Ariston Clas 24 FF User guide

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INDEX
General Information................................................................................................... 3
General Information...................................................................................................... 3
Control Panel.................................................................................................................... 4
Overall wiew..................................................................................................................... 5
Technical Information................................................................................................... 6
Installation ..............................................................................................8
Reference Standards ..................................................................................................... 8
Sitting the appliance..................................................................................................... 8
Overall dimensions........................................................................................................ 9
Clearences......................................................................................................................... 9
Monting the appliance...............................................................................................10
Electrical connection...................................................................................................10
Gas Connection.............................................................................................................11
Water connection.........................................................................................................11
Pipe work.........................................................................................................................11
By-pass .............................................................................................................................11
System design ...............................................................................................................11
Drain Cocks.....................................................................................................................11
Safety valve discharge................................................................................................12
Air release points..........................................................................................................12
Main water feed - Central Heating.........................................................................12
Domestic Water.............................................................................................................12
Flue connection ............................................................................................................13
Fitting the coaxial flue ................................................................................................14
Fitting 80/125 Flue.......................................................................................................15
Fitting the flue (Twin pipe) .......................................................................................17
Electrical connection...................................................................................................21
Peripheral unit connection.......................................................................................21
Room Thermostat connection.................................................................................22
Outdoor sensor connection .....................................................................................22
Wiring Diagram for connection to an open Vented Cylinder.......................23
Wiring Diagram for connection to an MTS Vented Cylinder.........................24
Electrical diagram.........................................................................................................25
Water circuit diagram..................................................................................................27
Commissioning .....................................................................................28
Ignition preparation....................................................................................................28
Initial start-up ................................................................................................................28
De-aeration cycle .........................................................................................................28
Checking the gas settings.........................................................................................29
Supply working pressure check..............................................................................29
Checking the maximum power...............................................................................29
Checking the minimum power ...............................................................................29
Checking the maximum c.h. power.......................................................................30
Soft Light adjustment.................................................................................................30
Ignition Delay adjustment ........................................................................................30
Adjustment the Maximum absolute Heating power ......................................30
Gas table..........................................................................................................................31
Gas changeover ............................................................................................................31
Auto function.................................................................................................................32
Boiler protection devices.....................................................................33
Safety shut-off ...............................................................................................................33
Shutdown........................................................................................................................33
Malfunction warning ..................................................................................................33
Table summarising error codes...............................................................................33
Anti-frost device ...........................................................................................................34
Combustion Analysis ..................................................................................................34
Product of combustion Discharge Monitoring .................................................34
Flue test mode...............................................................................................................34
settings - adjustment - problem identication menus......................35
Menu 2 - Boiler parameter ........................................................................................36
Menu 3 - Boiler with storage and boiler with solar kit....................................37
Menu 4 - Zone 1 parameter......................................................................................38
Menu 5 - Zone 2 parameter......................................................................................39
Menu 7 - Test & Utilities..............................................................................................40
Menu 8 - Service Parameter......................................................................................40
Maintenance .........................................................................................42
General comments ......................................................................................................42
Operational test ............................................................................................................42
Draining procedures ...................................................................................................42
Draining the D.H.W. system and indirect cylinder............................................42
Draining the System....................................................................................................43
Completion.....................................................................................................................43
Operational Checks .....................................................................................................43
Instructing the end user ............................................................................................43
Maintenance Guide ..............................................................................44
General access...............................................................................................................44
Electrical unit .................................................................................................................45
Control box access.......................................................................................................45
Fuse ...................................................................................................................................45
Main P.C.B. .......................................................................................................................46
Display P.C.B....................................................................................................................46
Hydraulic unit ................................................................................................................47
Richt hand hydraulic block assembly....................................................................47
3 way valve .....................................................................................................................48
Draining ...........................................................................................................................48
Automatic air vent........................................................................................................49
Primary water pressure sensor ................................................................................49
Pump.................................................................................................................................50
C.H. Filter..........................................................................................................................50
D.H.W. flow switch assembly....................................................................................51
Left hand hydraulic block assembly......................................................................52
D.H.W. Temperature sensor.......................................................................................53
Safety valve.....................................................................................................................53
By-pass assmbly............................................................................................................54
Seconday exchanger...................................................................................................54
Temperature sensor & overheat thermostat ......................................................55
Main heat exchanger ..................................................................................................56
Burner unit......................................................................................................................57
Spark generator ............................................................................................................58
Elctrodes assembly ......................................................................................................58
Burner...............................................................................................................................59
Manifold...........................................................................................................................59
Fun.....................................................................................................................................60
Air pressure switch.......................................................................................................60
Gas valve .........................................................................................................................61
Annual Maintenance...................................................................................................62
Short List........................................................................................................................63
Benchmark - Gas boiler commissioning checklist .....................................65

