Ferroli Optimax 25 C Troubleshooting guide

OPTIMAX 25 C
wall-mounted gas fired,
pre-mix
condensing combination boiler
cod. 3544782/1 - 08/2004
G C N° 47-267-34
INSTRUCTIONS FOR USE INSTALLATION AND MAINTENANCE

Optimax 25 C
2
IMPORTANT
Your “benchmark” Installation, Commissioning and Service Record Log Book will be enclosed in
your customer information pack.
“This record must be completed and left with the end user”.
Ferroli 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.
• Read the warnings given in this manual thoroughly.
They provide important information for safe instal-
lation, use and maintenance
• By law the instruction manual 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
my 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 arecomplete
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.

Optimax 25 C
3
1. OPERATING INSTRUCTIONS..................................................................4
1.1 Introduction.............................................................................................................4
1.2 Control panel ..........................................................................................................5
1.3 Turning ON and OFF ..............................................................................................6
1.4 Adjustments ............................................................................................................6
1.5 Maintenance............................................................................................................7
1.6 Faults.......................................................................................................................7
1.7 Optional Time Clock ...............................................................................................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..............................................................................13
2.5 Electrical Connections ..........................................................................................13
2.6 Flue system ...........................................................................................................14
2.7 Condensate outlet connection .............................................................................20
2.8 Ferroli Optimax (optional) Time clock installation. ..............................................22
3. SERVICE AND MAINTENANCE............................................................23
3.1 Adjustments ..........................................................................................................23
3.2 System start-up.....................................................................................................24
3.3 Maintenance..........................................................................................................25
3.4 Troubleshooting ....................................................................................................27
4 TECHNICAL CHARACTERISTICS AND DATA.........................................29
4.1 Dimensions and connections ................................................................................29
4.2 General view and main components ....................................................................30
4.3 Hydraulic diagram.................................................................................................31
4.4 Technical data table ..............................................................................................32
4.5 Diagrams ...............................................................................................................33
4.6 Wiring diagram .....................................................................................................34

4
Optimax 25 C
1. OPERATING INSTRUCTIONS
1.1 Introduction
Dear Customer,
Thank you for choosing Optimax 25 C, a FERROLI wall-mounted boiler of the latest generation, featuring
advanced design and cutting-edge technology.
Optimax 25 C 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 pre-mix burner, with a large ceramic surface, equip-
ped 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, pump, expansion
vessel, safety valve, flow sensor, temperature sensors, a safety thermostat and a low pressure switch.
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
appliance temperature control. 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
Optimax 25 C
1.2 Control panel
23 41 5
°C°C
fig. 1
1 - System temperature adjustment / Summer/Winter selection
This knob is used to adjust the system temperature from 20°C to 90°C and can switch over between
summer / winter. To increase the system temperature, turn the knob clockwise; anticlockwise to decrease
it. To select the summer mode, turn it anticlockwise to the minimum setting. (See page 6)
2 - ON-OFF / Reset / Test
Holding the key down for at least 5 seconds turns off the boiler. To turn it back on, press the key again
for 5 seconds.
Pressing the key resets boiler operation after a shutdown or lock-out.
Pressing the key 3 times within 5 seconds automatically takes you to TEST operation, (15mins at maxi-
mum heating output) to exit test mode repeat the process by pressing the key a further 3 times within
5 seconds.
3 - Multi-function
In combination with the reset key, this is used to access the Installer menu.
4 - Operating display
On stand-by and during boiler operation this indicates the boiler operating temperature, (a flame point
at the bottom of the display will illuminate to indicate the burner has lit) or a fault code if a problem
occurs.
5 - Hot water temperature adjustment control
Used to set the hot water temperature, turning the knob clockwise increases the temperature, anti-
clockwise decreases it. The adjustment range goes from 40 to 65°C (see page 6).

