Fer FERtech 25 OV Troubleshooting guide

FERtech 25 OV
INSTRUCTIONS FOR USE INSTALLATION AND MAINTENANCE
cod. 3540U431 - 11/2009 (Rev. 00)
8
Seasonal Efficiency
(SEDBUK)
band A
G C N° 41-267-39

FERtech 25 OV
2Cod. 3540U431 - 11/2009 (Rev. 00)
• Read the warnings given in this manual thoroughly.
They provide important information for safe instal-
lation, use and maintenance
• By law the instruction manual must be left with the
end user.
• If the appliance is sold or transferred to another
owner or if the owner moves, leaving the appliance
behind, always ensure that the manual is kept with
the appliance for consultation by the new owner
and /or installer.
• Incorrect installation or poor maintenance absolves
the manufacturer from all liability for damage to
people or property.
• Installation and maintenance must be carried out
in conformity with current legislation, according
to the manufacturer’s instructions and by qualified
personnel.
• Before service or maintenance work is, carried out
isolate the appliance from the mains electricity
supply.
• In the event of malfunction or faulty operation, iso-
late the appliance. Do not attempt to repair or carry
out any other operation on the appliance directly.
Contact qualified personnel only.
• Repairs or the replacement of components must be
carried out exclusively by qualified personnel using
original spare parts only. Failure to respect the above
may compromise the safety of the appliance.
• To guarantee efficient operation, the appliance must
be serviced once a year by a corgi registered engi-
neer.
• The appliance may not be used for purposes other
than those for which it was explicitly designed. Any
other use is considered improper and therefore dan-
gerous.
• Incorrect installation and use or failure to follow the
instructions provided by the manufacturer absolve
the manufacturer from all liability for damage.
• After unpacking, check that thecontents are complete
and undamaged.
• Keep the packaging out of reach of children as it is
potentially hazardous.
• To clean external parts, use a damp cloth moistened
with soapy water if necessary. Avoid using abrasive
cleaning products and solvents.
This symbol indicates “Caution” and is placed next to all safety information.
Strictly follow these instructions in order to avoid danger and damage to persons,
or property.
This symbols calls attention to a note or important information, please read thor-
oughly.
IMPORTANT
•Your "benchmark" Installation, Commissioning and Service Record Log Book is enclosed in the
last pages of this manual. “This record must be completed and left with the end user”.
Fer is a member of the Benchmark initiative and fully supports the aims of the programme.
Benchmark has been introduced to improve the standards of installation and commissioning of
central heating systems in the UK and to encourage the regular servicing of all central heating
systems to ensure safety and efficiency. Please see installation and servicing guidelines.
•"Fer declare that no substances harmful to health are contained in the appliance or used
during the appliance manufacture”.

