Fondital TAHITI DUAL Line Quick start guide

IST 03 C 262 - 03
INSTALLATION
USE AND MAINTENANCE
TAHITI DUAL
GB
High quality Italian product
MADE IN ITALY

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Dear Customer,
Thank you for choosing and buying one of our boilers. Please read these instructions carefully in order to install,
operate and service the boiler properly.
The Manufacturer recommends that Customers contact authorized qualified personnel only for maintenance
and repair operations.

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General information for fitters, maintenance technicians and users
This INSTRUCTION MANUAL, which is an integral and indispensable part of the product, must be handed over to the user by the fitter and must
be kept in a safe place for future reference. The manual must accompany the boiler should it be sold or its possession transferred.
This boiler is designed for connection to a central heating system (all models) and to a hot domestic water system (models
CTN and CTFS only).
Any other use is considered incorrect and therefore dangerous.
The boiler must be installed in compliance with the applicable laws and standards and according to the manufacturer’s instructions given in
this manual. Incorrect installation may cause injury to people or animals and damage to property. The manufacturer shall not be held liable
for any such injury or damage.
Damage or injury caused by incorrect installation or use, or by failure to follow the manufacturer’s instructions will relieve manufacturer of any
and all contractual and extra-contractual liability.
Before installing the boiler, check that the technical data correspond to the requirements for its correct use in the system.
Check that the boiler is intact and has not been damaged during transport and handling. Do not install equipment which is damaged or
faulty.
Do not obstruct the air intake or heat dissipation openings.
Only Manufacturer-approved accessories or optional kits must be installed.
All the packaging materials can be recycled and must be disposed of correctly. They must be sent to a specific waste management site. Keep
the packaging out of the reach of children as it may represent a hazard.
In the event of failure or faulty operation, switch off the boiler. Do not attempt to make any repairs and contact a qualified technician.
Manufacturer-approved parts must be used for all repairs to the boiler.
Failures to comply with the above requirements may affect the safety of the boiler and endanger people, animals and property.
The Manufacturer recommends that Customers contact an authorized Service Centre for maintenance and repairs.
Routine boiler maintenance should be performed according to the schedule in the relevant section of this manual.
Appropriate boiler maintenance ensures efficient operation, preservation of the environment, and safety for people,
animals and property. Incorrect and irregular maintenance can be a source of danger for people, animals and property.
If the boiler is to remain inactive for a long time, disconnect it from the power mains and close the gas tap.
Warning! If the boiler is disconnected from the mains, the electronic anti-freeze function will not operate.
Should there be a risk of freezing, add anti-freeze to the heating system. It is not advisable to empty the system as this may result in damage.
Use specific anti-freeze products suitable for multi-metal heating systems.
If you smell gas:
 •donottouchanyelectricalswitchesanddonotturnonelectricalappliances;
 •donotigniteflamesandextinguishanycigarettes;
 •closethemaingastap;
 •opendoorsandwindows;
 •contactaServiceCentre,aqualifiedfitterorthegassupplycompany.
Never use a flame to detect a gas leak.
WARNING
This boiler has been built for installation in the country indicated on packaging and the rating plate.
Installation in a country other than the specified one may be a source of danger for people, animals and property.
The Manufacturer cannot be held contractually or extra-contractually liable in the event of failure to comply with the above.

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RAPID OPERATING INSTRUCTIONS
These instructions can be followed for rapid ignition, regulation and immediate use of the boiler, provided it has been
installed by an authorized fitter, started up for the first time and set up for correct operation.
If the boiler is equipped with other accessories, these instructions are not sufficient to ensure correct operation.
Reference must be made to the full instructions for the boiler and all mounted accessories.
For a detailed description of how the boiler operates and safety instructions during operation, refer to the instructions shown in this manual.
1. Open the gas shut-off valve upstream of the boiler.
2. Turn on the main electric switch upstream of the boiler: the green mains light on the control panel (1, pic. 1) comes on.
3. If you do not want to activate the CH function, turn the selector (9, pic. 1) to SUMMER. Only the DHW function is now active.
4. If you want to activate the CH function, turn the selector (9, pic. 1) to WINTER. Both the DHW and CH functions are now active.
5. To regulate the DHW temperature, move the DHW regulation knob (10, pic. 1) to the intermediate position (approx. 45°C).
Then regulate as required.
6. To regulate the CH temperature, move the CH regulation knob (11, pic. 1) to 3 o’clock (approx. 70°C). Then regulate as required.
7. Enter the desired room temperature on the thermostat in the room (if present).
The boiler is now ready to operate.
If the boiler shuts down, you can restart it by moving the selector (9, pic. 1) to the RESET position for a few seconds and then to the desired
position.
Boiler status on
SUMMER position
Boiler status on
WINTER position
DHW temperature
regulation knob
CH temperature
regulation knob
Mains light
Boiler status on
RESET position

