Biasi RIVA ADVANCE HE M110B.24SM/C User manual

Wall hung, fan flue, room sealed, high efficiency gas boiler
Service manual
RIVA ADVANCE HE
Models: G.C. Appl. No.
M110B.24SM/C 47---583---11
M110B.32SM/C 47---583---12
M110B.24SR/C 41---580---07
Leave this manual adjacent to the gas meter

Ta b le o f co n t e n t s
1 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 4............
3Diagrams 5...........................
3.1 Wiring diagram
M110B.24SM/... M110B.32SM/... 5.......
3.2 Wiring diagram M110B.24SR/... 6........
3.3 Circuit voltages 7......................
4Faultfinding 8........................
5 Condensing heat exchanger 10..........
5.1 Function 10.............................
5.2 Removal 10............................
5.3 Cleaning 11............................
6 D.h.w. heat exchanger 12...............
6.1 Function 12.............................
6.2 Removal 12............................
7Pump 13...............................
7.1 Function 13.............................
7.2 Checks 13.............................
7.3 Removal 13............................
8 Three way diverter valve 15.............
8.1 Function 15.............................
8.2 Checks 15.............................
8.3 Removal of the electric actuator 15........
8.4 Removal of the diverter group and its
internal parts 16.........................
9 Electronic control/ignition p.c.b. 17......
9.1 Function 17.............................
9.2 Selection and adjustment devices 17......
9.3 Checking the temperature 18.............
9.4 Operation lights 19......................
9.5 Setting the boiler control function modes 19
9.6 Adjustment of maximum useful output
in c.h. mode 20.........................
9.7 Reignition frequency setting 20...........
9.8 Combi / C.H. only mode setting 21........
9.9 Checks 22.............................
9.10 Removal of the electronic control p.c.b 22..
9.11 Thermal control in the ” ”mode 24......
9.12 Thermal control in the ” ”mode 25......
10 Transformer 26.........................
10.1 Removal 26............................
10.2 Check the transformer 26................
11 Gas valve 27...........................
11.1 Function 27.............................
11.2 Description of the parts 27...............
11.3 Adjustment 27..........................
11.4 Checks 28.............................
11.5 Removal of the gas valve 28..............
12 Primary circuit flow switch 30...........
12.1 Function 30.............................
12.2 Checks 30.............................
12.3 Removal 30............................
13 Expansion vessel and
temperature-- pressure gauge 31........
13.1 Function 31.............................
13.2 Checks 31.............................
13.3 Removal of the expansion vessel 31.......
13.4 Removal of the temperature---pressure
gauge 31...............................
14 D.h.w. flow switch, filter and flow limiter 32
14.1 Function 32.............................
14.2 Description and location of parts 32.......
14.3 Checks 32.............................
14.4 Removal of the sensor 32................
14.5 Removal of the flow switch group
and d.h.w. circuit filter 32.................
14.6 Flow limiter 32..........................
15 Temperature probe 34..................
15.1 Function 34.............................
15.2 Checks 34.............................
15.3 Removal of the c.h.Temperature probe 34..
15.4 Removal of the d.h.w.Temperature probe 35
16 By-- pass valve 36......................
16.1 Function 36.............................
16.2 Removal 36............................
17 Fan and Air box 37.....................
17.1 Function 37.............................
17.2 Removal of the Air box and the Fan 37.....
18 Ignition and detection electrodes,
burner and spark generator 38..........
18.1 Function 38.............................
18.2 Removal of the Ignition
and detection electrodes 38..............
18.3 Removal of the burner 38................
18.4 Removal of the front insulation panel 39....
18.5 Removal of the rear insulation 39..........
18.6 Removal of the spark generator 40........
18.7 Checks 40.............................
19 Safety thermostat 42...................
19.1 Function 42.............................
19.2 Checks 42.............................
19.3 Removal 42............................
20 Flue temperature probe NTC
and Safety thermal fuse 43..............
20.1 Function 43.............................
20.2 Removal 43............................
20.3 Checks 43.............................
21 Condensate trap 45....................
21.1 Function 45.............................
21.2 Check the cleanness of the trap 45........
21.3 Removal 45............................
22 Short spare parts list 46................

