Strebel Mital User manual

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0099
STREBEL MITAL
&
STREBEL MONTREUX
Fan Assisted Wall Mounted Gas
Combination
&
System Boilers
USER, INSTALLATION,
COMMISSIONING & MAINTENANCE
INSTRUCTIONS.
APR-01

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Contents
Page No.
1.0 Introduction ----------------------------------------------------------------------------------- 3
2.0 General Precautions ------------------------------------------------------------------------ 3
3.0 Installation ------------------------------------------------------------------------------------ 3
3.1 Reference Regulations ---------------------------------------------------------- 3
3.2 Packaging -------------------------------------------------------------------------- 3
3.3 Boiler Location -------------------------------------------------------------------- 3
4.0 Technical Data ------------------------------------------------------------------------------- 4
5.0 Ventilation ------------------------------------------------------------------------------------- 6
6.0 Flueing ----------------------------------------------------------------------------------------- 6
7.0 Boiler Siting ----------------------------------------------------------------------------------- 8
8.0 Flue Assembly ------------------------------------------------------------------------------- 8
9.0 Flue & Boiler Accessories------------------------------------------------------------------ 9
10.0 Gas Supply ----------------------------------------------------------------------------------- 10
10.1 L.P.G. Conversion ------------------------------------------------------------- 10
11.0 Cold Water Supply (Mital, Mital plus & Mital max only) --------------------------- 10
12.0 Sealed Primary System ------------------------------------------------------------------- 11
13.0 Electrical System ---------------------------------------------------------------------------- 12
13.1 Internal wiring ---------------------------------------------------------------------- 12
13.2 External Controls ----------------------------------------------------------------- 12
14.0 Commissioning ------------------------------------------------------------------------------ 17
14.1 Handing Over ---------------------------------------------------------------------- 18
15.0 Maintenance ---------------------------------------------------------------------------------- 19
15.1 Fault Finding ----------------------------------------------------------------------- 19
15.2 Fault Finding Guide -------------------------------------------------------------- 20
16.0 Users Instructions --------------------------------------------------------------------------- 21
Illustrations:
Figure 1. Boiler Dimensions & Clearances Figure 14. Montreux Internal Wiring Diagram
Figure 2. Air Vent Positions Figure 15. Mital plus Internal Wiring Diagram
Figure 3. Flue Terminal Position Figure 16. Montreux plus & max Internal Wiring
Figure 4. Boiler & Manifold Fixing Points Diagrams
Figure 5. Manifold Assembly Figure 17. Mital max Internal Wiring Diagrams
Figure 6. Flue Adapters Figure 18. Honeywell V4600 Gas Valve
Figure 7. Coaxial Flue System Figure 19. SIT 826 Nova Gas Valve
Figure 8. Twin Pipe Flue System Figure 20. SIT 826 Nova Gas Valve, High and
Figure 9. Boiler Flue Gate Low Gas Pressure Adjustment.
Figure 10. CWS Flow Valve Figure 21. Burner Fixing Screws.
Figure 11. HWS Flow / Temp Graph Figure 22. Mital & Montreux Control Panel
Figure 12a - d. Resistance & Pump Diagram Figure 23. Mital plus, Mital max, Montreux plus &
Figure 13. Mital Internal Wiring Diagram Montreux max Control Panel

