Biasi GARDA HE M96.24SM/B User manual

Wall hung,fanflue,roomsealed,highefficiencygasboiler
Servicemanual
GARDAHE
Models: G.C.Appl.No.
M96.24SM/B47---970---25
M96.28SM/B47---970---26
GARDAHESILVER
Models: G.C.Appl.No.
M96.24SM/D47---970---27
M96.28SM/D47---970---28
Leavethismanualadjacent tothegasmeter

Tableofcontents
1Overall information1..................
1.1Overall View1.........................
1.2Hydraulicdiagram1....................
2Generalaccess andemptying
hydraulic circuits2....................
2.1Nomenclature2........................
2.2Bodypanels2.........................
2.3Controlpanel2........................
2.4Access tothesealedchamber3.........
2.5Emptyingtheprimarycircuit3...........
2.6Emptyingthed.h.w.circuit3............
3Diagrams4...........................
3.1Wiringdiagram4.......................
3.2Functionalflowdiagrams6..............
3.3Circuitvoltages7......................
4Faultfinding9........................
5Primaryheatexchanger11..............
5.1Function11.............................
5.2Removal11............................
5.3Cleaning11............................
6Condensingheatexchanger12..........
6.1Function12.............................
6.2Removal12............................
7D.h.w.heatexchanger13...............
7.1Function13.............................
7.2Removal13............................
8Pump14...............................
8.1Function14.............................
8.2Checks14.............................
8.3Removal14............................
9Three waydivertervalve15.............
9.1Function15.............................
9.2Checks15.............................
9.3Removalofthe electricactuator15........
9.4Removalofthedivertergroup
anditsinternalparts16..................
10 Electronic controlp.c.b.17..............
10.1Function17.............................
10.2Selectionandadjustmentdevices17......
10.3Checkingthetemperature17.............
10.4Operationlights18......................
10.5Dip---switchselectors19.................
10.6Settings20.............................
10.7Ignitiongaspressureadjustment20.......
10.8Checks20.............................
10.9Removalofthe electronic controlp.c.b20. .
10.10 Thermalcontrolinthe” ” mode22......
10.11 Thermalcontrolinthe” ” mode22......
11 Full sequenceignitiondevice23.........
11.1Function23.............................
11.2Checks23.............................
11.3Removal23............................
11.4Ignitionandcontrolsequence24..........
12 Modulating gasvalve25................
12.1Function25.............................
12.2Nomenclatureoftheparts25.............
12.3Adjustment25..........................
12.4Checks26.............................
12.5Removaloftheon---off operatorscoils26. .
12.6Removalofthegasvalve26..............
13 Primarycircuitflowswitch27...........
13.1Function27.............................
13.2Checks27.............................
13.3Removal27............................
14 Expansionvesseland
temperature-- pressuregauge28........
14.1Function28.............................
14.2Checks28.............................
14.3Removalofthe expansionvessel28.......
14.4Removalofthetemp.---pressuregauge28.
15 D.h.w.flowswitch,filterandflowlimiter29
15.1Function29.............................
15.2Nomenclatureandlocationofparts29.....
15.3Checks29.............................
15.4Removaloftheflowswitchsensor29......
15.5Removaloftheflowswitchgroup
and d.h.w.circuitfilter29.................
15.6Flowlimiter30..........................
16 Temperatureprobe31..................
16.1Function31.............................
16.2Checks31.............................
16.3Removal31............................
17 By--pass valve32......................
17.1Function32.............................
17.2Removal32............................
18 Fan,venturideviceandairpressure
switch33..............................
18.1Function33.............................
18.2Checks33.............................
18.3RemovaloftheFan34...................
18.4Inspectionandremovalofventuridevice35
18.5RemovaloftheAirpressureswitch35.....
19 Ignitionand detectionelectrodes36.....
19.1Function36.............................
19.2Checks36.............................
19.3Removal36............................
20 Safetythermostat37...................
20.1Function37.............................
20.2Checks37.............................
20.3Removal37............................
21 Fluethermostat38.....................
21.1Function38.............................
21.2Checks38.............................
21.3Removal38............................
22 Condensatetrap39....................
22.1Function39.............................
22.2Removal39............................
23 Shortsparepartslist40................