3
FERtech 25 OV
Cod. 3540U431 - 11/2009 (Rev. 00)
1. OPERATING INSTRUCTIONS .................................................................4
1.1 Introduction ............................................................................................................4
1.2 Control panel ..........................................................................................................5
1.3 Turning ON and OFF ..............................................................................................6
1.4 Adjustments ............................................................................................................7
1.5 Maintenance............................................................................................................8
1.6 Faults.......................................................................................................................8
2. INSTALLATION.......................................................................................9
2.1 General Instructions................................................................................................9
2.2 Boiler location .......................................................................................................10
2.3 Boiler water connections ......................................................................................11
2.4 Connection to the gas system..............................................................................14
2.5 Electrical Connections ..........................................................................................14
2.6 Flue system ...........................................................................................................17
2.7 Condensate outlet connection .............................................................................23
3. SERVICE AND MAINTENANCE............................................................25
3.1 Adjustments ..........................................................................................................25
3.2 System start-up.....................................................................................................26
3.3 Maintenance..........................................................................................................27
3.4 Troubleshooting....................................................................................................29
4. TECHNICAL CHARACTERISTICS AND DATA..........................................................31
4.1 Dimensions and connections ................................................................................31
4.2 General view and main components ....................................................................32
4.3 Hydraulic diagram.................................................................................................33
4.4 Technical data table..............................................................................................34
4.5 Wiring diagram .....................................................................................................35
BENCHMARK ...........................................................................................36
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FERtech 25 OV
4Cod. 3540U431 - 11/2009 (Rev. 00)
1. OPERATING INSTRUCTIONS
1.1 Introduction
Dear Customer,
Thank you for choosing FERtech 25 OV, a FER wall-mounted boiler of the latest generation, featuring
advanced design and cutting-edge technology.
FERtech 25 OV is a high-efficiency condensing pre-mix appliance for heating with extremely low emis-
sions, running on natural gas or LPG.
The boiler consists of an aluminium laminar heat exchanger providing effective condensation of the
water vapour contained in the flue gases, permitting extremely high efficiency.
Above the heat exchanger, in the boiler, there is a ceramic surface pre-mix burner, equipped with
electronic ignition and ionization flame control, which achieves extremely low emissions while ensuring
high reliability and long life operation.
The boiler is totally room sealed from the installation room: the air needed for combustion is drawn from
outside. The boiler also includes a modulating speed fan, modulating gas valve, safety valve, temperature
sensors, a safety thermostat and a flue gas sensor.
Thanks to the twin microprocessor control and adjustment system with advanced self-diagnosis, unit
operation is for the most part automatic. The power for heating is automatically governed by the control
system.
The user only has to set the temperature desired inside the home (by means of a room thermostat and
or regulate the temperature of the system). The adjustment and control system will provide optimum
operation throughout the year.
The display continuously provides information on the unit’s operating status and it is easily possible
to obtain additional information on the sensor temperatures, set-points, etc. or configure them. Any
operating problems associated with the boiler or system is immediately signalled by the display and, if
possible, corrected automatically.

5
FERtech 25 OV
Cod. 3540U431 - 11/2009 (Rev. 00)
1.2 Control panel
eco/comfort
reset
1
14
11
7
6
5
4
3
2
15
13
8
12
fig. 1
1= Domestic Hot Water temperature setpoint decreasing push button (not used)
2= Domestic Hot Water temperature setpoint increasing push button (not used)
3= Central Heating water temperature setpoint decreasing push button
4= Central Heating water temperature setpoint increasing push button
5= Display LCD
6= Reset
7= On-Off push button
8= Domestic Hot Water symbol
11 = Multi-function indication
12 = Degrees indication
13 = Central Heating mode operation
14 = Central Heating symbol
15 = Burner on and actual load indication
Indication during boiler operation
Demand mode
The Boiler heat demand (generated by the Programmer, room thermostat and cylinder thermostat) is
indicated by the flashing of the Hot Air symbol over the radiator (part. 13 and 14 – fig. 1). The display
(part. 11 – fig. 1) indicates the actual System water temperature and, during the delay time, the text
“d2”.
eco/comfort
reset
eco/comfort
reset
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fig. 2

FERtech 25 OV
6Cod. 3540U431 - 11/2009 (Rev. 00)
1.3 Turning ON and OFF
Without main power supply
To avoid damage caused by freezing during long shutdowns in winter, it is advisable to drain all
water from the system.
Ignition
Ensure the power is on to the appliance.
For the first 120 seconds, the display shows FH that identifies the Air purge function.
During the first 5 seconds, the display shows the software version of the pcb.
Open the gas cock on the boiler and purge the air from the pipework upstream of the gas valve.
When the FH disappears, the boiler is ready to function automatically whenever the external controls
are calling for heat.
Turning off
Press the eco/comfort (part. 7 - fig. 1) for 5 seconds.
•
•
•
•
eco/comfort
reset
fig. 3 - Boiler without main power supply
eco/comfort
reset
eco/comfort
reset
fig. 4 - Ignition
eco/comfort
reset
fig. 6 - Turning off
fig. 5 - Air purge