3
general information
This manual is an integral and essential part of the product. It
should be kept with the appliance so that it can be consulted by
the user and our authorised personnel.
Please carefully read the instructions and notices about the unit
contained in this manual, as they provide important information
regarding the safe installation, use and maintenance of the
product.
For operating instructions please consult the separate Users
Manual.
General Instructions
Read the instructions and recommendations in these Installation
and Servicing Instructions carefully to ensure proper installation,
use and maintenance of the appliance.
Keep this manual in a safe place. You may need it for your own
reference while Servicing Technicians or your installer may need
to consult it in the future.
The CLAS FF is a combined appliance for the production of central
heating (C.H.) and domestic hot water (D.H.W. - FF models).
The CLAS FF SYSTEM is a system boiler designed for the production
of (C.H.) only.
These appliances are for domestic use only and must be used only
for the purpose for which they have been designed.
The manufacturer declines all liability for damage caused by
improper or negligent use.
No asbestos or other hazardous materials have been used in the
fabrication of this product.
Before connecting the appliance, check that the information
shown on the data plate and the table in section 7 comply with
the electric, water and gas mains of the property. You will find the
data plate on the reverse of the control panel.
The gas with which this appliance operates is also shown on the
label at the bottom of the boiler.
Do not install this appliance in a damp environment or close to
equipment which spray water or other liquids.
Do not place objects on the appliance.
Do not allow children or inexperienced persons to use the
appliance without supervision.
If you smell gas in the room, do not turn on or off light switches,
use the telephone or any other object which might cause sparks.
Open doors and windows immediately to ventilate the room.
Shut the gas mains tap (at or adjacent to the gas meter) or the
valve of the gas cylinder and call your Gas Supplier immediately.
Always disconnect the appliance either by unplugging it from
the mains or turning off the mains switch before cleaning the
appliance or carrying out maintenance.
In the case of faults or failure, switch off the appliance and turn off
the gas tap. Do not tamper with the appliance.
For repairs, call your local Authorised Servicing Agent and request
the use of original spare parts. For in-guarantee repairs contact
MTS (GB) Limited.

4
general information
CLAS 24 FF
CLAS 30 FF
1
2
3
4
5
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10
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6
12
I
1
2
3
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7
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15
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12
11
10
9
8
Legend
1. Display
2. RESET button
3. Red LED (illuminated = boiler lockout)
4. Heating System Pressure Gauge
5. Selector knob for Summer/Winter Central Heating
Temperature Adjustment Knob
6. Programming “-” key
7. MENU/OKbutton
8. ESC button
9. Programming “+” key
1
2
3
4
5
6
7
16
15
14
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11
9
8
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3
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24
9
6
12
I
10. Domestic Hot Water adjustment knob (COMBI models)
11. Time clock (optional)
12. ON/OFF Switch
13. “COMFORT” Function L.E.D (COMBI models)
Heating only L.E.D (SYSTEM models)
14. Green led (auto function activate)
15. AUTO button (to active Thermoregulation)
16. COMFORT button (COMBI models)
Heating only button (SYSTEM models)
CLAS SYSTEM 21 FF
CLAS SYSTEM 28 FF
Fig. 1
Fig. 2

5
general information
Overall wiew
Legend
1. Flue connector
2. Air pressure switch
3. Condensate trap
4. Main Heat Exchanger
5. Overheat thermostat
6. Flow temperature probe
7. Burner
8. Ignition electrodes
9. Gas valve
10. Spark generator
11. D.H.W. temperature probe
12. Safety valve (3 bar)
13. Secondary heat exchanger
14. Drain valve
15. D.H.W. Flow switch
16. Circulation Pump with air release valve
17. Water pressure sensor
18. Diverter valve
19. Detection Electrode
20. Combustion Chamber Insulation Panel
21. Combustion Chamber
22. Expansion vessel
23. Fan
24. Combustion Analysis Test Point
1
2
3
5
6
7
9
10
12
13 14 15
16
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18
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21
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24
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8
4
1
2
3
5
6
7
9
10
12
14
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17
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20
21
22
23
24
8
4
Fig. 3 Fig. 4
CLAS 24/30 FF CLAS SYSTEM 21/28 FF