1
1Overall information
1.1 Overall View
Fan
Safety
thermostat
Burner
Ignition
electrodes
Gas valve
Control
panel
Automatic
air purger
Pump
D.h.w. temp.
probe
D.h.w.
heat exchanger
Expansion
vessel
Detection
electrode
valve
Condensing
Diverter valve
Main circuit
Flue temperature
heat exchanger
Condensate
trap
flow switch
C.h. temp.
probe
probe NTC
Air box
Gas restrictor
Transformer
Switch
D.h.w. Flow
Spark
Generator
Condensing heat
exchanger air
purger valve
C.h. pressure
relief valve
Safety thermal
fuse
Air hose
Codensate
trap
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
2General access and emptying
hydraulic circuits
2.1 Nomenclature
2
6
1
54
3
Fig. 2.1
1 Right side panel
2 Front panel
3 Control panel lid
4 Control panel cover
5 Service panel
6 Left side panel
2.2 Body panels
Warning: isolate the boiler from the mains
electricity supply before removing any
covering or component.
For the most part of the check and maintenance oper-
ations it is necessary to remove one or more panels of
the case.
The side panels can be removed only after the removal
of the front panel.
To remove the front panel remove screws A(Fig. 2.2),
lift the panel and remove it.
A
Fig. 2.2
To remove the side panels loosen the screws Band C
(Fig. 2.3), bring the base of the panels away from the
boiler and lift them, freeing them from the top hooks.
B
D
CB
Fig. 2.3 --- bottom view of the boiler
2.3 Control panel
Warning: isolate the boiler from the mains
electricity supply before removing any
covering or component.
To gain access to the parts located inside the control
panel proceed as follows:
1 Remove the front panel of the case.
2 Loosen the screws Band C(Fig. 2.3).
3RemovethescrewsD.
4 Move the lower part of the side panels as indi-
cated in Fig. 2.4 and pull the control panel.
When completely pulled out, the panel can rotate
45˚downwards to facilitate the service oper-
ations on the internal parts.

General access and emptying hydraulic circuits
3
Fig. 2.4
5RemovethescrewsEand remove the service
panel (Fig. 2.5).
E
F
F
Fig. 2.5
6RemovethescrewsFandremovethecontrol
panel lid (Fig. 2.5).
2.4 Access to the sealed chamber
G
G
Fig. 2.6
To gain access to the parts contained in the sealed
chamber it is necessary to remove the lid of the sealed
chamber.
For this purpose, remove the front and side panels of
the case, remove the screws Gas indicated in Fig. 2.6
and remove the lid.
2.5 Emptying the primary circuit
1 Close the c.h. circuit flow and return cocks H.
(Fig. 2.7).
H
K
Fig. 2.7 --- bottom view of the boiler
2 Remove the front and right panels of the boiler.
3 Open the drain tap I(Fig. 2.9 combi or Fig. 2.10
only c.h.) until the boiler is completely emptied.
4 To help the draining of the primary circuit loose
the condensing heat exchanger air purger valve
J(Fig. 2.8).
J
Fig. 2.8
Attention: some water could remain in the condens-
ing heat exchanger.
5 Close drain tap once the emptying has been
completed.

General access and emptying hydraulic circuits
4
I
Fig. 2.9
I
Fig. 2.10
2.6 Emptying the d.h.w. circuit
6 Close the d.c.w. inlet cock K(Fig. 2.7).
7 Open one or more hot water taps until the boiler
has been completely emptied.

5
3Diagrams
3.1 Wiring diagram
M110B.24SM/... M110B.32SM/...
Ignition
electrodes
Flame detection
electrode
External controls
terminal block
Electric supply
terminal block Three way
diverter valve
Pump
Fan
Primary circuit
flow switch
D.h.w. flow
switch
C.h. temperature
probe NTC
Gas valve
Safety
thermostat
Flue
temperature
D.h.w. temperature
probe NTC
probe NTC
LD1LD2LD3
F1F2
F3
K1
K2
K3
K4
LD4
P6
T3
X1
X2
X3
X5
X6
X7
X10X11
X12
X13
X17
X23
X24
P3
X14
X15
SB1
X16
X22
X9
bu bn
bu
bn
bububnbn
123
LN
gnye bu
bn
bn
bkbu
bn bu
gnye
bn bk bu
bn
gnye bu
gnye
bnbu rd wh bk bu bn
gnye
gnye
bu
bn
bu
gnye
1
4
5
bu bn
bn bu
whog
wh
gy
t
t
bk rd
rd
bk
bu
bu
bu bu
wh
bu
wh
bu
M
~
rdbk
bugy
wh
rd
gy
bu
wh
bk
t
bk
wh
wh
bk
bkwh
NO
COM
rd
rd
rd
rd
gy gy
gy
gy
Transformer
230V~ / 24V~
Spark
Generator
Time switch
rd
gn
bk
wh
bn = brown
bu = blue
bk = black
wh = white
rd = red
gy = grey
gn = green
ye = yellow
vt = violet
og = orange
gnye = green/yellow
gnye
rdwh = red/white
bn
whwh
Safety
thermal fuse
t
gy
gy
wh
M
~3
2
1
rdbk wh