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1.0 Introduction
Thank you for choosing our products. We
recommend that these instructions be used to ensure
the safe operation of the boiler and to maximise their
performance.
The data plate for the boilers is located behind the
control panel cover.
Boiler names:
Mital - wall hung gas-fired combination boiler with fan
assisted flue; output 23.2 kW.
Mital plus - room sealed wall hung gas-fired
combination boiler with fan assisted flue and
electronic ignition; output 23.2 kW.
Mital max - room sealed wall hung gas fired
combination boiler with fan assisted flue and
electronic ignition; output 31.3kW.
Montreux - wall hung gas-fired system boiler with fan
assisted flue; output 23.2 kW.
Montreux plus - room sealed wall hung gas-fired
system boiler with fan assisted flue and electronic
ignition; output 23.2 kW.
Montreux max - room sealed wall hung gas-fired
system boiler with fan assisted flue and electronic
ignition; output 31.3 kW.
2.0 General Precautions
•This instruction manual is an integral and
essential part of the appliance, and must be left
with the end user and stored near to the boiler for
further consultation during maintenance etc.
•These instructions must be read thoroughly before
proceeding, failure to follow the instructions may
affect the safety, performance and warranty of the
appliance.
•Installation must be carried out by professional,
qualified CORGI REGISTERED ENGINEERS in
compliance with all current regulations and
manufacturers instructions.
•The installation of the boiler must also be in
accordance with the current I.E.E. Regulations,
the By-laws of the Local Water Undertaking, Local
Authority requirements and all relevant British
Standards.
•The appliance must be installed in a suitable
environment that is NOT explosive, flammable,
corrosive or damp.
•Neither the supplier or the manufacturer will be
responsible for any damage to property, persons,
animals or the boiler, as a result of tampering,
improper use, installation or maintenance.
•Packaging parts (i.e. plastic bags, polystyrene,
wood, clips, nails, etc.) can be harmful to
children and must be disposed of immediately
and correctly.
•To avoid damage caused by low temperatures it is
recommended that the boiler should be drained
down if left unused for a long period. Neither the
supplier or manufacturer is responsible for faults,
break downs, water leakage or any consequential
damage caused by low temperature.
•To comply with the Warranty these instructions
must be adhered to and only original spare parts
and kits used.
•In the event of breakdown the appliance should be
isolated and a qualified CORGI REGISTERED
SERVICE ENGINEER contacted.
•This appliance MUST have an annual service and
inspection by a suitably qualified CORGI
REGISTERED ENGINEER.
3.0 Installation
3.1 Reference Regulations
Detailed recommendations are contained in the
following :
BS 5440 :1 & 2, BS 4543, BS 5540 :2, BS 6798, BS
5449, BS 5546, BS 6891, Gas Safety Regulations
1984. All other relevant regulations must be
adhered to whether they are listed above or not.
3.2 Packaging
The packing material and the cardboard cover must
be removed without turning the boiler upside down.
The boiler should be kept in a vertical position
and on the polystyrene lower base. Never place
the boiler directly onto the floor.
To remove the cardboard cover open the base of the
box and lift the box off the boiler.
Each boiler is supplied in three separate containers:
1. boiler
2. connection manifold, valves and angled
connecting pipes.
3. flue kit
any extras or additions will be packed separately.
3.3 Boiler Location
Mital & Montreux - Both these appliances are NOT
ROOM SEALED and therefore must NOT be
installed in a bedroom, bedsitting room or any room
containing a bath or a shower.
These boilers must be sited 0.5 metres from
combustible materials i.e. curtains etc.
Mital plus, Mital max, Montreux plus & Montreux
max are room sealed and can be installed in any
room, although particular attention is drawn to the
requirements of the IEE Regulations and, in
Scotland, the electrical provisions with respect to the
installation in a room containing a bath or shower.
If the boiler is to be installed in a room that
contains a bath or shower the boiler MUST be

