biasi service manual
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Wall hung, fan flue, room sealed gas boiler
SERVICE MANUAL
ParvaModels: G.C. Appl. No.
M90.24S 47--970--13M90.28S 47--970--14
Leave this manual adjacent to the gas meter
Biasi U.K. LtdUnit 32/33, Planetary Road
Industrial Estate, Neachells LaneWillenhall, Wolverhampton WV 13 3XB
Tel: 01902 304 400
Table of contents1 Overall information 1. . . . . . . . . . . . . . . . . .1.1 Overall View 1. . . . . . . . . . . . . . . . . . . . . . . . .1.2 Hydraulic diagram 1. . . . . . . . . . . . . . . . . . . .2 General access and emptying
hydraulic circuits 2. . . . . . . . . . . . . . . . . . . .2.1 Nomenclature 2. . . . . . . . . . . . . . . . . . . . . . . .2.2 Body panels 2. . . . . . . . . . . . . . . . . . . . . . . . .2.3 Control panel 2. . . . . . . . . . . . . . . . . . . . . . . .2.4 Access to the sealed chamber 3. . . . . . . . .2.5 Emptying the primary circuit 3. . . . . . . . . . .2.6 Emptying the d.h.w. circuit 3. . . . . . . . . . . .3 Diagrams 4. . . . . . . . . . . . . . . . . . . . . . . . . . .3.1 Wiring diagram 4. . . . . . . . . . . . . . . . . . . . . . .3.2 Functional flow diagrams 5. . . . . . . . . . . . . .3.3 Circuit voltages 6. . . . . . . . . . . . . . . . . . . . . .4 Fault finding 7. . . . . . . . . . . . . . . . . . . . . . . .
5 Primary heat exchanger 9. . . . . . . . . . . . . .5.1 Characteristics 9. . . . . . . . . . . . . . . . . . . . . . .5.2 Removal 9. . . . . . . . . . . . . . . . . . . . . . . . . . . .5.3 Cleaning 9. . . . . . . . . . . . . . . . . . . . . . . . . . . .6 D.h.w. heat exchanger 10. . . . . . . . . . . . . . .6.1 Function 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.2 Removal 10. . . . . . . . . . . . . . . . . . . . . . . . . . . .7 Pump 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7.1 Function 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . .7.2 Checks 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . .7.3 Removal 11. . . . . . . . . . . . . . . . . . . . . . . . . . . .8 Three way diverter valve 12. . . . . . . . . . . . .8.1 Function 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . .8.2 Checks 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . .8.3 Removal of the electric actuator 12. . . . . . . .8.4 Removal of the diverter group
and its internal parts 13. . . . . . . . . . . . . . . . . .9 Electronic control p.c.b. 14. . . . . . . . . . . . . .9.1 Function 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . .9.2 Selection and adjustment devices 14. . . . . .9.3 Checking the temperature 14. . . . . . . . . . . . .9.4 Operation/Service lamps 15. . . . . . . . . . . . . .9.5 Dip---switch selectors 16. . . . . . . . . . . . . . . . .9.6 Ignition gas pressure adjustment 17. . . . . . .9.7 Max c.h. power adjustment 17. . . . . . . . . . . .9.8 Checks 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . .9.9 Removal of the electronic control p.c.b 17. .9.10 Thermal control in the ” ”mode 19. . . . . .9.11 Thermal control in the ” ”mode 19. . . . .
10 Full sequence ignition device 20. . . . . . . . .10.1 Function 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . .10.2 Checks 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . .10.3 Removal 20. . . . . . . . . . . . . . . . . . . . . . . . . . . .10.4 Ignition and control sequence 21. . . . . . . . . .11 Modulating gas valve 22. . . . . . . . . . . . . . . .11.1 Function 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . .11.2 Nomenclature of the parts 22. . . . . . . . . . . . .11.3 Adjustment 22. . . . . . . . . . . . . . . . . . . . . . . . . .11.4 Checks 23. . . . . . . . . . . . . . . . . . . . . . . . . . . . .11.5 Removal 23. . . . . . . . . . . . . . . . . . . . . . . . . . . .12 Primary circuit flow switch 24. . . . . . . . . . .12.1 Function 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . .12.2 Checks 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . .12.3 Removal 24. . . . . . . . . . . . . . . . . . . . . . . . . . . .13 D.h.w. flow switch, filter and flow limiter 2613.1 Function 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . .13.2 Nomenclature and location of parts 26. . . . .13.3 Checks 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . .13.4 Removal of the flow switch sensor 26. . . . . .13.5 Removal of the flow switch group
and d.h.w. circuit filter 26. . . . . . . . . . . . . . . . .13.6 Flow limiter 27. . . . . . . . . . . . . . . . . . . . . . . . . .14 Temperature probe 28. . . . . . . . . . . . . . . . . .14.1 Function 28. . . . . . . . . . . . . . . . . . . . . . . . . . . . .14.2 Checks 28. . . . . . . . . . . . . . . . . . . . . . . . . . . . .14.3 Removal 28. . . . . . . . . . . . . . . . . . . . . . . . . . . .15 By--pass valve 29. . . . . . . . . . . . . . . . . . . . . .15.1 Function 29. . . . . . . . . . . . . . . . . . . . . . . . . . . . .15.2 Removal 29. . . . . . . . . . . . . . . . . . . . . . . . . . . .16 Fan and Air pressure switch 30. . . . . . . . . .16.1 Function 30. . . . . . . . . . . . . . . . . . . . . . . . . . . . .16.2 Checks 30. . . . . . . . . . . . . . . . . . . . . . . . . . . . .16.3 Removal of the Fan 30. . . . . . . . . . . . . . . . . . .16.4 Removal of the Air pressure switch 31. . . . .17 Ignition and detection electrodes 32. . . . .17.1 Function 32. . . . . . . . . . . . . . . . . . . . . . . . . . . . .17.2 Checks 32. . . . . . . . . . . . . . . . . . . . . . . . . . . . .17.3 Removal 32. . . . . . . . . . . . . . . . . . . . . . . . . . . .18 Safety thermostat 33. . . . . . . . . . . . . . . . . . .18.1 Function 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . .18.2 Checks 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . .18.3 Removal 33. . . . . . . . . . . . . . . . . . . . . . . . . . . .19 Short spare parts list 34. . . . . . . . . . . . . . . .
1
1 Overall information1.1 Overall View
Fan
Safetythermostat
Main heatexchanger
Burner
Ignitionelectrodes
Gas valve
Controlpanel
Combustionchamber
Automaticair release
Pump
D.h.w. temp.probe
D.h.w.heat exchanger
Expansionvessel
Detectionelectrode
valve
D.h.wflow switch
Diverter valve
Air pressureswitch
Main circuitflow switch
1.2 Hydraulic diagram
Central heating (c.h.) operation Domestic hot water (d.h.w.) operation
C.h.water flow
C.h.water return
D.h.w.inlet
D.h.w.outlet
2
2 General access and emptyinghydraulic circuits
2.1 Nomenclature
2
6
1
5 4
3
Fig. 1
1 Right side panel2 Front panel3 Control panel lid4 Control panel cover5 Service panel6 Left side panel
2.2 Body panels
Warning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
For the most part of the check and maintenance oper-ations it is necessary to remove one or more panels ofthe case.
The side panels can be removed only after the removalof the front panel.
To remove the front panel remove screws A (Fig. 2), liftthe panel and remove it.
A
Fig. 2
To remove the side panels loosen the screws B and C(Fig. 3), bring the base of the panels away from theboiler and lift them, freeing them from the top hooks.
