Symona 24 Bithermal User manual

Wall-hung boiler with integrated heat exchanger
G20 ENGINEERING SRL Loc. Campogrande 13, 29013 CARPANETO PIACENTINO (PC), Italy
tel. + 39 0523 850513 - fax. [phone] - www.aircontrol-pc.com - www.g20engineering.com
A G20 ENGINEERING brand
Bithermal
ITALIAN DESIGN
MADE IN ITALY
INSTALLATION, COMMISSIONING, USE AND MAINTENANCE MANUAL

1
SYMONA 24 KW BITHERMAL MANUAL
VERS. 10/2014 - REV.3

2
CONTENTS
GENERAL INFORMATION
General requirements 2
-General instructions 2
Use and operation 3
-Description of the device 3
-Components 3
-Interface description 4
-Season selection 4
-Temperature adjustment 5
-Operation with room thermostat 6
-Special functions 6
-Faults 6
-Fault codes table 7
Installation 8
-Operational diagram 8
-Wiring diagram 8
- Graphs for the head available to the system 9
-Installation 9
-Hanging the boiler 10
-Layout of connections 11
-Plumbing in the boiler 11
-Filling the system 12
-Connection to the gas supply 12
-Connection to the electrical system 13
-Combustion gas evacuation and air intake
system: compatible applications 14
-Combustion gas evacuation and air intake
system: installation 15
-Checking the effectiveness of
combustion gas evacuation 17
-Combustion gas evacuation circuit
diaphragms 17
-Combustion gas evacuation system:
warnings 18
Adjustment and maintenance 19
-Preliminary maintenance operations 19
-General maintenance operations 19
-SERVICE function 19
-Power adjustment 21
-Gas pressure check 22
-Checking the pressure at the burner 22
-Checking mains gas supply
dynamic pressure 23
-Checking pressure at burner at max
power 24
-Changing fuels 24
-Conguring the software
for a change in fuel 25
-Conguration menu access 26
-Installer menu 27
-Conguration menu 27
-Thermostat installation 28
-Special functions 29
-Technical Data 30
GENERAL REQUIREMENTS
This manual, supplied with every boiler, should be
considered as an integral component as it contains
instructions for the correct, safe and appropriate
installation, use and maintenance of the system.
The manual must always be kept by the user of
the boiler and made available for the installation
and/or maintenance technicians to consult. It must
also accompany the boiler if it should be moved
or otherwise transferred.
The manufacturer shall not be held responsible
for any damage caused by failure to follow the
instructions contained in this manual, nor:
If the boiler is used for purposes other than those
for which it was built
If any part or circuit of the boiler is modied
If accessories or kits not approved by the
manufacturer are installed
If ordinary and extraordinary maintenance is not
performed by qualied personnel
If applicable technical and legal requirements
have not been observed during installation and
maintenance of the boiler
WARNING!
If the boiler should cease to function or not function
correctly, deactivate it immediately by turning it off
and then shutting off the gas supply. Do not attempt
any repairs or direct work on the boiler.
Only personnel with the necessary qualications
and licenses must perform maintenance on the
boiler. Any repairs must be performed using only
original parts and accessories.
SYMBOLS USED IN THE MANUAL:
Advice, suggestion, note
Important information, indications of
methods and operations which could
compromise correct operation of the
boiler and create a hazard

3
DESCRIPTION OF THE BOILER
COMPONENTS
The Symona 24 Bithermal wall-hung boiler is
the entry-level product in the Symona range.
Assembled with care using high-quality
components, the Symona 24 Bithermal is
compact and elegant. With its simple and
intuitive interface, this wall-hung boiler is
ideal where performance and simplicity are
required.
Symona 24 Bithermal
1) FUME EXTRACTOR
2) SAFETY THERMOSTAT
3) PRIMARY BITHERMAL HEAT EXCHANGER
4) DHW SENSOR
5) HEATING SENSOR
6) COMBUSTION CHAMBER
7) BURNER
8) IGNITION MONOELECTRODE
9) GROUND ELECTRODE
10) PRESSURE GAUGE
11) CIRCULATOR UNIT
12) DHW PRIORITY VALVE
13) WATER PRESSURE SWITCH
14) SAFETY VALVE
15) GAS VALVE
16) EXPANSION TANK
17) COMBUSTION GAS PRESSURE SWITCH
Pict. 1
Pict. 2
USE AND OPERATION