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CONTENTS
Warning page 2
General information for fitters, maintenance technician and users page 3
Rapid operating instructions page 4
1. Instructions for the user page 7
1.1 Control panel page 7
1.2 Operating the boiler page 8
1.2.1 Switching on page 8
1.2.2 Operation page 9
1.2.3 External temperature probe operation (optional) page 10
1.3 Boiler shut-down page 11
1.3.1 Burner shut-down page 11
1.3.2 Shut-down due to overheating page 11
1.3.3 Shut-down due to incorrect draught (clogging) of the flue system page 11
1.3.4 Shut-down due to low water pressure page 11
1.3.5 Shut-down due to temperature probe malfunction page 11
1.4 Maintenance page 12
1.5 Notes for the user page 12
2. Technical characteristics and dimensions page 12
2.1 Technical characteristics page 12
2.2 Dimensions page 14
2.3 Plumbing layout and gas connections page 16
2.4 Operating data page 18
2.5 General characteristics page 19
3. Instructions for the fitter page 20
3.1 Installation standards page 20
3.2 Installation page 20
3.2.1 Packaging page 20
3.2.2 Deciding where to install the boiler page 20
3.2.3 Positioning the boiler page 20
3.2.4 Installing the boiler page 22
3.2.5 Boiler room ventilation page 22
3.2.6 Air intake/flue gas system of natural draught boilers page 22
3.2.7 Air intake/flue gas system of forced draught boilers page 23
3.2.7.1 Configuration of air/flue system pipes types : B22, C12, C32, C42, C52, C82 page 24
3.2.7.2 Ø 100/60 diameter coaxial pipe air/flue system page 25
3.2.7.3 Ø 80 mm diameter split pipe air/flue system page 26
3.2.8 Testing boiler efficiency page 28
3.2.8.1 “Chimney sweep” function page 28
3.2.8.2. Checking combustion performance page 29
3.2.9 Gas mains connection page 29
3.2.10 Plumbing connections page 30
3.2.11 Adjustable by-pass page 30
3.2.12 Power mains connection page 30
3.2.13 Room thermostat connection (optional) page 31
3.2.14 Open Therm remote control connection (optional) page 31
3.2.15 External temperature probe installation (optional) and “sliding temperature” operation page 31
3.2.16 Installation of the phone operation device (optional) page 32
3.3 Loading the system page 32
3.4 Starting the boiler page 33
3.4.1 Preliminary checks page 33
3.4.2 Switching on and off page 33
3.5 Wiring layout page 34
3.6 Adaptation for use with other gases and burner adjustment page 35
4. Testing the boiler page 36
4.1 Preliminary checks page 36
4.2 Switching on and off page 36
5. Maintenance page 36
5.1 Maintenance schedule page 36
5.2 Analysis of combustion parameters page 37
6. Troubleshooting page 38

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LIST OF PICTURES
pic. 1 - Control panel page 7
pic. 2 - Temperature regulation curves page 10
pic. 3 - Filling tap page 11
pic. 4 - Dimensions mod. CTN and RTN page 14
pic. 5 - Dimensions mod. CTFS and RTFS page 15
pic. 6 - Plumbing diagram for CTN 24 page 16
pic. 7 - Plumbing diagram for CTFS 24/28 page 16
pic. 8 - Plumbing diagram for RTN 24 page 17
pic. 9 - Plumbing diagram for RTFS 24/28 page 17
pic. 10 - Boiler template page 21
pic. 11 - Connection to the chimney for CTN and RTN page 23
pic. 12 - Dimensions for connecting to the flue gas pipe for CTN page 23
pic. 13 - Air intake / flue gas discharge with coaxial ducts (CTFS and RTFS) page 25
pic. 14 - Dimensions for connecting to the coaxial air intake/flue gas discharge pipe (CTFS and RTFS) page 25
pic. 15 - Split kit 0SSDOPPIA03 (CTFS 24 and RTFS 24) page 26
pic. 16 - Split kit 0SSDOPPIA06 (CTFS 28 and RTFS 28) page 26
pic. 17 - Air intake / flue gas discharge with split ducts (CTFS and RTFS) page 27
pic. 18 - Dimensions for connecting to the split air intake/flue gas discharge pipes page 27
pic. 19 - Examples of installation of split air intake / flue gas discharge pipes page 28
pic. 20 - Examples of installation of split air intake / flue gas discharge pipes page 28
pic. 21 - Opening the panel page 28
pic. 22 - “Chimney-sweep” function page 29
pic. 23 - Examples of combustion efficiency measuring points page 29
pic. 24 - Gas mains connection page 29
pic. 25 - Adjustable by-pass page 30
pic. 26 - Installation of the Open Therm remote control page 31
pic. 27 - P6 trimmer position – thermoregulation curves page 32
pic. 28 - Central heating curves in operation with external probe page 32
pic. 29 - Electric layout page 34
pic. 30 - Gas conversion – gas selection jumper page 35
pic. 31 - Gas conversion – gas valve modulation coil page 35
pic. 32 - Gas conversion – pressure test point page 35
pic. 33 - Gas conversion – control panel settings page 35
pic. 34 - Gas conversion – gas valve adjustment page 35
LIST OF TABLES
No. 1 table - Colour displayed by Light in relation to boiler operation status page 8
No. 2 table - Colour displayed by Light in relation to boiler malfunction status page 8
No. 3 table - Calibration data for CTN 24 and RTN 24 page 18
No. 4 table - Calibration data for CTFS 24 and RTFS 24 page 18
No. 5 table - Calibration data for CTFS 28 and RTFS 28 page 18
No. 6 table - General data for each model page 19
No. 7 table - Combustion data for CTN 24 and RTN 24 page 19
No. 8 table - Combustion data for CTFS 24 and RTFS 24 page 19
No. 9 table - Combustion data for CTFS 28 and RTFS 28 page 19
No. 10 table - Relation between temperature (°C) and nominal resistance (Ohm) of CH probe SR and DHW probe SS page 34

