Biasi Activ A 25S User manual

Wall hung, fan flue, room sealed, high efficiency gas boiler
Service manual
ActivA
Models: G.C. Appl. No.
Activ A 25C 47---583---21
Activ A 30C 47---583---22
Activ A 35C 47---583---23
Activ A 18S 41---583---11
Activ A 25S 41---583---12
Activ A 30S 41---583---13
Leave this manual adjacent to the gas meter

Ta b le o f c o 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 Main electronic p.c.b. box 3.............
2.5 Emptying the primary circuit 3...........
2.6 Emptying the d.h.w. circuit 4............
3Diagrams 5...........................
3.1 Wiring diagram
Activ A 25C Activ A 30C.Activ A 35C. 5....
3.2 Wiring diagram
Activ A 18S Activ A 25S Activ A 30S 6.....
3.3 Circuit voltages 7......................
4Faultfinding 8........................
4.1 Display diagnostic 10....................
5 Condensing heat exchanger 11..........
5.1 Function 11.............................
5.2 Removal 11............................
5.3 Cleaning 12............................
6 D.h.w. heat exchanger 13...............
6.1 Function 13.............................
6.2 Removal 13............................
7Pump 14...............................
7.1 Function 14.............................
7.2 Checks 14.............................
7.3 Removal pump 14.......................
7.4 Removal electrical capacitor 15...........
8 Three way diverter valve 16.............
8.1 Function 16.............................
8.2 Checks 16.............................
8.3 Removal of the electric actuator 16........
8.4 Removal of the tree way diverter valve 17..
8.5 Removal of the diverter group 17..........
9 Main electronic control/ignition p.c.b. 18.
9.1 Function 18.............................
9.2 Selection and adjustment devices 18......
9.3 Checking the temperature 19.............
9.4 Setting the boiler control function modes 20
9.5 Checks 22.............................
9.6 Removal of the electronic control p.c.b 22..
9.7 Thermal control in the ” ”mode 23......
9.8 Thermal control in the ” ”mode 24......
10 Control panel electronic p.c.b. 25.......
10.1 Function 25.............................
10.2 Info modality 25.........................
10.3 Function modes setting modality 25.......
10.4 Removal of the control panel electr. p.c.b 25
11 Gas valve 27...........................
11.1 Function 27.............................
11.2 Description of the parts 27...............
11.3 Adjustment 27..........................
11.4 Checks 29.............................
11.5 Removal of the gas valve 29..............
12 Primary circuit flow switch 30...........
12.1 Function 30.............................
12.2 Checks 30.............................
12.3 Removal 30............................
13 Expansion vessel and pressure gauge 30
13.1 Function 30.............................
13.2 Checks 30.............................
13.3 Removal of the expansion vessel 31.......
13.4 Removal of the pressure gauge 31........
14 D.h.w. flow switch, filter and flow limiter 33
14.1 Function 33.............................
14.2 Description and location of parts 33.......
14.3 Checks 33.............................
14.4 Removal of the sensor 33................
14.5 Removal of the flow switch group
and d.h.w. circuit filter 33.................
14.6 Flow limiter 34..........................
15 Temperature probe 35..................
15.1 Function 35.............................
15.2 Checks 35.............................
15.3 Removal of the c.h.Temperature probe 35..
15.4 Removal of the d.h.w.Temperature probe 35
16 By -- pass valve 37......................
16.1 Function 37.............................
16.2 Removal 37............................
17 Fan and Air box 38.....................
17.1 Function 38.............................
17.2 Removal of the Fan and the Air box 38.....
18 Ignition and detection electrodes
and burner 39..........................
18.1 Function 39.............................
18.2 Removal of the Ignition and detection
electrodes 39...........................
18.3 Removal of the burner 39................
18.4 Checks 39.............................
19 Safety thermostat 41...................
19.1 Function 41.............................
19.2 Checks 41.............................
19.3 Removal 41............................
20 Flue temperature probe NTC
and Safety thermal fuse 42..............
20.1 Function 42.............................
20.2 Removal 42
............................
20.3 Checks 42.............................
21 Condensate trap 43....................
21.1 Function 43.............................
21.2 Check the cleanness of the trap 43........
21.3 Removal 43............................
22 Short spare parts list 44................

