Biasi M90E.24S User manual

Wall hung, fan flue, room sealed gas boiler
SERVICE MANUAL
RIVA COMPACT
Models: G.C. Appl. No.
M90E.24S 47--970--17
M90E.28S 47--970--18
M90E.32S 47--970--21
Leave this manual adjacent to the gas meter
Biasi UK Ltd
Newman Park, Western Way
Wednesbury, WS10 7BJ
Sales Tel No: 0121 506 1340
Sales Fax No: 0121 506 1360
Service Tel No: 0121 506 1350
Service Fax No: 0121 506 1370
www.biasi.co.uk

1
Ta b l e o f c o n t e n t s
1 Overall information 2..................
1.1 Overall View 2.........................
1.2 Hydraulic diagram 2....................
2 General access and emptying
hydraulic circuits 3....................
2.1 Nomenclature 3........................
2.2 Body panels 3.........................
2.3 Control panel 3........................
2.4 Access to the sealed chamber 4.........
2.5 Emptying the primary circuit 4...........
2.6 Emptying the d.h.w. circuit 4............
3Diagrams 5...........................
3.1 Wiring diagram 5.......................
3.2 Circuit voltages 6......................
4Faultfinding 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............................
7Pump 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 starting control p.c.b. 14......
9.1 Function 14.............................
9.2 Selection and adjustment devices 14......
9.3 Checking the temperature 15.............
9.4 Operation lamps 15.....................
9.5 Setting the boiler control function modes 16
9.6 Reignition frequency setting 16...........
9.7 Ignition gas pressure adjustment 16.......
9.8 Adjustment of useful c.h. output 17........
9.9 Gas conversion 18......................
9.10 Checks 19.............................
9.11 Removal of the electronic control p.c.b 19..
9.12 Thermal control in the ” ”mode 21......
9.13 Thermal control in the ” ”mode 22......
10 Modulating gas valve 23................
10.1 Function 23.............................
10.2 Nomenclature of the parts 23.............
10.3 Adjustment 23..........................
10.4 Checks 24.............................
10.5 Removal of the on---off operators coils 24..
10.6 Removal of the gas valve 24..............
11 Primary circuit flow switch 25...........
11.1 Function 25.............................
11.2 Checks 25.............................
11.3 Removal 25............................
12 Expansion vessel and
temperature -- pressure gauge 26........
12.1 Function 26.............................
12.2 Checks 26.............................
12.3 Removal of the expansion vessel 26.......
12.4 Removal of the temperature---pressure
gauge 26...............................
13 D.h.w. flow switch, filter and flow limiter 27
13.1 Function 27.............................
13.2 Nomenclature and location of parts 27.....
13.3 Checks 27.............................
13.4 Removal of the flow switch sensor 27......
13.5 Removal of the flow switch group
and d.h.w. circuit filter 28.................
13.6 Flow limiter 28..........................
14 Temperature probe 29..................
14.1 Function 29.............................
14.2 Checks 29.............................
14.3 Removal 29............................
15 By--pass valve 30......................
15.1 Function 30.............................
15.2 Removal 30............................
16 Fan, venturi device and Air pressure
switch 31..............................
16.1 Function 31.............................
16.2 Checks 31.............................
16.3 Removal of the Fan 31...................
16.4 Inspection and removal of the venturi
device 32..............................
16.5 Removal of the Air pressure switch 32.....
17 Ignition and detection electrodes 33.....
17.1 Function 33.............................
17.2 Checks 33.............................
17.3 Removal 33............................
18 Safety thermostat 35...................
18.1 Function 35.............................
18.2 Checks 35.............................
18.3 Removal 35............................
19 Short spare parts list 37................

2
1Overall information
1.1 Overall View
Fan
Safety
thermostat
Main heat
exchanger
Burner
Ignition
electrodes
Gas valve
Control
panel
Combustion
chamber
Automatic
air release
Pump
D.h.w. temp.
probe
D.h.w.
heat exchanger
Expansion
vessel
Detection
electrode
valve
D.h.w
flow switch
Diverter valve
Air pressure
switch
Main circuit
flow 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
outle
t

3
2General access and emptying
hydraulic circuits
2.1 Nomenclature
2
6
1
54
3
Fig. 1
1 Right side panel
2 Front panel
3 Control panel lid
4 Control panel cover
5Servicepanel
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.
Thesidepanelscanberemovedonlyaftertheremoval
of the front panel.
To remove the front panel remove screws A(Fig. 2), lift
the panel and remove it.
A
Fig. 2
To remove the side panels loosen the screws Band C
(Fig. 3), bring the base of the panels away from the
boiler and lift them, freeing them from the top hooks.
B
D
C
Fig. 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. 3).
3RemovethescrewsD
4 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 rotate
45˚downwards to facilitate the service oper-
ations on the internal parts.