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1. INSTRUCTIONS FOR THE USER
1.1. Control panel
1. Power mains connection light (green)
This light indicates that the power supply to the boiler is on.
2. Indicator light (red)
When this light is on, it means the temperature of the water in the heating system is between 25°C and 35°C.
When this light is flashing, it means the boiler has shut down due to a malfunction.
3. Indicator light (red)
When this light is on, it means the temperature of the water in the heating system is between 36°C and 45°C.
When this light is flashing, it means the boiler’s safety thermostat has shut the boiler down.
4. Indicator light (red)
When this light is on, it means the temperature of the water in the heating system is between 46°C and 55°C.
When this light is flashing, it means there is a fault in the exhaust system (CTN and RTN models) or in the air intake and/or flue discharge piping
(CTFS and RTFS models).
5. Indicator light (red)
When this light is on, it means the temperature of the water in the heating system is between 56°C and 65°C.
When this light is flashing, it means the burner has shut down.
6. Indicator light (red)
When this light is on, it means the temperature of the water in the heating system is between 66°C and 75°C.
When this light is flashing, it means the water pressure in the boiler is too low.
7. Indicator light (red)
When this light is on, it means the temperature of the water in the heating system is between 76°C and 85°C.
When this light is flashing, it means the CH temperature is above 85°C.
8. Indicator light (yellow)
When this light is on, it means the flame is present on the burner.
When this light is flashing, it means the boiler has shut down due to a malfunction.
9. Boiler mode
When the knob is in the OFF position the boiler is in stand-by mode.
When the knob is in the SUMMER position , the boiler supplies DHW only.
When the knob is in the WINTER position , the boiler supplies both CH and DHW.
When the knob is in the ANTI-FREEZE position , only the boiler anti-freeze function is active.
When the knob is turned to the RESET position and back , the boiler resumes operation.
10. DHW temperature regulator
This knob is used to set the DHW temperature within the range 35 - 57°C.
WARNING
The boiler has a special built-in regulator that limits DHW flow up to 10 litres per minute. In addition to the DHW temperature set on this regu-
lator, the DHW temperature also depends on the amount of water requested by the user and the supply temperature.
11. CH temperature adjustment
This knob is used to set the temperature of the water in the heating system. The setting range is 35 - 78°C.
12. Water pressure gauge
The water pressure gauge indicates the pressure of the water in the heating system.
pic. 1 - Control panel
1 2 3 4 5 6 7 8 9 10 11
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COLOUR DISPLAY ACCORDING TO BOILER STATUS
Regular Working LIGHT 1 LIGHT 2 LIGHT 3 LIGHT 4 LIGHT 5 LIGHT 6 LIGHT 7 LIGHT 8
Power connected to boiler Green n/a n/a n/a n/a n/a n/a n/a
Burner on Green n/a n/a n/a n/a n/a n/a Yellow
CH temperature < 25°C Green OFF OFF OFF OFF OFF OFF n/a
26°C < CH temperature < 35°C Green Red OFF OFF OFF OFF OFF n/a
36°C < CH temperature < 45°C Green OFF Red OFF OFF OFF OFF n/a
46°C < CH temperature < 55°C Green OFF OFF Red OFF OFF OFF n/a
56°C < CH temperature < 65°C Green OFF OFF OFF Red OFF OFF n/a
66°C < CH temperature < 75°C Green OFF OFF OFF OFF Red OFF n/a
76°C < CH temperature < 85°C Green OFF OFF OFF OFF OFF Red n/a
No. 1 table – Colour displayed by Light in relation to boiler operation status
Malfunction LIGHT 1 LIGHT 2 LIGHT 3 LIGHT 4 LIGHT 5 LIGHT 6 LIGHT 7 LIGHT 8
Power is missing OFF OFF OFF OFF OFF OFF OFF OFF
Safety thermostat shutdown Green OFF Red L OFF OFF OFF OFF OFF
Flue gas thermostat shutdown (CTN)
Air/flue gas pressure switch shutdown (CTFS) Green OFF OFF Red
L OFF OFF OFF OFF
Shutdown due to flame absence Green OFF OFF OFF Red L OFF OFF OFF
Water pressure switch shutdown Green OFF OFF OFF OFF Red L OFF OFF
Gas valve alarm Green OFF Red L OFF OFF OFF OFF Yellow L
Water temperature switch alarm (>85 °C) Green OFF OFF OFF OFF OFF Red L OFF
DHW flow probe alarm Green Red L OFF OFF OFF OFF OFF OFF
CH flow probe alarm Green Red L OFF OFF OFF OFF OFF Yellow L
Externalcylinderprobealarm Green Red LA OFF OFF OFF OFF OFF Yellow LA
Remote control malfunction Green OFF OFF Red L OFF OFF OFF Yellow L
No. 2 table – Colour displayed by Light in relation to boiler malfunction status
KEY TO ACRONYMS
OFF LIGHT off
RED LIGHT on, displaying the colour shown on the table
L RED LIGHT or lights flashing, displaying the colour shown on the table
LA RED LIGHTS flashing, displaying in sequence the colours shown on the table
n/a LIGHT status not relevant
1.2. Operating the boiler
1.2.1. Switching on
These instructions presuppose that the boiler has been installed by an authorized fitter, started up for the first time
and set up for correct operation.
• Open the gas stop cock.
• Connect the boiler to the mains power supply (LIGHT 1on the control panel comes on).
• Choose boiler mode by operating the “OFF/SUMMER/WINTER/ANTI-FREEZE” selector (9).
• Turn the CH temperature adjustment knob (11) to set the temperature required for the heating system.
• Turn the DHW temperature knob (10) to set the temperature required for the DHW (CTN, CTFS).
• Set the room temperature on the thermostat, if there is one.
WARNING: If the boiler is not used for a long time, particularly if it runs on LPG, ignition may be difficult.
Before operating the boiler, switch on another gas-powered device (e.g. kitchen range or oven). Be aware that even if this procedure
isfollowed,theboilermaystillexperiencesomestartingdifficultiesandshutdownonceortwice.
Reset the boiler by operating knob (9), then turn the knob back to the required position.