7
FERtech 25 OV
Cod. 3540U431 - 11/2009 (Rev. 00)
When the boiler is turned off with this key, the p.c.b is still powered, heating operation is disabled and
the display is off however the frost protection will still be active.
To totally isolate close the gas cock ahead of the boiler and disconnect electrical power.
To avoid damage caused by freezing during long shutdowns in winter, it is advisable to drain all
water from the system.
To turn the boiler on again, press eco/comfort (part.7 - fig.1) for 5 seconds.
The boiler is ready to function automatically whenever the external controls are calling for heat.
1.4 Adjustments
Heating temperature setting
To set the system flow temperature, use the CH push buttons (Part. 3 and 4 – fig. 1). It can be varied
from a minimum of 20°C to a maximum of 90°C.
Room temperature adjustment (using a room thermostat )
Using the room thermostat, set the temperature desired in the rooms. Controlled by the room ther-
mostat, the boiler lights and heats the system water to the system delivery setpoint temperature. The
burner shuts down when the desired temperature in the room is reached.
A room thermostat and programmer are a mandatory requirement (Building regulations Doc ‘L’
2002).
eco/comfort
reset
fig. 7
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eco/comfort
reset
fig. 8

1.6 Faults
In the unlikely event of an operating problem, or component failure, the display flashes and a fault
identification code appears.
FERtech 25 OV
8Cod. 3540U431 - 11/2009 (Rev. 00)
1.5 Maintenance
It is strongly recommended to carry out annual maintenance of the boiler and heating system. Please
refer to the “maintenance” section in this manual.
The casing, the control panel and the aesthetic parts of the boiler can be cleaned using a soft and damp
cloth, do not use abrasives or solvents.
The boiler is equipped with an advanced self-diagnosis system that signals any faults on the display.
Some faults (“A“ indication) cause a boiler shutdown. In this case, operation must be reset manually by
pressing the reset (Part. 6 – fig. 1) for 1 second.
Other faults (“F“ indication) cause temporary shutdowns that are automatically reset as soon as the
value causing the fault comes back within the boiler’s normal working range.
Listed below are some anomalies that can be caused by simple, user-solvable problems.
If the problem remains after two attempts at resetting, contact the Fer Service Centre.
For other faults, refer to section 3.4 “Troubleshooting”.
Fault Cure
No burner ignition
Make sure that the gas cocks ahead of the boiler
and on the meter are open.
Press the RESET button (for 1 second).
In case of repeated shutdowns, contact the Fer-
Service Department.
Before calling a Fer service engineer, check that the problem is not due to there being no gas
or electricity.

9
FERtech 25 OV
Cod. 3540U431 - 11/2009 (Rev. 00)
2. INSTALLATION
2.1 General Instructions
This device must only be used for the purpose for which it is specially designed. This unit is
designed to heat water to a temperature below boiling point and must be connected to a heat-
ing system and/or a water supply system for domestic use, compatible with its performance,
characteristics and its heating capacity. Any other use is considered improper.
BOILER INSTALLATION MUST ONLY BE PERFORMED BY QUALIFIED PERSONNEL, IN ACCORDANCE
WITH ALL THE INSTRUCTIONS GIVEN IN THIS TECHNICAL MANUAL, THE PROVISIONS OF CURRENT
LAW, THE RECOMENDATION OF BS STANDARDS, ANY LOCAL REGULATIONS AND THE RULES OF
COMPETENT WORKMANSHIP.
Incorrect installation can cause damage or physical injury for which the manufacturer declines any re-
sponsibility.
This appliance must be installed strictly in accordance with these instructions and
regulations:
The Gas Safety Regulations (Installations & Use).
The Local Building Regulations.
The Building Regulations (Part L).
The Buildings Standards (Scotland - Consolidated) Regulations.
British Standards Codes of Practice:
B.S. 5440 Part 1 Flues
B.S. 5440 Part 2 Air supply
B.S. 5449 FORCED CIRCULATION HOT WATER SYSTEMS
B.S. 6798 INSTALLATION OF GAS FIRED HOT WATER BOILERS
B.S. 6891 GAS INSTALLATIONS
B.S. 7671 IEE WIRING REGULATIONS
B.S. 4814 SPECIFICATION FOR EXPANSION VESSELS
B.S. 5482 INSTALLATION OF LPG
B.S. 7593 TREATMENT OF WATER IN DOMESTIC HOT WATER CENTRAL HEATING SYSTEMS
B.S. 5546 INSTALLATION OF HOT WATER SUPPLIES FOR DOMESTIC PURPOSES
Model Water Bye Laws
B.S. 5955-8 PLASTIC PIPEWORK INSTALLATION
For Northern Ireland the rules in force apply