General access and emptying hydraulic circuits
4
Fig. 4
5RemovethescrewsEand remove the service
panel (Fig. 5);
6 To gain access to the electronic regulation PCB
and the full sequence ignition device remove the
screws Fand 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 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. 6
and remove the lid.
2.5 Emptying the primary circuit
1 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. circuit
5 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.

5
3Diagrams
3.1 Wiring diagram
ON
1
L N
g/v
g/v cm
Electrical
supply terminal
block
c
m
gr
n
M
~
tt
probe NTC
DHW temperature
probe NTC
CH temperature
COM
NO mg/v c
n
n
c
ccbr
r
DHW flow
switch pressure switch
Primary
diverter valve
Three way
Pump
Modulating gas valve
n
b
n
g/v
m
b
g/v
r
n
c
nn
c
c
gr n
cb
rr
M
~NO
COM
n
gr
b
gr
g/v nc
g/v
g/v
g/v
Fan Safety
thermostat
Air pressure
switch
ignition
electrodes
Flame detection
electrode
gr
n
c
g/v
m --- b r o w n
c --- b l u e
n --- b l a c k
b --- w h i t e
r --- r e d
gr--- grey
a --- o r a n g e
g --- y e l l o w
g/v --- yellow/green
r
1
2
3
M
~
rcn
3
2
1
r
c
Wiring diagram for boiler equiped with full sequence ignition device type: ceza
Time switch
r
n
b
v
gr
v --- g r e e n
123
mc n
m
n
c
External controls
terminal block
bn

Diagrams
6
3.2 Circuit voltages
ON
1
230~
Fan
0
Safety
thermostat
230~
Eletric supply
terminal block
230~
0230~
0
3waydiverter
valve
230~
Pump
230~
Gas valve
Modulating
Electrical voltages with burner on
during c.h. or d.h.w. operation
only during c.h. operation
only during d.h.w. operation

7
4Fault finding
Components to check
Section of the manual ! (note ref. in brackets)
---
(2)
---
(3)
---
(4)
---
(5)
67.2 8.2 9.10 10.4 11.2 13.5 14.2 15 16.2 17.2 18.2 ---
(8)
---
(9)
--- ---
Appliance operation
lamp green (1)
L o c k --- o u t s i g n a l l a m p r e d
Defect #
Power supply line
Gas supply line
Flue pipes
C.h. circuit
D.h.w. circuit
D.h.w. heat exchanger
Pump
Diverter valve
D.h.w. flow switch
Fuse (regulation p.c.b.)
regulation ignition p.c.b
Function selectors (reg. p.c.b)
Gas valve (on--- off operators)
Gas valve (modulating operator)
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 and venturi device
Air pressure switch
Ignition electrode
Detection electrode
Safety thermostat
Injectors
Expansion vessel
Safety valve
Pressure gauge
OFF
OFF
The boiler does not start either in c/h or d.h.w. mode. Fan still.
J J J
By pressing the reset push--- button the boiler turns on and operates correctly.
J J
(7)
J J J
u
lses
By pressing the reset push--- button the boiler starts the ignition cycle. The burner doesn’t light on, the igni-
tion sparks continue and the boiler locks again.
J J J J
O N --- f a s t p u
ON
By pressing the reset push--- button the boiler starts the ignition cycle. The burner lights on, the ignition sparks continue and the boiler locks again.
J J J J J
The burner doesn’t light either in c.h. or d.h.w. mode. Fan turn.
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 J J J
fast pulses
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
O N ---
f
OFF
The boiler lights for a short while on c.h. Normal operation on d.h.w. function.
J J