4
INTERFACE DESCRIPTION
SEASON SELECTION
TURNING THE BOILER ON
Turn on the boiler’s electrical supply at the
switch which must be installed on the power
supply line to the boiler. The display will turn on
immediately, showing all possible symbols for
5 seconds, then the software version located
on the board’s microprocessor for a further
5 seconds. The boiler will then place itself in
standby and no symbol will be displayed.
Turn the lower knob (B) clockwise to the “MIN”
position. The minimum hot water regulation
temperature will be displayed for 5 sec.
(ashing tap), then the temperature of the hot
water circuit will be displayed permanently.
The device is now on and ready for use.
TURNING THE BOILER OFF
Turn the bottom knob (B) anticlockwise to the
“RESET/OFF” position.
The display will turn off (no symbol displayed)
and the boiler will stop any currently active
function and place itself in standby.
The ANTI-FROST functions remain active in this
condition. (page 6)
The boiler has two operating modes, which
depend on the active functions in response
to the external temperature or the user
requirements:
SUMMER mode deactivates all central
heating functions, maintaining only domestic
hot water production. This mode is selected
by turning the upper knob (A) to the “SUN”
symbol.
In this mode, the temperature of the water in
the central heating circuit is displayed when
the boiler is in standby. When hot water is
being supplied, the output temperature of the
water is displayed together with the ashing
symbol indicating the mode (TAP) and the
burner on symbol (FLAME).
WINTER mode is activated by turning the
upper knob (A) to the “MIN” position.
In this mode, the device satises requests
both for domestic hot water and for central
heating, when required. In this mode, the
temperature of the water in the heating
In this mode the boiler is inactive
but its electricity supply is still
connected!
circuit is displayed when the boiler is in
standby. When hot water is being supplied,
the output temperature of the water is
displayed together with the ashing symbol
indicating the mode (TAP) and the burner on
symbol (FLAME).
When functioning in central heating mode,
the temperature of the water in the CH circuit
is displayed, together with the burner on
symbol (FLAME) and the symbol indicating
the mode (RADIATOR).
MAX
RESET/OFF
MIN
MIN
MAX
A
B
Pict. 3

5
TEMPERATURE ADJUSTMENT
It is possible to regulate the temperature of
the domestic hot water supplied as well as
that for the central heating. Once the desired
temperature has been set, it will be reached,
if possible, when supplying these services and
maintained at the set value.
Turn the lower knob (B) clockwise to increase
the temperature of hot water supplied and
anticlockwise to decrease it; the corresponding
value is displayed together with the ashing
DHW symbol (TAP) for 5 seconds, after which
it returns to the previous display mode and
the value is stored. The minimum hot water
temperature which can be set is 30°C, the
maximum 60°C.
Turn the upper knob (A) clockwise to increase the
temperature of the central heating circuit and
anticlockwise to decrease it; the corresponding
value is displayed together with the ashing CH
symbol (RADIATOR) for 5 seconds, after which
it returns to the previous display mode and the
value is stored. The temperature values which
can be selected depend on the type of system
which the boiler is connected to: for underoor
heating systems min 28° - max 57° C, for radiator
systems min 50° - max 80° C
ASK YOUR AREA INSTALLER FOR
INFORMATION ON THE TYPE OF
SYSTEM CONNECTED AND RESPECTIVE
ADJUSTMENTS
Pict. 4 Pict. 5
MA X
R E S E T /OFF
MIN
MIN
MA X
A
MAX
RESET/OFF
MIN
MIN
MAX
A