6
general information
GEN. NOTES
Model Name CLAS 24 FF CLAS 30 FF
CE certification (pin) 1312BR4793 1312BR4793
Boiler type C12-C32-C42-C52-B22-B32
ELECTRICAL PERFORMANCE
Max/min nominal heat input(Hi) kW 25.8 / 11.0 30.0 / 13.0
Max/min nominal heat input (Hs) kW 28.7 / 12.2 33.3 / 14.4
Max/min nominal heat input for hot water (Hi) kW 27 / 11.0 31.3 / 13.0
Max/min nominal heat input for hot water (Hs) kW 30 / 12.2 34.8 / 14.4
Heat output: max/min kW 24.2 / 9.8 28.1 / 11.6
Heat output for hot water: max/min kW 26.2 / 9.8 29.5 / 11.6
Combustion efficiency (at flue) Hi/Hs % 95.0 93.9
Gross efficiency of nominal heat input (60/80 °C) Hi/Hs % 94.8 / 84.5 93.6 / 84.3
Gross efficiency at 30 % at 47°C Hi/Hs % 93.6 / 84.3 93.2 / 83.9
Gross efficiency at minimum power Hi/Hs % 89.2 / 80.3 89.3 / 80.4
Number of efficiency stars (Directive 92/42/EEC) stars *** ***
Rating Sedbuk Band / % class D D
Ma. heat loss to the casing (∆T = 50°C) % 0.4 0.3
Heat loss through the flue when burner on % 5.0 6.1
Heat loss through the flue when burner off % 0.4 0.4
EMISSIONS IN C.H.
Residual discharge head Pa 100 104
Nox class class 3 3
Flue fumes temperature (G20) °C 98 114
CO2 content2(G20) % 6.6 6.4
CO content (0 %02) ppm 40 92
O2 content2 (G20) % 8.7 8.9
Max Discharge of Products of Combustion (G20) kg/h 97 67.5
Excess air % 62.8 74
HEATING CIRCUIT
Load losses water side (max) ∆T=20°C mbar 200 200
Residual head for the system bar 0.25 0.25
Expansion vessel pre-charged pressure bar 1 1
Maximum central heating circuit pressure bar 3 3
Expansion vessel capacity l 8 8
Central heating temperature: max/min (Approx) °C 85 / 35 85 / 35
DOMESTIC HOT WATER CIRCUIT
Domestic hot water temperature max/min (Approx) °C 60 / 36 60 / 36
Specific flow rate of domestic hot water system (10 min. with ∆T=30°C)) instant boilers
l/min 12.5 14.1
D.H.W. flow rate ∆T=25°C l/min 15.0 16.9
D.H.W. flow rater ∆T=35°C l/min 10.7 12.1
Hot water comfort stars (EN13203) stars 3 3
D.H.W. minimum flow rate l/min 1.7 1.7
Domestic hot water pressure max bar 7 7
ROOMELECTRICAL
DATA
Power supply voltage/frequency V/Hz 230/50 230/50
Power consumption W 127 136
Minimum operating room temperature °C +5 +5
Electric system grades of protection IP X5D X5D
Weight kg 31 31
Dimensions (W x H x D) : mm 400/770/315 400/770/315
Technical Information

7
general information
GEN. NOTES
Model Name CLAS SYSTEM
21 FF
CLAS SYSTEM
28 FF
CE certification (pin) 1312BR4793 1312BR4793
Boiler type C12-C32-C42-C52-B22-B32
ELECTRICAL PERFORMANCE
Max/min nominal heat input(Hi) kW 25.8 / 11.0 30.0 / 13.0
Max/min nominal heat input (Hs) kW 28.7 / 12.2 33.3 / 14.4
Max/min nominal heat input for hot water (Hi) kW 27 / 11.0 31.3 / 13.0
Max/min nominal heat input for hot water (Hs) kW 30 / 12.2 34.8 / 14.4
Heat output: max/min kW 24.2 / 9.8 28.1 / 11.6
Combustion efficiency (at flue) Hi/Hs % 95.0 93.9
Gross efficiency of nominal heat input (60/80 °C) Hi/Hs % 94.8 / 84.5 93.6 / 84.3
Gross efficiency at 30 % at 47°C Hi/Hs % 93.6 / 84.3 93.2 / 83.9
Gross efficiency at minimum power Hi/Hs % 89.2 / 80.3 89.3 / 80.4
Number of efficiency stars (Directive 92/42/EEC) stars *** ***
Rating Sedbuk class D D
Ma. heat loss to the casing (∆T = 50°C) % 0.4 0.3
Heat loss through the flue when burner on % 5.0 6.1
Heat loss through the flue when burner off % 0.4 0.4
EMISSIONS IN C.H.
Residual discharge head mbar 100 104
Nox class class 3 3
Flue fumes temperature (G20) °C 98 114
CO2 content2(G20) % 6.6 6.4
CO content (0 %02) ppm 40 92
O2 content2 (G20) % 8.7 8.9
Max Discharge of Products of Combustion (G20) Kg/h 97 67.5
Excess air % 62.8 74
HEATING CIRCUIT
Load losses water side (max) ∆T=20°C mbar 200 200
Residual head for the system bar 0.25 0.25
Expansion vessel pre-charged pressure bar 1 1
Maximum central heating circuit pressure bar 3 3
Expansion vessel capacity l 8 8
Central heating temperature: max/min °C 85 / 35 85 / 35
DOMESTIC HOT WATER CIRCUIT
Domestic hot water temperature max/min (Approx) °C 60 / 36 60 / 36
ROOMELECTRICAL
DATA
Power supply voltage/frequency V/Hz 230/50 230/50
Power consumption W 127 136
Minimum operating room temperature °C +5 +5
Electric system grades of protection IP X5D X5D
Weight kg 31 31
Dimensions (W x H x D) : mm 400/770/315 400/770/315