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situated so that it cannot be touched while the
person is using the bath or shower.
General
The wall must be flat and vertical, and of suitable
load bearing capacity.
Adequate space must be allowed around the boiler to
facilitate installation, servicing and maintenance, the
required clearances are shown in figure 1.
The boiler MUST be positioned so the top of the
boiler is a minimum of 2.2 metres from floor level or
suitable provision made to restrict accidental access
to the top of the boiler.
The position must permit a satisfactory flue terminal
position.
4.0 Technical Data
Combination Boilers System Boilers
Model Mital Mital
plus Mital max Montreux Montreux plus Montreux max
Input kW 13.2 - 26.4 13.2 - 26.4 17.4 - 34.8 13.2 - 26.4 13.2 - 26.4 17.4 - 34.8
Output kW 11.6 - 23.2 11.6 - 23.2 15.6 - 31.3 11.6 - 23.2 11.6 - 23.2 15.6 - 31.3
DHW Flow Rate
at 25°C t Lt/min 13.3 13.3 17.9 -- -- --
Flue Size mm 60 100 100 60 100 100
Electrical Supply 230 volts - 50 Hz - Single Phase
Heating Circuit
Pressure Bar max
min 3 0.5 3 0.5 3 0.5 3 0.5 3 0.5 3 0.5
DHW Circuit
Pressure Bar max
min 6 0.4 6 0.4 6 0.4 -- -- --
Dimensions (mm) Height
Width
Depth
850
450
350
850
450
350
850
600
350
850
450
350
850
450
350
850
600
350
Clearances (mm) Top
Bottom
Front
Sides
400
400
350
25
400
400
350
25
400
400
350
25
400
400
350
25
400
400
350
25
400
400
350
25
Weight (empty) kg 43 49 69 39 45 55
Features: Fan Assisted X X X X X X
Room Sealed __ X X
__ X X
Instantaneous
DHW capability X X X __ __ __
Built-in Pump
(Circulating) X X X X X X
Electronic Ignition __ X X
__ X X
Permanent Pilot X __ __ X __ __
Slow Start Burner X X X X X X
Overheat
Thermostat X X X X X X
Safety Valve 3 Bar X X X X X X

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Figure.1 - Boiler Dimensions & Clearances.
KEY
Connections (mm)
1 DHW outlet 15
2 Safety valve discharge 15 Top 400
3 Gas supply 15 Clearances (mm) Bottom 400
4 Electrical cables -- Front 350
5 Mains water inlet 15 Sides 25
6 Heating flow 22
7 Heating return 22
MODEL Mital Mital Mital Montreux Montreux Montreux
DIMENSION plus max plus max
A Width of Unit 450 450 600 450 450 600
B Inside of fixing point 75 75 75 75 75 75
C Centre of DHW connection 55 55 55 55 55 55
D Depth of Unit 350 350 350 350 350 350
E Centre of combustion air inlet * -- 155 200 -- 155 200
F Centre Exhaust outlet 195 195 185 195 195 185
G Centre Exhaust outlet 265 265 310 265 265 310
H Height of Unit 850 850 850 850 850 850
Flue connection 60 100 60 100 100 100
* Connection for Mital plus, Mital max, Montreux plus & Montreux max when used with a twin flue system.

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5.0 Ventilation
Mital & Montreux
Combustion ventilation - a permanent air vent is required directly to outside, or to an adjacent room ventilated to
outside, with a minimum of 100 cm² of free air space. If air ventilation is to be via another room, the room cannot be
a bathroom, bedroom, garage or a room that contains either a shower or a bath.
Compartment Ventilation - if the boiler is to be installed in either a cupboard or compartment, permanent air vents
are required at high and low levels see table below for sizes. Where the compartment air vents communicate with a
room, the room must itself be ventilated with a minimum of 100 cm².
The air vents must both communicate with the same wall/room, and if communicated into a room, the room must
not be a bathroom, bedroom, garage or a room that contains either a shower or a bath.
Compartment Ventilation
Boiler Type Combustion
Ventilation Position of vents Air from Room Air from Outside
Mital &
Montreux 100 cm² High Low 201 cm² 402 cm² 100 cm² 201 cm²
Mital plus &
Montreux plus None Required High Low 201 cm² 201 cm² 100 cm² 100 cm²
Mital max &
Montreux max None Required High Low 285 cm² 285 cm² 142 cm² 142 cm²
Figure. 2 - Air Vent Positions.
Boiler
type Boiler
location In a Room In a compartment Vented to a Room In a compartment Vented to Outside
Mital
Montreux
Mital plus
Mital max
Montreux plus
Montreux max
6.0 Flueing
General Position
•Siting should not cause an obstruction or the discharge a nuisance. It should be remembered that in certain
weather conditions a terminal may steam.
•If the terminal is below 2 metres from floor level or where people have access a terminal guard must be fitted.
The guard must be symmetrically positioned ensuring a minimum of 50mm gap between the end of the terminal
and the guard.
•If the terminal is within 600mm below plastic guttering, then an aluminium shield of 1.25 metres long should be
fitted to the under side of the guttering.
•The terminal or flue must not be closer than 25mm to any combustible material.