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1.2.2. Operation
CENTRAL HEATING
Use the regulation knob (11, pic. 1) to set the temperature in the central heating system.
The temperature setting range is 35-78°C (from the counter-clockwise limit position to the time limit position).
The CH temperature can be read from lights 2÷7 (pic. 1) on the control panel.
To prevent frequent ignition and switching off in heating mode, the boiler has a 4-minute waiting time between subsequent ignitions.
If the water temperature in the system fall below 40°C, waiting procedure is aborted and the boiler re-ignites (Antifast function).
DHW
The domestic hot water supply function is active on models CTN and CTFS, and on models RTN and RTFS with an (optional) external water
heater. This function always has priority over central heating water.
For models CTN and CTFS, the temperature setting range is 35-57°C (from the counter-clockwise limit position to the time limit of regulation
knob 10).
For models RTN and RTFS with an (optional) external water heater with an NTC probe (10 kΩ @ β=3435; refer to the water heater specifica-
tions), the temperature setting range is 35-57°C (from the counter-clockwise limit position to the time limit of regulation knob 10).
For models RTN and RTFS with an (optional) external water heater with thermostat probe, the desired HDW temperature must be set on the
water heater (refer to the attached instructions). Regulation knob 10 has no effect on this configuration.
The boiler is fitted with a flow-limiting device that allows a maximum DHW flow of 10 litres per minute.
The DHW flow rate depends on the boiler’s thermal capacity and the mains water supply temperature, and can be calculated from the fol-
lowing formula:
K
l = DHW litres per min. = ---
ΔT
K represents:
- 334 (CTN 24)
- 341 (CTFS 24)
- 410 (CTFS 28)
ΔT = DHW temperature – mains water supply temperature
E.g. In model CTFS 24, if the mains water supply temperature is 8°C and DHW is required at 38°C, the value of ΔT is:
ΔT = 38°C – 8°C = 30°C
and DHW litres (l per minute) available at the required temperature of 38°C is
I = 341 / 30 = 11.4 [litres per minute - mixed water to the tap]
ANTI-FREEZE
This boiler is fitted with an anti-freeze protection system, which works when the following functions are activated: SUMMER, WINTER and
ANTI-FREEZE.
The anti-freeze function only protects the boiler, not the whole heating system.
The heating system must be protected using a room thermostat, although this is disabled when the selector is set
to the ANTI-FREEZE or OFF mode.
Therefore, if you want to protect both the boiler and the system, turn to WINTER mode on selector 9.
When the heating water temperature sensor detects a water temperature of 5°C, the boiler switches on and stays on at its minimum thermal
power until the temperature reaches 30°C or 15 minutes have elapsed. The pump continues to operate even if the boiler shuts down.
In models CTN and CTFS, anti-freeze function also protects the DHW circuit.
When the DHW temperature sensor detects a temperature of 5°C, the boiler switches on and stays on at its minimum thermal power until the
temperature reaches 10°C or 15 minutes have elapsed (the deviating valve is in the DHW position). The pump continues to operate even if the
boiler shuts down.

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In boilers with an external heater for the supply of domestic hot water, which have a thermostat-type temperature sensor, the anti-freeze
function does NOT protect the water heater. It can be protected by setting the boiler to Summer or Winter , or by setting a value above
0°C on the water heater thermostat.
In CH boilers with an external water heater for the supply of domestic hot water, which have an NTC temperature sensor (10 kΩ @ β=3435;
refer to the boiler specifications), the anti-freeze function protects the water heater as well.
When the external cylinder temperature sensor detects a water temperature of 5°C, the boiler switches on and stays on at its minimum thermal
power until the temperature of the water in the external cylinder reaches 10°C or 15 minutes have elapsed. The pump continues to operate
even if the boiler shuts down.
The CH system can be protected effectively against freezing by means of specific anti-freeze additives suitable for use in multi-metal
systems.
Do not use car engine anti-freeze products, and periodically check the effectiveness of the anti-freeze product.
PUMP ANTI-BLOCKING FUNCTION AND DEVIATING VALVE
If the boiler remains inactive for long time and
• knob 9is not on OFF,
• the boiler is not electrically disconnected from the mains,
the circulation pump (for all models) and the deviating valve (for models CTN and CTFS only) are automatically activated for a while every 24
hours to prevent them from blocking.
1.2.3.Externaltemperatureprobeoperation(optional)
The boiler can be equipped with an (optional) external temperature probe, by means of which the boiler adjusts the CH water temperature
according to the outdoor temperature, in other words, increasing the CH water temperature when the outdoor temperature decreases, and
vice-versa. This increases energy-saving operation (this boiler mode is called“sliding temperature operation”).
The boiler microprocessor program determines CH water temperature variations.
When an external temperature probe is connected to the boiler, the CH water temperature adjusting knob (11, pic. 1) loses its function and
becomes a room temperature control device.
When knob 11 is turned fully counter-clockwise, the room temperature setting is 15°C; when set to 9 o’clock, the temperature is 18°C; when
set to 12 o’clock, the temperature is 25°C; when set to 3 o’clock the temperature is 32°C; when it is turned fully clockwise the temperature is
35°C.
For the best curve setting, it is advisable to set the temperature at around 20°C.
Picture 2 shows the curves for af room temperature of 20°C. As this value is increased via the regulation knob 11, the curves move upwards.
With this setting, if for example you select the curve corresponding to coefficient 1, with an outdoor temperature of -4°C, the flow temperatu-
re will be 50°C.
Refer to subsection 3.2.15 for detailed sliding temperature operation.
pic. 2 - Temperature regulation curves External temperature (°C)
CH flow temperature (°C)
Thermoregulation curves
coefficient