6
OPERATION WITH ROOM THERMOSTAT
Energy savings regulations REQUIRE the boiler
to be connected to a room thermostat in
order to optimally regulate and maintain the
temperature in domestic environments.
ASK YOUR AREA INSTALLER FOR
INFORMATION ON THE INSTALLATION
AND OPERATION OF A ROOM
THERMOSTAT.
SPECIAL FUNCTIONS
FAULTS
• Central heating system anti-frost function
The anti-frost function is always active; it
prevents the water in the central-heating
system from freezing. If the temperature sensor
in this circuit detects that the temperature
has become too low, the circulating unit
is activated and the burner is turned on at
minimum power. The function remains active
until a preset temperature (8°C) is reached,
preventing the water contained in the central
heating system from freezing.
All functions supported by the boiler are
managed by a microprocessor-based system
which, aside from allowing the system to run
perfectly in order to maintain the greatest level
of comfort possible, constantly monitors the
functional parameters, ensuring they fall within
the necessary safety interval by a wide margin,
and therefore that all devices present are
functioning perfectly. Whenever the malfunction
of any component or conditions which could
compromise safe operation of the system are
detected, the microprocessor system places
the device into a limited operation mode or
even completely prevents it from operating.
The microprocessor system is able to detect and
issue warnings for the main fault conditions to
allow the system to be brought back to normal
conditions as soon as possible. Fault warnings
are given on the LCD display. The malfunction is
detected and an intermittent warning displayed
immediately, consisting of a number preceded
by the error symbol E Pict. 6. Faults are displayed
on any screen of the main menu. Conditions
causing transitory faults are possible. Many of
these are recognised and cause a temporary
block which is automatically reset once the
condition causing the fault has stopped. Some
of these provide for the possibility to attempt to
restore operation manually.
To reset the system following a fault, turn the
lower knob (B) fully anticlockwise to the “RESET/
OFF” position, wait for a few seconds then turn
the knob back to the starting position. If the boiler
has reset correctly all previously set functions
will be restored; if the fault remains this will be
indicated on the display. For models designed to
operate only in heating mode, if the lower knob
(B) is in the “MIN” position, it is necessary to turn
it fully clockwise to the (MAX) position, then turn
it fully the other way to the “RESET/ OFF” position.
ALWAYS LEAVE THE SYSTEM TURNED
ON AND ALL SHUT-OFF VALVES OPEN
IF THE SYSTEM IS LIKELY TO BE EXPOSED
TO LOW TEMPERATURES
THIS FUNCTION DOES NOT GUARANTEE
COMPLETE PROTECTION OF THE
SYSTEMS, AS IT IS DEPENDENT ON A
CONTINUOUS MAINS ELECTRICITY
AND GAS SUPPLY
ASK YOUR AREA INSTALLER FOR
INFORMATION ON CONFIGURING
YOUR SYSTEM IN ORDER TO PROTECT
IT AGAINST LOW TEMPERATURES
MAX
RESET/OFF
MIN
MIN
MAX
B
Pict. 6

7
FAULT CODE TABLE
IF A FAULT IS NOT SOLVED AFTER 2
MANUAL RESET ATTEMPTS THEN THE
AUTHORISED TECHNICAL ASSISTANCE
CENTRE MUST BE CALLED.
RETURN THE KNOB TO THE REQUIRED
POSITION BASED ON THE DESIRED HOT
WATER TEMPERATURE.
Pict. 6
Code Possible cause Behaviour Possible actions
E1 Ignition failed Boiler locked
Ensure gas supply valves
before boiler are open
Reset the boiler
Consult technical support
E2 Combustion gas pressure
switch fault Boiler locked Consult technical support
E3 Heating system temperature
sensor fault Boiler locked Consult technical support
E4 Domestic hot water system
temperature sensor fault
DHW supplied in provisional
mode
Heating functions normally
Consult technical support
E5 Gas regulation valve fault Operation at reduced
power Consult technical support
E6 High temperature detected
by heating system sensor
Device in stand-by
Normal DHW supply Wait for automatic unlocking
E7 Combustion gas pressure
switch microswitch fault Boiler locked Reset the boiler Consult technical support
E8 Central heating system
pressure too low Boiler locked
Check for leaks in CH system
Restore sufcient water
pressure to CH system
Consult technical support
E9 Central heating system
water temperature too high Boiler locked Reset the boiler Consult technical support
E10 Central heating system
pressure too HIGH (> 2.7 bar) Boiler locked
Check that the lling loop
cock is fully closed, restore
pressure to the correct level
by draining some water from
the system
E12 Electronic board anomaly Boiler locked Consult technical support
E15 Combustion gas pressure
switch fault Automatic recovery attempt Wait for automatic unlocking Consult technical support
E30 Parameter conguration
error Boiler locked Check and recongure the parameters