Diagrams
6
3.2 Wiring diagram
M110B.24SR/...
LD1LD2LD3
F1F2
F3
K1
K2
K3
K4
LD4
P6
T3
X1
X2
X3
X5
X6
X7
X10X11
X12
X13
X17
X23
X24
P3
X14
X15
SB1
X16
X22
X9
Ignition
electrodes
Flame detection
electrode
External controls
terminal block
Electric supply
terminal block
Pump
Fan
Primary circuit
flow switch
C.h. temperature
probe NTC
Gas valve
Safety
thermostat
Flue
temperature
probe NTC
bu bn
bu
bn
bububnbn
123
LN
gnye bu
bn
bn
bkbu
bn bu
gnye
bn bk bu
bn
gnye bu
gnye
bnbu bu bn
gnye
gnye
bu
bn
bu
gnye
1
4
5
bu bn
bn bu
whog
wh
gy
t
bu
bu
bu bu
M
~
rdbk
bugy
wh
rd
gy
bu
wh
bk
t
bk
wh
wh
bk
bkwh
NO
COM
rd
rd
rd
rd
gy gy
gy
gy
Transformer
230V~ / 24V~
Spark
Generator
bn = brown
bu = blue
bk = black
wh = white
rd = red
gy = grey
gn = green
ye = yellow
vt = violet
og = orange
gnye = green/yellow
gnye
rdwh = red/white
bn
whwh
Safety
thermal fuse
t
gy
gy
wh

Diagrams
7
3.3 Circuit voltages
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~
Safety
thermostat
0
Fan
0
Main circuit
LD1LD2LD3
F1F2
F3
K1
K2
K3
K4
LD4
P6
T3
X1
X2
X3
X5
X6
X7
X10X11
X12
X13
X17
X23
X24
P3
X14
X15
SB1
X16
X22
X9
Supply network
230~
Pump
230~ 0230~0
3way
diverter valve
230~
Gas valve
24~
Transformer
24=
230~
0
5=
D.h.w.
Flow switch
pressure switch

8
4Fault finding
Components to check
Section of the manual ! (note ref. in brackets)
10 ---
(1)
---
(2)
---
(3)
21.1 ---
(4)
67.2 8.2 9.9 11.4 12.2 14.5 15.2 16 17 18.7 18.7 19.2 19.2 20.1 ---
(7)
--- ---
L o c k --- o u t s i g n a l l a m p r e d
Defect #
Transformer
Power supply line
Gas supply line
Flue pipes
Condensate drain pipe and trap
C.h. circuit
D.h.w. circuit
D.h.w. heat exchanger
Pump
Diverter valve
D.h.w. flow switch
Fuses (Electronic p.c.b.)
Electronic p.c.b.
Boiler settings
Gas valve
Main circuit flow switch
D.h.w. filter
Main circuit temp. probe
D.h.w. temp. probe
B y --- p a s s v a l v e
Fan air restrictor
Spark generator
Ignition electrode
Detection electrode
Safety thermostat
Gas restrictor
Flue temperature probe NTC
Expansion vessel
Safety valve
Pressure gauge
By pressing the reset push--- button the boiler turns on and operates cor- rectly.
J J J J J J J J J J
By pressing the reset push--- button the boiler starts the ignition cycle. The burner doesn’t light on and the boiler locks again.
J J J J J J J J J J J
ON
By pressing the reset push--- button the boiler starts the ignition cycle. The burner lights on and the boiler
locks again.
J J J J J
The boiler does not start either in c/h or d.h.w. mode. All the operation lights OFF Fan still.
J J J J
The burner doesn’t light either in c.h. or d.h.w. mode. Fan turns.
J J J J
The burner doesn’t light either in c.h. or d.h.w. mode. Fan doesn’t turn.
J J J J J
The boiler doesn’t control the d.h.w. temperature. Turning the d.h.w. temp. adjustment knob hasn’t effect on the modulation of the flame. The boiler operates correctly on c.h.
J J
OFF
The boiler lights for a short while on c.h. Normal operation on d.h.w. function.
J J J J J