6
Optimax 25 C
1.4 Adjustments
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).
Heating temperature setting
To set the system flow temperature, use the C.H control knob (ref. 1 - fig. 1). It can
be varied from a minimum of 20°C to a maximum of 90°C.
To set the central heating temperature, use the C.H control knob. Turning it clockwise
increases the temperature, turning it anticlockwise decreases it.
When adjusting the control knob the display will flash for 5 seconds and
display the set point temperature. It will then revert to showing the actual
temperature.
1.3 Turning ON and OFF
Ignition
• Open the gas cock on the boiler.
• Purge the air from the pipework upstream of the gas valve.
• Ensure the power is on to the appliance.
• Press the key to turn the appliance on (fig 1 item 2)
• The boiler is now ready to function automatically whenever the external controls are calling for
heat.
Turning off
Press the key for 5 seconds (see fig. 1).
When the boiler is turned off with this key, the p.c.b is still powered, heating operation is disabled and
the display appears 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.
Domestic hot water temperature adjustment
To set the hot water temperature, use the D.H.W. control knob. Turning it clockwise
increases the temperature, turning it anticlockwise decreases it. It can be varied from
a minimum of 40°C to a maximum of 65°C.
When adjusting the control knob the display will flash for 5 seconds and
display the set point temperature. It will then revert to showing the actual
temperature.

7
Optimax 25 C
Example
Boiler failed to light
Insufficient system pressure
Make sure that the gas isolation valve up-stream of the boiler
and on the meter are open.
Press the RESET button (2 Fig. 1).
Fill the system to 1-1.5 bar by use of the filling loop.
Fault CureDISPLAY
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.
1.6 Faults
In the unlikely event of an operating problem, or component failure, the display flashes and a fault
identification code appears.
Listed below are the faults that can be caused by simple, user-detectable problems.
The boiler is equipped with an advanced self-diagnosis system. Should a fault occur with the boiler, the
display will show the fault code. There are some faults that in order to restore operation it requires you
to press RESET (2 - fig. 1); if the boiler fails to start, it may be necessary to rectify the fault indicated
by the operating LEDs (faults from 1 to 26); other faults cause temporary shutdown that are automatically
reset as soon as the value comes back within the boiler’s normal working range (faults from 30 to 47).
Summer/Winter selection
To select Summer/Winter, use knob 1 (fig. 1).
Turning it onto (Summer) turns off the heating function but the frost protection remains active.
Turning it onto (Winter) turns on heating, via the room stat and programmer.
The boiler can still produce domestic hot water during summer mode whenever there is a dem-
mand.
Before calling the FERROLI Caresafe centre, check that the problem is not due to an installation
error or there being no gas or electricity.
If the problem remains after two attempts at resetting, contact your nearest FERROLI Caresafe.
For further fault codes, refer to section 3.4 “Troubleshooting”.

Optimax 25 C
8
AUTO
+
-
R
OVER RIDE
x
x
4
A
B
E
RDP
AUTO P
OI
F
P
To set time of day
1. Slide switch (A) to left position
2. Using button + and - adjust until the correct time is shown on display (B).
Pre Set Programmes. The timer is pre programmed with 3 ON and 3 OFF times.
To Set Own ON and OFF times. Symbol in Display = ON time
If these are suitable no programming is required and the slide switch (A) can be moved to the Auto
position and the central heating will be ON for these periods.
(12:00 - 12:00 will not switch on the boiler)
1.1 Use buttons + and - to set 1st ON time eg. 6:00
Display
2.1 Use buttons + and - to set OFF time, eg. 9:00
Display
3.1 Use button + and - to set 2nd ON time, eg. 12:30
Display
4.1 Use button + and - to set 2nd OFF time eg. 14:00
Display
5.1 Use button + and - to set 3rd ON time, eg. 16:00
Display
6.1 Use button + and - to set 3rd OFF time eg. 23:30
Display
8. On completion of programming slide switch (A) to
Auto position, the time of day will be displayed and the
central heating will switch ON and OFF according to the
programme set.
1. Slide switch (A) to right position (P)
Display
2. Press button (P)
Display
3. Press button (P)
Display
4. Press button (P)
Display
5. Press button (P)
Display
6. Press button (P)
Display
7. The timer can be programmed with up to 8 ON and
8 OFF times by repeating the above procedure.
6:30 1
8:30 2
12:00 3
12:00 4
6:00 1
9:00 2
12:30 3
14:00 4
16:30 5
22:30 6
16:00 5
23:30 6
6:30 - 8:30
12:00 - 12:00
16:30 - 22:30
1.7 Optional Time Clock
If a ferroli 24 hour time clock is fitted to the boiler this will control the central heating, the pre set times
will only come into operation when both selector switches are moved to the “Auto” position.
A Slide switch: set clock - auto - set programme
B Display. Symbol in Display = Timer ON
P Select programme ON/OFF 1.....8
D Push buttons Time + Time -
E Over-ride: Boiler will switch ON if it is OFF; and OFF if it is ON
F I=Heating continuous - AUTO=Heating timed - O=Heating disabled
R Reset (with pencil) only with switch Ain set clock position
Over ride
By pressing the over ride button (E) the timer programme is over ridden ie, if programme is in OFF time it will come ON
and if in ON time will go OFF.
The timer will revert back to it set programme on reaching the next ON or OFF time.
When the programme is on over ride the sign will be shown in the display window (B).
Reset Button
By the use of a pencil the reset button can be pushed (R). This will clear all programmes apart from those factory pre set.
Reset is only possible with switch (A) in set Clock position!