FERtech 25 OV
10 Cod. 3540U431 - 11/2009 (Rev. 00)
Minimum
A
B
D
2,5 cm
20 cm
60 cm
(via an openable panel)
C30 cm
Table 1
fig. 9
A A
B
D
C
2.2 Boiler location
The unit’s combustion chamber is sealed
off from the installation room and therefore
requires no compartment ventilation.
The installation room must be sufficiently
well ventilated to prevent any dangerous
conditions from forming in the event of even
slight gas leakage. This safety standard is
required by the EEC Directive no. 90/396 for
all gas units, including those with a so-called
sealed chamber.
Therefore the place of installation must be
free of dust, flammable materials or objects
or corrosive gases. The room must be dry
and not subject to freezing.
The boiler is designed to be installed on a
solid wall. The wall fixing must ensure a stable
and effective support for the appliance, using
the bracket and fixings supplied.
If the unit is enclosed in a cupboard or
mounted alongside, there must be space
for normal maintenance work. Fig. 9 and
tab. 1 give the minimum clearances to leave
around the unit.
Safe Handling of Substances
Care should be taken when handling the boiler
insulation panels, which can cause irritation to the skin. No asbestos, mercury or CFCs are included in
any part of the boiler.
Product Handling Advice
When handling or lifting always use safe techniques - keep your back straight, bend your knees, don’t
twist - move your feet, avoid bending forwards and sideways and keep the load as close to your body
as possible.
Where possible transport the boiler using a sack truck or other suitable trolley.
Always grip the boiler firmly, and before lifting feel where the weight is concentrated to establish the
centre of gravity, repositioning yourself as necessary.

11
FERtech 25 OV
Cod. 3540U431 - 11/2009 (Rev. 00)
fig. 10
2.3 Boiler water connections
The heating capacity of the unit should be previously established by
calculating the building’s heat requirement according to current regu-
lations. For good operation and long life of the boiler, the plumbing
system must be well proportioned and always complete with all those
accessories that guarantee regular operation and running, room ther-
mostat, trv’s etc. The flow and return must be a minimum diameter of
22mm for the first 3 metres from the appliance.
If the flow and return pipes follow a path where air pockets could form
in certain places, it is essential to install vent valves at these points.
Also, install type “A” drain cock device at the lowest points in the
system to allow complete draining.
The temperature differential between the flow manifold and the return
to the boiler should not exceed 20° C.
A minimum flow of 6 litres/min is required through the heat exchan-
ger, calibrated on site. An automatic by-pass must be fitted to the
system.
Do not use the water system pipes to earth electrical applian-
ces.
Before installation, carefully flush all the pipes of the heating system
to remove residues or impurities that could affect the unit’s operation
(BS 7593 Building regs Doc L).
Make the connections to the appliance as shown in fig. 10.
Key
1 System flow (22 mm compression union)
3 Gas inlet (22 mm with isolation valve fitted)
5 System return - 22 mm compression union)
Make the boiler connection in such a way that its internal pipes are free of stress.
400
45
50
213 187
135
630
80 120
45 25
144
35
1 5
120
3

FERtech 25 OV
12 Cod. 3540U431 - 11/2009 (Rev. 00)
fig. 11
Make Up Water
This appliance is designed to work on an open vented fully pumped heating system only, (see fig 12 page
13). The make up of water must be made via a suitably sized cold feed and expansion tank installed to
the current regulations.
This appliance is not suitable for gravity type installations or primatic type cylinders only indirect ones
should be used.
The system must be fully pumped due to the complex design of the Aluminium Laminar heat exchang-
ers high efficiency design.
Attention - is drawn to the Model Water Byelaws.
Fittings manufactured from duplex (alpha-beta) brass are not acceptable for underground use and certain
water undertakings will not accept their use above ground.
The connecting kits shown in fig. 4 are supplied as standard.
Key
A = Nut
B = Compression olive
C = Nipple
F = 1 2 gas seal - Blue
Gas isolation valve
AB
F
A
22
mm
22
mm
ACBB
X2
X1
Flow
Return