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Figure. 3 - Flue Terminal Position
Dimension Minimum Distances from the Flue Terminal (mm)
A Directly below an opening window 300
B Directly below an air vent 300
C Below gutters, soil pipes or drain pipes 75
D Below a Balcony 200
E Horizontal from a window or door on the same wall 300
F Horizontal from an air vent on the same wall 300
G From vertical drain pipes and soil pipes 75
H From external corners 300
I From internal corners 300
J Below eaves 200
L Above ground, roof or balcony level 300
M Vertical from a terminal on the same wall 1500
N Horizontal from a terminal on the same wall 300
O From a surface facing a terminal 600
P From a terminal facing a terminal 1200
7.0 Boiler Siting

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The boiler is mounted by means of the two anchoring
hooks supplied.
Measure and mark the two boiler fixing points on the
wall and the pipe manifold position, making sure that
the distance from boiler fixings to manifold fixings is
688mm. Ensure that the minimum clearances around
the boiler are achieved as per Figure 1, and that the
top of the boiler is a minimum of 2.2 metres from the
finished floor level (F.F.L.) or suitable provision made
to restrict accidental access to the top of the boiler.
Figure. 4 - Boiler & Manifold Fixing Points
The connection manifold is provided complete with
valves and angled connecting pipes, this provides
two functions :
•It provides the bottom fixing for the boiler and
must be adequately secured to the wall.
•The manifold enables the system to be completely
pre-piped and tested with the boiler being the final
fix. Thus minimising security risks.
WARNING :- Remove the straight connector from the
pipe connections on the boiler, making sure any
blanking pieces are disposed of.
The manifold kit is assembled by first feeding the
threaded end of the 90° angled pipe through the
manifold mounting plate, and then screwing the
isolating valve to the angled pipe with suitable jointing
(for the sanitary connection on the Mital and Mital
plus boilers a straight connector is provided).
The boiler pipe can then be connected to the isolation
valve and the straight connector made on to the
bottom of 90° bend using the fibre washers provided.
Figure. 5 - Manifold Assembly
8.0 Flue Assembly
Mital & Montreux - The standard flue assembly kit
contains 1 x 90° Bend, 1 Metre 60mm Ø flue pipe
and 60mm Ø terminal. Additional 1 metre flue
extensions and bends can be supplied at extra cost.
Maximum flue length with one 90° bend is 6 metres,
additional 90° bends are equivalent to 1 metre and
must be deducted from the maximum length allowed.
Mital plus, Mital max, Montreux plus & Montreux
max - The standard balanced flue assembly kit
contains 1 x 90° coaxial bend, 1 Metre 100mm Ø
coaxial flue pipe and 100mm Ø terminal. Additional 1
metre coaxial flue extensions and bends can be
supplied at extra cost.
With the Mital plus, Mital max, Montreux plus and
Montreux max boilers it is also possible to have a
twin pipe flue system so intake air and exhaust gas
can be in different positions.
Supplied with the boiler is a bag containing the
relevant flue adapters for use with a coaxial flue or a
twin pipe flue system.
Figure. 6 - Flue Adapters
For a coaxial flue system adapters A & B need to be
fitted as per Figure. 7.