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1.3. Boiler shut-down
If a malfunction occurs, the boiler automatically shuts down.
Refer to tables 1 and 2 for boiler status.
In order to determine the probable causes of the malfunction, refer to section 6 - Troubleshooting - at the end of this manual (in addition to
tables 1 and 2).
Follow the procedure described for the type of shut-down.
1.3.1. Burner shut-down
When the burner shuts down because the flame has gone out, light 5 (red) starts flashing. If this happens, proceed as follows.
• Check that the gas stopcock is open, and make sure the gas main is actually providing service by lighting a gas-powered kitchen appliance
such as a kitchen range or oven.
• Once the presence of gas has been veried, reset the burner by turning knob 9to the RESET position for 2 seconds, and then to the
desired operating mode. If the boiler does not shut down, and you have performed the reset procedures three times, contact an authorized
Service Centre or a qualied service engineer.
Should frequent burner shut-down occur, a recurrent malfunction may be present. Contact an authorized Service Centre or a qualied service
engineer.
1.3.2. Shut-down due to overheating
When the CH water gets too hot, the boiler shuts down, and light 3(red) starts flashing.
If this happens, contact an authorized Service Centre or a qualied service engineer.
1.3.3. Shut-down due to incorrect draught (clogging) of the flue system
If the burner shuts down due to a malfunction of the flue system (models CTN and RTN ) or the air intake and/or flue discharge piping (models
CTFS or RTFS), light 4starts to flash. If this happens, contact a Service Centre or a qualified service engineer.
1.3.4. Shut-down due to low water pressure
If red shout-down light 6comes on, it indicates low water pressure and intervention of the low water pressure switch.
Fill the boiler by opening tap А(рiс. 3): the water pressure must be 1÷1.3 bar when the boiler is cold.
In the event of low water pressure shut-down, proceed as follows:
• Turn the filling tap (pic. 3) counter-clockwise in order to let the water in.
• Leave the tap on until the water pressure gauge reads 1÷1.3 bar.
• Turn the tap off clockwise.
• Reset the burner by turning knob 9to the RESET position for 2 seconds, and then to the desired operating mode.
If boiler shuts down frequently, it means the boiler is malfunctioning. Contact an authorized Service Centre or a qualified service
engineer.
Once the loading procedure has been completed, turn of the filling tap properly. If this isn’t done, the boiler CH safety
valve may open and water will flow out as the pressure increases.
1.3.5. Shut-down due to temperature probe malfunction
If the burner shuts down due to temperature probe malfunction, the following lights start to flash:
• Red light no. 2 and yellow light no. 8 when CH probe malfunction occurs.
• Red light no. 2 when DHW probe malfunction occurs.
• Red light no. 2 and yellow light no. 8 (flashing alternately) for external cylinder probe (models RTN and RTFS with external boiler and NTC
temperature probe).
If this happens, contact a Service Centre or a qualified service engineer.
Filling tap
pic. 3 - Filling tap

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1.4. Maintenance
Routine boiler maintenance must be provided according to the applicable laws in the country of installation and following the instructions
given in the relevant section in this manual. Correct maintenance ensures that the boiler operates efficiently, is environmentally friendly, and
is not a danger to people, animals or property.
By law, only qualified personnel are allowed to service the boiler.
The Manufacturer recommends that Customers contact an authorized Service Centre for maintenance and repairs.
For maintenance interventions, refer to section 5 – Maintenance.
Theexternalboilerhousingmustonlybecleanedwithstandardhouseholdcleaningproducts.
Do not use water!
1.5. Notes for the user
The user may only access boiler parts that can be reached without using any technical equipment or tools. The user is not authorized
to remove the boiler housing or touch any of the internal parts.
No one, including qualified service engineers, is authorized to modify the boiler.
The manufacturer can not be held liable for damage to people, animals, or property due to tampering or improper work done to the boiler.
If the boiler remains inactive and the power supply disconnected for a long time, the pump may not operate.
Pump servicing includes removing the boiler housing and accessing the internal parts of the boiler, so this must only be done by a
qualified service engineer.
Pump blockage can be avoided by adding to the water lming additives suitable for multi-metal systems.
2. TECHNICAL CHARACTERISTICS AND DIMENSIONS
2.1. Technical characteristics
The boiler is equipped with an atmospheric burner. All versions are equipped with electronic ignition and ionization flame control.
The following models of boiler are available:
- CTN 24: open chamber and natural draught, electronic ignition and instant DHW supply (23.31 kW)
- RTN 24: open chamber and natural draught, electronic ignition, CH supply only (23.31 kW)
- CTFS 24: sealed chamber and forced draught, electronic ignition and instant DHW supply (23.77 kW)
- RTFS 24: sealed chamber and forced draught, electronic ignition, CH supply only (23.77 kW)
- CTFS 28: sealed chamber and forced draught, electronic ignition and instant DHW supply (28.6 kW)
- RTFS 28: sealed chamber and forced draught, electronic ignition, CH supply only (28.6 kW)
All models comply with the Directives issued in the country of destination indicated in the rating plate.
Installation in a country other than the specified one may be a source of danger for people, animals and property.
The main technical characteristics of the boiler are listed below:
Construction characteristics
- IPX4D electrically protected control panel
- Modulating electronic safety board
- Electronic ignition with external separate transformer and ionization flame detection
- Stainless steel multi-gas atmospheric burner
- Modulating gas valve with double shutter
- Mono-thermal, high performance, copper heat exchanger
- Stainless steel DHW heat exchanger (models CTN and CTFS)
- Motorized deviating valve (models CTN and CTFS)
- Three-speed circulation pump, equipped with a de-aerator
- Low water safety pressure switch
- 8-litre expansion vessel
- DHW priority flow switch (models CTN and CTFS)
- 10 litres/min DHW flow limiting device (models CTN and CTFS)
- Adjustable by-pass
- Boiler filling and draining taps
- CH (all models) and DHW (models CTN and CTFS) temperature probes
- Safety limit thermostat
- Flue thermostat (models TN)
- Flue pressure switch (models TFS)