1
1Overall information
1.1 Overall View
Flue temperature
probe NTC
Expansion
vessel
C.h. temperature
probe
Condensing
heat exchanger
Safety
thermostat
Detection
electrode
Ighition
electrodes
Burner
Fan
Air box
(air/gas mixer)
Pipe silencer
Electronic
control box
Condensate
trap
C.h. pressure
relief valve
Automatic air
purger valve
Pump
Control
panel
Electric actuator
diverter valve
Pressure
gauge
Gas valve
D.h.w. temperature
probe
Three way
diverter valve
B y --- p a s s
valve
Main circuit
pressure switch
D.h.w. heat
exchanger
Gas restrictor
D.h.w. flow
switch
1.2 Hydraulic diagram
Central heating (c.h.) operation Domestic hot water (d.h.w.) operation
D.h.w.
inlet D.h.w. outlet
C.h.
water flow
C.h.
water return

2
2General access and emptying
hydraulic circuits
2.1 Nomenclature
2
5
1
3
4
Fig. 2.1
1 Right side panel
2 Front panel
3 Control panel
4 Main electronic p.c.b. box
5 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 loosen screws A(Fig. 2.2).
A
B
B
Fig. 2.2 --- bottom view of the boiler
Pull the lower part of the front panel and lift it upwards
(Fig. 2.3).
C
C
Fig. 2.3
To remove the side panels loosen the screws B
(Fig. 2.2) and C(Fig. 2.3).
Pullthesidepanelstowardstheoutside.
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 To open the control panel by leverig with a screw-
driver in as shown in Fig. 2.4
D
Fig. 2.4
3 To access to the parts located inside the control
panel to free the hook D(Fig. 2.4) and turn it as
showninFig.2.5.

General access and emptying hydraulic circuits
3
Fig. 2.5
2.4 Main electronic p.c.b. box
Warning: isolate the boiler from the mains
electricity supply before removing any
covering or component.
To gain access to the parts located into main electronic
p.c.b. box proceed as follows:
1 Remove the front panel of the case.
Terminal block lid removal
2 To remove the terminal block lid E(Fig. 2.6), free
the front hooks.
E
Fig. 2.6
3 Slightly rotate the lid as indicated by the curved
arrow and free the rear hooks.
4Removethelid.
Main electronic p.c.b. lid removal
To get access to the main electronic p.c.b.:
5 Pull the box that contains the electronic p.c.b.
and rotate it (Fig. 2.7).
Fig. 2.7
6 Remove the terminal block lid E (Fig. 2.6).
7 Free the hooks placed on the three sides indi-
cated and rotate the lid towards left (Fig. 2.8).
Fig. 2.8
2.5 Emptying the primary circuit
1 Close the c.h. circuit flow and return cocks F.
(Fig. 2.9).
F
H
Fig. 2.9 --- bottom view of the boiler
2 Remove the front and right panels of the boiler.
3 Open the drain tap G(Fig. 2.10 combi or Fig. 2.11
only c.h.) until the boiler is completely emptied.
4 Close drain tap once the emptying has been
completed.

General access and emptying hydraulic circuits
4
G
OPEN
CLOSED
Fig. 2.10
G
Fig. 2.11
2.6 Emptying the d.h.w. circuit
5 Close the d.c.w. inlet cock H(Fig. 2.9).
6 Open one or more hot water taps until the boiler
has been completely emptied.

5
3Diagrams
3.1 Wiring diagram
Activ A 25C Activ A 30C.Activ A 35C.
1
2
3
L
N
M
~3
2
1
1
3
4
t
t
M
~
t
COM
NO
Room thermostat
Frostat
terminal block
Electric supply
terminal block
Pump
diverter valve
Three way Gas valve
D.h.w. temp.
probe NTC
D.h.w. flow
switch
External temp.
Remote
Fan
Ignition
electrodes Flame detection
electrode
Time switch (option)
Flue temp.
Safety
thermostat
pressure switch
Primary circuit
C.h. temperature
probe NTC
probe
Condensate
trap
bu
bn
bu
bk
bn
bu
bn
bk
bk
og
vt
bk
bu
bn
gnye
bu
bn
bk
bk
rd
rd
bu
gnye
bn
ye
bk
wh vt og bk
wh ye
bu
bu
bk
rd
bu
bu
bkrd
bk
bk
bk
bk
bk
bk
bk
bk
bu
bu
bk
bk
bu
bu
bk
bk
bu
bu bu
bu
rd
rd
rd
rd
rd
rd
bk
bk
bk
bk
whgy
gy
gy
gy bk
bu
wh
rd rd
wh
bu
bk
wh
wh
bu
bn
gnye
gnye
bk
bk
gnye bu
bn
bu
gy gy
bn = brown
bu = blue
bk = black
wh = white
rd = red
gy = grey
gn = green
ye = yellow
vt = violet
og = orange
gnye = green/yellow
rdwh = red/white
terminal block
probe NTC
Fuse 2AF 250VAC
5x20