8
OPERATING DIAGRAM
ELECTRICAL WIRING DIAGRAM
INSTALLATION
1) Primary heat exchanger
2) Burner
3) Gas valve
5) Safety valve
6) Filling loop cock
7) Hot water priority turbine
9) Circulator unit
10) Expansion tank
DOMESTIC
HOT
WATER
WATER INTAKE CH RETURN
1
2
3
10
9
7
6
5
GAS INTAKE CH FLOW
Pict. 7
Pict.8
CIRCULATOR NEUTRAL
CIRCULATOR PHASE
NEUTRAL
LINE
FAN LINE
FAN NEUTRAL
GAS VALVE MODULATOR
WATER PRESSURE
SWITCH
LIMIT TERNINAL
APS/
SAFETY FUME
THERMOSTAT
D.H.W. PROBE
HEATING PROBE
GND
SIGN
+5VDC
FLUX
GAS
VALVE
LINE POWER
NEUTRAL POWER
F
N
EARTHING
NEUTRAL
LINE
EARTHING
IGNITOR
X1
T5
X2 X4 X9
X6
X10
X5
X16
X17X12X19
X7
X3
X30
X13
BOILER
EARTHING
OPEN THERM /
ROOM THERMOSTAT

9
GRAPHS FOR THE HEAD AVAILABLE TO THE SYSTEM
INSTALLATION
Pict. 9
0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
120 180 240 300 360 540 600 660 720 840 900 960 1080
5.5
6
420 480 780 1020 1140 12601200
Q L/h
Dp mCa
for 15-60 (Symona 28/32Kw)
for 15-50 (Symona 24Kw)
Use:
The boiler has been constructed according
to current technical standards and the most
stringent safety rules. Despite this, improper
use may endanger persons and property as
well as damaging the boiler itself.
This boiler has been designed as a thermal
generator for closed-loop central heating
systems and for the production of domestic
hot water.
This boiler is only for heating water to a
temperature below that of boiling point at
atmospheric temperature.
Any use different from those outlined herein is
to be considered improper. The manufacturer/
supplier declines any responsibility for
damage or injury caused by improper use.
Use of the boiler according to its design also
means respecting the instructions given in
the operation and maintenance manuals
and observing the general inspection and
maintenance conditions.
General requirements
• Installation must only be performed by
qualied and licensed personnel. They also
assume responsibility for correct installation,
adjustment and commissioning. Adjustment,
maintenance and repair of the boiler
must only be performed by qualied and
authorised personnel.
• Do not install the boiler in environments
containing dust or strong vapours.
The presence of substances such as uorine,
chlorine, sulphur etc. (e.g. vapours from
sprays, solvents or detergents, paints,
adhesives or fuels) may cause the boiler’s
components or combustion gas evacuation
system to corrode and become damaged.
Avoid installing the boiler directly in
commercial/industrial premises (e.g. hair
salons, painting/carpentry workshops,
cleaning companies etc.).
• The boiler must be installed in ventilated
premises.
• Install the device respecting the minimum
distances and spaces in Pict. 10 (also when
installing inside an enclosure).
• Mount the boiler on a solid wall.
• Ensure that there are no depressions which
could cause the boiler to stand out from the
wall.
• Ensure you do not drill into tracked cables
or piping when drilling.

10
Pict. 10
Pict. 11
FASTENING THE BOILER TO THE WALL
Attach the cardboard template giving the
connection and fastening schemes to the
wall, paying attention to the boiler dimensions
and necessary clearances. (Pict. 11)
• Use a suitable bit to drill the holes indicated
by the two wall plug symbols on the template.
• Remove the template; insert the two wall
plugs in the previously prepared holes, then
hang the boiler, inserting the hooks of the
plugs in the specic holes.
Fasten the template so that its axis
coincides perfectly with that of the
boiler
750
MURO / WALL
* =DIMENSIONE VALIDA SOLO CON KIT DEL COSTRUTTORE / DIMENSION VALID WITH THE MANUFACTURED KIT ONLY
65 107
63
68
3/4" 1/2" 3/4"
MANDATA RISCALD.
C.H. OUTPUT
INGRESSO GAS
GAS INLET
ACQUA CALDA SANITARIA
D.H.W.
6365
107
37*
1/2" 3/4"
175
RITORNO RISCALD.
C.H. INPUT
INGRESSO ACQUA SAN.
D.H.W. INLET
DIMA
TEMPLATE
18
470
230
82,5 24DS / 24BT
28-32DS / 35CN
82
340
24DS / 24BT
28-32DS / 35CN
65* 67* 65*67*