Optimax 25 C
9
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 hea-
ting 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
COMPEDENT WORKMANSHIP.
Incorrect installation can cause damage or physical injury for which the manufacturer declines any
responsibility.
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

Optimax 25 C
10
Minimum
A
B
D
2,5 cm
20 cm
60 cm
(via an openable panel)
C30 cm
Table 1
fig. 2
A A
B
D
C
2.2 Boiler location
The unit’s combustion circuit 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, inclu-
ding 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 design 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 cupboard or moun-
ted alongside, there must be space for normal
maintenance work. Fig. 2 and tab. 1 give the
minimum clearances to leave around the unit.

Optimax 25 C
11
fig. 5
1 2 3 5
6
7 4
40 68 107 77,5 57,5 50
400
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 regulations. For good operation and long life of the boiler, the plum-
bing system must be well proportioned and always complete with all those accessories that guarantee
regular operation and running, room thermostat, trv’s and automatic bypass etc. The flow and return
must be a minimum diameter of 22mm for the first 3 meters from the appliance.
If the flow and return pipes follow a path where air pockets could form in certain places, it is esential
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 requied through the heat exchanger, it is therefore essential to fit a
automatic bypass a min of 3 meters away from the appliance, calobrated on site.
Do not use the water system pipes to earth electrical
appliances.
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. 5.
Key
1 System flow (22 mm with isolation valve fitted)
2 DHW outlet (15 mm with isolation valve fitted)
3 Gas inlet (22 mm with isolation valve fitted)
4 Cold main inlet (15 mm with isolation valve fitted)
5 System return - 22 mm with isolation valve fitted (c/w filter)
6 System drain
7 Condense outlet
It is essential to install the isolation valves supplied between the boiler and heating system, allowing the
boiler to be isolated from the system if necessary.
The safety valve outlet must be connected to a 15mm diameter copper pipe, with a continual
fall from the boiler to allow system water out onto the ground in the event of over-pressure in
the heating circuit. If this is not done, and the drain valve trips and floods the room, the boiler
manufacturer is not to be held responsible. The outlet should face back against the outer bri-
ckwork or building face to prevent harm or injury from hot water discharging in the evet of an
over-pressuried system.
Make the boiler connection in such a way that its internal pipes are free of stress. If a check valve is
installed on the tap water circuit (where applicable), it is necessary to mount a safety valve between the
boiler and this circuit (check valve minimum 3 meters from boiler).