B
D
D
C
C
Fig. 3 --- bottom view of the boiler
2.3 Control panelWarning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
To gain access to the parts located inside the controlpanel proceed as follows:1 Remove the front panel of the case2 Loosen the screws B and C (Fig. 3).3 Remove the screws D4 Move the lower part of the side panels as indi-
cated in Fig. 4 and pull the control panel.When completely pulled out, the panel can rotate45° downwards to facilitate the service oper-ations on the internal parts.
General access and emptying hydraulic circuits
3
Fig. 45 Remove the screws E and remove the service
panel (Fig. 5);6 To gain access to the electronic regulation PCB
and the full sequence ignition device remove thescrews F and remove the control panel lid(Fig. 5);
E
F
F
Fig. 5
2.4 Access to the sealed chamber
G
G
Fig. 6
To gain access to the parts contained in the sealedchamber it is necessary to remove the lid of the sealedchamber.For this purpose, remove the front and side panels ofthe case, remove the screws G as indicated in Fig. 6and remove the lid.
2.5 Emptying the primary circuit1 Close the c.h. circuit flow and return cocks H.
(Fig. 7).
H
H
J
Fig. 7 --- bottom view of the boiler
2 Remove the front and right panels of the boiler.3 Open the drain tap I (Fig. 8) until the boiler is com-
pletely emptied.4 Close drain tap again once the emptying has
been completed.
I
Fig. 8
2.6 Emptying the d.h.w. circuit5 Close the d.c.w. inlet cock J (Fig. 7);6 Open one or more hot water taps until the boiler
has been completely emptied.
4
3 Diagrams3.1 Wiring diagram
Ignitionelectrodes
Flame detectionelectrode
bn = brownbu = bluebk = blackwh = whiterd = redgy = grey
Safetythermostat
External controls Electric supply Fan Air pressureswitch
Time switch
123
tbk bk
t
bk
bkbk
M~
M~
bkbk
bk
bk
bkbk
bk
gy
M~
bk
bk
bkterminal blockterminal block
gy bk
Pump
Modulating
Primary circuitD.h.w. temperatureprobe NTC
Three waydiverter valve
gas valve
D.h.w. flowswitch flow switch
C.h. temperatureprobe NTC
Electroniccontrol p.c.b.
Full sequenceignition device
gn = greengnye = green---yellow
gnye gnyebnbu
gyrd
bu
wh rd
bu
rd
bubnbubn
bnbubnbu
bkbn bu31 2 bk gnyebu
rd
wh
bnbu
bubn
bubn
gnye
gnye
gnye
gnye
gnyegnye
gnye
gnye
gnye
gnye bu bn
bnbu
rd rd wh bu
rd bu
rd
rd gy
bn
bu
bububn
bugyrd
gnye
gy
wh gnye bnbu
bnbu
bk
rdbkwhgn
NC
COM
NO
Diagrams
5
3.2 Functional flow diagrams
PTCJ1---1
L
General layout
Transformer
N
Electroniccontrol p.c.b.(low voltage section)
J1---2
J3---3
J3---5J3---4
J3---2J3---1
J2---4J2---5
Three waydiverter valve
Pump
Full sequenceignition device
Fuse 1,6A T
PTCJ1---1
L
Transformer
ACTIVE CIRCUITINACTIVE CIRCUIT
L --- LINE N --- NEUTRAL
N
Electroniccontrol p.c.b.(low voltage section)
J1---2
J3---3
J3---5J3---4
J3---2J3---1
J2---4J2---5
Three waydiverter valve
Pump
Full sequenceignition device
Fuse 1,6A T
Heat request on d.h.w.
PTCJ1---1
L
Transformer
N
Electroniccontrol p.c.b.(low voltage section)
J1---2
J3---3
J3---5J3---4
J3---2J3---1
J2---4J2---5
Three waydiverter valve
Pump
Full sequenceignition device
Fuse 1,6A T
Heat request on c.h.
Diagrams
6
3.3 Circuit voltages
230~Supp
lyne
twor
k
230~
230~
0
Electrical voltages with burner on
during c.h. or d.h.w. operation
only during c.h. operation
only during d.h.w. operation
230~
230~
230~
0
Pump
Full sequenceIgnition device
3wa
ydi
verte
rvalv
e
0 0
Electroniccontrol p.c.b.
230~ 230~
ModulatingGas valve
Safetythermostat
0
Fan
230~
230~
0
Electroniccontrol p.c.b.
Airpressureswitch
7
4Fa
ultf
indi
ngCo
mpo
nent
sto
chec
kSe
ctio
nof
the
man
ual!
(not
ere
f.in
brac
kets)
--- (2)
--- (3)
--- (4)
--- (5)
67.
28.
29.
810
.211
.412
.213
.514
.215
16.2
17.2
18.2
--- (8)
--- (9)
------
Applianceoperationlampgreen(1)
Lock---outsignallampred
Defe
ct#
Powersupplyline
Gassupplyline
Fluepipes
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)
Fullsequencedevice
Gasvalve(on---offoperators)
Gasvalve(modulatingoperator)
Maincircuitflowswitch
D.h.w.filter
Maincircuittemp.probe
D.h.w.temp.probe
By---passvalve
Fanandventuridevice
Airpressureswitch
Ignitionelectrode
Detectionelectrode
Safetythermostat
Injectors
Expansionvessel
Safetyvalve
Pressuregauge
OFF
OFF
The
boile
rdoe
snot
start
eithe
rin
c/h
ord.
h.w.
mod
e.Fa
nsti
ll.
JJ
J
Bypr
essin
gth
ere
setp
ush-
--but
ton
the
boile
rtur
nson
and
oper
ates
corre
ctly.
JJ (7
)J
JJ
ulses
Bypr
essin
gth
ere
setp
ush-
--but
ton
the
boile
rsta
rtsth
eig
nitio
ncy
cle.
The
burn
erdo
esn’
tlig
hton
,the
igni
-tio
nsp
arks
cont
inue
and
the
boile
rlo
cksa
gain
.
JJ
JJ
ON---fastpul
ON
Bypr
essin
gth
ere
setp
ush-
--but
ton
the
boile
rsta
rtsth
eig
nitio
ncy
cle.
The
burn
erlig
hts
on,t
heig
nitio
nsp
arks
cont
inue
and
the
boile
rloc
ksag
ain.
JJ
JJ
J
The
burn
erdo
esn’
tligh
teith
erin
c.h.
ord.
h.w.
mod
e.Fa
ntu
rn.
JJ
JJ
The
burn
erdo
esn’
tligh
teith
erin
c.h.
ord.
h.w.
mod
e.Fa
ndo
esn’
ttur
n.
JJ
JJ
JJ
JJ
stpulses
The
boile
rdoe
sn’t
cont
rolth
ed.
h.w.
tem
pera
ture
.Tu
rnin
gth
ed.
h.w.
tem
p.ad
justm
ent
knob
hasn
’tef
fect
onth
em
odul
atio
nof
the
flam
e.Th
ebo
ilero
pera
tesc
orre
ctly
onc.
h.
JJ
ON---fas
OFF
The
boile
rlig
htsf
ora
shor
twhi
leon
c.h.
Norm
alop
erat
ion
ond.
h.w.
func
tion.
