pints, a 6 radiatorsystemabout 4’/4 pintsand a 9 radiatorsystemabout 6Y4 pints.
After thesystemhasbeenfilled,vent andmakeafinal checkforwater soundness.

19. FINALASSEMBLY AND HANDINGOVER THE INSTALLATION
1. Fitand securethe remainingouter panelsandcontrolscoverwith referencetoframe 2.
2. Set the timer to the correct time (do not rotatethe dial anticlockwise).Handthe User Instructionsto the User and instructin the
3. Advise the User of the precautionsnecessary to prevent damage to the system and to the building inthe event of the system
4. Advise the Userthat for continuedefficientand safeoperationof the boilerit isimportantthat adequateservicingiscarriedout at
5. Leaveapermanentcardattached to the boilergiving:
20. ANNUAL SERVICING
Thefollowingaspectsof the boilerandinstallationshouldbeexamined,and rectifiedas necessary.
1. Run the boiler and check the operation of its controls.
2. Checkthe installationof the flueterminaland ensureitisnotobstructed.
3. Removethe combustionfan and ensurethat it iscleanandfree of debris.Checkthe impellerfor freedomof rotation.
4. Removethe combustionchamberfront andcheck if the burneror heatexchanger requirescleaning.
5. Examinethe maininjectororificeandensureitisclearand undamaged.
6.
If asufficientlylargepilotflame cannot beachievedexaminethe piiotinjectororificetoensureitisclear and undamaged.
7. Inspectwaterfilter,clean or replace if damaged.
8. When refittingthe innercase checkthatthe sealisingoodconditionandensurethat itcompressessatisfactorily.
On completionof the servicerunthe boilerandensurethat itoperatessatisfactorily.
The boilerdataplateispositionedonthe innercase.
The procedurefor Annual Servicingisgiveninframes
26 to 28.
WARNING: Beforecommencingwork: Set the programmeselector switches to ‘CH off, ‘HW off!
Allow the boiler to cooland isolatethe electricitysupply.
Turn off thegas supply at the gas service cock.
safeoperationof the boilerandcontrols.
remaininginoperativeduringfrost conditions.
leastonce ayear by aqualifiedserviceengineerorthe localGasRegion.
a. Nameandaddressof installer. b. Dateof installation. c.
A wiringdiagramof the externalcircuit.
IMPORTANT: Alwaystestfor gassoundnessafter servicingany gascarryingcomponentsandcheckcontrolsfunctions.
1. Pull off faciacover.
2. Removefront panel. Undo 2 screwsandpull off front panel.
3. Removeinnercasefront (4 screws).
4. Disconnectplugcomingfromthefan motor.
5. Disconnectthe plugfrom theair flowsensor.
6. Removefluehoodandfan assemblyasdescribedinframe 6,
Keepthese two decorative itemssafe from damage.
steps 3 to 5.
Note: Onsideexit unitsitisfirst necessarytoslidethe hoodand
fanassemblysidewaysto disengagethefluetube.
7. Removecombustionchamberfront platetogether with thefront
insulationpanel
(4 screws).
8. Unscrewnutssecuringpilotsupplyandelectrode to the pilot
burner body.
9. Removepilotshield (2 screws).Seeframe 32, for illustrationof
pilotassembly.
10. Detachpilotburnerbody (1 screw) andliftaway, takingcareto
retainthe pilotinjector.
11. Remove 2 securingscrewsandwithdraw mainburner.
Air sensor Overheat
-Y\
Innercasefront
Front panel
CLEANINGTHE BOILER
1 REASSEMBLY
brush. Brushback to front NOT sideways. Removeany fallen
depositsfromthe boilerbase. replacetheearthleadwhen securingthe pilotburnerinposition.
Ensurethattheseal
is intactwhen refittingthe innercasefront.
5. Select program ‘CH off‘ ‘HW inst’and set the hot water and
4. Gentlyremovefan motor/impellerfrom fancase (3 screws).
Examine,checkingthatthe impeller runsfree andclean
if
necessary.