Optimax 25 C
12
fig. 4
Fig. 5
3
2
1
4
Key
A=Nut
B = Compression olive
D=3/4 seal (green)
E=1/2 seal (green)
F=1/2 gas seal (blue)
G=Filter
H=Cap
Flow isolation valve
Hot water connection
Gas isolation valve
Cold water isolation valve
Return isolation valve
22
22
22
15
15
A
A
A
A
AB
B
B
B
B
D
D
E
E
F
GH
RED
YELLOW
BLUE
BLUE
The isolation valve kit shown in Fig. 4 is supplied as standard.
Make Up Water
Provision must be made for replacing water lost from the sealed system. Reference should be made
to BS6798, for methods of filling and making up sealed systems. There must be no direct connection
between the boiler's central heating system and the mains water supply. The use of mains water to
charge and pressurise the system directly, is conditional upon the Local Water Byelaws. Again any such
connection must be disconnected after use. Ensure the filling point is on the return pipe to the boiler.
Attention - is drawn to the Model Water Byelaws.
Key
1. C.H. filling valve.
2. Temporary connection.
3. Cold water supply valve.
4. Double check valve.

Optimax 25 C
13
Water treatment
If treatment is used ferroli limited recommanded 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 Division
Cookson Electronics, Forsyth Road Betz Dearborn LTD
Sheerwater, Woking, surrey, GU21 5RZ Widnes, Cheshire WA8 8ND
Tel: [phone] Tel: [phone]
Note - If the boiler is installed in 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 whitout 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 com-
mercial propane.
Do not use pipes of a smaller size than the combination 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 ligthing from cold before checling 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, a combustion test should
should be carried out instead (see page 26 combustion analyser testing).
The isolation kit shown in Fig. 4 is supplied as standard.
2.5 Electrical Connections
The unit must be installed in conformity with current national and local regulations.
Connection to the electrical grid
The boiler must be connected to a single-phase, 230 Volt-50 Hz electric line.
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 for connection to the electricity line. The connections to
the supply must be made with a permanent connection and equipped with a double pole switch which
contacts have a minimum opening of at least 3 mm, and fused at max. 3A between the boiler and the
line. It is important to respect the polarities (LIVE: brown wire / NEUTRAL: blue wire / EARTH: yellow-
green wire) in making connections to the electrical supply.

Optimax 25 C
14
fig. 8
Remove if
external
controls
fitted
230 Vac
8
7
6
5
4
3
2
1
L
N
fig. 9
External controls
CAUTION: THE ROOM THERMOSTAT AND
TIME CLOCK WORK AT 230 V - 50 Hz PHASE
(fig. 9).
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.
Acces to the electrical terminal board
Follow the instructions given in fig. 8 to access the electrical connection terminal board (fig. 8). The
layout of the terminals for the various connections is given in the wiring diagram in the Tecnical Data
chapter.
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 Ferroli flue system and accessories should be used on this appliance,
as per BS 5440 2000 and C.E. test certification.

Optimax 25 C
15
* = between
10 e 60 mm
* = between
10 e 60 mm
80
Standard 1KWMA53A
Flue kit
215 185
Install level
Install level
50*110
95
80
30 50*
30
95
S 50*
P
110
L
DS
P
125
S
30
95
DS50*
L
30
95
215 185
175
Drill the wall 10÷20 mm
more than the
pipe diameter
185215
175
Drill the wall 10÷20 mm
more than the pipe diameter
Install level
Install level
Side view
View from above
fig. 10a
Side Outlet
fig. 10b
Front view
View from above
P = S + 160 mm
Rear Outlet
L = S + D + 170 mm
Connection with concentric flue system
The unit can be connected to a concentric air/flue duct with a wall or rooftop 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 (1KWMA53A) this must be installed level, for non-standard flue lenghts over
1mtr a fall of 3 mm per metre should be incorporated.
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. 10a and 10b). 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)

Optimax 25 C
16
Angled roof tile
1KWMA82U
1KWMA56U
950
50
1KWMA71W
max. 6 mt 60/100
max. 16 mt 80/125
Roof end piece
1KWMA83U
68
215 185
95050
50 950
50
1000 125
10
Vertical Outlet
fig. 10c
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.

Optimax 25 C
17
4
5
1KWMA83W
1KWMA82U
1KWMA84U
120 120 65
95
175
370
Ø80
AIR
Ø80
FUMES Remove
the closing
cap
KWMR54A
80 84 80
1KWMR54A
2
Ref.
2
4
5
23
23
1
Vertical air pipe Ø80
Vertical flue pipe Ø80
80 Ø vertical flue Kit
Description Equivalent
loss
23,0 m
36,8 m
12,0 m
71,8 m
Total
Table 3
fig. 11
fig. 12
Connection with 80 mm pipe system
The unit can be connected to a system of separate air/flue
pipes for a wall or rooftop outlet as shown fig 11 - 12 .
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 2.5 linear metres, i.e. it has a loss
equal to that of 2.5 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 75 equivalent metres, i.e. the maximum permissible
for this model of boiler.
For complete flue options please contact ferroli or
check our comprehensive flue manual.