1
1Overall information
1.1Overall View
Fan
Safety
thermostat
Main heat
exchanger
Burner
Ignition
electrodes
Gasvalve
Control
panel
Combustion
chamber
Automatic
air release
Pump
D.h.w.temp.
probe
D.h.w.
heatexchanger
Expansion
vessel
Detection
electrode
valve
Condensing
Divertervalve
Airpressure
switch
Maincircuit
Fluethermostat
heatexchanger
Condensate
trap
flowswitch
C.h.temp.
probe
1.2Hydraulicdiagram
Centralheating(c.h.)operationDomestichot water(d.h.w.)operation
C.h.
waterflow
C.h.
water return
D.h.w.
inlet
D.h.w.
outlet

2
2Generalaccess andemptying
hydraulic circuits
2.1Nomenclature
2
6
1
54
3
Fig.1
1Rightsidepanel
2Frontpanel
3Controlpanel lid
4Controlpanelcover
5Servicepanel
6Leftsidepanel
2.2Bodypanels
Warning:isolatetheboilerfromthemains
electricitysupplybeforeremovingany
coveringorcomponent.
Forthemostpartofthecheckandmaintenanceoper-
ationsitisnecessarytoremoveoneormorepanelsof
thecase.
Thesidepanelscanberemovedonlyaftertheremoval
ofthefrontpanel.
ToremovethefrontpanelremovescrewsA(Fig.2),lift
thepanelandremoveit.
A
Fig.2
ToremovethesidepanelsloosenthescrewsBandC
(Fig.3),bringthebaseofthepanelsawayfromthe
boilerandlift them,freeingthemfromthetophooks.
B
D
C
Fig.3--- bottomviewoftheboiler
2.3Controlpanel
Warning:isolatetheboilerfromthemains
electricitysupplybeforeremovingany
coveringorcomponent.
Togainaccess tothepartslocatedinsidethecontrol
panelproceedasfollows:
1Removethefrontpanelofthecase
2LoosenthescrewsBandC(Fig.3).
3RemovethescrewsD
4Movethelowerpartofthesidepanelsasindi-
catedinFig.4and pull thecontrolpanel.
Whencompletelypulledout,thepanelcanrotate
45°downwardstofacilitatetheserviceoper-
ationsontheinternalparts.

Generalaccess andemptyinghydraulic circuits
3
Fig.4
5RemovethescrewsEandremovetheservice
panel(Fig.5);
6Togainaccess tothe electronicregulationPCB
andthefull sequenceignitiondeviceremovethe
screwsFandremovethecontrolpanel lid
(Fig.5);
E
F
F
Fig.5
2.4Access tothesealedchamber
G
G
Fig.6
Togainaccess tothepartscontainedinthesealed
chamberitisnecessarytoremovethelidofthesealed
chamber.
Forthispurpose,removethefrontandsidepanelsof
thecase,removethescrewsGasindicatedinFig.6
andremovethelid.
2.5Emptyingtheprimarycircuit
1Closethec.h.circuitflowandreturncocksH.
(Fig.7).
H
H
J
Fig.7--- bottomviewoftheboiler
2Removethefrontandrightpanelsoftheboiler.
3OpenthedraintapI(Fig.8)untiltheboileriscom-
pletelyemptied.
4Closedraintapagainoncethe emptyinghas
beencompleted.
I
Fig.8
2.6Emptyingthed.h.w.circuit
5Closethed.c.w.inletcockJ(Fig.7);
6Openoneormorehotwatertapsuntiltheboiler
hasbeencompletelyemptied.

4
3Diagrams
3.1Wiringdiagram
Ignition
electrodes
Flamedetection
electrode
bn=brown
bu=blue
bk=black
wh=white
rd=red
gy=grey
Safety
thermostat
ExternalcontrolsElectricsupplyFanAirpressure
switch
Timeswitch
123
t
bkbk
t
bk
bk bk
M
~
M
~
bk
bk
bk
bk
M
~
bk
bk
bk
terminalblockterminalblock
gy bk
Pump
PrimarycircuitD.h.w.temperature
probeNTC
Three way
divertervalve
D.h.w.flow
switchflowswitch
C.h.temperature
probeNTC
Electronic
controlp.c.b.
Full sequence
ignitiondevice
gn=green
ye=yellow
rd
bu
whrd
bu
rd
bu
bn
bu
bn
bn
bu
bn
bu
bk bn bu
3 1 2
bk
gnye
bu
rd
bu bn
gnye gnye
gnye
gnye
gnye gnye gnye
gnye
bu bn
bn
bu
rd rd
wh
bu
rd
bu
rd
rd
gy
bn
bu
bu bu bn
bu
gy
rd
gnye
br
br
gnye
bn bu
bn
bu
bk
rd
bk
wh
gn
NC
COM
NO
vt=violet
og=orange
gnye=green/yellow
bu
bn
bk
bu
bn
bu
bn
Wiringdiagramforboilerequipedwithfull sequenceignitiondevicetype:Bertelli&PartnersFM30
bk
bk
Modulating
gasvalve
gnye
gnye
bu
gnye
gy
bn
br
Flue
thermostat
gnye
Condensate
trap
bu
bu