8
installation
Reference Standards
The technical information and instructions provided herein below are
intended for the installer / Servicing Technician so that the unit may
be installed and serviced correctly and safely.
In the United Kingdom the installation and initial start up of the
boiler must be by a CORGI Registered Installer in accordance with the
installation standards currently in effect, as well as with any and all
local health and safety standards i.e. CORGI.
In the Republic of Ireland the installation and initial start up of the
appliance must be carried out by a Competent Person in accordance
with the current edition of I.S.813 “Domestic Gas Installations”, the
current Building Regulations, reference should also be made to the
current ETCI rules for electrical installation.
This appliance must be installed by a competent installer in accordance
with current Gas Safety (installation & use) Regulations.
The installation of this appliance must be in accordance with the
relevant requirements of the Local Building Regulations, the current
I.E.E. Wiring Regulations, the bylaws of the local water authority,
in Scotland, in accordance with the Building Standards (Scotland)
Regulation and Health and Safety document No. 635 “Electricity at
work regulations 1989”and in the Republic of Ireland with the current
edition of I.S. 813, the Local Building Regulations (IE).
C.O.S.H.H.
Materials used in the manufacture of this appliance are non-hazardous
and no special precautions are required when servicing.
Installation should also comply with the following British Standard
Codes of Practice
BS 7593:1992 Treatment of water in domestic hot
water central heating systems
BS 5546:1990 Installation of hot water supplies for
domestic purposes
BS 5440-1:2000 Flues
BS 5440-2:2000 Air supply
BS 5449:1990 Forced circulation hot water systems
BS 6798:1987 Installation of gas red hot water
boilers of rated input not exceeding
60kW
BS 6891:1989 Installation of low pressure gas pipe
up to 28mm
BS 7671:2001 IEE wiring regulations
BS 4814:1990 Specication for expansion vessels
BS 5482:1994 Installation of L.P.G.
and in the Republic of Ireland in accordance with the following Codes
of Practice:
I.S. 813 Domestic Gas Installations
Siting the Appliance
The appliance may be installed in any room or indoor area, although
particular attention is drawn to the requirements of the current I.E.E.
Wiring Regulations, and in Scotland, the electrical provisions of the
Building Regulations applicable in Scotland, with respect to the
installation of the combined appliance in a room containing a bath
or shower, the location of the boiler in a room containing a bath or
shower should only be considered if there is no alternative.
Where a room-sealed appliance is installed in a room containing a
bath or shower the appliance and any electrical switch or appliance
control, utilising mains electricity should be situated so that it cannot
be touched by a person using the bath or shower, specifically in
accordance with current IEE Wiring Regulations.
The location must permit adequate space for servicing and air
circulation around the appliance as indicated on page 9.
The location must permit the provision of an adequate flue and
termination.
For unusual locations special procedures may be necessary.
BS 6798-1987 gives detailed guidance on this aspect.
A compartment used to enclose the appliance must be designed
specifically for this purpose. No specific ventilation requirements are
needed for the installation within a cupboard.
This appliance is not suitable for outdoor installation.
The type C appliances (in which the combustion circuit, air vent intake
and combustion chamber are air-tight with respect to the room in
which the appliance is installed) can be installed in any type of room.
Secondary ventilation is not required with this boiler. The boiler must
be installed on a solid, non-combustible, permanent wall to prevent
access from the rear.

9
installation
Overall Dimensions
28
770
200
150
315
120 120
200
180
65 6567 67
25770
28
770
200
120 120
200
132 132
Legend:
A = Central Heating Flow (22mm nut & olive)
B = Domestic Hot Water Outlet (15mm nut & olive)
C = Gas Inlet (15mm)
D = Domestic Cold Water Inlet (15mm nut & olive)
E = Central Heating Return (22mm nut & olive)
Clearances
In order to allow access to the interior of the boiler for
maintenance purposes, the boiler must be installed in
compliance with the minimum clearances indicated in Fig. 6
A = 450 mm
B = 60 mm
C = 300 mm
D = 450 mm
E = 350 mm
D
BB
D
BB
A
C
A
E
Fig. 5
CLAS 24/30 FF
CLAS SYSTEM 21/28 FF
Fig. 6
CLAS SYSTEM 21/28 FF