11
Pict. 11
Pict. 12
LAYOUT OF CONNECTIONS
PLUMBING THE BOILER IN
Connect the water and central heating
pipes to the boiler, respecting the positions
and distances indicated (Pict. 12); take
particular care when connecting pipes to
ensure they are not placed under pressure
in order to minimise the danger of future
leaks. Use appropriate tools and procedures
for tightening.
Flush thoroughly before
connecting the pipes to ensure
that any impurities present in
the piping and radiators are
completely removed.
Connect the safety valve outlet
so that its operation would not
cause any damage to persons
or property
• Use piping of not less than 1/2”
diameter
• Ensure that the line is always at
atmospheric pressure by using
suitable traps (do not connect
pipes directly to the valve outlet)
• Connect the safety valve outlet
line to the household grey water
drainage system
• Apply suitable protection to the
drainage line – the water carried
in it may be at high temperatures
• The manufacturer assumes no
responsibility for damage caused
to persons or property due to
operation of the safety valve
Do not use the plumbing pipework
connections as earth points for
electrical equipment

12
FILLING THE SYSTEM
CONNECTION TO THE MAINS GAS SUPPLY
When all of the boiler connections have
been plumbed in, it is possible to proceed
to ll the central heating circuit. Perform the
operation slowly to help all air bleed out of
the system. When lling, check all the internal
and external parts of the system to make sure
they are perfectly tight.
• Open the bleed valves on the radiators
• Gradually open the lling loop cock Pict. 13,
ensuring that any automatic air bleed valves
installed on the system are working correctly.
• Close the radiator bleed valves as soon as
water starts to come out
• Check on the boiler pressure gauge that
a pressure of between 1.3 and 1.6 bar has
been reached
• Close the lling loop and then
Before connecting the boiler to the mains gas,
check that it is designed to function with the
available type of gas. Thoroughly flush all the
gas pipes to remove any residues which could
compromise correct operation of the boiler.
The gas supply must be connected to the
boiler intake (Pict. 14), following all applicable
regulations. Rigid metal piping or continuous-wall
stainless-steel hose must be used and a shut-off
valve must be connected before the boiler.
Check that the ow rate from the line from the
gas meter is sufcient to support the simultaneous
use of all equipment connected to it. Check
that there is no signicant drop in pressure along
the distribution line from the gas meter; pipes of
sufcient diameter must therefore be used to satisfy
this requirement.
Perform the lling and topping
up of the system with the boiler
completely off and all parts at
ambient temperature.
Always close the filling loop
cock once you have nished the
operation
Pict. 13
Pict. 14

13
CONNECTION TO THE MAINS ELECTRICAL SYSTEM
Check that all connections are
perfectly tight before opening the
boiler’s gas connection.
Check that all devices necessary
for creating and limiting the
maximum permissible pressure
of the relative gas are installed
in the system before opening the
boiler’s gas connection.
For safe installation of the boiler it must also be
correctly connected to the mains electrical
supply in accordance with all applicable
regulations, and in particular it must be
connected to a suitable protective earthing
system.
The device is tted with a three-core electrical
cable supplied without a plug. It must be
connected to the mains with a dedicated
connection via a dual-pole switch whose
contacts have an opening of at least 3 mm.
It is important to respect the correct polarity
(LIVE: brown cable / NEUTRAL: blue cable /
EARTH: yellow-green cable) when wiring in
the boiler. When installing or replacing the
power-supply cable, the earth conductor
must be left 2 cm longer than the others. If it
is necessary to completely replace the pre-
wired power-supply cable, it will be necessary
to access the PCB compartment:
• Cut power to the boiler using the power
switch installed before it
• Remove the lower cover by removing the
four screws; turn the instrument panel to the
open position
• Remove the rear case cover by unscrewing
the 4 screws
• Identify the terminals next to the PCB (Pict.
15) and disconnect the live, neutral and
earth poles of the pre-wired cable; remove
the cable
Connect the new cable in the same position
• Close the rear cover and screw it closed
• Return the panel to its operational position
and reposition the lower protection.
For connecting or replacing conductors, use
H05VV -F, H05VVH2-F CEI EN 60228 or better
rated cable.
Do not use the gas supply
pipework connections as earth
points for electrical equipment.
Always install a gas shut-off valve
before the device. This must have
a YELLOW valve handle and must
be placed in a position which
allows full access to it.
Pict. 14
Pict. 15
L
N