Diagrams
5
bn=brown
bu=blue
bk=black
wh=white
rd=red
gy=grey
gn=green
ye=yellow
vt=violet
og=orange
gnye=green/yellow
Ignition
electrodes
Flamedetection
electrode
ExternalcontrolsElectricsupplyFanAirpressure
switch
Timeswitch
123
t
bkbk
t
bk
bk bk
M
~
M
~
bk
bk
bk
bk
bk
bk
M
~
bk
bk
bk
terminalblockterminalblock
gy bk
Pump
Modulating
PrimarycircuitDHWtemperature
probeNTC
Three way
divertervalve
gasvalve
DHWflow
switchflowswitch
CHtemperature
probeNTC
Electronic
controlp.c.b.
Full sequence
ignitiondevice
gnye
gnye
bu
gnye
gyrd
bu
whrd
bu
rd
bu
bn
bu
bn
bn
bu
bn
bu
bk bn bu
3 1 2
rd
bu bn
bn
gnye gnye
gnye
gnye
gnye
gnye gnye gnye
gnye
bu bn
bn
bu
rd rd
wh
bu
rd
bu
rd
rd
gy
bn
bu
bu bu bn
bu
gy
rd
gnye
gnye
vt
og
bn
bu
bk
rd
bk
wh
gn
NC
COM
NO
bn
gnye
bu
Wiringdiagramforboilerequipedwithfull sequenceignitiondevicetype:Honeywell FPLD
Safety
thermostat
FanFlue
thermostat
Condensate
trap
br
brbr
bu
bu
bu
bn
bk
bu
bn
bu
bn

Diagrams
6
3.2Functionalflowdiagrams
PTCJ1--- 1
L
General layout
Transformer
N
Electronic
controlp.c.b.
(lowvoltagesection)
J1--- 2
J3--- 3
J3--- 5
J3--- 4
J3--- 2J3--- 1
J2--- 4J2--- 5
Three way
divertervalve
Pump
Full sequence
ignitiondevice
Fuse1,6AT
PTCJ1--- 1
L
Transformer
ACTIVECIRCUIT
INACTIVECIRCUIT
L--- LINEN--- NEUTRAL
N
Electronic
controlp.c.b.
(lowvoltagesection)
J1--- 2
J3--- 3
J3--- 5
J3--- 4
J3--- 2J3--- 1
J2--- 4J2--- 5
Three way
divertervalve
Pump
Full sequence
ignitiondevice
Fuse1,6AT
Heatrequestond.h.w.
PTCJ1--- 1
L
Transformer
N
Electronic
controlp.c.b.
(lowvoltagesection)
J1--- 2
J3--- 3
J3--- 5
J3--- 4
J3--- 2J3--- 1
J2--- 4J2--- 5
Three way
divertervalve
Pump
Full sequence
ignitiondevice
Fuse1,6AT
Heatrequestonc.h.

Diagrams
7
3.3Circuitvoltages
230~
Supplynetwork
230~
230~
0
Electricalvoltageswithburneron
duringc.h.ord.h.w.operation
onlyduringc.h.operation
onlyduringd.h.w.operation
230~
230~
230~
0
Pump
Full sequence
Ignitiondevice
3waydivertervalve
0 0
Electronic
controlp.c.b.
230~230~
Modulating
Gasvalve
Safety
thermostat
0
Fan
230~
230~
0
Electronic
controlp.c.b.
Air
pressure
switch
Diagramsforboilerequipedwithfull sequenceignitiondevicetype:Bertelli&PartnersFM30