10
installation
Mounting the Appliance
After removing the boiler from its packaging, remove the template
from the box. Note: Pay particular attention to any test water that
may spill from the appliance.
Place the template in the position the appliance is to be mounted
and after ensuring it is hanging squarely, use it to drill the holes for
the hanging bracket and flue pipe(s) NB: For further information
relating to the flue installation please refer to Flue Installation -
page 13. (If the appliance is to be fitted on a wall of combustible
material, the wall must be protected by a sheet of fireproof
material).
If the appliance is to be fitted into a timber framed building,
guidance should be sought from the Institute of Gas Engineers
document Ref: IGE/UP/7.
Drill the wall and plug using those supplied with the connections
kit, position the hanging bracket and secure with the wall bolts
supplied, assembl the connection kit and secure to the wall.
Position the appliance on the hanging bracket and connect the
valves to the boiler connections. (see also Gas Connections, Water
Connections - page 11).
Electrical Connection
For safety purposes, have a competent person carefully check the
electrical system in the property, as the manufacturer will not be
held liable for damage caused by the failure to earth the appliance
properly or by anomalies in the supply of power. Make sure that
the residential electrical system is adequate for the maximum
power absorbed by the unit, which is indicated on the rating
plate. In addition, check that the section of cabling is appropriate
for the power absorbed by the boiler.
The boiler operates with alternating current, as indicated in
the Technical Information tables on pages 6 and 7, where the
maximum absorbed power is also indicated. Make sure that the
connections for the neutral and live wires correspond to the
indications in the diagram. The appliance electrical connections
are situated on the reverse of the control panel.
Important!
In the event that the power supply cord must be changed, replace
it with one with the same specifications.
Note: The diagrams for the electrical system and external wiring
configurations can be found on pages ?? and ??.
Should external controls be required, the design of the external
electrical circuits should be undertaken by a competent person.
Warning, this appliance must be earthed.
External wiring to the appliance must be carried out by a
competent person and be in accordance with the current I.E.E.
Regulations and applicable local regulations.
The appliance is supplied with a fly-lead already connected,
this must be connected to a 240v supply fused at 3A and must
facilitate complete electrical isolation of the appliance, by the use
of a fused double pole isolator having a contact separation of at
least 3 mm in all poles or alternatively, by means of a 3 A fused
three pin plug and unswitched shuttered socket outlet both
complying with BS 1363.
The point of connection to the Electricity supply must be readily
accessible and adjacent to the appliance unless the appliance
is installed in a bathroom when this must be sited outside the
bathroom.
400
65676765
120
120
ø80
ø80
ø80
ø100
770
250
580 830
105
195
90
725
1/2"
1/2" 3/4"
3/4"
3/4"
195
105
120 180
105
315
150
180
315
150
ø 80 + ø 80 ø 60/100 - ø 80/125
300
50
20
330
Fig. 7

11
installation
Gas Connection
The local gas region contractor connects the gas meter to the
service pipe.
If the gas supply for the boiler serves other appliances ensure that
an adequate supply is available both to the boiler and the other
appliances when they are in use at the same time.
Pipe work must be of an adequate size. Pipes of a smaller size than
the boiler inlet connection must not be used.
Water Connections
View of the Boiler Connections
Legend:
A = Central Heating Flow
B = Domestic Hot Water Outlet
C = Gas Inlet
D = Domestic Cold Water Inlet
E = Central Heating Return
F = Safety Valve Outlet
H = Drain valve
Central Heating
Detailed recommendations are given in BS 6798:1987 and
BS 5449-1:1990, the following notes are given for general
guidance.
Pipe Work:
Copper tubing to BS EN 1057:1996 is recommended
for water pipes. Jointing should be either with capillary
soldered or compression fittings.
Where possible pipes should have a gradient to ensure air
is carried naturally to air release points and water flows
naturally to drain taps.
The appliance has a built-in automatic air release valve,
however it should be ensured as far as possible that the
appliance heat exchanger is not a natural c ollecting
point for air.
Except where providing useful heat, pipes should be
insulated to prevent heat loss and avoid freezing.
Particular attention should be paid to pipes passing through
ventilated spaces in roofs and under floors.
By-pass:
The appliance includes an automatic by-pass valve, which
protects the main heat exchanger in case of reduced or
interrupted water circulation through the heating system,
due to the closing of thermostatic valves or radiators.
System Design:
This boiler is suitable only for sealed systems.
Drain Cocks:
These must be located in accessible positions to permit the
draining of the whole system and should be fitted at all low
points. The taps must be at least 15mm nominal size and
manufactured in accordance with BS 2870:1980.
A B CDE
F
H
A CE
F
H
CLAS 24/30 FF
CLAS SYSTEM 21/28 FF
Fig. 8