13
User interface
- RESET, STANDBY, SUMMER/WINTER, SUMMER and ANTIFREEZE function selector
- CH temperature switch (35 -78°C)
- DHW temperature switch for models C and R equipped with external cylinder and NTC temperature probe (35 - 57°C)
- Leds indicating water temperature
- Water pressure gauge
- Lights indicating:
• Mains power connection
• Flame presence
• Burner shut-down
• Burner shut-down due to overheating
• Burner shut-down due to incorrect flue draught (models TN)
• Burner shut-down due to flue pressure switch intervention (models TFS)
• Low water pressure
• CH or DHW temperature probe fault
• Remote control connection fault
Operating characteristics
- CH mode electronic flame modulation, timer-controlled flame rising ramp (50 seconds)
- DHW mode electronic flame modulation, timer-controlled flame rising ramp (for models C and R equipped with external cylinder and NTC
temperature probe)
- DHW priority function
- CH flow anti-freeze function (ON: 5°C, OFF: 30°C or after 15 min. operation)
- DHW flow anti-freeze function (ON: 5°C, OFF: 10°C or after 15 min. operation; for models C and R equipped with external cylinder and NTC
temperature probe)
- External boiler anti-freeze function (ON: 5°C, OFF: 10°C or after 15 min. operation; only for model R equipped with external cylinder and NTC
temperature probe)
- “Anti–Legionnaires’ disease ” function (only for model R equipped with external cylinder and NTC temperature probe)
- Timer-controlled “chimney sweep” function (15 minutes)
- Flame propagation function during ignition
- CH max heat output adjusting trimmer
- Ignition heat output adjusting trimmer
- Timer-controlled room thermostat (240 seconds when CH flow temperature > 40°C)
- Pump post-circulation function in CH, anti-freeze or chimney sweep mode (180 seconds)
- Pump post-circulation function in DHW (30 seconds)
- CH temperature post-circulation function: > 85°C: 30 seconds
- Safety post-circulation function (ON: 95°C; OFF: 90°C – models TFS)
- Pump and deviating valve anti-locking function (180 seconds operation after 24 hours of boiler inactivity)
- Can be connected to a room thermostat (optional)
- Can be connected to an external temperature probe (optional supplied by the Manufacturer)
- Can be connected to an Open Therm remote control (optional supplied by the Manufacturer)
- Can be connected to a cylinder timer connection (only for model R equipped with external cylinder and NTC temperature probe)

14
2.2. Dimensions
G
450
750
325
131
218232
138
177
43 56 98 75 98 80
C
FR
M
G
RS
RC
SV
G Gas intake
M CH flow
C DHW flow (CTN only)
F Mains water intake
R CH return
RC Filling tap
RS Discharge tap
SV 3bar safety valve discharge tap
CTN and RTN models
bottom view top view
pic. 4 - Dimensions mod. CTN and RTN

15
450
750
325
134
120 85
165
85
138
177
43 56 98 75 98 80
GM
C
FR
RC
RS
165
SV
G Gas intake
M CH flow
C DHW flow (CTFS only)
F Mains water intake
R CH return
RC Filling tap
RS Discharge tap
SV 3bar safety valve discharge tap
CTFS and RTFS models
pic. 5 - Dimensions mod. CTFS and RTFS
bottom view top view

16
2.3. Plumbing layout and gas connections
1. DHW temperature probe
2. Gas valve
3. CH temperature probe
4. Burner nozzles
5. Burner
6. Ignition electrode
7. Safety thermostat
8. Secondary heat exchanger plate
9. Extractor hood
10. Flue gas safety thermostat
11. De-aerator
12. Flame detection electrode
13. Expansion vessel
14. Pump
15. Filling tap
16. Water pressure switch
17. Safety valve
18. DHW flow limiting device (max. 10 litres
/minute)
19. Flow switch
20. Mains water inlet filter
GGas intake
MCH flow
CDHW flow
F Mains water intake
RCH return
1. DHW temperature probe
2. Gas valve
3. CH temperature probe
4. Burner nozzles
5. Burner
6. Ignition electrodes
7. Safety thermostat
8. Mono-thermal heat exchanger
9. Sealed combustion chamber
10. Flue gas extraction fan
11. Flue gas pressure test point
12. Flue gas pressure safety switch
13. Air intake/flue gas pipe
14. Flue gas pressure test point
15. Flame detection electrode
16. Expansion vessel
17. De-aerator
18. Pump
19. Filling tap
20. Water pressure switch
21. Safety valve
22. DHW flow limiting device (max. 10 litres
/minute)
23. Flow switch
24. Mains water inlet filter
25. Secondary heat exchanger plate
26. Adjustable by-pass
27. Three-way valve
GGas intake
MCH flow
CDHW flow
F Mains water intake
RCH return
CTN 24
2
3
4
5
7
8
1
10
9
6
11
13
14
16
15
17
18
19
20
12
pic. 6 - Plumbing diagram for CTN 24
CTFS 24/28
1
13
2
3
4
5
6
7
8
9
10
11
12
14
15
17
16
18
20
19
22
23
24
25
26
27
21
pic. 7 - Plumbing diagram for CTFS 24/28