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Figure. 7 - Coaxial Flue System.
For a twin pipe flue system adapters C & D need to
be fitted as per Figure. 8.
Figure. 8 - Twin Pipe Flue System.
The Mital plus and Montreux plus are supplied with a
flue gate that is positioned on the front of the flue
hood. It has two positions (-) & (+) (Figure 9) which is
dictated by maximum flue length.
With the flue gate in position (-) for a coaxial flue
system with one 90º bend and the standard terminal
fitted, the maximum equivalent flue pipe length is 1.5
metres. For a twin pipe system the maximum
equivalent flue pipe for the intake and exhaust with a
90º bend and the standard terminal is 1.5 meters for
each.
For greater flue runs the gate should be moved to
position (+) which then increases the maximum
equivalent flue length for the coaxial flue system to
3.5 metres with one 90º bend and the standard
terminal fitted. For a twin pipe system the maximum
equivalent flue pipe for the intake and exhaust with a
90º bend and the standard terminal is increased to
3.5 meters for each.
For the Mital max & Montreux max the maximum
equivalent flue length for coaxial flue is 3.5 metres
with one 90º bend and the standard terminal fitted.
For a twin pipe system the maximum equivalent flue
pipe for the intake and exhaust with a 90º bend and
the standard terminal is 3.5 meters for each.
In all cases additional 90º bends are equivalent to 1
metre and must be deducted from the maximum flue
length allowed.
Figure. 9 - Boiler Flue Gate.
NOTE : The flues must be installed with a 3º drop
from the boiler to ensure any condense or rain
water drains towards the terminal thus
preventing damage to the boiler.
The Mital and Montreux flue can be installed into a
chimney providing it is of suitable size and
construction and in a accordance with current
regulations. For installing the Mital plus, Mital Max,
Montreux plus and Montreux max boilers into a
chimney the twin flue pipe system must be used.
When cutting coaxial flue it is essential to ensure the
inner exhaust pipe is sufficiently longer than the outer
ventilation pipe to ensure a good seal is achieved.
9.0 Flue and Boiler Accessories
Mital & Montreux
60mm Ø Flue Kit (60º bend, 1m flue, terminal, seals)
90º 60mm Ø bend
1m 60mm Ø flue extension
45º 60mm Ø bend
Mital plus, Montreux plus, Montreux max
Coaxial Flue Kit (90º bend, 1m flue, terminal, seals)
90º coaxial bend
1m coaxial flue extension
45º coaxial bend
General
Programmer Automatic
bypass valve
Increased expansion
vessel 8 dm³
Increased pump
Increased expansion
vessel 12 dm³

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10. Gas Supply
The gas meter and gas supply must be capable of
supplying the quantity of gas for the boiler (see table
below) in addition to the demand from other gas-fired
appliances.
The meter and gas supply must be sized to ensure a
nominal pressure of 20 mbar is available at the
appliance. The gas supply should be checked to
ensure that the gas line is sound and that it has been
installed in accordance with current regulations
relating to gas installations.
Boiler Type Boiler Gas
Consumption m³/hr
Mital, Mital plus,
Montreux & Montreux
plus 2.8
Mital max &
Montreux max 3.69
10.1 LPG Conversion
Conversion kit :
LPG Kit Part Used on:
0.75mm GPL Injectors all
copper washers all
2 x “GPL” Stickers all
1 x 0.22 Pilot Injector Mital & Montreux
1 x Silicon Gasket plus & max models
5 x Fibre washers plus & max models
1. Isolate the boiler from the mains electricity
supply.
2. Loosen the two screws on the control panel and
pull the panel forward.
3. Remove pilot and exchange injector (Mital &
Montreux)
4. Remove the ignition & detection electrodes
(Mital plus, Mital max, Montreux plus &
Montreux max)
5. Remove the burner (see maintenance section &
figure 23)
6. Replace the burner injectors
7. Replace sticker on gas valve and inside of
control panel to show new fuel
8. Re-assemble boiler
9. Test all connections disturbed for leaks
10. Adjust high & low gas pressures as per
commissioning instructions and figure 20,21 &
22.
11. Re-seal test points and check for leaks.
11.0 Cold Water Supply (Mital, Mital plus
& Mital max only)
A minimum pressure of 0.4 bar is required at the
appliance to enable the boiler to function. However a
greater pressure is required if the stipulated flow rate
is to be achieved.
A direct mains water connection is permitted by the
Water Authorities. It is recommended that reference
be made to local requirements.
Where ever possible the cold water supply to the
boiler should be the first connection off the mains
water supply to minimise hot water flow reduction
when other water services are in use.
Within the boiler is a flow valve that must be adjusted
to account for local water pressure conditions and to
provide the temperature desired (see figures 10 &
11).
If the mains inlet water pressure is greater than 6 bar
then a pressure reducing valve must be fitted to the
mains water supply to the boiler.
Figure. - 10 CWS Flow Valve
Figure. - 11 HWS Flow/Temp Graph
12.0 Sealed Primary System
All the Mital & Montreux range of boilers must be
fitted with a bypass if thermostatic radiator valves are
used, alternatively one radiator can be used as a
bypass by fitting it with standard radiator valves to
enable dissipation of heat from the boilers.
Both the Mital & Montreux boiler ranges are supplied
with all the necessary components. The expansion