13
FERtech 25 OV
Cod. 3540U431 - 11/2009 (Rev. 00)
To DHW taps
min. 2 m
max.
150 mm
Isolating valve
Drain
Flow
Return
Open
Vent
Motorised valve
22 mm
DHW
Isolating
valve
CH Pump
Automatic By-pass
Motorised valve
22 mm CH
Balancing
valve
15 mm
22 mm
Indirect cylinder
Indirect coil missing
45°
500 mm
Open
Vent
Static Head
Radiator Radiator
Schematic layout for fully pumped heating and hot water. (Close couple)
Fig. 12

FERtech 25 OV
14 Cod. 3540U431 - 11/2009 (Rev. 00)
2.5 Electrical Connections
The unit must be installed in conformity with current national and local regulations.
Connection to the electrical Supply
The boiler must be connected to a single-phase, 230 Volt-50 Hz electric supply.
The unit’s electrical safety is only guaranteed when correctly connected to an efficient earthing
system executed according to current safety standards. Have the efficiency and suitability of the
earthing system checked by professionally qualified personnel. The manufacturer is not responsible
for any damage caused by failure to earth the system. Also make sure that the electrical system
is adequate for the maximum power absorbed by the unit, as specified on the boiler dataplate,
in particular ensuring that the cross sectional area of the system’s cables is suitable for the power
absorbed by the unit.
The boiler is prewired and provided with a cable and fitted with a 3 amp plug for connection to the
electricity supply.
Water treatment
If treatment is used fer limited recommended only the use of Fernox or Sentinel water treatment products,
which must be used in accordance with the manufactures instructions. for further information contact:
Fernox Manufacturing Co. LTD. Sentinel Performance Solutions Ltd
Cookson Electronics, Forsyth Road The Heath Business & Technical Park
Sheerwater, Woking, surrey, GU21 5RZ Runcorn, Cheshire WA7 4QX
Tel: [phone] Tel: [phone]
Note - If the boiler is installed on an existing system any unsuitable additives must be removed by tho-
rough cleansing. All systems should be cleansed according to B.S. 7593.
Note - In hard water areas treatment to prevent lime scale may be necessary.
Note - It is important that the correct concentration of the water treatment product is maintained in
accordance with the manufacturers instructions.
2.4 Connection to the gas system
If necessary the local Gas supplier should be consulted, at the installation planning stage, in order to
establish the availability of an adequate supply of gas.
An existing service pipe must not be used without prior consultation with the local Gas supplier.
A gas meter can only be connected by the Local Gas supplier, or by a Local Gas suppliers Contractor.
Installation pipes should be fitted in accordance with BS6891.
Appliance inlet working pressure must be 20mbar MINIMUM, for NG and 37 mbar minimum for LPG.
Do not use pipes of a smaller size than the boiler inlet gas connection (22 mm).
The complete installation must be tested for gas soundness and purged as described in BS689.
All pipework must be adquately supported. An isolating gas valve is provided and should be
fitted on the boiler gas inlet. Please wait 10 minutes when lighting from cold before checking
gas rate. Gas pressures should be checked after the boiler has operated for 10 minutes to reach
thermal equilibrium. This appliance has no facility to check the burner pressure and the gas
valve is sealed and should not be adjusted. A combustion test can be carried out (see page 28
combustion analyser testing).
The isolation kit shown in Fig. 11 is supplied as standard.

15
FERtech 25 OV
Cod. 3540U431 - 11/2009 (Rev. 00)
fig. 13
The user must never change the unit’s power cable. If the cable gets damaged, switch off the unit
and have it changed only by professionally qualified personnel. If changing the electric power cable,
use only “HAR H05 VV-F” 3x0.75 mm2cable with a maximum outside diameter of 8 mm.
Access to the electrical terminal block
Follow the instructions given in fig. 13 to access the electrical connection terminal block. The layout of
the terminals for the various connections is given in the wiring diagram in the Technical Data chapter.
Key
62 Time Clock (optional)
fig. 14
Room thermostat
Remove connections 5 - 6 if external control fitted.
If using external controls the switched line can be connected into terminal 5 of the electrical
block ( see fig 15 and 16 ).
Warning: the
room thermo-
stat works at
230V