JJ
8
Com
pone
ntst
och
eck
Sect
ion
ofth
em
anua
l!(n
ote
ref.
inbr
acke
ts)---
------ (9
)--- (8
)18
.217
.216
.215
14.2
13.5
12.2
11.4
10.2
9.8
8.2
7.2
6--- (5
)--- (4
)--- (3
)--- (2
)
Applianceoperationlampgreen(1)
Pressuregauge
Safetyvalve
Expansionvessel
Injectors
Safetythermostat
Detectionelectrode
Ignitionelectrode
Airpressureswitch
Fanandventuridevice
By---passvalve
D.h.w.temp.probe
Maincircuittemp.probe
D.h.w.filter
Maincircuitflowswitch
Gasvalve(modulatingoperator)
Gasvalve(on---offoperators)
Fullsequencedevice
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
Fluepipes
Gassupplyline
Powersupplyline
Defe
ct#
Lock---outsignallampred
The
boile
rdoe
snot
supp
lyd.
h.w.
(col
dwa
terf
rom
the
tap)
.Re
gular
oper
atio
nin
c/h
mod
eev
endu
ring
adr
awin
gof
fd.h
.w.
JJ
J
On
c/h
mod
eth
ete
mpe
ratu
reof
the
main
circu
itrea
ches
75°C
and
the
c/h
syste
mdo
esno
thea
t.Th
ebo
ilero
pera
tesc
orre
ctly
ond.
h.w.
mod
e.
JJ
Inco
rrect
mod
ulat
ion
JJ
J
s
Noisy
bolie
rJ
J
malpulses
The
boile
rope
rate
scor
rect
lybu
tthe
gasp
ress
ure
toth
ebu
rner
rem
ainsa
tm
inim
um.
JJ
---norm
F
Poor
d.h.
w.te
mpe
ratu
reJ
JJ
JJ (1
0)
ON--
OFF
Low
d.h.
w.flo
wra
teJ
JJ
------
Wat
erlea
ksfro
mth
esa
fety
valve
dur-
ing
oper
atio
non
c/h
JJ
JJ
------
Wat
erlea
ksfro
mth
esa
fety
valve
when
the
boile
riso
ff.J
JJ
Note
1Fo
rdet
ailss
eese
ctio
n9.
4of
this
man
ual.
Furth
erus
eful
info
rmat
ion
can
beob
tain
edby
switc
hing
the
elec
troni
ccon
trolp
.c.b
.inth
ese
rvic
eop
erat
ion
mod
e(s
eese
ctio
n9.
4of
this
man
ual).
2Ch
eck
for2
30V~
betw
een
line
(L)a
ndne
utra
l(N)
Verif
yth
ein
tegr
ityof
supp
lyca
ble,
plug
and
exte
rnal
fuse
s.Ch
eck
the
polar
ityof
line
and
neut
ralc
onne
ctio
n3
Verif
yth
eso
undn
ess
ofth
ega
ssu
pply
pipe
,the
posit
ion
of
stop
valve
s.Ch
eck
the
gasp
ress
ure
atth
ein
lette
stpo
into
fthe
gasv
alve
(see
sect
.11.
3)wi
thth
eboi
lerat
rest
and
durin
gop
erat
iona
ndco
mpa
reitw
ithth
eva
lues
give
non
the
insta
llatio
nbo
oklet
.
4Ch
eckf
orso
undn
essa
ndab
senc
eof
obstr
uctio
ns.V
erify
that
the
flue
term
inal
isco
rrect
lyin
stalle
d(s
eecle
aran
ces)
and
en-
sure
that
exha
ustg
asis
nots
ucke
dba
ckby
the
boile
r.
5Ch
eck
fors
ound
ness
ofth
ecir
cuita
ndve
rify
itsco
rrect
fillin
g(s
eeals
oin
stalla
tion
man
ual).
6A
jam
med
by---p
assc
ould
caus
ethe
over
---hea
ting
ofth
emain
circu
itand
the
inte
rven
tion
ofth
esa
fety
ther
mos
tat.
7Ch
eckt
hem
inim
umga
spre
ssur
eatth
eout
lette
stpo
into
fthe
gasv
alve
(see
sect
.11.
3)an
dco
mpa
reitw
ithth
eva
lue
give
non
the
insta
llatio
nbo
oklet
.8
Verif
yth
ecle
anne
ssof
inje
ctor
s.9
Chec
kthe
pres
suriz
atio
nof
thee
xpan
sion
vess
el.Re
fert
oth
ein
stalla
tion
man
ualfo
rpro
perv
alues
.10
d.h.
w.pr
essu
reto
ohi
ghor
flow
rate
too
high
.Ifne
cess
aryi
n-se
rta
flow
rate
limite
r(13
.6).
9
5 Primary heat exchanger5.1 Characteristics
The primary heat exchanger A in Fig. 9 has the functionof transferring heat produced from combustion of thegas to the water circulating in it.
A
Fig. 9
The hydraulic circuit is composed of 8 elliptical pipesconnected in parallel (Fig. 10).
Fig. 10
5.2 Removal
Warning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
1 Empty the primary circuit of the boiler.2 Remove the case panels and the sealed chamber
lid (see section 2).3 Remove the combustion chamber lid B by un-
screwing the screws C (Fig. 11).3b For model M90.28S only, remove the screw D and
the plate E.4 Remove the clips F and the safety thermostat G.
It is not necessary to disconnect it from the wiring.
D
F
C
B E
G
Fig. 11
5 Remove the fork H (Fig. 12), lift the pipe I and ro-tate it right then move it downwards freeing it fromthe heat exchanger connection.
6 Remove the motor of the three way diverter valve(see section 8.3).
7 Loosen the two connection J and completely un-screw the connections K.
8 Rotate the pipe L and move the pipe M down-wards freeing it from the heat exchanger connec-tion.
9 Remove the heat exchanger by sliding it for-wards.
10 Reassemble the boiler carrying out the removaloperations in reverse order.
H
IJ
K
M
L
Fig. 12
5.3 CleaningIf there are deposits of soot or dirt between the bladesof the heat exchanger, clean with a brush or non---me-tallic bristle brush.In any case, avoid any actions that can damage the pro-tective varnish with which the exchanger has been cov-ered.
10
6 D.h.w. heat exchanger6.1 Function
The d.h.w heat exchanger A in Fig. 13 allows the instan-taneous transfer of heat from the primary hydraulic cir-cuit to the water destined for d.h.w use.
A
Fig. 13
The schematic structure is shown in Fig. 14.
Primary hydraulic circuitDomestic hot water circuit
Fig. 14
6.2 RemovalWarning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
1 Remove the front and right hand side panels ofthe case.
2 Empty the primary circuit and the d.h.w circuit ofthe boiler.
3 Remove the motor of the three way diverter valve(see section 8.3).
4 Completely unscrew the two connections B andremove the pipe C (Fig. 15).
B
C
Fig. 155 Completely unscrew the two Allen key screws D
(Fig. 16) which hold the exchanger to the brassgroups.
D
Fig. 166 Move the exchanger towards the rear of the boiler
and extract it.Reassemble the d.h.w. heat exchanger carrying out theremoval operations in the reverse order.Attention. When reassembling the exchanger besure to put the off center location/securing pin indi-cated in Fig. 17 towards the left side of the boiler.
Fig. 17
11
7 Pump7.1 Function
The pump A in Fig. 18 has the function of making thewater in the main circuit circulate through the main heatexchanger and therefore through the c.h. system (dur-ing the c.h. function) or through the secondary heat ex-changer (during the d.h.w. function).
A
Fig. 18
7.2 ChecksWarning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
n Check that the pump is not seized and that themovement of the rotor is not subject to mechanical im-pediments.With the boiler off, remove the front panel. Remove theair release plug of the pump and turn the rotor with ascrewdriver.n Check the electrical continuity.With the boiler off, remove the front panel and discon-nect the connector B (Fig. 19).Measure the electrical resistance between the pumpsupply connections.Electrical resistance of the windings (at ambient tem-perature) must be about 230 Wn Check the absence of starting defects.With the boiler off remove the front case panel.Remove the air release plug from the pump. Start theboiler and with a screwdriver, turn the rotor in the direc-tion of the arrow. If there is a defect in starting, the rotorwill begin to turn normally only starting it manually.
n Check that the impeller is integral with the rotor.With the boiler off remove the front and right hand sidecase panels, lower the control panel and empty the pri-mary circuit.Remove the pump head by undoing the screws whichhold it to the pump body and check that the impeller isfirmly joined to the rotor.