Optimax 25 C
18
KWMA86A
KWMA85A
KWMA84U
Air Flue
Vertical Horizontal Vertical Horizontal
KWMA65W
KWMA01W
KWMA83W • 1,00 m
Description
Pipe Ø 80
male-female
Bend 45°Ø 80 mm
male - female
Bend 90°Ø 80 mm
male - female
Description
Horozontial
flue terminal
Horozontial
air terminal
Vertical flue
terminal
111.62
1.2 1.8
1.5 2.0
Equivalent losses in
metres (linear)
5
2
Air Flue
Vertical Horizontal Vertical Horizontal
Equivalent losses in
metres (linear)
12
Accessories Ø 80 Accessories Ø 80
Table 4 Table 5
The stated loss values refer to genuine Ferroli flue accessories.
Terminal Position
P
D, E
Q
Q
l
BC
A
G
F
L
J
HH
K
N
N
MM
Q
fig. 13
Table of Ø80 flue and accessory

Optimax 25 C
19
Minimum Dimensions of Flue Terminal Positions
Directly below an opening, air brick,
opening windows, etc.
Above an opening, air brick,
opening windows, etc.
Horizontally to an opening, air brick,
opening windows, etc.
Below gutters, soil pipes or drain pipes
Below balconies or car port roof
Below eaves
From a vertical drain pipe or soil pipe
From an internal or external corner
From a surface facing the terminal
From a terminal facing the terminal
From the wall on which the terminal is mounted
From a vertical structure on the roof
Above intersection with roof
Horizontally from a terminal on the same wall
Vertically from a terminal on the same wall
From an opening in the car port (e.g. door,
window) into the dwelling
Above ground roof or balcony level
300mm
300mm
300mm
200mm
75mm
200mm
150mm
100mm
300mm
600mm
300mm
300mm
150mm
1200mm
1200mm
1500mm
N/A
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
NOTE
N/A = Not applicable
In addition, the terminal should not be nearer than 150mm (fanned draugt) or
300mm (natural draugt) to an opening in the building fabric formed for the purpose
of accommodating a built-in element such as a window frame.
Condensing Terminal Positions: If the flue is to be terminated at low level, then the
potential effect of the plume must be considered.
The plume should not be directed:
across a frequently used access route
across a neighbouring property
towards a window or door

Optimax 25 C
20
fig. 14
0,5 lt.
A
B
Connection to collective flues or single flues with natural draught
If you are then going to connect the Optimax 25 C boiler to a collective flue or a single flue with natural
draught, the flue must be expressly designed by professionally qualified technical personnel in conformity
with the standards and rules in force.
In particular, flues must have the following characteristics:
• Be sized according to the method of calculation stated in the standard
• Be airtight to the products of combustion, resistant to the fumes and heat and waterproof for the
condensate
• Have a circular or square cross-section (some hydraulically equivalent sections are permissible), with
a vertical progression and with no constrictions
• Have the flue conveying the hot fumes adequately distanced or isolated from combustible mate-
rials
• Be connected to just one unit per floor, for at most 6 units in all (8 if there is a compensation duct or
opening)
• Have no mechanical suction devices in the main ducts
• Be at a lower pressure, all along their length, under conditions of stationary operation
• Have at their base a collection chamber for solid materials or condensation of at least 0.5 m, equipped
with a metal door with an airtight closure.
2.7 Condensate outlet connection
The boiler is equipped with an internal air-trap to drain off the conden-
sate. Fit the inspection coupling Aand the hose B, pushing it on for
approximately 3 cm and securing it with a clamp.
Fill the air-trap with approximately 0.5 ltrs of water and connect the hose
to the waste system, or soakaway.