FERtech 25 OV
16 Cod. 3540U431 - 11/2009 (Rev. 00)
Central heating Demand
The heat demand can be controlled by the room thermostat (terminal 5-6) or by a switch line 230 V
(terminal 5).
Standard Systems
For a general pipe layout and wiring diagram on the “S” and “Y” plan systems please see fig.
15a, 15b, and 16a, 16b.
Wiring diagram
4321
unction Box
NEL
Terminal 5 - SWITCH LINE
12345678910
PROGRAMMER
DHW ON
CH ON
NEUTRAL
LIVE
CH
zone
valve
DHW
zone
valve
Room Thermostat
Cylinder Thermostat
N
E
L
230 Vac
BROWN BLUE
GREY ORANGE
L
65
Central
heating
pump
NEL
Pre-Fitted flex
from boiler
Fig. 15b
Remove
Link
between
terminals 5-6
OPTIMAX
FERROLI
BOILER
Balancing
valve
C.H.
Zone Valve
Automatic
bypass
(mimimum flow of 6l min.)
A.A.V
A.A.V
DHW
zone
valve
*Note: cold feed and expansion
not shown for clarity
(see fig. 12)
Auto air vent
Fig. 15a
FERtech “S” Plan
Pipe layout

17
FERtech 25 OV
Cod. 3540U431 - 11/2009 (Rev. 00)
fig. 16b
Wiring diagram
4321
unction Box
NL
12345678910
PROGRAMMER
NEUTRAL
LIVE
CH ON
DHW ON
DHW OFF
BLUE
WHITE
GREY
ORANGE
Room Thermostat
Cylinder Thermostat
N
E
L
240 Vac
Honeywell V4073H mid position
3 WAY ZONE VALVE
2
1
C
Terminal 5 - SWITCH LINE
L
65
Central
heating
pump
NE L
Pre-Fitted flex
from boiler
Remove
Link
between
terminals 5-6
2.6 Flue system
The unit is “type C” with a sealed chamber and forced draught, the air inlet and flue outlet must be
connected to one of the following flue systems. With the aid of the tables and methods of calculation indi-
cated, before commencing installation, it is first necessary to check that the flue system does not exceed
the maximum permissible length. The current standards and local regulations must be observed.
It should be noted that only Fer flue system and accessories should be used on this appliance,
as per BS 5440 2000 and C.E. test certification.
FERtech “Y” Plan
Pipe layout
Auto air vent
Automatic
bypass
(mimimum flow of 6LTR min.)
OPTIMAX
FERROLI
BOILER Balancing
valve
A.A.V
A.A.V
*Note: cold feed and expansion
not shown for clarity
(see fig. 15)
fig. 16a

FERtech 25 OV
18 Cod. 3540U431 - 11/2009 (Rev. 00)
* = between
10 e 60 mm
* = between
10 e 60 mm
80
84
95
50*
80
95 30
50*
Standard 041025G0
Flue kit
200 200
30
P
125
S
DS50*
L
30
95
84
L
DS
200 200
144
Drill the wall 10÷20 mm
more than the
pipe diameter
200200
144
Drill the wall 10÷20 mm
more than the pipe diameter
Install level
Install level
Install level
Install level
Side view
View from above
fig. 17a
Side Outlet
fig. 17b
Front view
View from above
P = S + 129 mm
Rear Outlet
L = S + D + 185 mm
Connection with concentric flue system
The unit can be connected to a concentric air/flue duct with a Horizontal or Vertical outlet as shown on
the following drawings. Numerous accessories are available on request to meet the various installation
requirements. Please refer to our “flue manual” or the price list.
Standard concentric flue installation
Horizontal flue installation
1. Define the position for installing the unit.
2. If using standard flue (041025G0) this must be installed level, for non-standard flue lengths over 1mtr
a fall of 3 mm per metre should be incorporated back to the boiler.
3. Make a hole of diameter 10 - 20 mm greater than the nominal diameter of the concentric pipe used.
4. If necessary, cut the terminal length to size, ensuring that the external pipe protrudes from the wall
by between 10 and 60 mm (fig. 17a and 17b). Remove the cutting burrs.
5. Connect the flue to the boiler, positioning the seals correctly. Seal the flue into the wall with silicone
or sand + cement and cover with wall seals provided.
Flue seals should be lubricated with a silicone type grease to prevent damage (grease not sup-
plied)