7.3 RemovalWarning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
1 Remove the front and right hand side case panels2 Empty the primary circuit of the boiler.3 Extract and lower the control panel.4 Disconnect the connector B (Fig. 19).5 Remove the fork C and move the pipe upwards
freeing it from the outlet port of the pump.6 Move the locking plate D left until it stops. It is not
necessary to extract it completely.7 Unscrew the two screws E that hold the pump on
the frame
D E
B
C
Fig. 198 Remove the fork F (Fig. 20), the capillary pipe and
remove the pump towards the front of the boiler.
F
Fig. 20
Reassemble the pump carrying out the removal oper-ations in the reverse order. When reassembling thepump, check the correct location of the O---ring gasketin the inlet port of the pump that seals the connectionbetween the pump and the brass group .
12
8 Three way diverter valve8.1 Function
The diverter valve A (Fig. 21) has the function of modify-ing the hydraulic circuit of the boiler by means of anelectric command given by the electronic control p.c.b.in order to send the water that exits the primary heat ex-changer towards the c.h. system or towards the d.h.w.heat exchanger.
A
Fig. 21
8.2 Checksn Check the electrical continuityFig. 22 indicates the relationship between the electriccommand coming from the electronic control p.c.b.and the position of the actuator B (brass spindle) whenthe boiler operates on d.h.w. mode.Fig. 23 indicates the relationship between the electriccommand coming from the electronic control p.c.b.and the position of the actuator B (brass spindle) whenthe boiler operates on c.h. mode.In both figures the relationship between the position ofthe actuator and the resistance of the motor windings(the motor must be disconnected from the wiring) isalso given.
B
bn = brownbu = bluebk = black
0V
230
V
Spindle Bnot visible
Open circuit
9,4 Kohm
bk bnbu
3
1
2
Fig. 22 --- D.h.w. mode
B
bn = brownbu = bluebk = black
230
V0
V
Spindle Bvisible
Open circuit
9,4 Kohm
bk bnbu
3
1
2
Fig. 23 --- C.h. mode
8.3 Removal of the electric actuatorWarning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
1 Remove the front case panel.2 Disconnect the connectors C (Fig. 24).3 Remove the fixing spring D and remove the
actuator E.Reassemble the actuator carrying out the re-moval operations in the reverse order.When reassembling the actuator, refer to Fig. 22or to the wiring diagram in section 3.1 for the cor-rect wiring connection.
Three way diverter valve
13
D
CE
Fig. 24
8.4 Removal of the diverter group and itsinternal parts
1 Remove the front and both side case panels.2 Empty the primary circuit and the d.h.w circuit of
the boiler.3 Remove the electric actuator (see section 8.3).4 Remove the fixing spring F (Fig. 25) and remove
the primary circuit flow switch G.5 Disconnect the c.h. temperature probe H.6 Unscrew the connector I, the c.h. flow connector
and the d.h.w. outlet connector.
F
G
I H
Fig. 25
7 Remove the d.h.w. heat exchanger (see section6.2).
8 Remove the fork J and move away the pipe K(Fig. 26).
9 Unscrew the screw L and remove the divertergroup.
J
K
L
Fig. 26 Rear view of the boiler10 Refer to the exploded view in Fig. 27 to remove
the internal parts of the three way diverter valve.
Fig. 2711 Reassemble the diverter group carrying out the
removal operations in the reverse order.
14
9 Electronic control p.c.b.9.1 Function
From other boiler devices....C.h. temperature probe NTCD.h.w. temperature probe NTCD.h.w. flow switchPrimary circuit flow switchRoom thermostat (if fitted)Time switchFlame presence signal**from the full sequence ignition device
On the Electronic control p.c.b.......Function control*C.h. temperature adjustment*D.h.w. temperature adjustment*Function dip---switchesMax. c.h. gas pressure adjustmentIgnition gas pressure adjustmentBoiler reset button**control panel fascia
Inlet Information
PumpThree way diverter valveFull sequence ignition deviceModulation operatorAppliance operation light*Operation/service lampsLock---out signal lamp**control panel fascia
Outlet command
Fig. 28
The fundamental function of the Electronic controlp.c.b. is that of controlling the boiler in relation to the ex-ternal needs (i.e. heating the dwelling or heating thewater for d.h.w. use) and operating in order to keep thetemperature of the hydraulic circuits constant.This is obviously possible within the useful power andmaximum working temperature limits foreseen.Generally, the Electronic control p.c.b. receives inlet in-formation coming from the boiler (the sensors) or fromthe outside (knobs, room thermostat, etc.), processesit and consequently acts with outlet commands onother components of the boiler (Fig. 28).9.2 Selection and adjustment devices
On the Electronic control p.c.b. several selection, ad-justment and protection devices are located. (Fig. 29).Some of these devices are directly accessible by theuser (function control, temperature adjustment poten-tiometers etc.) others are accessible by removing theservice panel or the control panel lid.
345678
9
11
12
14
10
1
2
13
Fig. 291 J3 connector2 J2 connector3 Lock---out signal lamp4 Boiler reset button5 Function control / C.h. temperature adjustment6 D.h.w. temperature adjustment7 Service lamps (service mode)8 Appliance operation lamp (normal use mode)9 Dip---switch selectors10 Setting jumpers11 Ignition gas pressure adjustment (ACC.)12 Maximum c.h. gas pressure adjustment (RISC.)13 J1 connector14 Fuse 1,6 A T
9.3 Checking the temperatureThe Electronic control p.c.b. makes it possible tosepar-ately adjust the c.h. water flow temperature and d.h.w.outlet temperature.The temperature of the water is converted into an elec-tric signal by means of temperature probes.
Electronic control p.c.b.
15
The user, setting the desired temperature with the con-trol panel knobs operates the variable elements (5 and6 in Fig. 29) of the electronic control p.c.b.If the power requested is lower than 40% of the maxi-mum power output then control is achieved by switch-ing ON the burner at minimum power, then switchingOFF (ON/OFF function). If the power requested ishigher, then the burner is switched ON at maximumpower and will control by modulating to 40% of themaximum power output.During the c.h. operation (Fig. 30), the signal comingfrom the c.h. temperature probe is compared to the sig-nal given by the control panel through the adjustmentmade by the user (knob ). The result of such a com-parison operates the modulation of the gas valve,consequently changing the useful output of the boiler.
Fig. 30
When the boiler functions in d.h.w. (Fig. 31), the signalcoming from the d.h.w. temperature probe is comparedwith the signal given by the control panel through theadjustment made by the user (knob ).
75 ° C
Fig. 31
Normally, the result of the comparison between thesetwo signals directly operates the adjustment elementsof the gas valve modulation device, adjusting the usefuloutput generated in order to stabilize the temperatureof the exiting water.If during the d.h.w. mode operation, the temperature ofthe primary circuit goes over 75°C, the useful output isautomatically reduced so that the primary circuit can-not reach excessive temperatures.
The control sequences in function and in func-tion are illustrated in detail in sections 9.10 and 9.11.9.4 Operation/Service lamps
The Electronic control p.c.b. is provided with threelamps (L.E.D. indicators) 7 in Fig. 29 that give optical in-formation during the normal operation of the boiler orfor service purpose.f Normal operationOnly the green lamp on the left is directly visible on thecontrol panel fascia and it gives information during thenormal operation of the boiler. The other two lamps arenormally switched off.