8
Components to check
Section of the manual ! (note ref. in brackets)
---------
(9)
---
(8)
18.217.216.21514.213.511.210.49.108.27.26---
(5)
---
(4)
---
(3)
---
(2)
Appliance operation
lamp green (1)
Pressure gauge
Safety valve
Expansion vessel
Injectors
Safety thermostat
Detection electrode
Ignition electrode
Air pressure switch
Fan and venturi device
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 (modulating operator)
Gas valve (on--- off operators)
Function selectors (reg. p.c.b)
regulation ignition p.c.b
Fuse (regulation p.c.b.)
D.h.w. flow switch
Diverter valve
Pump
D.h.w. heat exchanger
D.h.w. circuit
C.h. circuit
Flue pipes
Gas supply line
Power supply line
Defect #
L o c k --- o u t s i g n a l l a m p r e d
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 75°Candthec/h
system does not heat. The boiler operates correctly on d.h.w. mode.
J J
Incorrect modulation J J J
s
Noisy bolier J J
m
al pulse
s
The boiler operates correctly but the gas pressure to the burner remains at minimum.
J J
--- n o r
m
F
Poor d.h.w. temperature J J J J J
(10)
ON
-
OF
F
Low d.h.w. flow rate J J J
--- ---
Water leaks from the safety valve during operationonc/h
J J J J
--- ---
Water leaks from the safety valve when the boiler is off.
JJJ
Note 1 For details see section 9.4 of this manual.
Further useful information can be obtained by switching the electronic control p.c.b. in the service operation mode (see section 9.4 of this manual).
2 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
3 Verify the soundness of the gas supply pipe, the position of
stop valves. Check the gas pressure at the inlet test point of the gas valve (see sect. 10.3) with the boiler at rest and during operation and compare it with the values given on the installation booklet.
4 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.
5 Check for soundness of the circuit and verify its correct filling
(see also installation manual).
6 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.
7Checktheminimum gas pressure at the outlet test point of the
gas valve (see sect. 10.3) and compare it with the value given on the installation booklet.
8 Verify the cleanness of injectors. 9 Check the pressurization of the expansion vessel. Refer to the
installation manual for proper values.
10 d.h.w. pressure too high or flow rate too high. If necessary in-
sert a flow rate limiter (13.6).

9
5Primary heat exchanger
5.1 Characteristics
The primary heat exchanger Ain Fig. 1 has the function
of transferring heat produced from combustion of the
gas to the water circulating in it.
A
Fig. 1
The hydraulic circuit is composed of 8 elliptical pipes
connected in parallel (Fig. 2).
Fig. 2
5.2 Removal
Warning: isolate the boiler from the mains
electricity supply before removing any
covering 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 Bby un-
screwing the screws C(Fig. 3).
3b For model M90E.28S and M90E.32S only, re-
move the screw Dand the plate E.
4RemovetheclipsFand the safety thermostat G.
It is not necessary to disconnect it from the wiring.
B
C
D
E
F
G
Fig. 3
5 Unscrew the connection H(Fig. 4), lift the pipe I
and rotate it right then move it downwards freeing
it from the heat exchanger connection.
6 Remove the motor of the three way diverter valve
(see section 8.3).
7 Completely unscrew the connection Jand rotate
the pipe K. downwards freeing it from the heat ex-
changer connection.
8 Remove the heat exchanger by sliding it for-
wards.
9 Reassemble the boiler carrying out the removal
operations in reverse order. Fit the clips Fwith
the arrow pointing upwards as illustrated in
Fig. 3.
H
I
J
K
Fig. 4
5.3 Cleaning
If there are deposits of soot or dirt between the blades
of 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.
Warning: After cleaning or replacement as
detailed above refer to section Combustion
analysis check in the chapter Maintenance of
the installation instructions manual.

10
6D.h.w. heat exchanger
6.1 Function
The d.h.w heat exchanger Ain Fig. 1 allows the instan-
taneous transfer of heat from the primary hydraulic cir-
cuit to the water destined for d.h.w use.
A
Fig. 1
The schematic structure is shown in Fig. 2.
Primary hydraulic circuit
Domestic hot water circuit
Fig. 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 Remove the motor of the three way diverter valve
(see section 8.3).
4 Completely unscrew the two Allen key screws B
(Fig. 3) which hold the exchanger to the brass
groups.
B
Fig. 3
5 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.
Attention. When reassembling the exchanger be
sure to put the off center location/securing pin indi-
cated in Fig. 4 towards the left side of the boiler.
Fig. 4