Water Filter
clean or replace.
centralheatingcontrolsto position 8. Check operation of main
burnerand pilot by openinga hot water tap fully. The unitwill go
throughthe ignitionsequence and the pilotwill light, asecondor
so afterthe pilotis litthe main gas solenoid will open andthe
main burnerwill light. (The pilot isturned
off whenever the main
burner is off). The electronicsmay need upto 30 secondsto
6. Returnthecontrolsand programmeselector to theiroriginal
Note:
Ensurecorrect
motororientation
when reassembling.
Page 13

2l. REPLACEMENT OF PARTS
The procedurefor the replacementof parts isgiven inframes29 to 61.
WARNING: Beforecommencingwork: Set the programmeselectorswitch to
‘CH off‘, ‘HW off‘!
Allow the boiler to cool and isolatethe electricity supply.
Turn off thegas supply at the gas service cock.
IMPORTANT:Always test for gassoundnessafter completing any exchange of gas carryingcomponents andcarry out functional
checksof controls.
NOTE: When the electricity
is first switched on there is a delay of approximately 30 seconds whilst the electronics ‘warm up’
beforethe boiler respondstoany commands.
Whenever the boiler central heating circuit is drained, the sealed system pressure (if applicable) must be checked upon
completion.Referto the commissioninginstructions,page 11, for pressurisingand purgingthe system.
All operationsrequirethefaciacover and front panelto be removed - see frame26, steps 1 and 2.
Frames 29 to
37 involve replacement of components within the room sealed section of the boiler. All necessitate removal
of the innercase front
- see frame26, step 3 - careto betaken as the seal may partially adhereto the panel.
TO REPLACE THE SPARK
ELECTRODE
Refertoframe32for illustration.
1. Unscrew nutsecuringelectrodetothepilotburnerbody.Loosen
the pilotburner body (1screw)toaid removalof theelectrode.
2. Removepilot shield(2screws) and clampingbracket(2screws).
3. Detachthefaciapanel(4screws) andcarefullypullforward.
4. Pull off spark electrodeleadfrom theignitioncontrolboard,swing
5. Reassemblein reverseorder with new electrodebutleavethe
6. Checkspark gap (seeframe24).
7. Replacepilotshield.
controlbox downandwithdraw throughthe back of thecontrolbox.
pilotshield off.
%ark electrodelead
TO REPLACETHE BURNER*OR
BURNER INJECTOR
NOTE: The burnerfittedmaybeeither Furigas(silver)or Bray(blue).
Eithermay beusedas a replacementfor theother.
Burner
1. Removeburner as describedinframe 26, steps 7 to 11.
2. Reassembleinreverseorder with new burner.
Burner Injector
1. Removeburner asdescribed inframe 26, steps 7 to 11.
2. Unscrewinjectorfromthemanifold(seeframe
27 for illustration).
3. Replacewith new injector,usingasmallamountof sealing
compound.
TO REPLACETHE PILOT INJECTOR
OR PILOTBURNER
Refertoframe32for illustration.
PilotInjector
1. Unscrewnutsecuringpilotsupplytothepilot burner body.
2. Removepilot shield (2screws)and clamping bracket
(2 screws).
3. Detachthepilotburnerbody(1
- screw)and liftawayto carefully
4. Reassembleinreverseorder with newpilotinjectorleavingthe
5. Check pilotflame (seeframe 24).
6. Replacepilotshield.
Pilot Burner
1. Unscrewnutssecuringelectrodeand pilotsupply to the pilot
2. Removepilotshield (2screws)andclampingbracket (2screws).
3. Detachpilotburnerbody (1screw) andliftaway,takingcareto
retainthepilotinjector.
4. Reassembleinreverseorder withcompletenew pilotburner body
leavingthe pilot shield
off andtest for gassoundness. Donot
forgetto replacetheearthleadwhen securingthepilotburnerin
position.
removethe pilotinjector.
pilotshield
off andtest for gassoundness.
burnerbody.