Electronic control p.c.b.
16
The following table gives the relationship between thevisible lamp indication and its meaning.
Boiler in stand---by condition.(function control in position).Anti--- freeze system active.
A short pulse every 4 seconds
(function control in position).Anti--- freeze system active.
Boiler ON condition(function control in orposition)
1 second ON 1 second OFF
(function control in orposition)
Very fast pulses (4 per second)
Faulty boiler or irregularoperation as:--- Empty primary circuit--- No primary circuit flow--- Lack of burner ignition--- Lack of burner ignition--- Excessive temperature in
the primary circuit.--- Dip---switch 3 left in the OFF
position--- Faulty temperature probe
f Service operation
With the boiler switched ON ( or ), by movingand re---setting to its original position any of the functionselectors 9 (Fig. 29), the Electronic control p.c.b. goesinto service operation mode and all the lamps (7 inFig. 29) are then activated.To reset the Electronic control p.c.b. to the normal oper-ation it is necessary to turn the knob to the posi-tion or switch off the boiler for a short while at the fusedspur isolation switch.The following table gives the relationship between eachof the possible lamp combinations and their meaning.
Normally operating boiler
C.h. operation
D.h.w. operation
Frost protect operation
D.h.w. operationExcessive temperature on primary circuit
Faulty c.h. temperature probe NTC
Faulty d.h.w temperature probe NTC
Faulty primary circuit(no water or absence of flow)
Lack of burner ignition (no ignition signal fromthe full seqence ignition device)
Ignition gas pressure adjustment
Minimum gas pressure adjustment
LampOFF
LampON
Flashing lamp, aloneor simultaneously
with an other lamp.
Flashing lamp,alternate withanother lamp.
9.5 Dip---switch selectorsThe function selectors 9 (Fig. 29 and Fig. 32) are micro-switches with which it is possible to select the variousboiler control function modes.In Fig. 32 the selectors are illustrated in the configur-ation in which the boiler is set in the factory (natural gasboiler).
ON (1)
OFF (0)
1 2 3 4
9
Gas conversionIgnition gas pressure adjustmentReignition frequency
Minimum gas pressure adjustment
Fig. 32f Selector 1This forces the boiler to operate at the minimum gaspressure in order to allow the adjustment of the mini-mum gas pressure at the burner (on the modulation op-erator of the gas valve).After any adjustment operation the selector has to bebrought back to the normal position (ON).
Electronic control p.c.b.
17
f Selector 2This selects the boiler functions on the basis of the typeof gas used.It allows the selection of the maximum supply currentgiven to the modulator device.To set selector 2 correctly follow the table in Fig. 33.
Gas supply Position of selector Approx. Max currentthrough the modu-lator device
Natural gas On 120 mAL.P.G. Off 165 mA
Fig. 33
f Selector 3This forces the functioning of the boiler in order to allowthe optimal gas pressure at the burner to be adjustedduring the ignition phase.The adjustment (see section 9.6) is done by means ofthe potentiometer ”11”marked “ACC”(Fig. 29 on page14).After the adjustment operations bring the selector backto the normal position (ON).
gas pressure calibration Normal
ON (1)
OFF (0)
Fig. 34
f Selector 4This allows you to select the minimum time that mustpass between two ignitions of the burner in c.h. func-tion.
30 sec. 3 min.
ON (1)
OFF (0)
Fig. 35
9.6 Ignition gas pressure adjustment
By using the device ”11”(Fig. 29) marked “ACC.”onthe Electronic control p.c.b., it is possible to adjust thegas pressure at the injectors in the ignition phase.This pressure is maintained at the injectors until ignitionoccurs (ionization signal from the full sequence ignitiondevice).To carry out the adjustment move the function selector3 to the OFF position (Fig. 34) and use the adjustmentdevice ”11”(ACC).Adjust the gas pressure at the injectors to the value indi-cated in the tables of the User/Installation manual
(Technical information section, Gas pressures at theburner table).By rotating the device clockwise the pressure in-creases.Check the regular ignition of the burner by turning theboiler on and off repeatedly.After the adjustment operations bring the selector 3back to the normal position (ON).
9.7 Max c.h. power adjustmentBy using device 12 (Fig. 29) marked “RISC.”on theElectronic control p.c.b., you can limit the maximumuseful output delivered during the c.h. operating mode.This adjustment does not influence the maximum use-ful output delivered during the d.h.w. operating mode.By rotating the device clockwise the pressure in-creases.
9.8 Checksn Check that the fuse is completeIf the Electronic control p.c.b. does not supply any de-vice (pump, fan, etc.) check that the fuse 14 (Fig. 29) iscomplete.If the fuse has blown replace it with one that has thesame characteristics after having identified the reasonfor failure.n Check the setting jumpers positionTwo setting jumpers must be fitted on the Electroniccontrol p.c.b. as shown in Fig. 36.The numbers refer to the marking printed on the circuitboard.
1 2 3 4 5 6 7 8 9Fig. 36
9.9 Removal of the electronic control p.c.b
Warning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
1 Gain access to the parts located inside the con-trol panel as explained in the section 2.3 of thismanual.
2 Remove all the wiring connected to the Electroniccontrol p.c.b..To disconnect the connectors J1, J2 and J3 (13,2 and 1 in Fig. 29) delicately flex the hook presenton one side of each socket.
3 Remove the spindles of the c.h. and d.h.w. tem-perature adjustment knobs by delicately pullingthem with pliers in the direction shown by thearrow in Fig. 37.
Electronic control p.c.b.
18
Fig. 37
4 Unscrew the four screws that hold the Electroniccontrol p.c.b. on to the control panel.
5 Remove it by lifting its rear edge and freeing itfrom any of the wiring.
6 Re---assemble the Electronic control p.c.b. fol-lowing the removal procedures in the reverseorder.
ImportantWhen re---assembling the Electronic control p.c.b.:7 Fit the p.c.b. into the control panel by first insert-
ing the front lower edge under the control knobshafts. Lower the rear edge and ensure that nowiring is trapped beneath.
8 Insert the spindles in the control panel knobs un-till the notch A (Fig. 38) reaches the potentio-meter edge. It is not necessary to force them inthe knob.
9 While tightening the screws that fix the Electroniccontrol p.c.b. on the control panel, keep thep.c.b. towards the control panel fascia makingsure of the contact between the boiler reset but-ton B and the tab C (Fig. 38).
A B C
Fig. 38
AttentionAfter installing the Electronic control p.c.b. :
10 Make sure the c.h. ( ) and d.h.w. ( ) tem-perature adjustment knobs can move freely forthe complete range.If not, remove the spindle again as described atstep 3, turn the knob half a turn and re--- insert thespindle.
11 Operate the boiler and close the gas inlet cock sothat the boiler goes into the safety lock---out state.Verify the correct operation of the boiler reset but-ton by pressing and releasing it.
Electronic control p.c.b.
19
9.10 Thermal control in the ” ”mode
See functioning with the functioncontrol in the mode
(sec. 9.11)
Takingwater from the domestic hot
water circuit?
Switch in the function mode
NOYES
Is primary circuittemperature higher than that
selected?NO
Request for heat fromroom thermostat?
Starts the circulatorOperates motorised valve
Supplies the ignition device
NO
Circulator offOperates motorised valve
Ignition device off
YES
YES
Fig. 39
9.11 Thermal control in the ” ”mode
Is domestichot water outlet temperature
lower than thatrequired?