11
7Pump
7.1 Function
The pump Ain Fig. 1 has the function of making the
water in the main circuit circulate through the main heat
exchanger 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. 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. 2).
Measure the electrical resistance between the pump
supply connections.
Electrical resistance of the windings (at ambient tem-
perature) must be about 230 Ω
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 panels
2 Empty the primary circuit of the boiler.
3 Extract and lower the control panel.
4 Disconnect the connector B (Fig. 2).
5 Unscrew the connection Cand move the pipe up-
wards freeing it from the outlet port of the pump.
6RemovetheforkDand the capillary pipe
7 Remove the locking plate Eright (Fig. 2).
E
B
C
D
Fig. 2
8 Loosen the connection F,removetheforkGand
the pipe H.
9 Unscrew the two screws Ithat hold the pump on
the frame (Fig. 3)and remove the pump towards
the front of the boiler.
I
G
H
F
Fig. 3
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 brass group .

12
8Three way diverter valve
8.1 Function
The diverter valve A(Fig. 1) has the function of modify-
ing 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. 1
8.2 Checks
nCheck the electrical continuity
Fig. 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. 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
re = red
bu = blue
bk = black
0V
230 V
Spindle B
not visible
Open circuit
9,4 Kohm
bk
re
bu
3
1
2
F i g . 2 --- D. h . w. m o d e
B
re = red
bu = blue
bk = black
230 V
0V
Spindle B
visible
Open circuit
9,4 Kohm
bk bn bu
3
1
2
F i g . 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. 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. 2 or
to the wiring diagram in section 3.1 for the correct
wiring connection.

Three way diverter valve
13
D
C
E
Fig. 4
8.4 Removal of the diverter group and its
internal 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. 5) 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
IH
Fig. 5
7 Remove the d.h.w. heat exchanger (see section
6.2).
8RemovetheforkJand move away the pipe K
(Fig. 6).
9 Unscrew the screw Land remove the diverter
group.
J
K
L
Fig. 6 Rear view of the boiler
10 Refer to the exploded view in Fig. 7 to remove the
internal parts of the three way diverter valve.
Fig. 7
11 Reassemble the diverter group carrying out the
removal operations in the reverse order.

14
9Electronic starting control 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
Room thermostat (if fitted)
Time switch
Flamepresencesignal*
*from the full sequence ignition device
On the Electronic starting control
p.c.b.......
Function control*
C.h. temperature adjustment*
D.h.w. temperature adjustment*
Function dip---switches
Max. c.h. gas pressure adjustment
Ignition gas pressure adjustment
Boiler reset button*
*control panel fascia
Inlet Information
Pump
Three way diverter valve
Full sequence ignition device
Modulation operator
Appliance operation light*
Operation/service lamps
L o c k --- o u t s i g n a l l a m p *
*control panel fascia
Outlet command
Fig. 1
The fundamental function of the Electronic starting con-
trol 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 starting control 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. 1).
9.2 Selection and adjustment devices
On the Electronic starting control p.c.b. several selec-
tion, adjustment and protection devices are located.
(Fig. 2).
Some of these devices are directly accessible by the
user (function control, temperature adjustment poten-
tiometers etc.) others are accessible by removing the
service panel or the control panel lid.
4
3
5
6
7
9
11
14
10
1
2
13
15
8
12
Fig. 2
1 Connector J1 electric supply terminal block
2 Fuse F1 (3,15A --- 250V)
3 Connector J3 (Pomp, three way diverter valve)
4 Connector J16 (On---off operators gas valve)
5 Connector J19 (Flame detection electrode)
6 Connector J15 (Fan, Air pressure switch, Safety
thermostat)
7 Connector J20 e J21 (Ignition electrodes)
8 Connector J4 Time switch
9 Lock --- out signal lamp
10 Boiler reset button
11 Function control / C.h. temperature adjustment

Electronic starting control p.c.b.
15
12 Connector J7 c.h. temperature probe NTC,
primary circuit flow switch, modulating gas valve
13 Connector J6 d.h.w. temperature probe NTC,
d.h.w. flow switch
14 D.h.w. temperature adjustment
15 Operation lamps
9.3 Checking the temperature
The Electronic starting control 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 (11 and
14 in Fig. 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. 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 modulation of the gas valve,
consequently changing the useful output of the boiler.
Fig. 3
When the boiler functions in d.h.w. (Fig. 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 ).
75 ˚C
Fig. 4
Normally, the result of the comparison between these
two signals directly operates the adjustment elements
of the gas valve modulation device, adjusting the useful
output generated in order to stabilize the temperature
of the exiting water.
If during the d.h.w. mode operation, the temperature of
the primary circuit goes over 75°C, the useful output is
automatically 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 9.13 and 9.12.
9.4 Operation lamps
The Electronic starting control p.c.b. is provided with
three lamps (L.E.D. indicators) 15 in Fig. 2 that give op-
tical information during the normal operation of the
boiler or for service purpose.
fNormal operation
Only the green lamp on the left is directly visible on the
control panel fascia and it gives information during the
normal operation of the boiler. The other two lamps are
normally switched off.
The following table gives the relationship between the
visible lamp indication and its meaning.