9
Components to check
Section of the manual ! (note ref. in brackets)
---------
(7)
20.119.219.218.718.7171615.214.512.211.49.98.27.26---
(4)
21.1---
(3)
---
(2)
---
(1)
10
L o c k --- o u t s i g n a l l a m p r e d
Pressure gauge
Safety valve
Expansion vessel
Flue temperature probe NTC
Gas restrictor
Safety thermostat
Detection electrode
Ignition electrode
Spark generator
Fan air restrictor
B y --- p a s s v a l v e
D.h.w. temp. probe
Main circuit temp. probe
D.h.w. filter
Main circuit flow switch
Gas valve
Boiler settings
Electronic p.c.b.
Fuses (Electronic p.c.b.)
D.h.w. flow switch
Diverter valve
Pump
D.h.w. heat exchanger
D.h.w. circuit
C.h. circuit
Condensate drain pipe and trap
Flue pipes
Gas supply line
Power supply line
Transformer
Defect #
The boiler does not supply d.h.w. (cold water from the tap). Regular operation in c/h mode even during a drawing off d.h.w.
J J J
On c/h mode the temperature of the main circuit reaches 90qCandthec/h
system does not heat. The boiler operates correctly on d.h.w. mode.
J J J
Incorrect modulation J J J J Noisy bolier J J J J J J Poor c.h. / d.h.w. temperature (9) J J J J J
F
Poor d.h.w. temperature. Regular operationinc/hmode.
J J J
(8)
J
OF
F
Low d.h.w. flow rate J J J
---
Water leaks from the safety valve dur- ing operation on c/h
J J J J J
---
Water leaks from the safety valve when the boiler is off.
J J
Note Useful information can be obtained also from the optical indication given by the appliance oper- ation lights (see section 9.4). 1 Check for 230V~ between line (L) and neutral (N)
Verify the integrity of supply cable, plug and external fuses. Check the polarity of line and neutral connection
2 Verify the soundness of the gas supply pipe, the position of
stop valves.
3 Check for soundness and absence of obstructions. Verify that
the flue terminal is correctly installed (see clearances) and en- sure that exhaust gas is not sucked back by the boiler.
4 Check for soundness of the circuit and verify its correct filling
(see also installation manual).
5 A j a m m e d b y --- p a s s c o u l d c a u s e t h e o v e r --- h e a t i n g o f t h e m a i n
circuit and the intervention of the safety thermostat.
6 Using the flue analyzer, check the CO2value of the flue gases.
This reading is a reference value for the gas valve setting.
7 Check the pressurization of the expansion vessel. Refer to the
installation manual for proper values.
8 d.h.w. pressure too high or flow rate too high. If necessary in-
sert a flow rate limiter (14.6).
9 The boiler doesn’t reach the nominal heat input.

10
5Condensing heat exchanger
5.1 Function
The Condensing heat exchanger Ain Fig. 5.1 has the
function of transferring heat produced from combus-
tion of the gas and from the flue exhausted gas to the
water circulating in it.
A
B
C
Fig. 5.1
By reducing the combustion products temperature, the
latent heat of the vapour is transferred to the water cir-
cuit, allowing an extra gain of useful heat.
The condensed vapour is then drained through the
condensate trap Band the draining pipe C.
5.2 Removal
Warning: isolate the boiler from the mains
electricity supply before removing any
covering or component.
1 Disconnect the flue system from the boiler.
2 Remove the fan group (rubber pipe, gas pipe) fol-
lowing the instructions from 1 to 6 in section 17.2.
3 Disconnect the detection electrode connector D,
the ignition electrodes connector Eand the earth
wire F.
4 Disconnect the fan connector Gby pressing the
plastic hook placed on the side of the connector
(Fig. 5.2).
5 Unscrew the nuts H(Fig. 5.2).
6 Remove the fan---burner group I.
7 Empty the primary circuit of the boiler.
8RemovetheclipsJ(Fig. 5.2).
9 Loosen the connection Kand slightly move the
pipe Lupwards, turn it towards left (Fig. 5.2) and
then move the pipe downwards freeing it from the
Condensing heat exchanger.
H
I
FE
I
J
G
D
KLM N
Fig. 5.2
10 Loosen the connection Mand slightly move the
pipe Nupwards, turn it towards left (Fig. 5.2) and
then move the pipe downwards freeing it from the
Condensing heat exchanger.
Q
O
P
R
Fig. 5.3