Supplies the ignition device Ignition device off
Circulator on
YES NO
Switch in the function mode
Takingwater from the domestic hot
water circuit?YES Circulator off
Ignition device offNO
Fig. 40
20
10 Full sequence ignition device10.1 Function
The Full sequence ignition device used on the boilercarries out the following fundamental functions:f does a sequence of operations (ignition cycle)
which lead to the ignition of the gas at the burnerf checks the presence of the flame during the en-
tire period in which it is activatedf supplies the fan and checks its functioning by
means of the signal coming from the air pressureswitch.
The Full sequence ignition device is supplied by theelectronic control p.c.b. when the ignition of the burneris requested.The Full sequence ignition device has a safety functionand any incorrect interventions or tampering can resultin conditions of dangerous functioning of the boiler.The Full sequence ignition device can lock the function-ing of the boiler (lock state) and stop its functioning upto the resetting intervention. The lock is signalled by thelighting of the lock---out signal lamp and the device canbe reset only by using the boiler reset button placed onthe control panel fascia.Some components which are connected to the devicecan activate the lock state. The causes of a lock statecould be:f The intervention of the safety thermostat (over-
heat of the primary circuit).f A fault on gas feedingf Faulty ignition (faulty ignition electrodes, their wir-
ing or connection).f Faulty flame detection (faulty detection electrode,
its wiring or connection).f Gas injectors blockedf Faulty modulation gas valve (faulty on---off oper-
ators or not electrically supplied).f Faulty Full sequence ignition device.Other components like the air pressure switch can tem-porarily stop the ignition of the burner but allow its igni-tion when the cause of the intervention has stopped.Fig. 42 shows the sequence of the operations that arecarried out at the starting of every ignition cycle andduring normal functioning.
10.2 Checksn Lock sequenceStart the boiler until the burner is ignited.
With the burner firing, interrupt the gas supply. The Fullsequence ignition device must carry out a completeignition cycle and then stop.By turning the boiler on and off by means of the functionswitch the device must not unlock and the burner mustnot turn on.n Control of flue gas expulsionWith the boiler operating and the burner on, open thenegative pressure test point of the Venturi device.At the moment of opening the burner must turn off.
10.3 Removal
Warning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
1 Gain access to the parts located inside the con-trol panel as explained in the section 2.3 of thismanual.
2 Remove all the wiring connected to the Full se-quence ignition device.To disconnect the connectors A, delicately flex thehook present on one side of each socket(Fig. 41).
3 Unscrew the two screws B that hold the Full se-quence ignition device on the panel and removethe component.
A
A
B
B
Fig. 41
4 Re---assemble the Full sequence ignition devicefollowing the removal procedures in the reverseorder.
Full sequence ignition device
21
10.4 Ignition and control sequence
lock memorised?
supply from the electronic control circuit
Air pressure switch atrest?
NO
NO
starts fan
YES
Air pressure switch atwork?
NO
beginning of wait period
presence of flame?NO YES
YES
Air pressure switch atwork?
NO
YES
starts ignition dischargesopens gas valve
beginning of ignition period
flame presence?
end of ignitionperiod?NO
NO YES
closes gas valvestops fan
interrupts ignition dischargesmemorizes lock
turns on lock---out light
YES
reset push---buttonpressed?
NO YES
cancels lock
interrupts ignition dischargesgas valve open
flame presence?
Air pressure switch atwork?
NO
YES
YES
closes gas valve
NO
YES
Safety thermostatopens the circuit?NO YES
Fig. 42
22
11 Modulating gas valve
11.1 Function
The Modulating gas valve A in Fig. 43 controls the gasinflow to the boiler burner.
A
Fig. 43
By means of an electric command given to the on---offoperators the passage of the gas through the Modula-ting gas valve can be opened or closed.
By means of an electric command given to the modula-tion operator the pressure can be varied and thereforethe gas flow rate to the burner (modulation). The mo-dulation operator has mechanical components whichallow the adjustment of the minimum and maximumpressure exiting the valve.
11.2 Nomenclature of the parts (Fig. 44)
1 Modulation operator’s electric connectors2 Minimum gas pressure adjustment3 On---off operators4 Maximum gas pressure adjustment5 On---off operators electric connector6 Gas valve inlet pressure test point7 Modulation operator8 Gas valve outlet pressure test point
3
7
1
6
8
5
2
4
Fig. 44
11.3 Adjustment
Warning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
1 Remove the front panel of the case.2 Open the gas valve inlet pressure test point (6 in
Fig. 44) at the valve input, connect a suitablepressure gauge and check the gas pressure ofthe supply network.
3 Remove the gauge and close the pressure testpoint 6.
4 Open the gas valve outlet pressure test point (8in Fig. 44) and connect the gauge;
5 Remove the protection cap from the mechanicalpressure adjustment components;
6 Start the boiler at its maximum power.Operate the boiler in d.h.w. mode or ensure thatthe boiler is not range rated if the test is carried outin c.h. mode.
7 Rotate the maximum gas pressure adjustment (4in Fig. 44) until you obtain the required pressure(by rotating clockwise the pressure increases).
8 Disconnect one of the two connectors (1 inFig. 44) or, alternatively, remove the service panelas explained in the section 2.3 of this manual andset the dip---switch selector 1 (see section 9.5) tothe OFF position.
9 Rotate the minimum gas pressure adjustment (2in Fig. 44) until you obtain the required pressure(by rotating clockwise the pressure increases).
10 Turn the boiler off and re---connect the wire to themodulating operator (or set the dip---switch se-lector 1 back to the ON position).
11 Start the boiler and check again the maximumgas pressure setting.
12 Turn the boiler off and disconnect the gauge.Important: after the gas pressure checks and anyadjustment operations, all of the test points must besealed.
Modulating gas valve
23
11.4 ChecksWarning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
n Check the modulation operator coil1 Remove the front panel of the case.2 Disconnect the connectors B (Fig. 46) from the
modulating operator and measure the electricalresistance of the coil. Its electrical resistancevalue must be approx. 80 W*.
n Check the on---off operators coils1 Remove the front panel of the case.2 Disconnect the electrical connector C (Fig. 46).3 Measure the electrical resistance between the
connector pins of the on---off operators as illus-trated in Fig. 45.
Lower on---off operatorapprox. 920 W*
Upper on---off operatorapprox. 6 400 W*
* at ambient temperature.Fig. 45
11.5 RemovalWarning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
1 Remove the front panel of the case as explainedin the section 2.3 of this manual.
2 Disconnect the connectors B and C (Fig. 46).3 Turn off the gas supply and disconnect the gas
isolation cock connector from the inlet port of thegas valve.
4 Unscrew the connectors D and remove the pipeE
5 Unscrew the screws F and remove the valve.6 Reassemble the valve carrying out the removal
operations in reverse order.After any service operation on the components ofthe gas circuit check all the connections for gasleaks.
B
C
D
E
F
Fig. 46
24
12 Primary circuit flow switch12.1 Function
The Primary circuit flow switch (A in Fig. 47) function isto detect water flowrate through the primary hydrauliccircuit of the boiler.
A
Fig. 47
This hydraulic/membrane operated electrical micro---switch device will control the functioning of the ignitioncontrol circuit, providing there is an adequate quantityand flow of water in the primary circuit. Any failure of thepump or obstructions in the primary circuit, whilst ineither c.h. or d.h.w. modes, will not allow the device tooperate.This device is connected to the electronic control p.c.b.and if, after the pump operates, it does not activate with-in 20 seconds the control board will indicate that a faultcondition (see section 9.4 of this manual) has occurred.