Diagrams
6
3.2 Wiring diagram
Activ A 18S Activ A 25S Activ A 30S
1
2
3
L
N
1
3
4
t
M
~
t
COM
NO
Room thermostat
Frostat
terminal block
Electric supply
terminal block
Pump
Gas valve
External temp.
Remote
Fan
Ignition
electrodes Flame detection
electrode
Time switch (option)
Flue temp.
Safety
thermostat
pressure switch
Primary circuit
C.h. temperature
probe NTC
probe
Condensate
trap
bu
bn
bu
bn
bk
bk
og
vt
gnye
bu
bn
bk
bk
rd
rd
bu
gnye
bn
ye
bk
wh vt og bk
wh ye
bu
bu
bk
rd
bu
bu
bkrd
bk
bk
bk
bk
bk
bk
bk
bk
bu
bu
bk
bk
bu
bu
bk
bk
rd
rd
bk
bk
bk
bk
whgy
gy
gy
gy bk
bu
wh
rd rd
wh
bu
bk
wh
wh
bu
bn
gnye
gnye
bk
bk
gnye bu
bn
bu
gy gy
bn = brown
bu = blue
bk = black
wh = white
rd = red
gy = grey
gn = green
ye = yellow
vt = violet
og = orange
gnye = green/yellow
rdwh = red/white
terminal block
probe NTC
Fuse 2AF 250VAC
5x20

Diagrams
7
3.3 Circuit voltages
230~
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 circuitSupply network
230~
Pump
230~ 0230~0
3way
diverter valve
230~
Gas valve
0
5=
D.h.w.
Flow switch
pressure switch

8
4Fault finding
Components to check
Section of the manual ! (note ref. in brackets)
---
(1)
---
(2)
---
(3)
21.1 ---
(4)
5 6 7.2 8.2 14.3 9.5 10 11.4 12.2 14.5 15.2 16 17 18.4 19.2 19.2 20.1 ---
(7)
--- --- ---
Appliance lock---out (*)
Defect #
Power supply line
Gas supply line
Flue pipes
Cond. drain pipe and trap
C.h. circuit
D.h.w. circuit
Condensing heat exchanger
D.h.w. heat exchanger
Pump
Diverter valve
D.h.w. flow switch
Fuses (Electronic p.c.b.)
Main electronic p.c.b.
Boiler settings
Control panel electr. p.c.b.
Gas valve
Main circuit pressure 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
Ignition electrode
Detection electrode
Safety thermostat
Gas restrictor
Flue temp. probe NTC
Expansion vessel
Safety valve
Pressure gauge
External temp. probe
Er 01 J J J J Er 02 J J J Er 03 J Er 04 J J Er 05 J Er 06 J Er 07 J
r”
Er 08 J
s”Er
Er 09 J J
c
ate
s
Er 10 J J
indi
c
Er 11 J J J
p
lay i
Er 14 J J J
Disp
Li 01 J

9
Components to check
Section of the manual ! (note ref. in brackets)
------------
(7)
20.119.219.218.4171615.214.512.211.4109.514.38.27.265---
(4)
21.1---
(3)
---
(2)
---
(1)
Appliance lock---out (*)
External temp. probe
Pressure gauge
Safety valve
Expansion vessel
Flue temp. probe NTC
Gas restrictor
Safety thermostat
Detection electrode
Ignition electrode
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 pressure switch
Gas valve
Control panel electr. p.c.b.
Boiler settings
Main electronic p.c.b.
Fuses (Electronic p.c.b.)
D.h.w. flow switch
Diverter valve
Pump
D.h.w. heat exchanger
Condensing heat exchanger
D.h.w. circuit
C.h. circuit
Cond. drain pipe and trap
Flue pipes
Gas supply line
Power supply line
Defect # The boiler does not start either in c/h or d.h.w. mode. The control panel display OFF Fan still.
J J J J
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
d
isplay
On c/h mode the temperature of the main circuit reaches 90Cand the c/h system does not heat. The boiler operates correctly on d.h.w. mode.
J J J
on di
Incorrect modulation J J J J
t
ion
o
Noisy bolier J J J J J J
d
icati
Poor c.h. / d.h.w. temperature (9) J J J J J
”Er” ind
Poor d.h.w. temperature. Regular operationinc/hmode.
J J J
(8)
J
No ”
Low d.h.w. flow rate J J J
---
Water leaks from the safety valve duringoperationonc/h
J J J J J J
---
Water leaks from the safety valve when the boiler is off.
J J J
* Lock out is indicated as “Er”onthedisplay. Note Useful information can be obtained also from the optical indication given by the appliance display (see section 4.1). 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
4.1 Display diagnostic
An help for the fault finding may be given by the display
indications.
The display on the control panel gives many informa-
tion.
Only the indications useful for the fault finding are here
described.
The following table gives the relationship between the
indications of error of the display and their meaning.
Er 01 + RESET Lack of burner ignition
Er 02 + RESET Safety thermostat lockout
Er 03 + RESET Other faults
Er 04 +Faulty primary circuit (no water or
absence of flow)
Er 05 +Faulty fan control system
Er 06 +Faulty c.h. temperature probe
NTC
Er 07 +Faulty d.h.w. temperature probe
NTC
Er 08 +Faulty external temperature probe
NTC (if fitted)
Er 09 +Faulty flue temperature probe
NTC
Er 10 + RESET Lockout --- flue temperature probe
NTC (Flue temperature > 120 ˚C)
Er 11 + RESET Parasite flame
Er 14 +
Faulty primary circuit (no water or
absence of flow) (temperature in-
crease > 2K/s) (the boiler can’t
restart for 10 minutes)
Er 14 + RESET
Faulty pump (absence of water
flow in the main circuit) or primary
temperature above 105 ˚C
Li 01 Primary circuit temperature limit
during d.h.w. operation