Electronic starting control p.c.b.
16
Boiler in stand --- by condition.
(function control in
p
o
s
i
t
i
o
n
)
A short pulse every 4 seconds
position).
Anti--- freeze system active.
Boiler ON condition
(function control in or
p
o
s
i
t
i
o
n
)
1secondON1secondOFF
position)
Very fast pulses (4 per second)
Faulty boiler or irregular
operation as:
--- Empty primary circuit
--- No primary circuit flow
---
L
a
c
k
o
f
b
u
r
n
e
r
i
g
n
i
t
i
o
n
---
L
ac
k
o
f
b
urner
i
gn
i
t
i
on
--- E x c e s s i v e t e m p e r a t u r e i n
the primary circuit.
--- Faulty temperature probe
--- Faulty air pressure switch
9.5 Setting the boiler control function modes
It is possible to select the various boiler control function
modes by using the function selector knob A and the
D.h.w. temperature control knob B (Fig. 5).
The knob B is used just for boiler setting and doesn’t
affect the boiler functions during the normal operation.
During the function modes setting, the boiler does not
operate.
C
ED A
B
Fig. 5
9.6 Reignition frequency setting
It is possible to select the minimum time that must pass
between two ignitions of the burner in c.h. function
mode.
1 Turn the boiler ON positioning the function selec-
tor knob A as indicated in Fig. 6.
C
ED AB
Fig. 6
2 Keep pressed the reset button C for about 10 sec-
onds until the lock ---out signal lamp D blinks.
ON
LD1 LD2 LD3
E
Fig. 7
3 The lamps E should give the indication as in Fig. 7
--- Fig. 8 (reignition frequency). If not, press the
reset button repeatedly to obtain it.
Where: Lamp OFF
Lamp ON
Fig. 8
At this step it is possible to visualize the current setting
by keeping the reset button C pressed for more than 5
seconds. The lamps E will flash a number of times
corresponding to the setting (Fig. 9).
4 To change the setting turn the knob B on a posi-
tion corresponding to the desidered delay.
By turning the knob B, the lock --- out signal lamp
D blinks quickly (2 per seconds) indicating that
the setting has changed and must be memo-
rised.
Setting No.
BDelay (minutes)
1
4
2
35
6
7
0
1
23
3½
4
1½
Fig. 9
5 To memorize the setting keep pressed the reset
button C for about 5 seconds until the lights E
briefly blinks simultaneously.
6 To reset the boiler to the normal operation turn it
OFF and ON by the function selector knob A. In
any case, the boiler automatically resets to its nor-
mal operation after 10 minutes.
Factory setting = 3minutes
9.7 Ignition gas pressure adjustment
1 Turn the boiler OFF.
2 Remove the front panel of the case.
3 Open the gas valve outlet pressure test point (8,
see section 10.2) and connect the gauge.
4 Turn the boiler ON positioning the function selec-
tor knob A as indicated in Fig. 10 and ensure that