5. Checksparkgapand pilotflame (seeframe24).
6. Replacepilotshield.

TO REPLACETHE COMBUSTION
CHAMBER INSULATIONPANELS
1. Removeflue hoodassemblyandburneras describedinframe
26, steps 4 to 11.
1 2. Slideoutthe two sidepanels.
two rearbrackets (6 screws).
out. Fit new panel, locatingloweredgefirst.
3. Carefullydetachthecombustionchamber andair guidesfromthe
4. Removethe rearpanelbypullingforwardatthetop, then lifting
5. Refitchamber and air guidesontothe two rearbrackets (6 screws).
6. Carefullyslidein two newsidepanels.
7. Reassembleinreverseorderwith newfront panel.
anel
ustionchamber
TO REPLACETHE AIR FLOW
SENSOR
1. Remove two screws retainingair flow sensor to associate
metalworkandcarefullypullfreefrom sensingtube.
2. Unplugfrom theleadassembly and replacewith new sensor.
3. Reassembleinreverseorder.
TO REPLACETHE FAN
1. Disconnectplughocketcomingfrom thefan motor and lead
assemblytothe air flow sensor.
2. Remove 2 screwssecuringfan assemblyto flue hood,and 4 bolts
securingflue hoodtocombustionchamber.
3. Carefullyslideflue hoodoutfromunderthefanassembly,take
carenottodamagethegasketonthebaseof thefan assembly,
renew
if necessarybeforereassembly,then removefan and pull
off theflue tubesleeve.
4. Separatethe fanfrom itsbaseplate (4 screws).
5. Reassembleinreverseorderwith new fan.
Fan
Fluetube sleeve
(rear
exit shown)
\
TO REPLACETHE MAINHEAT
EXCHANGER
1. Removecombustion chamber as describedinframe 33, steps 1
and 3.
2. Closethe system isolationvalves. Drainthe boiler down usingthe
safety valve. See Water System, page 6.
3. Removethe overheat cut - offdevice, see frame 36.
4. Loosentwotubing nutsand remove heat exchanger (sealed
system).
5. Loosentwo tubing nuts andopen ventconnectionand remove
heatexchanger(opensystem).
6. Reassembleinreverseorder
Tubing
nuts
TO REPLACE THE OVERHEAT
CUT - OFF DEVICE
Overheatcut - off device is markedwith white paint.
1. Removethe push - rod & buttonassemblyfrom the cut - off device.
2. Removethe two push - ontags to the cut - off device.
3. Removethetwo retainingscrews.
4. Reassemblein reverseorder. The tags may be refitted eitherway.
Push rod
Sleeve
. Overheat
cut-off device
GasValve
1 I \To Manifold
See frames 39 to 41.
Page 15

I Frames 38 on do not require removilof the mmseal compartment
TO REPLACETHE GASVALVE
Referto illustration,frame 38.
1. Ensurethat the gas supply is off and electricity supply is
2. Removebottomcase panel (8 screws).
3. Swingdown control box (2 screws),see frame 52.
4. Remove CH pumpto gainaccesstothe topfixing screws (see
5. Removegrey cover (1screw) from the mainsolenoidto
isolated.
frame 55).
disconnect lead. Unscrewearthterminaland pull
off thetag
terminals (polarity not important).
6. Disconnecttag terminalsfrom themodulatingcoil and pilot
solenoid.
7. Disconnect pilotsupply.
8. Remove 8 screws retainingthe gas valve in position (4socket
9. Transfer the uniontothe new valve usinga littlejointing
type on top, 4 underneathtothechassis).
compound.
10. Usingnew ‘0 ring between manifoldand valve, reassemblein
reverseorder taking care not to connectterminals to the
wrong solenoid, refertothewiring diagram on page 20.
11. Refillthe water system and check for water soundness.
12. Test for gas soundness and referto Commissioning
instructions.Daae 12.frames 24 and 25.
front cover
TO REPLACETHE MODULATING
1 COIL
1. Ensurethatthegassupplyis off andelectricitysupplyisisolated.
2. Disconnectthetwotag terminals.
3. Removethe two screwsandcarefullyliftoff thecomplete
4. Reassembleinreverseorderwith new coil. -
assembly.