12
installation
Safety Valve Discharge:
The discharge should terminate facing downward on the
exterior of the building in a position where discharging
(possibly boiling water & steam) will not create danger or
nuisance, but in an easily visible position, and not cause
damage to electrical components and wiring.
The discharge must not be over an entrance or a window or
any other type of public access.
Air Release Points:
These must be fitted at all high points where air naturally
collects and must be sited to facilitate complete filling of
the system.
The appliance has an integral sealed expansion vessel to
accommodate the increase of water volume when the
system is heated.
It can accept up to 8 litres (1.8 gal) of expansion water. If
the heating circuit has an unusually high water content,
calculate the total expansion and add an additional sealed
expansion vessel with adequate capacity. This should be
located on the return pipe work as close as possible to the
pump inlet.
0
50
100
150
200
250
300
350
400
450
500
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300
mbar
l/h
Mains Water Feed - Central Heating:
A method for initially filling the heating
system is supplied with the connection kit.
The filling loop is connected between the
cold water inlet and the central heating
flow connections, and incorporates a non-
return valve. To operate the filling loop,
it is necessary to open both quarter turn
handles, once the required pressure has
been achieved, close both handles and
disconnect the hose in accordance with
water byelaws. Note: The installer should
ensure that there are no leaks as frequent
filling of the heating system can lead to
premature scaling of the main exchanger
and failure of hydraulic components.
Domestic Water:
The domestic water must be in accordance
with the relevant recommendation of
BS 5546:1990. Copper tubing to BS EN
1057:1996 is recommended for water
carrying pipe work and must be used for
pipe work carrying drinking water, a scale
reducer should also be used to reduce the
risk of scale forming in the domestic side
of the heat exchanger.
Residual Head of the Boiler ∆T 20°C
Fig. 9
Fig. 10
GAS
GAS

13
installation
Flue Connections
Flue System
The provision for satisfactory flue termination must be
made in accordance with BS 5440-1.
The appliance must be installed so that the flue terminal is
exposed to outside air.
The terminal must not discharge into another room or
space such as an outhouse or lean-to.
It is important that the position of the terminal allows a free
passage of air across it at all times.
The terminal should be located with due regard for the
damage or discolouration that might occur on buildings in
the vicinity and consideration must be given to adjacent
boundaries.
In cold or humid weather water vapour may condense on
leaving the flue terminal. The effect of such“pluming”must
be considered.
If the terminal is less than 2 metres above a balcony,
above ground or above a flat roof to which people have
access, then a suitable terminal guard must be fitted. When
ordering a terminal guard, quote the appliance model
number.
The minimum acceptable spacing from the terminal to
obstructions and ventilation openings are specified in Fig.
11.
TERMINAL POSITION mm
A - Directly above or below an openable
window or other opening 300
B - Below gutters, solid pipes or drain pipes 75
C - Below eaves 200
D - Below balconies or car-port roof 200
E - From vertical drain pipes and soil pipes 150
F - From internal or external corners 300
G - Above ground or balcony level 300
H - From a surface facing a terminal 600
I - From a terminal facing a terminal 1200
J - From an opening in the car port
(e.g. door, window) into dwelling 1200
K - Vertically from a terminal in the same wall 1500
L - Horizontally from a terminal in the same wall 300
M - Horizontally from an opening window 300
N - Fixed by vertical flue terminal
NOTE: THE FLUE MUST NOT TERMINATE IN A PLACE
LIKELY TO CAUSE NUISANCE.
Fig. 11

14
installation
Fitting the Coaxial Flue (Horizontal)
(For Vertical Flue and Twin Pipe Instructions see pages 13 and 14)
Contents:
1x Silicone O-Ring (60mm)
1x Elbow (90o)
2x Wall Seals (Internal & External)
1x Flue Pipe including Terminal (1 metre - 60/100)
2x Flue Clamps
4x Screws
2x Foam Seals
Once the boiler has been positioned on the wall, insert the elbow
into the socket (Fig 12) and rotate to the required position. Note:
It is possible to rotate the elbow 360oon its vertical axis.
Using the flue clamps, seals and screws supplied (Figs. 12 and 14)
secure the elbow to the boiler.
The 1 metre horizontal flue kit (3318000) supplied is suitable for
an exact X dimension of 811mm, and the 750mm horizontal flue
kit (3318001) is suitable for an exact X dimension of 699mm.
Measure the distance from the face of the external wall to
the face of the flue elbow (X - Fig 12), add 23 mm to this
measurement, you now have the total length of flue required
(including the terminal), this figure must now be subtracted from
860mm, you now have the total amount to be cut from the plain
end of the flue.
Cut the flue to the required length ensuring that the distance
between the inner and the outer flue is maintained (Fig 2.8).
e.g. X = 508mm + 22mm = 530mm
860 - 530 = 330mm (Length to be cut from the plain end
of the flue).
Once cut to the required length, ensure that the flue is free from
burrs and reassemble the flue. If fitting the flue from inside of the
building attach the grey outer wall seal to the flue terminal and
push through the flue through the hole, once the wall seal has
passed through the hole, pull the flue back until the seal is flush
with the wall. Alternatively, the flue can be installed from outside
of the building, the grey outer seal being fitted last.
80 mm
23 mm
23 mm
23 mm
23 mm
Screws
Foam Seal
Flue Clamp
Fig. 12
Fig. 13
Fig. 14