Electronic starting control p.c.b.
17
the timer selector switch and room thermostat, if
fitted, are set to “heat demand”.
Run the boiler in c.h. mode (do not open any
d.h.w. tap).
C
ED AB
Fig. 10
5 Keep pressed the reset button C for about 10 sec-
onds until the lock ---out signal lamp D blinks.
ON
LD1 LD2 LD3
E
Fig. 11
6 The lamps E should give the indication as in
Fig. 11 --- Fig. 12. If not, press the reset button re-
peatedly to obtain it.
Where: Lamp OFF
Lamp ON
Fig. 12
7 Keep pressed the reset button C for about 5 sec-
onds until the lock---out signal lamp D is switched
OFF.
The boiler runs in c.h. mode and the lamps E give
the indication as in Fig. 13.
Where: Lamp OFF
Flashing lamp, alone
or simultaneously
with an other lamp.
Fig. 13
8 Rotate the knob B on a position corresponding to
an adequate ignition pressure.
Refer to the value indicated in the tables of the
User/Installation manual (Technical information
section, Gas pressures at the burner table).
By rotating clockwise the pressure increases.
9 Make a note of the position of the knob B.
10 Turn the boiler OFF and ON positioning the func-
tion selector knob A as indicated in Fig. 14
C
ED AB
Fig. 14
11 Keep pressed the reset button C for about 10 sec-
onds until the lock ---out signal lamp D blinks.
12 Press the reset button C repeatedly (4 times) until
the lamps E give the indication as in Fig. 15 (igni-
tion pressure adjustment mode).
Where: Lamp OFF
Lamp ON
Fig. 15
13 Turn the knob B to the minimum (fully counter-
clockwise) and then on the position correspon-
ding to the position obtained on step 8.
By turning the knob B, the lock --- out signal lamp
D blinks quickly (2 per second) indicating that the
setting has changed and must be memorised.
14 To memorize the setting keep pressed the reset
button C for about 5 seconds until the lights E
briefly blinks simultaneously.
15 To reset the boiler to the normal operation turn it
OFF and ON by the function selector knob A
checking the ignition pressure and that the
burner lights up uniformly. In any case, the boiler
automatically resets to its normal operation after
10 minutes.
9.8 Adjustment of useful c.h. output
This adjustment does not influence the maximum use-
ful output delivered during the d.h.w. operating mode.
1 Turn the boiler OFF.
2 Remove the front panel of the case.
3 Open the gas valve outlet pressure test point (8,
see section 10.2) and connect the gauge.
4 Turn the boiler ON positioning the function selec-
tor knob A as indicated in Fig. 16 and ensure that
the timer selector switch and room thermostat, if
fitted, are set to “heat demand”.
Run the boiler in c.h. mode (do not open any
d.h.w. tap).
C
ED AB
Fig. 16

Electronic starting control p.c.b.
18
5 Keep pressed the reset button C for about 10 sec-
onds until the lock ---out signal lamp D blinks.
ON
LD1 LD2 LD3
E
Fig. 17
6 The lamps E should give the indication as in
Fig. 17 --- Fig. 18. If not, press the reset button re-
peatedly to obtain it.
Where: Lamp OFF
Lamp ON
Fig. 18
7 Keep pressed the reset button C for about 5 sec-
onds until the lock---out signal lamp D is switched
OFF.
The boiler runs in c.h. mode and the lamps E give
the indication as in Fig. 19.
Where: Lamp OFF
Flashing lamp, alone
or simultaneously
with an other lamp.
Fig. 19
8 Rotate the knob B to obtain the pressure to the
burner to meet with the central heating system re-
quirements.
Refer to diagrams indicated in the tables of the
User/Installation manual (Commissioning sec-
tion, Adiustment of useful c.h. output).
By rotating clockwise the pressure increases.
9 Make a note of the position of the knob B.
10 Turn the boiler OFF and ON positioning the func-
tion selector knob A as indicated in Fig. 20
C
ED AB
Fig. 20
11 Keep pressed the reset button C for about 10 sec-
onds until the lock ---out signal lamp D blinks.
12 Press the reset button C repeatedly (2 times) until
the lamps E give the indication as in Fig. 21 (use-
ful c.h. output adjustment mode).
Where: Lamp OFF
Lamp ON
Fig. 21
13 Turn the knob B to the minimum (fully counter-
clockwise) and then on the position correspon-
ding to the position obtained on step 8.
By turning the knob B, the lock --- out signal lamp
D blinks quickly (2 per second) indicating that the
setting has changed and must be memorised.
14 To memorize the setting keep pressed the reset
button C for about 5 seconds until the lights E
briefly blinks simultaneously.
15 To reset the boiler to the normal operation turn it
OFF and ON by the function selector knob A
checking the ignition pressure and that the
burner lights up uniformly. In any case, the boiler
automatically resets to its normal operation after
10 minutes.
9.9 Gas conversion
Refere to User/Installation manual (Gas conversion
section, Procedures)
1 Turn the boiler OFF positioning the function selec-
tor knob A as indicated in Fig. 22.
C
ED AB
Fig. 22
2 Remove the front panel of the case.
3 Disconnect the C.h. temperature probe NTC
(Fig. 23)
Fig. 23
4 Keep pressed the reset button C for about 10 sec-
onds until the lock ---out signal lamp D blinks.