Modulatingcoil I\/
TO REPLACETHE PROGRAMME
TIMER
1. Detachthe facia panel (4 screws),carefully pulling itforward,
and removethe electricscover (4 screws).See frame 42.
2. Notingtheir positions, removeall leadterminals from the
programmetimer.
3. Removetimer (3 screws).
4. Reassemblewith new timer in reverseorder. Check connections
with diagram on page20.
Leadconnector 1 I/ I
I
Maincontrolboard
TO REPLACE MAIN GAS VALVE
OPERATING SOLENOID
Referto illustration,.frame 38.
Ensurethat the gas supply is off and electricity supply is isolated.
1. Disconnectthe two tag terminals tothe modulatingcoil.
2. Remove greycover (1screw) from the solenoid. Disconnectthe
earth terminaland tag terminals (polarity not important).
3. Removethetwo screws retainingthe modulatingcoil and
carefullyliftoff the coil.
4. Removethefour screwssecuringthesolenoidto the
gas valve
and carefullylift off the solenoid.
Reassem bly
Reassembleinreverseorder with a newsolenoid.Testfor gas
soundnessand burnerpressure,referto Commissioning
instructions,page 12,frames 24 and25.
Accessto the Electrics
m See frames 43 to 51.
\
cover
TO REPLACEPOTENTIOMETER
AND LEADASSEMBLY
The controlsfor Central Heatingand HotWater arewired tothe
same connector and must both be replaced.
1. Detachthefacia panel(4 screws),carefully pullingitforward,and
removethe electricscover (4 screws).Seeframe 42.
2.
Pull off the lead connector fromthe maincontrol board.
3. Push off bothfront knobsfrom behindthroughthe holes inthe
facia panel.
4. Unscrew2front mountingnutsand remove bothpotentiometers.
5. Reassemblein reverseorderwith new potentiometers,ensuring
that the locatingpegsare correctlypositions.

TO REPLACE THE PRESSURE
GAUGE
1. Closeoff the system isolationvalves. Removebottomcase panel
(seeframe 2),drainthe primary circuit by opening the safety
valve.
screws toallow control boxto swingdown.Seeframe 50.
body.
Feedthe capillary through.
2. Removethe bottomcase panel (8 screws)and remove 2 retaining
3. Removethe pressuresensor capillary from pressurerelief valve
4. Detachthefacia panel (4 screws) and carefully pullforwards.
5. Compressclipson bodyof gauge and pushthrough.
6. Reassemblewith new gauge in reverseorder.
7. Refillsystem and referto Commissioninginstructions,page 11,
frame 23.
TO REPLACETHE MAINCONTROL
BOARD
1. Removethe electricscover (4screws).See frame 42.
2. Carefully pulloff all connectorsfrom the maincontrol board.
3. Pullthe boardto disengagefrom thesupport pillarsand remove.
4. Reassemble in reverseorder with new maincontrol board.
Connectors
board
TO REPLACE THE CENTRAL
HEATING SELECTOR SWITCHAND/
OR THE DOMESTICWATER
SELECTOR SWITCH.
1. Detachthefacia panel (4 screws), carefully pullingitforwardand
2. Notingtheir positions, removeall lead terminalsfrom the central
removetheelectricscover (4 screws) (see frame 42).
heatingselector switchand/or the domestic water selector
switch.
3. Compressclipson body of switch(es) and pushthrough.
4. Reassemblewith new switch(es).Check connectionswith
diagramon page20.
Swtich
TO REPLACETHE IGNITION
CONTROL BOARD
1. Detachthefacia panel (4screws), carefully pullingitforward, and
2.
Pull off the connectorsandthespark electrodeleadfrom the
3. Pullthe boardtodisengagefrom the support pillarsand remove.
4. Reassemblein reverseorder with new ignitioncontrol board.
removetheelectricscover (4 screws). See frame 42.
ignitioncontrol board.