19
FERtech 25 OV
Cod. 3540U431 - 11/2009 (Rev. 00)
Pitch roof slate
1KWMA82U
1KWMA56U
950
50
041002X0
95050
50 950
50
max. 6 mt 60 100
max. 16 mt 80 125
Vertical Terminal
1KWMA83U
120 1000 125
10
Vertical Outlet
fig. 17c
Reduction factors for bends
1 m
0,5 m
0,5 m
0,25 m
Table 2b
Maximum permissible
duct length (Horizontal)
Ø mm
60/100
5 m 15 m
Ø mm
80/125
Table 2a
Maximum permissible
duct length (Vertical) 6 m 16 m
The total length in equivalent metres of the concentric flue must not exceed the maximum lengths stated
in the following table, note that each bend gives rise to the stated reduction. For example, a duct = 60/100
composed of 1 bend of 90° +1 horizontal metre + 2 bends of 45° + 1 horizontal metre has a total equivalent
length of 4 metres.
Vertical flueing
The installation of a concentric vertical flue can be carried out as follows,
Install the appliance as previously mentioned in this manual.
1. Connect onto the flue assembly at the top of the appliance a concentric vertical adaptor part number
1KWMA71W,
2. Use the required amount of 1mtr flue extensions (part number 1KWMA56U) inserting them spigot
down ensuring the seals are well lubricated with silicone grease (not supplied) and correctly located
into the sockets.
3. If required 45° bends (Part number1KWMA64A)
may be used with a resistance value of 0.5mtrs
each, the flue should be routed in such away
to avoid any unnecessary deviation and thus
minimise the amount of bends required.
4. The termination should be made through our
concentric flue outlet (part number 1KWMA83U)
in conjunction with a roof slate pitched (part
number 1KWMA82U) or flat roof (part number
1KWMA81U) The storm collar must be fixed on
using the three screws provided and sealed with
an external grade silicone (not supplied).
5. For longer flue lengths a 125mm concentric flue
system is available.
6. All flue installations must comply with BS5440
part 1 and must only be of Fèrroli manufacture.
The vertical flue must continually rise and be
supported throughout its length. The flue must
be inspected whilst commissioning the appliance
to ensure it is sound throughout its length.
This information is for guidance purposes and Fèr-
roli will in no way be held responsible for incorrect
installation following this guide.

FERtech 25 OV
20 Cod. 3540U431 - 11/2009 (Rev. 00)
Ref.
2
4
5
36
29
1
Vertical air pipe Ø80
Vertical flue pipe Ø80
80 Ø vertical flue Kit
Description Equivalent
loss
36 m
46,4 m
12,0 m
94,4 m
Total
Table 3
fig. 19
Connection with 80 mm pipe system
The unit can be connected to a system of separate air/flue
pipes for a Horizontal or Vertical outlet as shown fig 18 - 19
. Numerous accessories are available on request to meet
the various installation requirements. The components
used most frequently are stated in tables 4 - 5. Please
refer to the flue manual or the price list for additional
components.
To check you do not exceed the maximum permissible
flue length, it is necessary to make a simple calculation
before installation:
1. For each component, tables 4 - 5 provide an “equiva-
lent loss in linear metres”, depending on the position
of installation of the component (with air intake or flue
extraction, vertical or horizontal).
The loss is called “equivalent length” since it is compared
to the loss of one metre of flue (defined as equal to 1).
For example, a bend at 90° of Ø80 in flue extraction has
an equivalent loss of 2 linear metres, i.e. it has a loss
equal to that of 2 linear metres of flue length.
2. After completely defining the layout of the system of split
flues, add up the losses in equivalent metres, depending
on the installation position, of all the components and
accessories in the system.
3. Check that the total calculated loss is less than or equal
to 95 equivalent metres, i.e. the maximum permissible
for this model of boiler.
For complete flue options please contact fer or
check our comprehensive flue manual.
4
5
1KWMA83W
1KWMA82U
1KWMA84U
2
120 120 80
80
Ø80
AIR
Ø80
FLUE
Remove
the closing
cap
144
041039X0
041039X0
fig. 18