Condensing heat exchanger
11
11 Using pliers, remove the spring Omoving it
downwards and disconnect the rubber pipe P
(Fig. 5.3).
12 Unscrew the screws Qand remove the clamps
(Fig. 5.3).
13 Disconnect the two connectors Rby pressing the
plastic hook placed on the side of the connector
(Fig. 5.3).
14 Remove the Condensing heat exchanger by
levering it and sliding it forwards.
15 Reassemble the Condensing heat exchanger
carrying out the removal operations in reverse
order.
Ensure to tight the nuts H --- Fig. 5.2 firmly
5.3 Cleaning
If there are deposits of dirt on the coil of the Condensing
heat exchanger, clean with a bristle paintbrush and re-
move the dust with a hoover.
Warning: After cleaning or replacement as
detailed above, if it deemed necessary to
undertake a combustion analysis, refer to
the appropriate chapter Maintenance of the
installation instructions manual.
S
Fig. 5.4
The siliconic gasket SFig. 5.4 must be replaced
every 2 years.

12
6D.h.w. heat exchanger
6.1 Function
The d.h.w heat exchanger Ain Fig. 6.1 and Fig. 6.3 al-
lows the instantaneous transfer of heat from theprimary
hydraulic circuit to the water destined for d.h.w use.
A
Fig. 6.1
The schematic structure is shown in Fig. 6.2.
Primary hydraulic circuit
Domestic hot water circuit
Fig. 6.2
6.2 Removal
Warning: isolate the boiler from the mains
electricity supply before removing any
covering or component.
1 Remove the front and right hand side panels of
the case.
2 Empty the primary circuit and the d.h.w circuit of
the boiler.
3 Completely unscrew the Allen key screws B
(Fig. 6.3) which hold the exchanger to the brass
group.
4 Remove the electric actuator following the in-
structions in section 8.3.
B
A
Fig. 6.3
5 Remove the pump following the instructions in
section 7.3.
C
A
Fig. 6.4
6 Completely unscrew the Allen key screws C
(Fig. 6.4) which hold the exchanger to the plastic
groups.
7 Move the exchanger towards the rear of the boiler
and extract it.
Reassemble the d.h.w. heat exchanger carrying out the
removal operations in the reverse order.
Warning: to lubricate the O-- ring gaskets
exclusively use a silicone base grease
compatible to be in contact with foods and
approved by the local water Authorities.
Attention. When reassembling the exchanger be
sure to put the off centre location/securing pin indi-
cated in Fig. 6.5 towards the left side of the boiler.
Fig. 6.5

13
7Pump
7.1 Function
The pump Ain Fig. 7.1 and Fig. 7.2 has the function of
making the water in the main circuit circulate through
the main condensing heat exchanger and therefore
through the c.h. system (during the c.h. function) or
through the secondary heat exchanger (during the
d.h.w. function).
A
Fig. 7.1
7.2 Checks
Warning: isolate the boiler from the mains
electricity supply before removing any
covering or component.
nCheck that the pump is not seized and that the
movement of the rotor is not subject to mechanical im-
pediments.
With the boiler off, remove the front panel. Remove the
air release plug of the pump and turn the rotor with a
screwdriver.
nCheck the electrical continuity.
With the boiler off, remove the front panel and discon-
nect the connector B(Fig. 7.2).
Measure the electrical resistance between the pump
supply connections.
Electrical resistance of the windings (at ambient tem-
perature) must be about 230 8.
nCheck the absence of starting defects.
With the boiler off remove the front case panel.
Remove the air release plug from the pump. Start the
boiler and with a screwdriver, turn the rotor in the direc-
tion of the arrow. If there is a defect in starting, the rotor
will begin to turn normally only starting it manually.
nCheck that the impeller is integral with the rotor.
With the boiler off remove the front and right hand side
case panels, lower the control panel and empty the pri-
mary circuit.
Remove the pump head by undoing the screws which
hold it to the pump body and check that the impeller is
firmly joined to the rotor.
7.3 Removal
Warning: isolate the boiler from the mains
electricity supply before removing any
covering or component.
1 Remove the front and right hand side case pan-
els.
2 Empty the primary circuit of the boiler.
3 Extract and lower the control panel.
4 Disconnect the connector B (Fig. 7.2)(Fig. 7.3).
5 Loosen the connection C,and pull up and turn to
the left the pipe D.
6 C.h. only model remove the fork Eand remove
pressure gauge connection F(Fig. 7.3)
7 C.h. only model remove the fork G, loosen the
connection Hand remove the pipe I(Fig. 7.3)
C
A
B
D
K
J
Fig. 7.2
C
A
B
D
K
E
F
J
G
I
H
Fig. 7.3 c.h. only model
8 Remove the locking plate J.