\
Ignitioncontrolboard
~
TO REPLACETHE TRANSFORMER
AND LEADASSEMBLY
1. Removethe electrics cover (4screws).
2. Pull
off thetransformer leadassemblyfrom the meincontrol
board.
3. Removetransformer
(2 screws)from the control box.
4. Reassemblein reverseorderwith newtransformerand lead
assembly.
TO REPLACE THE NORMAUPURGE
SWITCH
1. Removethe electricscover (4 screws).Seeframe 42.
2. Removethe leadterminalsfrom the normal/purgeswitch
3. Compressclipson bodyof switch and pushthrough.
4. Reassemblewith new switch positionedwith terminalstowards
(polaritynot important).
the back of the control box. Check connections with diagram on
page 20.
I
Page 17

-
TO REPLACETHE CENTRAL
HEATINGFLOWSENSOR
1. Close off thesystem isolationvalves, removebottomcasepanel
(seeframe2), anddrainboilerdownusingthesafetyvalve.
2. Pull off terminalsfromthesensor.
3. Removesensor.
4. Reassembleinreverseorderwith newsensor.
5. RefillthesystemandrefertotheC,ommissioninginstructionson
page 11, frame 23.
Centralheating I 1
TO REPLACE A DOMESTICHOT
WATER INLET OR FLOWSENSOR
1. Close off the mainsinlet isolationvalve. SeeWater System,
2. Turnona hotwatertaptoallowwater todrainfrom the secondary
3. Removethebottomcasepanel (8 screws) andremove 2
page 6.
heatexchanger.
retainingscrewsto allowthecontrolbox to swingdown. See
frame 52.
4. Pull off thesensorterminals.
5. Removesensor.Therewill bea littlewater drainingfrom the
secondaryheatexchanger.
6. Replacewith newsensor andattachterminals. (Polaritynot
important).
7. Openmainsisolationvalve andrefillthesystem. Referto
Commissioninginstructions,page
11, frame 23.
Hot water
inletsensor
TO REPLACE A PUMP OR NON-
RETURNVALVE
1. Close off the systemisolationvalves.
2. Remove 2 screwsandallowthecontrolboxtoswingdown. See
frame 52.
3. Draindown boiler usingthe safetyvalve, see Water System, page
6.
4. Removewiringcase (1 screw), noteconnections anddisconnect
leads. Loosenunionsand removepumpandnon
- returnvalve
takingcarenottotwistthe pipework.
5. Reassemblein reverseorderwith new part and newwashers.
6. RefillthesystemandrefertotheCommissioninginstructionson
page11,frame23.
TO REPLACETHE SAFETY VALVE
1. Close off thesystem isolationvalves.
2. Removethe bottomcasepanel (8 screws).
3. Drainprimarycircuitusingthesafetyvalve, seeWater System,
page 6.
4. Remove2 screwstoallow thecontrolbox to swingdown, see
frame52.
5. Disconnectpressuregaugecapillary.
6. Loosenthe unionsholdingthevalve inposition,taking care not
7. Reassemble inreverse orderwith new part and new washers.
8. RefillthesystemandrefertotheCommissioning instructionson
to twist the pipework.
TO REPLACE THE LOW PRESSURE
CUT - OFF DEVICE
1. Ensurethat the electricitysupply is isolated.
2. Close off thesystem isolationvalves. Remove bottomcase panel
(seeframe
2), drainthe primarycircuit by openingthe safety
valve.
3. Remove 2 retainingscrews to allow control box to swing down
(seeframe
52).
4. Disconnectelectrical leadsand remove low pressurecut off
device.
5. Reassemble in reverse order with new part.
6. Open isolationvalve and referto theCommissioning instructions
II 1
on page 11, frame 23.
cut - offdevice

TO REPLACE OR CLEAN
REGULATOR AND FILTER
1. Closemainswater inletisolationvalve. Drainbyopeningthe lowest
hot water taps andthe drain point inthe mains isolation valve.
2. The flow regulator andfilter are situated inthe 15 mm mains
isolationvalve. Unscrewthetop nut, ease the inlet pipeasideand
allow todrain.