Diagrams
8
230~
Supplynetwork
230~
230~
0
Electricalvoltageswithburneron
duringc.h.ord.h.w.operation
onlyduringc.h.operation
onlyduringd.h.w.operation
230~
230~
230~
0
Pump
Full sequence
Ignitiondevice
3waydivertervalve
0 0
Electronic
controlp.c.b.
230~230~
Modulating
Gasvalve
Safety
thermostat
0
Fan
230~
230~
0
Electronic
controlp.c.b.
Air
pressure
switch
Diagramsforboilerequipedwithfull sequenceignitiondevicetype:Honeywell FPLD

9
4Faultfinding
Componentstocheck
Sectionofthemanual! (noteref.inbrackets)
---
(1)
---
(2)
---
(3)
22.1---
(4)
7 8.2 9.2 10.8 11.2 12.4 13.2 15.5 16.2 17 18.2 19.2 20.2 21.1---
(7)
---
(8)
--- ---
Lock---outsignal lampred
Defect #
Powersupplyline
Gas supplyline
Fluepipes
Condensatedrainpipeandtrap
C.h.circuit
D.h.w.circuit
D.h.w.heatexchanger
Pump
Divertervalve
D.h.w.flowswitch
Fuse(regulationp.c.b.)
Regulationp.c.b.
Functionselectors(reg.p.c.b)
Full sequencedevice
Gasvalve(on---off operators)
Gasvalve(modulatingoperator)
Maincircuitflowswitch
D.h.w.filter
Maincircuit temp.probe
D.h.w.temp.probe
By--- pass valve
Fanandventuridevice
Airpressureswitch
Ignitionelectrode
Detectionelectrode
Safetythermostat
Fluethermostat
Injectors
Expansionvessel
Safetyvalve
Pressuregauge
Bypressingtheresetpush--- button theboilerturnsonandoperates correctly.
J J
(6)
J J J
Bypressingtheresetpush--- button theboilerstartstheignitioncycle. Theburnerdoesn’tlighton,the ignitionsparkscontinueandthe boilerlocksagain.
J J J J J
ON
Bypressingtheresetpush--- button theboilerstartstheignitioncycle. Theburnerlightson,theignition sparkscontinueandtheboilerlocks again.
J J J J J J
Theboilerdoesnotstarteitherin c/hord.h.w.mode. All theoperationlightsOFF Fanstill.
J J J
Theburnerdoesn’tlighteitherin c.h.ord.h.w.mode. Fanturns.
J J J J
Theburnerdoesn’tlighteitherin c.h.ord.h.w.mode. Fandoesn’tturn.
J J J J J J J J
Theboilerdoesn’tcontrolthed.h.w. temperature. Turningthed.h.w.temp.adjustment knobhasn’teffectonthemodula- tionoftheflame. Theboileroperatescorrectlyonc.h.
J J
OFF
Theboilerlightsforashortwhileon c.h. Normaloperationond.h.w.function.
J J