11
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 Turn off the gas supply.
2 Removeallthecasepanels(seesection2).
3 Disconnect the flue system from the boiler.
4 Disconnect the air manifold D(Fig. 5.2) by pulling
it.
5 Disconnect the rubber pipe E.
6 Unscrew the gas connector F.
7 Remove the fixing fork Gand remove the gas pipe
H.
8 Unscrew the screws and remove the detection
electrode connector I(Fig. 5.2)
9 Unscrew the screws and remove the ignition elec-
trodes connector J.
10 Unscrew the screw and remove the overheat
thermostat K.
11 Disconnect the connector Lby pressing the plas-
tic hook placed on the side of the connector.
12 Disconnect the connector M
K
J
G
I
L
D
E
F
H
M
P
X
O
Q
R
S
T
W
O
X
Fig. 5.2
13 Disconnect the fan connector Nby pressing the
plastic hook placed on the side of the connector
(Fig. 5.3).
N
Fig. 5.3
14 Empty the primary circuit of the boiler.
15 Remove the expansion vessel following the in-
structions in section 13.3.
16 Remove the forks O(Fig. 5.2).
17 Loosen the connection Pand remove the pipe Q
from the Condensing heat exchanger.

Condensing heat exchanger
12
18 Loosen the connection Rand remove the pipe S
from the Condensing heat exchanger.
19 Unscrew the screws T.
20 Remove the fan---burner group.
U
V
W
Fig. 5.4
21 Using pliers, remove the spring Umoving it down-
wards and disconnect the rubber pipe V
(Fig. 5.4).
22 Loosen the screws W(Fig. 5.4 --- Fig. 5.2)
23 Unscrew the screws X(Fig. 5.2).
24 Remove the Condensing heat exchanger slightly
move it upwards, turn it frontwards freeing it from
the below screws W(Fig. 5.4 --- Fig. 5.2) and then
extractitforwards.
25 Reassemble the Condensing heat exchanger
carrying out the removal operations in reverse
order.
Ensure to tight the screws T --- Fig. 5.2 firmly
5.3 Cleaning
If there are deposits of dirt between the fins of the Con-
densing heat exchanger, clean with a bristle paintbrush
and remove 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.

13
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 the primary
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 panels of the case.
2 Empty the primary circuit and the d.h.w circuit of
the boiler.
3 Remove the control panel following the instruc-
tions from 3 in section 2.3.
4 Remove main electronic p.c.b. box following the
instructions from 5 in section 2.4.
5 Remove the pump following the instructions in
section 7.3.
6 Completely unscrew the Allen key screws B
(Fig. 6.3) which hold the exchanger to the plastic
groups.
B
A
B
Fig. 6.3
7 Move the exchanger towards the rear of the boiler
and extract it leftwards.
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. 6.4 towards the left side of the boiler.
Fig. 6.4

14
7Pump
7.1 Function
The pump Ain Fig. 7.1 and Fig. 7.3 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. 7.3).
Measure the electrical resistance between the pump
supply connections.
Electrical resistance of the windings (at ambient tem-
perature) must be about 213 Ω(coil 1) and 480 Ω(coil
2) (Fig. 7.2).
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.
213 Ω
480 Ω
Coil 1
Coil 2
Fig. 7.2
7.3 Removal pump
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 Disconnect the connector B (Fig. 7.3 --- Fig. 7.4)
following the indications given on the connector
box.
4 Disconnect the earth connector C
D
A
B
E
L
K
C
Fig. 7.3
5 Loosen the connection D,and pull up and turn to
the left the pipe E.