17
RTN 24 1. Expansion vessel
2. Gas valve
3. Burner nozzles
4. Expansion vessel filling tap
5. Ignition electrode
6. Heat exchanger
7. Extractor hood
8. Flue gas safety thermostat
9. Water pressure switch
10. Flame detection electrode
11. Safety thermostat
12. CH temperature probe
13. De-aerator
14. Pump
15. CH safety valve
GGas intake
MCH flow
F Mains water intake
RCH return
2
12
3
11
6
87
4
1
5
10
13
14
9
15
RTFS 24/28 1. Expansion vessel
2. Gas valve
3. Burner nozzles
4. Expansion vessel filling tap
5. Ignition electrode
6. Heat exchanger
7. Sealed combustion chamber
8. Flue gas extraction fan
9. Flue gas pressure test point
10. Air intake/flue gas pipe
11. Flue gas pressure micro-switch
12. Flue gas pressure safety switch
13. Flue gas pressure test point
14. Water pressure switch
15. De-aerator
16. Safety thermostat
17. Flame detection electrode
18. CH temperature probe
19. Pump
20. CH safety valve
GGas intake
MCH flow
F Mains water intake
RCH return
2
5
18
3
16
6
7
8
9
11
12 10
13
4
1
17
15
19
14
20
pic. 8 - Plumbing diagram for RTN 24
pic. 9 - Plumbing diagram for RTFS 24/28

18
2.4. Operating data
Burner pressures must be checked after the boiler has been operating for three minutes.
CTN 24 - RTN 24
Gas type Max.heat
input
Max.heat
output
Min. heat
output
Mains gas
pressure
Nozzle
diameter Burner pressure
(kW) (kW) (kW) (mbar) (mm) (mbar)
min max
Natural gas G 20 25.7 23.31 9.85 20 1.25 2.5 13.0
Butane gas G 30 25.7 23.31 9.85 29 0.77 5.3 27.0
Propane gas G 31 25.7 23.31 9.85 37 0.77 6.6 35.5
No. 3 table - Calibration data for CTN 24 and RTN 24
Hot water supply T 45°C = 7.4 l/min
Hot water supply T 40°C = 8.4 l/min
Hot water supply T 35°C = 9.6 l/min
Hot water supply T 30°C = 11.1 l/min *
Hot water supply T 25°C = 13.4 l/min *
*mixedwatertothetap
CTFS 24 - RTFS 24
Gas type Max.heat
input
Max.heat
output
Min. heat
output
Mains gas
pressure
Nozzle
diameter Burner pressure
(kW) (kW) (kW) (mbar) (mm) (mbar)
min max
Natural gas G 20 25.5 23.77 9.9 20 1.25 2.5 13.5
Butane gas G 30 25.5 23.77 9.9 29 0.77 5.3 27
Propane gas G 31 25.5 23.77 9.9 37 0.77 6.6 35.5
No. 4 table - Calibration data for CTFS 24 and RTFS 24
Hot water supply T 45°C = 7.6 l/min
Hot water supply T 40°C = 8.5 l/min
Hot water supply T 35°C = 9.7 l/min
Hot water supply T 30°C = 11.4 l/min *
Hot water supply T 25°C = 13.6 l/min *
*mixedwatertothetap
CTFS 28 - RTFS 28
Gas type Max.heat
input
Max.heat
output
Min. heat
output
Mains gas
pressure
Nozzle
diameter Burner pressure
(kW) (kW) (kW) (mbar) (mm) (mbar)
min max
Natural gas G 20 30.5 28.6 12.3 20 1.35 2.6 12.0
Butane gas G 30 30.5 28.6 12.3 29 0.80 4.7 28.9
Propane gas G 31 30.5 28.6 12.3 37 0.80 6 33.4
No. 5 table - Calibration data for CTFS 28 and RTFS 28
Hot water supply T 45°C = 9.1 l/min
Hot water supply T 40°C = 10.2 l/min*
Hot water supply T 35°C = 11.7 l/min*
Hot water supply T 30°C = 13.7 l/min *
Hot water supply T 25°C = 16.4 l/min *
*mixedwatertothetap