10
Componentstocheck
Sectionofthemanual! (noteref.inbrackets)
---------
(8)
---
(7)
21.120.219.218.21716.215.513.212.411.210.89.28.27---
(4)
22.1---
(3)
---
(2)
---
(1)
Lock---outsignal lampred
Pressuregauge
Safetyvalve
Expansionvessel
Injectors
Fluethermostat
Safetythermostat
Detectionelectrode
Ignitionelectrode
Airpressureswitch
Fanandventuridevice
By--- pass valve
D.h.w.temp.probe
Maincircuit temp.probe
D.h.w.filter
Maincircuitflowswitch
Gasvalve(modulatingoperator)
Gasvalve(on---off operators)
Full sequencedevice
Functionselectors(reg.p.c.b)
Regulationp.c.b.
Fuse(regulationp.c.b.)
D.h.w.flowswitch
Divertervalve
Pump
D.h.w.heatexchanger
D.h.w.circuit
C.h.circuit
Condensatedrainpipeandtrap
Fluepipes
Gas supplyline
Powersupplyline
Defect # Theboilerdoesnotsupplyd.h.w. (coldwaterfromthetap). Regularoperationinc/hmode even duringadrawingoff d.h.w.
J J J
Onc/hmodethetemperatureof themaincircuitreaches75°Cand thec/hsystemdoesnotheat. Theboileroperatescorrectlyon d.h.w.mode.
J J
IncorrectmodulationJ J J NoisybolierJ J Theboileroperatescorrectlybut thegaspressuretotheburner re- mainsatminimum.
J J
F
Poord.h.w.temperatureJ J J J J
(9)
OF
F
Lowd.h.w.flowrateJ J J
---
Waterleaksfromthesafetyvalve duringoperationonc/h
J J J J
---
Waterleaksfromthesafetyvalve whentheboilerisoff.
J J J
Note Usefulinformationcanbeobtainedalsofromthe opticalindicationgivenbytheapplianceoper- ationlights(see section10.4). 1Checkfor230V~betweenline(L)andneutral(N)
Verifytheintegrityofsupplycable,plugandexternalfuses. Checkthepolarityoflineandneutralconnection
2Verifythesoundness ofthegas supplypipe,thepositionof
stopvalves.
Checkthegaspressureat theinlet testpointofthegasvalve (see sect.12.3)withtheboileratrestand duringoperationand compareitwiththevaluesgivenontheinstallationbooklet.
3Checkforsoundness andabsenceofobstructions.Verifythat
theflueterminaliscorrectlyinstalled(see clearances)anden- surethatexhaustgasisnotsucked backbytheboiler.
4Checkforsoundness ofthecircuitandverifyitscorrectfilling
(see alsoinstallationmanual).
5Ajammed by---pass couldcausetheover---heatingofthemain
circuitandtheinterventionofthesafetythermostat.
6Checktheminimumgaspressureat theoutlet testpointofthe
gasvalve(see sect.12.3)andcompareitwiththevaluegiven ontheinstallationbooklet.
7Verifythecleanness ofinjectors. 8Checkthepressurizationofthe expansionvessel.Refertothe
installationmanualforpropervalues.
9d.h.w.pressuretoo highorflowratetoo high.Ifnecessaryin-
sertaflowratelimiter(15.6).

11
5Primaryheatexchanger
5.1Function
TheprimaryheatexchangerAinFig.9hasthefunction
oftransferringheatproducedfromcombustionofthe
gastothewatercirculatinginit.
A
Fig.9
Thehydraulic circuitiscomposedof8ellipticalpipes
connectedinparallel(Fig.10).
Fig.10
5.2Removal
Warning:isolatetheboilerfromthemains
electricitysupplybeforeremovingany
coveringorcomponent.
1Removethecasepanelsandthesealedchamber
lid(see section2).
2Emptytheprimarycircuitoftheboiler.
3RemovethecombustionchamberlidBbyun-
screwingthescrewsCandremovingtheclamp
D(Fig.11).
4RemovethescrewsEandtheplateF.
5LoosentheconnectionGandslightlymovethe
pipeHupwards.
6RemovetheclipIandthesafetythermostatJ.It
isnotnecessarytodisconnectitfromthewiring.
E
M
C
B
F
C
D
G
I
J
N
K
L
H
Fig.11
7LoosentheconnectionKandmovethepipeL
downwardsfreeingitfromtheconnectionofthe
primaryhetexchanger.
8RemovetheclipM
9MovethepipeNupwardsfreeingitfromthecon-
nectionandrotatetowardsright.
10 Removetheheatexchangerbyslidingitfor-
wards.
11 Reassembletheboilercarryingout theremoval
operationsinreverseorder.Fit theclipIwiththe
arrowpointingupwardsasillustratedin
Fig.11.
IMPORTANT-- donotforcetheconnectionGwhen
tightingit.
5.3Cleaning
Iftherearedepositsofsootordirtbetweentheblades
oftheheatexchanger,cleanwithabrushornon---me-
tallicbristlebrush.
Inanycase,avoidanyactionsthatcandamagethepro-
tectivevarnishwithwhichthe exchangerhasbeencov-
ered.
Warning:Aftercleaningor replacementas
detailedabove,ifitdeemednecessaryto
undertakeacombustionanalysis,referto
theappropriatechapterMaintenanceofthe
installationinstructionsmanual.