D
C
Fig. 48
12.2 ChecksWarning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
n Mechanical function1 Remove the front panel of the case.2 Start and stop the boiler either in d.h.w. or c.h.
mode.3 Looking through the switch box verify the position
of the shaft B referring to Fig. 49.
BBoiler OFF Boiler ONFig. 49
n Electrical checkIt is possible to verify the general operation of the switchby measuring the electric resistance between the con-tacts C. and N.O. of the switch.1 Remove the switch as explained in section 12.3.2 Measure the electrical resistance between the
tabs marked C. and N.O. (Fig. 50).The contact must be normally open.
3 Operate the switch by hand and verify that thecontact is now closed.
N.O.
do not use
C
Fig. 50
12.3 RemovalWarning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
n Removal of the switch1 Remove the front and right hand side panels of
the case.2 Remove the fork C (Fig. 48).3 Open the box and disconnect the switch.4 Re---assemble the parts proceeding in reverse
order of removal. Refer to Fig. 50 for the correctwiring connectors on the switch
n Removal of the membrane1 Remove the front and right hand side panels of
the case, turn off the flow and return isolationvalves and empty the primary circuit.
2 Remove the fork C that holds the micro---switchhousing D (Fig. 48).
3 Unscrew the four screws E (see Fig. 51) open thehydraulic operator and remove the membrane F.
Primary circuit flow switch
25
E
FG
H
Fig. 51
4 Reassemble the parts in reverse order of removal.When assembling the membrane, ensure that itsconcave side faces towards the actuator plate G andthe reference indicated aligns with the seat H (seeFig. 51).
26
13 D.h.w. flow switch, filter and flowlimiter
13.1 FunctionThe d.h.w. flow switch A in Fig. 52 is a device that gener-ates an electrical signal when hot water is drawn.
A
Fig. 52
When the flow rate through the d.h.w. circuit reachesabout 2,5 litres/min’, the float 4 (Fig. 54) is drawn to-wards the right.The resulting magnetic field of ring 3 increases and re-aches the flow switch sensor 1.The sensor generates an electrical signal that switchesthe boiler d.h.w operation ON.The state of the sensor is also indicated by means of thelamp B placed on the sensor body.
BC
Fig. 53
13.2 Nomenclature and location of parts(Fig. 54)
1 Flow switch sensor2 Plug3 Magnetic ring4 Float5 Spring6 Filter7 Body8 Spring seat9 Flow limiter (M90.28S optional accessory)10 Threaded ring
1
23
45
67
89
10
Fig. 54
13.3 ChecksWarning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
n Flow switch sensor operation1 Remove the front panel of the case.2 Switch on the boiler and open a d.h.w. tap. The
lamp B (Fig. 53) placed on the sensor body isswitched on when the flow rate reaches about 2,5litres/min’.
13.4 Removal of the flow switch sensor
Warning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
1 Remove the front panel of the case.2 Disconnect the connector C (Fig. 53) and remove
the sensor by pulling it towards the front of theboiler (the sensor is held in place by means of aspring).
13.5 Removal of the flow switch group andd.h.w. circuit filter
Warning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
1 Remove the front panel of the case and empty thed.h.w. circuit.
D.h.w. flow switch, filter and flow limiter
27
2 Remove the flow switch sensor (see section13.4).
3 Remove the gas valve (see section 11.5).4 Unscrew the plug 2 (Fig. 54) and extract the flow
switch group.5 To remove the filter from the flow switch group
separate the body 7 from the plug 2 (Fig. 54) byunscrewing it.
6 Reassemble the parts following the removing se-quence in reverse order.
13.6 Flow limiter
The M90.24S model is factory fitted with a 10 litre/min.flow limiter.
If on the M90.28S model the flow rate of the d.h.w. cir-cuit is too high, it is possible to limit it by installing a flowlimiter. The following sizes are available:
Nominal flow rate (litres/min) Colour10 Yellow12 Brown
To install the flow limiter:1 Remove the flow switch group as explained in the
section 13.5.2 Unscrew the threaded ring 10 (Fig. 54) and re-
move it from the body 7.3 Install the flow limiter 9 putting its smaller diam-
eter side towards the threaded ring.4 Reassemble the group following the above se-
quence in reverse order.
28
14 Temperature probe14.1 Function
The Temperature probe has the function of convertingthe temperature of the water in the hydraulic circuitwhere it is installed into an electrical signal (resistance).The relation between temperature and electrical resis-tance is stated in Fig. 55.
500100015002000250030003500400045005000550060006500700075008000850090009500
100001050011000115001200012500
20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100
W
° CFig. 55
On the boiler there are two Temperature probes. Oneon the output of the primary heat exchanger (c.h. Tem-perature probe) A in Fig. 56 and Fig. 57; one on itsinput, before the pump (d.h.w. Temperature probe) B inFig. 56 and Fig. 58.
A
c.h.flow
c.h.return
d.h.w.inlet
d.h.w.outlet
B
Fig. 56
14.2 Checksn Temperature---resistance relationship
Warning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
Disconnect the cable from the Temperature probe.Measure the temperature of the brass group where theTemperature probe is located and check the electricalresistance according to the graph in Fig. 55.
14.3 RemovalWarning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
Refer to Fig. 57 for the c.h. Temperature probeand to Fig. 58 for the d.h.w. Temperature probe.
1 To remove the Temperature probes remove thefront and right hand side panels of the case.
2 Empty the primary circuit of the boiler.3 Remove the electric connector of the Tempera-
ture probe and unscrew it.4 Reassemble the Temperature probe carrying out
the removal operations in reverse order.
A
Fig. 57
B
Fig. 58
29
15 By---pass valve15.1 Function
The By---pass valve A in Fig. 59 is located between thec.h. water flow and return and its function is that of guar-anteeing a minimum flow across the primary heat ex-changer if the circulation across the c.h. system is com-pletely closed.The By---pass valve is fitted on the rear side of the div-erter group.
A
Fig. 59
15.2 Removal
Warning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
1 Remove all the case panels.2 Empty the primary circuit of the boiler.3 Remove the diverter group as described in the
section 8.4 of this manual.4 Unscrew the connector B and remove the by---
pass valve C (Fig. 60).
C
B
Fig. 60
5 Reassemble the by---pass valve as illustrated inFig. 60 reversing the order of removal.
30
16 Fan and Air pressure switch16.1 Function
The function of the Fan is to force the products of com-bustion to the outside air via the flue system.The Fan is supplied by the full sequence ignition deviceat the beginning of the ignition cycle.Its correct functioning is controlled by means of a sys-tem incorporating a built in venturi device and an Airpressure switch.
16.2 Checksn Check of the fan
Warning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
1 Remove all the case panels and the sealedchamber lid.
2 Disconnect the connectors A (Fig. 61) andmeasure the electrical resistance of the motorthat has to be about 32 W --- M90.24S and 30 W--- M90.28S (at ambient temperature).
A
B
G
Fig. 61
n Check of the Air pressure switch operation
Warning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
1 Remove all the case panels and the sealedchamber lid.
2 Disconnect the wires and check the electrical re-sistance between the connections of the Air pres-sure switch (Fig. 62).
Between COM and N.O. the contact must be open.Between COM and N.C. the contact must be closed(electrical resistance zero).3 Connect the black wire (COM) and the brown
wire (N.C.).
4 Run the boiler (the Fan must run) and check thethe electric resistance between COM and N.O.
Between COM and N.O. the contact must beclosed (electrical resistance zero).
N.O.
N.C.