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vessel is pre-charged to 1.2 bar and guarantees
operation up to a heating system capacity of 140
litres operating at a maximum of 85°C (220 litres
Mital max & Montreux max) and with a static head of
up to 12 metres.
Filling of the system must be via a temporary hose
connection to the mains water supply, with a double
check valve assembly and test point on the system
side of the temporary connection. As per Water
Regulation Bye-law 14.
All valves and joints should be suitable for a working
pressure of 3 bar. Radiator valves should comply with
BS 2767:10. All other valves and fittings should
comply with BS1010.
The discharge from the Safety Valve MUST be run to
a safe position outside of the building. REMEMBER
the discharge from the safety valve will be HOT and
must be discharged at low level.
All boilers have an integral three speed pump built
into the boiler. In most cases Speed - lll is suitable. If
a greater pump is required this can be achieved by
replacing the standard pump with the larger pump
(see accessories).
Figure 12a - Mital, Mital plus boiler
Resistance & Pump diagram.
0
0.1
0.2
0.3
0.4
0.5
0.6
0 200 400 600 800 1000 1200 1400 1600 1800
Ltr/hr
Bar
Pump Duty
Boiler Resistance
2
13
Figure 12b - Mital max boiler Resistance &
Pump diagram.
0
0.1
0.2
0.3
0.4
0.5
0.6
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Ltr/hr
Bar
Pump Duty
Boiler Resistance
2
1
3
Figure 12c - Montreux, Montreux plus boiler
Resistance & Pump diagram.
0
0.1
0.2
0.3
0.4
0.5
0.6
0 200 400 600 800 1000 1200 1400 1600 1800
Ltr/hr
Bar
Pump Duty
Boiler Resistance
2
13
Figure 12d - Montreux max boiler
Resistance & Pump diagram.
0
0.1
0.2
0.3
0.4
0.5
0.6
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Ltr/hr
Bar
Pump Duty
Boiler Resistance
2
1
3
13.0 Electrical System
External wiring MUST be in accordance with current
I.E.E. Regulations and all other Local Regulations.
The boiler is supplied for 230 VAC, 50Hz, Single
Phase.
The method of connection to the electricity supply
must facilitate complete isolation of the boiler. This
can be achieved either by use of a fused three-pin
plug and shuttered socket outlet, both complying with
BS1363, or by use of a fused-double pole switch with
a contact separation in both poles of at least 3mm.
Which ever method is used the point of disconnection
of the electricity supply must be adjacent to the
boiler, with the exception of boilers that are fitted in
either a bathroom or shower room. In these cases the
point of disconnection MUST be outside the
bathroom and it is advised that the method of
disconnection should include removal of fuse to avoid
accidental re-connection.