12
6Condensingheatexchanger
6.1Function
Thereturnwaterflowsthroughthecondensingheatex-
changerAinFig.12 andFig.13.
Byreducingthecombustionproductstemperature,the
latentheatofthevapouristransferredtothewatercir-
cuit,allowinganextragainofusefulheat.
Thecondensedvapouristhendrainedthroughthe
condensatetrapBandthedrainingpipeC.
A
B
C
Fig.12
6.2Removal
Warning:isolatetheboilerfromthemains
electricitysupplybeforeremovingany
coveringorcomponent.
1Removethecasepanelsandthesealedchamber
lid(see section2).
2Emptytheprimarycircuitoftheboiler.
3RemovethefanDinFig.13 (see section18.3)
andtheairpressureswitchE(see section18.5).
4RemovethefluethermostatF(see section21.3)
5CompletelyloosentheconnectionGandslightly
movethepipeHupwards.
6RemovetheclipIandmovethepipeJdown-
wardsfreeingitfromtheconnection,thenturnit
towardsright.
7Usingpliers,removethespringKmovingitdown-
wardsand disconnect therubberpipeL.
8RemovethebracketMbyunscrewingthescrews
thatholditontheframe.
9Rotatethe exchangerasindicated bythearrow
andremoveit towardsthefrontoftheboiler.
10 RemovetheclipNandthepipeH.
DD
E
F
G
I
K
L
M
A
J
N
H
Fig.13
11 Reassemblethe exchangercarryingout there-
movaloperationsinreverseorder.
After reassemblingensurethat thefan--exchanger
andexchanger-- elbowgasketsarecorrectly
mountedandensureagoodsealing.
Warning:Aftercleaningor replacementas
detailedabove,ifitdeemednecessaryto
undertakeacombustionanalysis,referto
theappropriatechapterMaintenanceofthe
installationinstructionsmanual.

13
7D.h.w.heatexchanger
7.1Function
Thed.h.wheatexchangerAinFig.14 andFig.16 al-
lowstheinstantaneoustransferofheatfromtheprimary
hydraulic circuit tothewaterdestinedford.h.wuse.
A
Fig.14
Theschematicstructureis showninFig.15.
Primaryhydraulic circuit
D
o
m
e
s
t
i
c
h
o
t
w
a
t
e
r
c
i
r
c
u
i
t
Fig.15
7.2Removal
Warning:isolatetheboilerfromthemains
electricitysupplybeforeremovingany
coveringorcomponent.
1Removethefrontandrighthandsidepanelsof
thecase.
2Emptytheprimarycircuitandthed.h.wcircuitof
theboiler.
3CompletelyunscrewthetwoAllenkeyscrewsB
(Fig.16)which holdthe exchangertothebrass
groups.
B
A
Fig.16
4Movethe exchangertowardstherearoftheboiler
andextractit.
Reassemblethed.h.w.heatexchangercarryingout the
removaloperationsinthereverseorder.
Attention.Whenreassemblingthe exchangerbe
suretoput theoff centerlocation/securingpinindi-
catedinFig.17 towardstheleftsideoftheboiler.
Fig.17

14
8Pump
8.1Function
ThepumpAinFig.18 andFig.19 hasthefunctionof
makingthewaterinthemaincircuitcirculatethrough
themain heatexchanger,thecondensingheatex-
changerandthereforethroughthec.h.system(during
thec.h.function)orthroughthesecondaryheatex-
changer(duringthed.h.w.function).
A
Fig.18
8.2Checks
Warning:isolatetheboilerfromthemains
electricitysupplybeforeremovingany
coveringorcomponent.
nCheckthat thepumpisnotseizedandthat the
movementoftherotorisnotsubject tomechanicalim-
pediments.
Withtheboileroff,removethefrontpanel.Removethe
air releaseplugofthepumpandturntherotorwitha
screwdriver.
nCheckthe electricalcontinuity.
Withtheboileroff,removethefrontpaneland discon-
nect theconnectorB(Fig.20).
Measurethe electricalresistancebetweenthepump
supplyconnections.
Electricalresistanceofthewindings(atambient tem-
perature)mustbeabout230 W
nChecktheabsenceofstartingdefects.
Withtheboileroff removethefrontcasepanel.
Removetheair releaseplugfromthepump.Start the
boilerandwithascrewdriver,turntherotorinthedirec-
tionofthearrow.Ifthereisadefectinstarting,therotor
will begintoturn normallyonlystartingitmanually.
nCheckthat theimpellerisintegralwiththerotor.
Withtheboileroff removethefrontandrighthandside
casepanels,lowerthecontrolpanelandemptythepri-
marycircuit.
Removethepumphead byundoingthescrewswhich
holdit tothepump bodyandcheckthat theimpelleris
firmlyjoinedtotherotor.
8.3Removal
Warning:isolatetheboilerfromthemains
electricitysupplybeforeremovingany
coveringorcomponent.
1Removethefrontandrighthandsidecasepanels
2Emptytheprimarycircuitoftheboiler.
3Extractandlowerthecontrolpanel.
4Disconnect theconnectorB(Fig.19).
5LoosentheconnectionC,removetheforkDand
thepipeE.
B
C
D
E
A
Fig.19
6RemovetheforkF(Fig.20)andtheconnectionof
thecapillarypipeofthepressuregauge.
7RemovethelockingplateG
8CompletelyloosentheconnectionH.
9UnscrewthetwoscrewsIthatholdthepumpon
theframeandremovethepump.
FGHI
Fig.20
Reassemblethepumpcarryingout theremovaloper-
ationsinthereverseorder.Whenreassemblingthe
pump,checkthecorrectlocationoftheO---ring gasket
intheinletportofthepumpthatsealstheconnection
betweenthepumpandthebrass group.