Pump
14
9 Unscrew the two screws Kthat hold the pump on
theframeandremovethepump.
Reassemble the pump carrying out the removal oper-
ations in the reverse order. When reassembling the
pump, check the correct location of the O---ring gasket
in the inlet port of the pump that seals the connection
between the pump and the plastic group.

15
8Three way diverter valve
8.1 Function
The diverter valve A(Fig. 8.1) has the function of mod-
ifying the hydraulic circuit of the boiler by means of an
electric 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. 8.1
8.2 Checks
nCheck the electrical continuity
Fig. 8.2 indicates the relationship between the electric
command coming from the electronic control p.c.b.
and the position of the actuator B(brass spindle) when
the boiler operates in d.h.w. mode.
Fig. 8.3 indicates the relationship between the electric
command coming from the electronic control p.c.b.
and the position of the actuator B (brass spindle) when
the boiler operates in c.h. mode.
In both figures the relationship between the position of
the actuator and the resistance of the motor windings
(the motor must be disconnected from the wiring) is
also given.
B
rd = red
bk = black
wh = white
0V
230 V
Spindle B
not visible
Open circuit
9,4 Kohm
wh
rd
bk
3
1
2
F i g . 8 . 2 --- D . h . w. m o d e
B
rd = red
bk = black
wh = white
230 V
0V
Spindle B
visible
Open circuit
9,4 Kohm
wh
rd
bk
3
1
2
F i g . 8 . 3 --- C . h . m o d e
8.3 Removal of the electric actuator
Warning: isolate the boiler from the mains
electricity supply before removing any
covering or component.
1 Remove the front case panel.
2 Disconnect the connectors C(Fig. 8.4).
3 Remove the fixing spring Dand remove the
actuator E.
Reassemble the actuator carrying out the re-
moval operations in the reverse order.
When reassembling the actuator, refer to Fig. 8.2
--- Fig. 8.3 or to the wiring diagram in section 8.2
for the correct wiring connection.

Three way diverter valve
16
D
C
E
Fig. 8.4
8.4 Removal of the diverter group and its
internal parts
1 Removethefrontandbothsidecasepanels.
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. 8.5) and remove
the primary circuit flow switch G.
5 Disconnect both c.h. and d.h.w. temperature
probe, respectively Hand I.
6 Unscrew the connector J, the c.h. flow connector
and the d.h.w. outlet connector.
I
G
F
H
J
Fig. 8.5
7 Remove the d.h.w. heat exchanger (see section
6.2).
8RemovetheforkKandmoveawaythepipeL
(Fig. 8.6).
9 Unscrew the screw Mandremovethediverter
group.
L
L
M
Fig. 8.6 Rear view of the boiler
10 Refer to the exploded view in Fig. 8.7 to remove
the internal parts of the three way diverter valve.
Fig. 8.7
11 Reassemble the diverter group carrying out the
removal operations in the reverse order.
Warning: to lubricate the O-- ring gaskets
exclusively use a silicone base grease
compatible to be in contact with foods and
approved by the local water Authorities.