19
2.5. General characteristics
CTN 24 RTN 24 CTFS 24 RTFS 24 CTFS 28 RTFS 28
Category - II2H3+ II2H3+ II2H3+
Burner nozzles no. 12 12 13
Minimum CH flow rate l/h 550 550 670
Minimum CH pressure bar 0.5 0.5 0.5
Maximum CH pressure bar 3 3 3
Minimum DHW pressure bar 0.3 - 0.3 - 0.3 -
Maximum DHW pressure bar 8 - 8 - 8 -
DHW specific capacity (t 30 °C) l/min 11.1 - 11.4 - 13.7 -
Electrical power supply – voltage / frequency V ~ Hz 230 ~ 50 230 ~ 50 230 ~ 50
Power mains supply fuse A 2 2 2
Maximum power consumption W 90 130 150
Net weight kg 36.5 34.5 40.3 38.0 41.0 38.5
Natural gas consumption (*) m3/h 2.72 2.70 3.23
Butane gas consumption kg/h 2.02 2.01 2.40
Propane gas consumption kg/h 1.99 1.98 2.36
Maximum CH working temperature °C 83 83 83
Maximum DHW working temperature °C 62 - 62 - 62 -
Total capacity of expansion vessel l 8 8 8
Maximum recommended CH system capacity (**)
l 160 160 160
No. 6 table - General data for each model
(*) Value related to 15°C – 1013 mbar condition
(**) Maximum water temperature of 83°C, expansion vessel pressure 1 bar
CTN 24 - RTN 24 maxheatoutput min heat output 30% heat output
Boiler casing heat loss % 0.8 0.8 -
Flue system heat loss with burner on % 8.5 9.7 -
Flue system mass capacity g/s 16.2 13.7 -
Flue temp.– air temp. °C 85 50 -
CO2% 6.2 3.0 -
Boiler efficiency rate % 90.7 89.5 88.7
Efficiency rating (according to 92/42/CE) - ★★
NOx emission class - 2
CTFS 24 - RTFS 24 maxheatoutput min heat output 30% heat output
Boiler casing heat loss % 0.23 0.23 -
Flue system heat loss with burner on % 6.57 9.27 -
Flue system mass capacity g/s 12.9 14.0 -
Flue temp.– air temp. °C 98 60 -
CO2% 7.7 2.9 -
Boiler efficiency rate % 93.2 90.5 90.2
Efficiency rating (according to 92/42/CE) - ★★★
NOx emission class - 2
CTFS 28 - RTFS 28 maxheatoutput min heat output 30% heat output
Boiler casing heat loss % 0.2 - -
Flue system heat loss with burner on % 6.1 8.5 -
Flue system mass capacity g/s 17.7 19.1 -
Flue temp.– air temp. °C 86 57 -
CO2% 7.1 2.7 -
Boiler efficiency rate % 93.7 91.5 91.2
Efficiency rating (according to 92/42/CE) - ★★★
NOx emission class - 3
No. 7 table - Combustion data for CTN 24 and RTN 24
No. 8 table - Combustion data for CTFS 24 and RTFS 24
No. 9 table - Combustion data for CTFS 28 and RTFS 28

20
3. INSTRUCTIONS FOR THE FITTER
3.1. Installation standards
This is a II2H3+ boiler which must be installed in compliance with the applicable laws and standards in the country of installation.
3.2. Installation
Accessories and spare parts for installation and service procedures must be supplied by the Manufacturer.
The boiler cannot be guaranteed to operate properly if non-original accessories or spare parts are used.
3.2.1. Packaging
The boiler is delivered in a sturdy cardboard box. Remove the boiler from the box and check it for damage. The packing materials
can be recycled and should be disposed of at an appropriate waste collection site. Keep all packaging out of reach of children,
as it can be a health risk.
The Manufacturer can not be held liable for injury to people or animals or damage to property due to failure to follow the above
instructions.
The following is delivered together with the boiler:
• copper pipe kit for plumbing and gas connections;
• metal template for fixing the boiler to the wall;
• one plastic bag containing:
a) this installation, use and maintenance manual;
b) paper template for wall mounting the boiler (pic. 10);
c) two screws and wall plugs for fixing the boiler to the wall;
d) with model TFS 24: three diaphragms for flue gas exhaust (40, 42, and 45 mm diameters);
e) with model TFS 28: five diaphragms for flue gas exhaust (41, 44, 45, 47 and 49 mm diameters);
f) with model TFS: two closing caps with gaskets.
3.2.2. Deciding where to install the boiler
The following must be taken into account when deciding where to install the boiler:
• Refer to Subsections 3.2.6 and 3.2.7.
• Check the wall is strong enough to support the weight of the boiler.
• Do not fit the boiler above any equipment that may affect operation (kitchen appliances that emit steam or greasy vapour,
washing machines, etc.).
• Do not install natural draught boilers in corrosive or very dusty atmosphere areas, such as hairdressing salons or laundries as
this would greatly reduce the boiler’s lifespan.
3.2.3. Positioning the boiler
Each boiler is supplied with a paper “TEMPLATE” (pic. 10) for positioning the pipes for connecting the CH system, DHW system
and gas supply to the boiler and to the air intake/flue gas pipes before installing the boiler itself.
The TEMPLATE is made of heavy-duty paper and must be fixed onto the wall where the boiler is to be mounted. During installa-
tion it is advisable to use a spirit level. The template provides all the indications required for drilling the holes for fixing the boiler
to the wall, which is done using two screws and wall plugs.
The lower part of the TEMPLATE shows where to mark the exact point at which the couplings must be positioned for connecting
the boiler to the gas supply pipe, mains water supply pipe, DHW flow pipe, CH flow and return pipe.
The upper part shows the coupling positions for the air intake/flue gas pipes.
  Sincethetemperatureofthewallsonwhichtheboilerismountedandthetemperatureofthecoaxial
  fluesystemdonotexceed60°C,thereisnoneedtokeeptoaminimumdistancefromflammablewalls.
For boilers with split pipe flue system, in the presence of flammable walls and a flue gas system through
such walls, ensure proper insulation between wall and flue gas pipes.