3. Removeflow regulator and filter.
Clean or replacewith new
part(s) usinga new washer.
4. Reassemble in reverseorder.
5. Opena hot water tap to
DRAIN
POINT
clearair from thesystem.
ORiNG -0
KLATOR e
FILTER
DRAIN
POINT
15MM
ISOLATOR
VALVE
15mm
VALVE
- ISOLATOR
TO REPLACE OR DESCALETHE
SECONDARY HEAT EXCHANGER
1. Close off the isolationvalves.
2. Removethecasebottompanel (8 screws) andremovethe2
screwstoallowcontrolbox
to swingdown. Seeframe 52.
3. Drainboilerdownusingthesafetyvalve. SeeWater System,
page 6.
4. Removethesecondary heatexchanger support bracket
(6 screws). See frame 52.
5. Removebothhot water
sensors.Seeframe 53.
6. Loosenthe 4 unionsand
removeheatexchanger.
7. Replacewith new heat
exchanger usingnew '0'
ringssuppliedor descale
usingproprietarydescaling
agent
on 15 mm
connectionsonly.
8. Reassembleinreverse
order usingnew '0' rings.
9. Refillthesystemandrefer
to theCommissioning
instructionson page
11,
frame23.
TO REPLACETHE CASE SEALAND
m VIEWING WINDOW
Case Seal
1. The casesealisretainedby the groove itsits in.Simplypullout
2. Reassemblein reverseorder.
fromgroove to remove.
Viewing Window
1. Remove two nutsholdingwindow assembly to innercase (retain
thenutsandbracket).
2. Removeglassandgasket.
3. Replacewith new glass andgasket.
4. Reassembleinreverseorder.
TO REPLACETHE EXPANSIONVESSEL
1. Replacementof the expansion vessel isa majoroperation. Itis recommendedthat a new equivalent,vessel is addedtothe system.
Thisshould beconnected to ajunction at theentry of the RETURNpipeto the appliance,as closetothe applianceas possible.
Requirementof
885449 must becompliedwith for sealed systems.
2. If the faulty appliancevessel is leaking,you will needto isolatethe vessel by cuttingthe pipejoiningthe vessel to thewater manifoldand
cappingthe section connected to the manifold.
TO REPRESSURISETHE
m ' ' EXPANSIONVESSEL
1. Ensurethe electricitysupply isisolatedandclose off theboiler
2. Drainboilerdownusingthesafetyvalve.
3. Connectair pumpto the expansionvesselvalve (locatedat the
base
of theappliancebetweenthecentralheatingreturnand
mainwater inlet pipes)andrepressurisethevessel
to 0.5 bar
(7.5 psi).
isolatingvalves. SeeWater System, page 6.
Page 19

COLOURCODE
b - blue
P - purple
bk-black v - violet
br
- brown r - red
g - green w - while
gy - grey y - yellow
o - orange g/y - greenand
pk-mk yellow
TERMI~AL
BLOCK
k CABLE
CLAMP
-
-
L
1
WHEN FITTING
THERMOSTAT A
ROOM
1. Remarelink betwean R IN
and R MIT.
2. Connect Room Thermostat
between
R OUT and R IN.
The RwmThermanatN
may beconnectedto
supply N1.
WHEN FITTINGA FROST
THERMOSTAT:
ConnectFrostThermostat
between
P2 and R WT
Note:
EllJWeAlcsbka.rsseeued
Ifthis applianceisused on
an opensystemthena link
must be fitted between
L1and P1.
Any Earthwires from Frost or
mom thermostatsmay be
wired back tothe additional
earthontheterminalstrip.
CENTRALHEATING
(FLOW)SENSOR
II I
I Ill
IGNITION
I I I CONTROL
BOARD
L2
L3
F
L
F N
PRESSURE CHASSIS
br-
INLET
SENSORH kr
r
LOW PRESSURE
INDICATOR
CENTRAL
HEATING
TEMPERATURE
CONTROL
HOTWATER
TEMPERATURE
CONTROL
GASVALVE
TIMER