17
9Electronic control/ignition p.c.b.
9.1 Function
From other boiler devices....
C.h. temperature probe NTC
D.h.w. temperature probe NTC
D.h.w. flow switch
Primary circuit flow switch
Flue temperature probe NTC
Safety thermal fuse
Safety thermostat
Flame detection electrode
Room thermostat (if fitted)
Time switch
On the Electronic control/ignition
p.c.b.......
Function control
C.h. temperature adjustment
D.h.w. temperature adjustment
Boiler reset button
(control panel fascia)
Inlet Information
Pump
Three way diverter valve
Gas valve
Fan
Ignition electrodes
Appliance operation lights*
L o c k --- o u t s i g n a l l a m p *
*control panel fascia
Outlet command
Fig. 9.1
The fundamental function of the Electronic control/igni-
tion p.c.b. is that of controlling the boiler in relation to
the external needs (i.e. heating the dwelling or heating
the water for d.h.w. use) and operating in order to keep
the temperature of the hydraulic circuits constant.
This is obviously possible within the useful power and
maximum working temperature limits foreseen.
Generally, the Electronic control/ignition p.c.b. receives
inlet information coming from the boiler (the sensors)
or from the outside (knobs, room thermostat, etc.), pro-
cesses it and consequently acts with outlet commands
on other components of the boiler (Fig. 9.1).
The Electronic control/ignition p.c.b. is also a full se-
quence ignition device and does a sequence of oper-
ations (ignition cycle) which lead to the ignition of the
gas at the burner
It checks the presence of the flame during the entire
period in which it is activated and supplies the fan regu-
lating its speed.
The Electronic control/ignition p.c.b. has a safety func-
tion and any incorrect interventions or tampering can
result in conditions of dangerous functioning of the
boiler.
The Electronic control/ignition p.c.b. can lock the func-
tioning of the boiler (lock state) and stop its functioning
up to the resetting intervention. The lock is signalled by
the lighting of the lock---out signal lamp and the device
can be reset only by using the boiler reset button
placed on the control panel fascia.
Some components which are connected to the device
can activate the lock state. The causes of a lock state
could be:
fThe intervention of the safety thermostat (over-
heat of the primary circuit).
fThe intervention of the flue temperature probe
(overheat of the combustion products).
fA fault on gas supply.
fFaulty ignition (faulty ignition electrodes, their wir-
ing or connection).
fFaulty flame detection (faulty detection electrode,
its wiring or connection).
fFaulty condensate drainage.
fFaulty gas valve (faulty on---off operators or not
electrically supplied).
fFaulty Electronic control/ignition p.c.b..
Other components like the primary circuit flow switch
can temporarily stop the ignition of the burner but allow
its ignition when the cause of the intervention has
stopped.
Fig. 9.20 and Fig. 9.21 show the sequence of the oper-
ations that are carried out at the start of every ignition
cycle and during normal functioning.
9.2 Selection and adjustment devices
On the Electronic control/ignition p.c.b. several selec-
tion, adjustment and protection devices are located.
(Fig. 9.2).
Some of these devices are directly accessible by the
user (function control, temperature adjustment poten-

Electronic control/ignition p.c.b.
18
tiometers etc.) others, like the fuses, are accessible by
removing the service panel.
91 7 84 5
13 1112141719 151618
32 6 10
Fig. 9.2
1 x7 connector --- electric supply terminal block and
external controls terminal block.
2 Fuse F1, F2 3,15 A F
3 Fuse F3, 400 mA T
4 x12 connector --- pump and 3way diverter valve
5 x17 connector --- gas valve
6 x14 connector --- external temperature probe
(optional)
7 x9 connector --- safety thermostat, flue tempera-
ture probe NTC, c.h. temperature probe NTC
8 x11 connector --- d.h.w. temperature probe
9 x10 connector --- d.h.w. flow switch
10 x13 connector --- remote control (optional)
11 x2 connector --- timer
12 Lock---out signal lamp
13 Boiler reset button
14 Function control / C.h. temperature adjustment
15 x22 connector --- fan
16 x24 connector --- transformer
17 D.h.w. temperature adjustment
18 x5 connector --- transformer
19 Appliance operation lights
9.3 Checking the temperature
The Electronic control/ignition p.c.b. makes it possible
to separately 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.
The user, setting the desired temperature with the con-
trol panel knobs operates the variable elements (14 and
17 in Fig. 9.2) 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 switching
OFF (ON/OFF function). If the power requested is
higher, then the burner is switched ON at maximum
power and will control by modulating to 40% of the
maximum power output.
During the c.h. operation (Fig. 9.3), the signal coming
from the c.h. temperature probe is compared to the sig-
nal given by the control panel through the adjustment
made by the user (knob ). The result of such a com-
parison operates the fan speed thus regulating the gas
flow rate and consequently changing the useful output
of the boiler.
Fig. 9.3
When the boiler functions in d.h.w. (Fig. 9.4), the signal
coming from the d.h.w. temperature probe is compared
with the signal given by the control panel through the
adjustment made by the user (knob ).