15
9Three waydivertervalve
9.1Function
ThedivertervalveA(Fig.21)hasthefunctionofmodify-
ingthehydraulic circuitoftheboilerbymeansofan
electric commandgivenbythe electronic controlp.c.b.
inordertosendthewaterthatexitstheprimaryheatex-
changertowardsthec.h.systemortowardsthed.h.w.
heatexchanger.
A
Fig.21
9.2Checks
nCheckthe electricalcontinuity
Fig.22 indicatestherelationship betweenthe electric
commandcomingfromthe electronic controlp.c.b.
andthepositionoftheactuatorB(brass spindle)when
theboileroperatesind.h.w.mode.
Fig.23 indicatestherelationship betweenthe electric
commandcomingfromthe electronic controlp.c.b.
andthepositionoftheactuatorB(brass spindle)when
theboileroperatesinc.h.mode.
Inbothfigurestherelationship betweenthepositionof
theactuatorandtheresistanceofthemotorwindings
(themotormustbedisconnectedfromthewiring)is
alsogiven.
B
bn=brown
bu=blue
bk=black
0V
230 V
SpindleB
notvisible
Opencircuit
9,4Kohm
bk bn bu
3
1
2
Fig.22 --- D.h.w.mode
B
bn=brown
bu=blue
bk=black
230 V
0V
SpindleB
visible
Opencircuit
9,4Kohm
bk bn bu
3
1
2
Fig.23 --- C.h.mode
9.3Removalofthe electricactuator
Warning:isolatetheboilerfromthemains
electricitysupplybeforeremovingany
coveringorcomponent.
1Removethefrontcasepanel.
2Disconnect theconnectorsC(Fig.24).
3RemovethefixingspringDandremovethe
actuatorE.
Reassembletheactuatorcarryingout there-
movaloperationsinthereverseorder.
Whenreassemblingtheactuator,refertoFig.22
ortothewiringdiagraminsection3.1forthecor-
rectwiringconnection.

Three waydivertervalve
16
CDE
Fig.24
9.4Removalofthedivertergroupandits
internalparts
1Removethefrontand bothsidecasepanels.
2Emptytheprimarycircuitandthed.h.wcircuitof
theboiler.
3Removethe electricactuator(see section9.3).
4RemovethefixingspringF(Fig.25)andremove
theprimarycircuitflowswitchG.
5Disconnectbothc.h.and d.h.w.temperature
probe,respectivelyHandI.
6UnscrewtheconnectorJ,thec.h.flowconnector
andthed.h.w.outletconnector.
FG
J
H
I
Fig.25
7Removethed.h.w.heatexchanger(see section
7.2).
8RemovetheforkKandmoveawaythepipeL
(Fig.26).
9UnscrewthescrewMandremovethediverter
group.
K
L
M
Fig.26 Rearviewoftheboiler
10 Refertothe explodedviewinFig.27 toremove
theinternalpartsofthethree waydivertervalve.
Fig.27
11 Reassemblethedivertergroupcarryingout the
removaloperationsinthereverseorder.