Pump
15
F
G
H
I
J
K
L
D
E
C
A
B
Fig. 7.4
6 C.H. only model remove the fork F, loosen the
connection Gand remove the pipe H(Fig. 7.4).
7 C.H. only model remove the fork Iand remove the
pressure gauge pipe J(Fig. 7.4).
8 Remove the locking plate K(Fig. 7.3 --- Fig. 7.4).
9 Unscrew the two screws Lthat 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.
7.4 Removal electrical capacitor
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 Disconnect the connector B (Fig. 7.3) following
the indications given on the connector box.
3 Remove the connector Mof the cover box by
levering with a screwdriver in as shown in
(Fig. 7.5)
M
Fig. 7.5
4 Remove the capacitor connection block Nfreeing
it from the hook Oand pulling it as indicated by
the arrow (Fig. 7.6).
N O
Fig. 7.6

16
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.
Spindle B
visible
B
bk = black
230 V
0V
Open circuit
9,4 Kohm
bk
bn bu
3
1
2
bu = blue
bn = brown
F i g . 8 . 2 --- D . h . w. m o d e
bk = black
bu = blue
bn = brown
Spindle B
not visible
B
0V
230 V
Open circuit
9,4 Kohm
3
1
2
bk
bn
bu
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 B.
Reassemble the actuator carrying out the re-
moval operations in the reverse order.
When reassembling the actuator, refer to Fig. 8.2
or to the wiring diagram in section 8.2 for the cor-
rect wiring connection.

Three way diverter valve
17
C
DB
Fig. 8.4
8.4 Removal of the tree way diverter valve
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 E(Fig. 8.5)
5 Remove the tree way diverter valve Fby levering
with a screwdriver in as shown in Fig. 8.5.
F
E
G
Fig. 8.5
Reassemble the tree way diverter valve 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 tree way diverter
valvebesurethatthetreewaydiverteriscorrectly
oriented by matching the reference Gwith the notch
of the water group Fig. 8.5
8.5 Removal of the diverter group
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 H(Fig. 8.6) and remove
the primary circuit pressure switch I.
H
I
K
M
L
N
Fig. 8.6
5 Disconnect d.h.w. temperature probe, respect-
ively J(Fig. 8.7).
J
Fig. 8.7
6 Unscrew the connector K(Fig. 8.6), the c.h. flow
connector and the d.h.w. outlet connector.
7 Remove the d.h.w. heat exchanger (see section
6.2).
8RemovetheforkLand move away the pipe M
(Fig. 8.6).
9 Unscrew the screws Nand remove the diverter
group (Fig. 8.6).
10 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.

18
9Main electronic 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 pressure switch
Flue temperature probe NTC
Safety thermostat
Flame detection electrode
Room thermostat (if fitted)
Time switch (if fitted)
On the Main electronic control/ignition
p.c.b.......
Function control
C.h. temperature adjustment
D.h.w. temperature adjustment
Boiler reset button
(control panel electronic p.c.b.)
Inlet Information
Pump
Three way diverter valve
Gas valve
Fan
Ignition electrodes
Display indicates “Er”*
*control panel electronic p.c.b.
Outlet command
Fig. 9.1
The fundamental function of the Main electronic con-
trol/ignition p.c.b. is that of controlling the boiler in rela-
tion 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 con-
stant.
This is obviously possible within the useful power and
maximum working temperature limits foreseen.
Generally, the Main electronic control/ignition p.c.b. re-
ceives inlet information coming from the boiler (the
sensors) or from the outside (control panel electronic
p.c.b., room thermostat, etc.), processes it and conse-
quently acts with outlet commands on other compo-
nents of the boiler (Fig. 9.1).
The Main electronic control/ignition p.c.b. is also a full
sequence 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 Main electronic control/ignition p.c.b. has a safety
function and any incorrect interventions or tampering
can result in conditions of dangerous functioning of the
boiler.
The Main electronic control/ignition p.c.b. can lock the
functioning of the boiler (lock state) and stop its func-
tioning up to the resetting intervention. The lock---out is
signalled on the display of the control panel electronic
p.c.b. and can be reset only by using the boiler reset
button placed on the control panel electronic p.c.b.
(see section 10.1).
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 Main electronic control/ignition p.c.b..
Other components like the primary circuit pressure
switch can temporarily stop the ignition of the burner
but allow its ignition when the cause of the intervention
has stopped.
Fig. 9.13 and Fig. 9.14 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 Main electronic control/ignition p.c.b. several
selection, adjustment and protection devices are lo-
cated. (Fig. 9.2).