15
installation
Fitting 80/125 Flue (Horizontal and Vertical)
(For Coaxial Vertical Flue Instructions see page 13)
Should the flue require extending, the flue connections are push
fit, however, one flue bracket should be used to secure each metre
of flue.
Note: See page 20 for maximum and minimum flue runs.
Once the boiler has been positioned on the wall, it is necessary to
insert the Ø80/125 adaptor (Fig. 18) for both horizontal and verti-
cal flue runs into the boiler flue socket (not supplied with flue kit
- Part No 3318040).
Push the adaptor onto the boilers flue connection, grease the
seals then add extensions or elbows as required, secure the adap-
tor, using the clamp and screws provided.
To fit extensions or elbows it is first necessary to ensure that the
lip seal is fitted correctly into the inner flue, once verified, it is sim-
ply necessary to push them together, no clamps are necessary to
secure the flue components.
Before proceeding to fit the flue, ensure that the maximum flue
length has not been exceeded (See the tables on Page 20) and
that all elbows and bends have been taken into consideration, for
each additional 90oelbow 1 metre must be subtracted from the
total flue length, and for each 45o0.5 metres must be subtracted
from the total flue length (the height of the vertical adaptor and a
45obend can be seen in Fig. 17 and a 90obend in Fig. 16).
Note: DO NOT cut the vertical flue kit.
WARNING
If the chosen ue length requires the use of the restrictor, it is
already tted inside the ue gas collar. In the event of an in-
stallation which does not require the use of the restrictor, the
latter should be removed from the ue gas collar. See table A
(Page 20 and Fig 15).
3318036
3318040
3318037
3318040
3318040
180mm
Fig. 15
Fig. 16
Fig. 17 Fig. 18

16
installation
Note:
Max Length = a+a+a +b+b = a+a+a+0.5+0.5
Combined Length not to exceed 4m
Fitting the Coaxial Flue (Vertical)
(For Twin Pipe Instructions see page 17)
Contents:
1x Silicone O-Ring (60mm)
1x Elbow (90o)
2x Wall Seals (Internal & External)
1x Aluminium Flue Pipe including Terminal (Telescopic - 60/100)
2x Flue Clamps
8x Screws
2x Seals
The vertical flue kit is supplied with a specially designed weather
proof terminal fitted, it can be used either with a flat roof or a
pitched roof. (see Figs 20 and 21).
The Vertical flue kits maximum and minimum useable lengths
with both flat and pitched roof flashings are indicated in (Figs. 20
and 21).
Before proceeding to fit the flue, ensure that the maximum flue
length has not been exceeded and that all elbows and bends
have been taken into consideration, the maximum flue length is 4
metres, for each additional 90oelbow 1 metre must be subtracted
from the total flue length, and for each 45o0.5 metres must be
subtracted from the total flue length (the offset and height of 2 x
45ocan be seen in Fig. 22b).
Mark the position of the flue hole in the ceiling and/or roof (see
Fig. 20 for distance from wall to the centre of the flue).
Cut a 125mm diameter hole through the ceiling and/or roof and
fit the flashing plate to the roof.
Should it be necessary to cut the flue DO NOT cut the outer white
air inlet tube, cut the aluminium exhaust flue 6mm longer than
the outer white air tube when used at minimum length. DO NOT
cut more that 250mm from the inner aluminium exhaust flue.
To connect the vertical flue kit directly to the boiler, place the
adaptor (supplied with vertical flue kit) onto the exhaust manifold
and secure with the clamp, the vertical flue kit must then be
inserted through the roof flashing, this will ensure that the correct
clearance above the roof is provided as the terminal is a fixed
height.
Should extensions be required, they are available in 1 metre (Part
No. 3318005), 500mm (Part No. 3318006), they must be connected
directly to the boiler and secured with the clamp supplied before
connecting the adaptor to allow the vertical flue kit to be fitted.
In the event that extension pieces need to be shortened, they
must only be cut at the male end and it must be ensured that the
distance between the inner and outer flue are kept (Fig. 2.8, page
11).
180 mm
Fig. 19
Fig. 20
Fig. 21