”L”connectionCOM
”H”connection
Fig. 62
16.3 Removal of the Fan
Warning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
1 Remove all the case panels, the sealed chamberlid and the combustion chamber lid.
2 Disconnect the connectors A and the earth con-nection B (Fig. 61).
3 Disconnect the pipes which connect the venturidevice to the Air pressure switch.
4 Unscrew the screws C and remove the clamp D(Fig. 64).
4b For model M90.28S only, remove the screw E andthe plate F (Fig. 63).
E
F
Fig. 63
5 Unscrew the screws G (Fig. 61 and Fig. 64).andremove the flue hood with the Fan.
Fan and Air pressure switch
31
CD
G
Fig. 64
6 Remove the three screws securing the Fan to theflue hood.
7 Assemble the fan carrying out the removal oper-ations in reverse sequence.
Warning: to correctly connect the venturi device tothe Air pressure switch, refer to Fig. 65 for the modelM90.24S and to Fig. 66 for the model M90.28S.
--- +
Fig. 65
--- +
Fig. 66
16.4 Removal of the Air pressure switch
Warning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
1 Remove all the case panels and the sealedchamber lid.
2 Disconnect the wires from the Air pressureswitch.
3 Remove the pipes from the Air pressure switch.4 Unscrew the screws which hold the Air pressure
switch to the frame.5 Assemble the Air pressure switch carrying out the
removal operations in reverse sequence.
Warning: to correctly connect the Air pressureswitch, refer to Fig. 65 for the model M90.24S, toFig. 66 for the model M90.28S and Fig. 62 for thecorrect wiring.
32
17 Ignition and detection electrodes17.1 Function
Three electrodes are fitted on the burner. Two of themare the ignition electrodes and are fitted near the frontpart of the burner. The ignition sparks take place be-tween their metallic edges over the central ramp of theburner during the ignition sequence.The third electrode is the detection electrode and it de-tects the presence of the flame.
Ignition
Detection
Male
Female
Fig. 67
17.2 Checksn Check the position of the electrode edges
Warning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
1 Remove all the case panels, the sealed chamberlid and the combustion chamber lid.
2 Check for the correct distance between the me-tallic edges of the ignition electrodes (seeFig. 68).
Ignition
4 mm
Fig. 68
3 Check the integrity of the detection electrode andensure that its metallic edge is correctly placedover the ramp of the burner.
n Check the connection wires.
Warning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
1 Remove all the case panels, the sealed chamberlid and the combustion chamber lid.
2 Check for the integrity of the insulation of wireswhich connect the electrodes to the ignition de-vice.
17.3 Removal
Warning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
1 Remove all the case panels, the sealed chamberlid and the combustion chamber lid.
2 Disconnect the electrode wires from the full se-quence ignition device.
3 Remove the burner by unscrewing the fourscrews placed at the right and left sides of theburner.
3b For model M90.28S only, remove also the plate F(see Fig. 63 on page 30).
4 Unscrew the screws A (Fig. 69) which hold theelectrodes to the burner.
A
Fig. 69
5 Extract the electrodes from the burner.6 Assemble the electrodes carrying out the removal
operation in reverse order.Refer to Fig. 67 in order to recognize the elec-trodes and to correctly connect the wiring.
Note: the metallic edge of the detection electrode islonger than the one of the ignition electrodes.
33
18 Safety thermostat18.1 Function
The safety thermostat A in Fig. 70 is a device thatsenses the temperature of the primary circuit waterwhich flows in the outlet pipe of the primary heat ex-changer.If the temperature control system of the boiler fails andthe temperature of the primary circuit reaches a dan-gerous temperature, the safety thermostat opens theelectric circuit that supplies the on---off operators of thegas valve.Consequently, the full sequence ignition device at-tempts to light the burner and, at the end, locks theboiler and lights the lock---out signal lamp.
A
Fig. 70
18.2 ChecksWarning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
n Overheat temperature value1 Set the temperature control knobs to their max.
position and run the boiler in d.h.w. and c.h.2 Allow the boiler to reach its maximum operating
temperature (monitor the temperature gauge onthe instrument panel). The boiler should maintaina temperature below that of the safety thermostatand no overheat intervention should occur.
n Electrical function1 Remove all the case panels and the lid of the
sealed chamber.
2 Disconnect the safety thermostat and check itselectrical function. Normally (no intervention) thecontact must be closed (electrical resistance zeroW).
18.3 RemovalWarning: isolate the boiler from the mainselectricity supply before removing anycovering or component.
1 Remove all the case panels and the lid of thesealed chamber.
1b For model M90.28S only, remove the screw B andthe plate C (Fig. 71).
B
C
Fig. 71
2 Disconnect the wiring D (Fig. 72).3 Remove the spring E which holds the overheat
thermostat on the pipe of the primary heat ex-changer and remove it.
D
E
Fig. 72
4 Reassemble the overheat thermostat carrying outthe operations in reverse order.
5 Apply an adequate quantity of heat conductingcompound between the pipe and the thermostat.
34
19 Short spare parts listKey G.C. part no. Description Q.ty Manufac-
turer part no.Manufacturer’s reference
1 173---148 Burner (mod. M90.24S) 1 KI1004 102 Polidoro173---149 Burner (mod. M90.28S) 1 KI1004 147
2 169---069 Injectors for natural gas (mod. M90.24S) 12 KI1064 505 PolidoroInjectors for natural gas (mod. M90.28S) 14
169---070 Injectors for LPG (mod. M90.24S) 12 KI1064 506Injectors for LPG (mod. M90.28S) 14
3 Expansion vessel 1 BI1172 103 CIMM 6 litres4 Main heat exchanger (mod. M90.24S) 1 BI1172 100
Main heat exchanger (mod. M90.28S) 1 BI1172 1065 Fan (mod. M90.24S) 1 BI1336 104
Fan (mod. M90.28S) 1 BI1336 1056 Gas valve 1 BI1093 104 SIT 845 Sigma7 E05---422 Air pressure switch (mod. M90.24S) 1 BI1036 102 Yamatake---Honeywell C6065
169---127 Air pressure switch (mod. M90.28S) 1 KI1267 1038 Safety valve 1 BI1131 100 Orkly9 Combustion chamber side panels 2 BI1326 10010 Combustion chamber rear panel (mod. M90.24S) 1 BI1326 107
Combustion chamber rear panel (mod. M90.28S) 1 BI1326 10811 Combustion chamber front panel (mod. M90.24S) 1 BI1326 101
Combustion chamber front panel (mod. M90.28S) 1 BI1326 10212 Electronic regulation p.c.b. 1 BI1475 11613 Full sequence ignition device 1 BI1305 101 Bertelli & Partners FM3014 E01---204 D.h.w. heat exchanger (mod. M90.24S) 1 BI1001 101
E01---205 D.h.w. heat exchanger (mod. M90.28S) 1 BI1001 10215 Pump 1 BI1172 104 Wilo --- NFHUL 15/516 E00---684 Primary circuit flow switch 1 BI1011 50517 D.h.w. flow switch 1 BI1091 10418 E00---688 Main. flow switch membrane 1 BI1011 10319 Three way diverter valve (electric actuator) 1 BI1011 102 Elbi20 Overheat thermostat 1 BI1172 105 ELTH --- type 26121 169---083 Fuse 1,6 A T 1 BI1005 10522 164---026 Temperature probe (main or d.h.w. circuit) 1 BI1001 11723 Ignition electrode (left) 1 BI1123 10124 Ignition electrode (right) 1 BI1123 10325 Detection electrode 1 BI1123 10226 Temperature---pressure gauge 1 BI1475 108 IMIT
Short spare parts list
35
1 2
64
5
7
3
8
15 18
12 13
20 21 22 23 25 26
14 16
24
17 19
9
10
11 9
*1796208420*17962.0842.0 --- 0701 10A3
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