14
A qualified electrician should
check the suitability of the
protective earth system. The
manufacturer is not responsible
for any damage caused by the
lack of a suitable system earth.
Check that the electrical
connection is sufcient to satisfy
the boiler’s maximum power
consumption, indicated on the
boiler plate.
Extensions, adaptors or gang
sockets must not be used when
connecting the device to the
mains electrical system.
COMBUSTION GAS EVACUATION SYSTEM: COMPATIBLE APPLICATIONS
The boiler is a type C room-sealed fan-assisted
device; the air intake and flue must be
connected to a combustion gas evacuation/
air intake system. The types of permissible air
intake and combustion gas evacuation (ue)
systems are listed on the technical data plate
and summarised below:
• C12 concentric wall ue. The pipes may also
be split, but the outlets must be exposed to
similar wind conditions.
• C32 concentric vertical ue (with the same
specications as type C12)
• C42 combustion gas evacuation and air
intake in separate common ues, but which
are exposed to similar wind conditions
• C52 separate horizontal or vertical ues,
in any case in areas exposed to different
pressures
• C62 combustion gas evacuation and air
intake performed with pipes sold and certied
separately.
C12
C42 C52
C32
130
95
130
230
min.
130
250
500
500
Pict. 16

15
Pict. 17
COMBUSTION GAS EVACUATION SYSTEM: INSTALLATION
The boiler, based on its UNI 7129 classication,
can be connected to COAXIAL and SPLIT
intake and ue evacuation systems.
The “coaxial” system is composed of a single
pipe containing both the ue and intake pipes
on the same axis. The system provides for all
The large pressure drops which characterise
this system limit its length. The maximum
possible length therefore depends on the
components used to create the line and can
be determined by adding the “Equivalent
lengths” for each individual component used
(excluding the initial 90° elbow) listed in the
“COAXIAL SYSTEM” table.
IT IS ESSENTIAL NOT TO EXCEED THE MAXIMUM
PERMISSIBLE LENGTH!
Consult the maximum length values listed
in the “FLUE TECHNICAL CHARACTERISTICS
SUMMARY” on page 17 for COAXIAL systems
relative to the type of device installed.
The “split” flue system is composed of
one pipe for combustion gas evacuation
connected to the fan outlet and one for the
air intake connected to the hole on the roof of
the sealed chamber. The system provides for
all components necessary for completing the
COAXIAL SYSTEM 60/100 mm diameter
components necessary for completing the
line, including changes of direction, straight
sections of various lengths, connections to
the boiler and outside terminals as well as all
necessary seals. Below is a list of compatible
components with their relative characteristics:
line, including changes of direction, straight
sections of various lengths, connections to
the boiler and outside terminals as well as all
necessary seals, for both pipes. Below is a list
of compatible components with their relative
characteristics:
No. Description Pressure drop (Pa) Equivalent length m
1 Terminal L.990 25 2.8
2 Extension L.1000 M-F 6 1
3Vertical anged coupling M 15 2.2
4 90° bend M-F 7 1.3
5 45° bend 6 1
6 Neoprene gasket d 128
7 Intake gasket d 100
8 Flue evacuation gasket d 60

16
SPLIT SYSTEM 80 mm diameter:
No. Description Pressure drop (Pa) Equivalent length m
1 Intake terminal L.950 15 0.8
2 Flue evacuation terminal L.990 3.5 1.5
3 Extension M-F L.1000 3 1
4 90° bend M-F 14 3
5 45° bend M-F 7 1.3
6 Intake adaptor d 80
7 Flue evacuation adaptor d 80
8L50 d 60 flue evacuation
connection
9 Neoprene gasket d 128
10 Neoprene gasket d 100
11 Collar gasket d 60
12 Gasket d 80
The maximum possible length therefore
depends on the components used to
create the line and can be determined by
adding the “Equivalent lengths” for each
individual component for both the intake and
evacuation lines listed in the “SPLIT SYSTEM”
table.
IT IS ESSENTIAL NOT TO EXCEED THE MAXIMUM
PERMISSIBLE PRESSURE DROP FOR THE DUCTS
(air intake + ue evacuation)!
Consult the maximum PRESSURE DROP
values listed in the “FLUE TECHNICAL
CHARACTERISTICS SUMMARY” for SPLIT
systems relative to the power and type of
device installed. (page 17)
Pict. 18