17
installation
When utilising the vertical flue system, action must be taken to
ensure that the flue is supported adequately to prevent the weight
being transferred to the appliance flue connection.
When the flue passes through a ceiling or wooden floor, there must
be an air gap of 25mm between any part of the flue system and any
combustible material. The use of a ceiling plate will facilitate this.
Also when the flue passes from one room to another a fire stop
must be fitted to prevent the passage of smoke or fire, irrespective
of the structural material through which the flue passes.
Fitting the Flue (Twin Pipe)
Where it is not possible to terminate the flue within the distance
permitted for coaxial flues, the twin flue pipe can be used by fitting
a special adaptor to the flue connector and using the aperture for
the air intake located on top of the combustion chamber.
For twin flue installation it is most important to avoid any possible
condense formation entering the appliance.
Should there be the possibility of condensation forming within
the flue, there are two options;
1) Where condense will form but can be negated with insulated
flue, install the insulated flue with a fall of 5mm in every metre
away from the boiler.
2) The exhaust flue will have a fall of 3oback to the boiler and a
suitable trap will be fitted on the exhaust as close to the boiler
as possible, condense will then be suitably disposed of.
Where the flue runs through cold spots, i.e. loft areas, condense
is likely to be formed, therefore a fall back to the boiler and a trap
is required.
Always ensure that the flue is adequately supported, avoiding low
points. (MTS supply suitable clamps as Part No. 705778).
To utilise the air intake it is necessary to:
Remove the blank intake by cutting it with a suitable knife (Fig.
23, page 20);
Insert the elbow/flue pipe into the air intake until it stops;
The twin flue pipes can be fitted with or without additional elbows
and need no clamps, simply ensure that the red o-ring is inserted
in the female end of the flue pipe and push the extension piece
fully into the previous section of flue pipe or elbow, check that the
o-ring is not dislodged when assembling the flue.
Twin pipe can also be converted back to Coaxial flue to enable
vertical termination with a coaxial kit by using the pipe bridge
(Twin - Coaxial Adaptor - Part No. 3318030). When running the
twin flue pipe vertically, a condense trap must always be used on
the exhaust pipe.
It is not possible to use the pipe bridge for horizontal
termination.
Minimum oset distance when using 2x 45° bends
WARNING
If the chosen ue length requires the use of the restrictor, it is
already tted inside the ue gas collar. In the event of an in-
stallation which does not require the use of the restrictor, the
latter should be removed from the ue gas collar. See table A
(Page 20 and Fig 22b).
Fig. 22a
Fig. 22b

18
installation
Note: Vertical twin flue installations must have a trap on the
exhaust. MTS supply a suitable condense trap Part No. 3318026
and recommend that this be used in the event that the flue may
form condense.
When siting the twin flue pipe, the air intake and exhaust terminals
must terminate on the same wall, the centres of the terminals must
be a minimum of 280 mm apart and the air intake must not be
sited above the exhaust terminal (refer to Fig. 27). The air intake
pipe can be run horizontally, however, the terminal and the final 1
metre of flue must be installed with a fall away from the boiler to
avoid rain ingress.
It is also strongly recommended that the air intake pipe run be
constructed of insulated pipe to prevent condense forming on
the outside of the tube.
The maximum permissible flue length for twin flue is dependent
on the type of installation.
For flue runs with the intake and exhaust pipes under the same
atmospheric conditions (Type 4) the maximum length is 44 metres
(31kW), for runs with the terminals under different atmospheric
conditions (Type 5) the exhaust terminal must extend 0.5 metres
above the ridge of the roof (this is not obligatory if the exhaust
and air intake pipes are located on the same side of the building).
For Type 5 also, the maximum permissible combined length is 40
metres.
The maximum length is reached by combining the total lengths
of both the air intake and exhaust pipes. Therefore a maximum
length of 40 metres for example, will allow a flue run of 20 metres
for the air intake and 20 metres for the exhaust pipes, also for each
90oelbow 1.3 metres must be subtracted from the total length
and for each 45oelbow 1 metre must be subtracted from the total
flue length.
Some of the acceptable flue configurations are detailed on page
19 (Fig. 26).
For further information relating to flue runs not illustrated, please
contact the Technical Department on 0870 241 8180.
IMPORTANT!!!
Where condense will form within the flue system, ensure there is
a fall back to the boiler of 3oand a suitable trap is fitted as close
to the boiler as possible. MTS supply a suitable collector Part No.
3318026.
195
105
120 180
Fig. 23
Fig. 24
Fig. 25

19
installation
Note: Drawings are indicative of ueing options only.
EXHAUST
AIR INTAKE
AIR INTAKE
AIR INTAKE MUST NOT BE
FITTED ABOVE THE EXHAUST
Fig. 26
Fig. 27

20
installation
Exhaust Type
MAXIMUM EXTENSION EXHAUSTAIR (m)
Diameter
of pipe
(mm)
CLAS 24 FF
CLAS SYSTEM 21 FF
CLAS 30 FF
CLAS SYSTEM 28 FF
Restrictor ø 44 Do not use
Restrictor Restrictor ø 44 Do not use Restrictor
MIN MAX MIN MAX MIN MAX MIN MAX
Coaxial Systems
C12
C32
C42
0,5 0,75 0,75 4 0,5 0,75 0,75 4
ø 60/100
B32 0,5 0,75 0,75 4 0,5 0,75 0,75 4
C12
C32
C42
0,5 3 3 11 0,5 3 3 11
ø 80/125
B32 0,5 3 3 11 0,5 3 3 11
Twin Pipe
Systems
C12
C32
C42
S1 = S2 S1 = S2
ø 80/80
0,5/0,5 15/15 15/15 26/26
0,5/0,5 11/11 11/11 25/25
C52
C82
1 + S2 1 + S2
ø 80/80
1/0,5 1/34 1/34 1/53 1/0,5 1/27 1/27 1/51
B22 0,5 35 35 54 0,5 28 28 52 ø 80
TABLE A