17
10 Electronic controlp.c.b.
10.1Function
Fromotherboilerdevices....
C.h.temperatureprobeNTC
D.h.w.temperatureprobeNTC
D.h.w.flowswitch
Primarycircuitflowswitch
Roomthermostat(if fitted)
Timeswitch
Flamepresencesignal*
*fromthefull sequenceignitiondevice
OntheElectronic controlp.c.b.......
Functioncontrol*
C.h.temperatureadjustment*
D.h.w.temperatureadjustment*
Functiondip---switches
Ignitiongaspressureadjustment
Boiler resetbutton*
*controlpanelfascia
InletInformation
Pump
Three waydivertervalve
Full sequenceignitiondevice
Modulationoperator
Applianceoperationlights*
Lock---outsignal lamp*
*controlpanelfascia
Outletcommand
Fig.28
ThefundamentalfunctionoftheElectronic control
p.c.b.isthatofcontrollingtheboilerinrelationtothe ex-
ternalneeds(i.e.heatingthedwellingorheatingthe
waterford.h.w.use)andoperatinginordertokeepthe
temperatureofthehydraulic circuitsconstant.
Thisisobviouslypossiblewithintheusefulpowerand
maximumworkingtemperaturelimitsforeseen.
Generally,theElectronic controlp.c.b.receivesinletin-
formationcomingfromtheboiler(thesensors)orfrom
theoutside(knobs,roomthermostat,etc.),processes
itandconsequentlyactswithoutletcommandson
othercomponentsoftheboiler(Fig.28).
10.2Selectionandadjustmentdevices
OntheElectronic controlp.c.b.severalselection,ad-
justmentand protectiondevicesarelocated.(Fig.29).
Someofthesedevicesaredirectlyaccessiblebythe
user(functioncontrol,temperatureadjustmentpoten-
tiometersetc.)othersareaccessiblebyremovingthe
servicepanelorthecontrolpanel lid.
34567
8
10
12
9
1
2
11
Fig.29
1J3connector
2J2connector
3Lock---outsignal lamp
4Boiler resetbutton
5Functioncontrol/C.h.temperatureadjustment
6D.h.w.temperatureadjustment
7Applianceoperationlights
8Dip---switchselectors
9Settingjumpers
10 Ignitiongaspressureadjustment(ACC.)
11 J1connector
12 Fuse1,6AT
10.3Checkingthetemperature
TheElectronic controlp.c.b.makesitpossibletosepar-
atelyadjust thec.h.waterflowtemperatureand d.h.w.
outlet temperature.
Thetemperatureofthewaterisconvertedintoanelec-
tricsignalbymeansoftemperatureprobes.
Theuser,settingthedesiredtemperaturewiththecon-
trolpanelknobsoperatesthevariable elements(5and
6inFig.29)ofthe electronic controlp.c.b.

Electronic controlp.c.b.
18
Ifthepower requestedislowerthan40%ofthemaxi-
mumpoweroutput thencontrolisachieved byswitch-
ingONtheburneratminimumpower,thenswitching
OFF (ON/OFF function).Ifthepower requestedis
higher,thentheburneris switchedONatmaximum
powerandwill controlbymodulatingto40%ofthe
maximumpoweroutput.
Duringthec.h.operation(Fig.30),thesignalcoming
fromthec.h.temperatureprobeiscomparedtothesig-
nalgivenbythecontrolpanelthroughtheadjustment
madebytheuser(knob).Theresultofsucha
comparisonoperatesthemodulationofthegasvalve,
consequentlychangingtheusefuloutputoftheboiler.
Fig.30
Whentheboilerfunctionsind.h.w.(Fig.31),thesignal
comingfromthed.h.w.temperatureprobeiscompared
withthesignalgivenbythecontrolpanelthroughthe
adjustmentmadebytheuser(knob).
75 °C
Fig.31
Normally,theresultofthecomparisonbetweenthese
twosignalsdirectlyoperatestheadjustmentelements
ofthegasvalvemodulationdevice,adjustingtheuseful
outputgeneratedinordertostabilizethetemperature
ofthe exitingwater.
Ifduringthed.h.w.modeoperation,thetemperatureof
theprimarycircuitgoesover75°C,theusefuloutputis
automaticallyreducedsothat theprimarycircuitcan-
notreachexcessivetemperatures.
Thecontrolsequencesinfunctionandinfunc-
tionareillustratedindetailinsections10.10 and10.11.
10.4Operationlights
TheElectronic controlp.c.b.isprovidedwiththree
lamps(L.E.D.indicators)7inFig.29 thatgiveopticalin-
formationduringtheoperationoftheboiler.
Thegreenlampontheleftgivesinformationwhether
theboilerisinstand---bymodeorduringthenormal
operationoftheboiler.
Thefollowingtablegivestherelationship betweenthe
lampindicationanditsmeaning.