17
FLUE SYSTEMS TECHNICAL CHARACTERISTICS
CHECKING THE EFFECTIVENESS OF THE COMBUSTION GAS EVACUATION SYSTEM
COMBUSTION GAS EVACUATION CIRCUIT DIAPHRAGMS
WARNING:
Check the installation of the air/exhaust system
(for both types) by detecting the pressure of
the fan exhaust fumes (signal to the pressure
switch) and using a pressure switch differential
of a suitable range 0 - 500 Pa.
In order to be able to adapt the air intake
and combustion gas evacuation systems to
the various installation requirements while
keeping the functional characteristics of
the device unchanged, in compliance with
all applicable regulations regarding energy
output efficiency, it is necessary to fit a
diaphragm between the fan and ue duct for
systems of minimum or intermediate length.
The size of the diaphragm depends on the
The detected value shall not be less than
shown in the table “EXHAUST TECHNICAL
FEATURES SUMMARY “, column “SIGNAL” for the
exhaust system and for the examined power
and type of device.
type and length of the ducts which the boiler
must be connected to, or in other words the
pressure drop for the entire combustion gas
evacuation and air intake system.
The “DIAPHRAGMS” table below gives
the dimensions of the diaphragms to be
positioned at the fan outlet (Pict. 19) by type
of duct and boiler.
Pict. 19
Model Power COAXIAL SYSTEM SPLIT SYSTEM
(intake + ue evacuation)
Max length Signal Max pressure drop
(intake/ue evacuation)
Signal
Symona 24 Bithermal 24 kW 5 metres >90 Pascal 184 Pascal >90 Pascal

18
DIAPHRAGMS
COAXIAL SYSTEM Diaphragm diameter
BETWEEN AND Symona 24 Bithermal
0.5 metres 1 metre 39 mm
>1 metre 2 metres 39 mm
>2 metres 3 metres 41 mm
>3 metres 4 metres 41 mm
>4 metres 5 metres -
SPLIT SYSTEM diaphragm diameter
Symona 24 Bithermal
>50 <80 Pascal Ø 37 mm
>80 <85 Pascal -
ALWAYS CONNECT A MINIMUM FLUE EVACUATION AND INTAKE SECTION FOR BOTH
SYSTEMS OF AT LEAST 0.5 METRES (COAXIAL PIPE = 0.5m + 90° BEND; SPLIT 0.25 m
FLUE EVACUATION + 0.25 m INTAKE + RESPECTIVE 90° BENDS)
FOLLOW APPLICABLE LEGISLATION AND REGULATIONS TO THE LETTER
INSTALL AIR INTAKE AND FLUE EVACUATION SYSTEMS CONFORMING TO THE
SPECIFICATIONS GIVEN ON THE TECHNICAL DATA PLATE AND OBSERVE ANY
LIMITATIONS ARISING FROM APPLICABLE LEGISLATION AND REGULATIONS TO THE
LETTER.
ONLY USE APPROVED COMPONENTS FOR AIR INTAKE AND COMBUSTION GAS
EVACUATION SYSTEMS WHICH ARE OF THE CORRECT DIMENSIONS AND PURPOSELY
DESIGNED AND MANUFACTURED FOR THE PURPOSE.
FOLLOW INSTALLATION INSTRUCTIONS TO THE LETTER.
INSULATE ANY FLUE SECTIONS WHICH WILL BE EXPOSED TO LOW TEMPERATURES.
TAKE MEASURES TO AVOID THE FORMATION OF EXCESSIVE CONDENSATION. ENSURE
THAT ANY CONDENSATION DOES NOT EVEN MINIMALLY AFFECT ANY INTERNAL
PART OF THE BOILER.
WHENEVER NECESSARY, PLACE APPROPRIATE CONDENSATE TRAPS ON THE FLUE
EVACUATION LINE:
Ensure the following before commissioning the boiler:
• THAT THE FLUE EVACUATION AND AIR INTAKE LINES ARE PERFECTLY SEALED
• THAT THEY ARE CORRECTLY POSITIONED AND FASTENED
• THAT THERE ARE NO MECHANICAL, THERMAL OR CHEMICAL STRESSES ON THE
LINES WHICH COULD EVEN MOMENTARILY COMPROMISE THEIR INTEGRITY.
INSTALL SYSTEMS TO ABSORB ANY THERMAL EXPANSION WHEN THE SECTIONS OF
FLUE DUCTING ARE LONGER THAN THE MINIMUM SPECIFIED LENGTHS.
AIR INTAKE AND COMBUSTION GAS EVACUATION SYSTEM: IMPORTANT INFORMATION