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ATTENTION: Ensure that the phase and neutral
electrical polarities are correct and the earth
connection is made. Any mistakes could permanently
lock out the burner.
Earth continuity and electrical tests must be carried
out prior to initial operation of the boiler. The
manufacturer and the supplier are NOT responsible
for any damage to persons or property resulting from
lack of compliance with this requirement.
13.1 Internal wiring
Diagrams of the internal wiring are provided in
figures13, 14, 15, 16 & 17 on the following page.
13.2 External Controls
For external controls reference should be made to
both the relevant control manufacturers Instructions
and the boiler wiring diagrams shown in figures
(13, 14, 15, 16 & 17).
If the integral programmer is to be utilised the
following sequence should be followed:
- Pull forward the front control panel cover.
- Loosen the left and right screws and remove the
control panel back cover.
- Breakout the cover disk on the panel.
- Mount the programmer by means of the four screws
provided.
- Make electrical connection using the cable
connector marked “programming timer”.

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Figure 13 Mital Internal Wiring Diagram Figure 14 Montreux Internal Wiring Diagram
E2
E3
EA
F
H
H2
IG
M1, 2 & 3
Gas Solenoid Modulation
Main Gas Solenoid
Ignition Electrode
Fuse
High Limit Thermostat
N/A
Boiler On / Off Switch
Hot Water Priority Switch
MN
MO
MR
MV
OP
PC
PF
PW
N/A
Permanent Live for Time Clock
Terminal Strip
Fan Motor
Heating Timer Connections
Pump
Air Pressure Switch
Water Pressure Switch
R
S1
S2
SL
SW
T1
T2
TA
N/A
Hot Water Control Thermostat Stage 2
Hot Water Control Thermostat Stage 1
Power On indication
Summer / Winter Switch
Boiler Control Thermostat Stage 2
Boiler Control Thermostat Stage 1
Room Thermostat (Optional)

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Figure 15 Mital Plus Internal Wiring Diagram
AE
CR
E1
E2
E3
EA
ER
F
F1
FT
H
H2
IG
Control Box
Rectifier (SIT Only)
Gas Safety Solenoid
Gas Solenoid Modulation
Main Gas Solenoid
Ignition Electrode
Flame Detection Probe
Fuse
Fuse
Electrical Filter
High Limit Thermostat
N/A
Boiler On / Off Switch
M1, 2 & 3
MN
MO
MR
MV
MX
OP
PB
PC
PF
PW
R
S1
Hot Water Priority Switch
N/A
Permanent Live for Time Clock
Terminal Strip
Fan Motor
N/A
Heating Timer Connections
Lock-Out Reset Button
Pump
Air Pressure Switch
Water Pressure Switch
N/A
Hot Water Control Thermostat Stage 2
S2
SA
SB
SF
SL
SW
T1
T2
TA
TIS
VZ
Hot Water Control Thermostat Stage 1
Low Water Pressure Warning Light
Lock-Out Warning Light
Flue Warning Light
Power On indication
Summer / Winter Switch
Boiler Control Thermostat Stage 2
Boiler Control Thermostat Stage 1
Room Thermostat (Optional)
Transformer
N/A

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Figure 16 Montreux Plus & Max Internal Wiring Diagram
AE
CR
E1
E2
E3
EA
ER
F
F1
FT
H
H2
Control Box
Rectifier (SIT Only)
Gas Safety Solenoid
Gas Solenoid Modulation
Main Gas Solenoid
Ignition Electrode
Flame Detection Probe
Fuse
Fuse
Electrical Filter
High Limit Thermostat
N/A
IG
MN
MO
MR
MV
MX
OP
PB
PC
PF
PW
R
Boiler On / Off Switch
N/A
Permanent Live for Time Clock
Terminal Strip
Fan Motor
N/A
Heating Timer Connections
Lock-Out Reset Button
Pump
Air Pressure Switch
Water Pressure Switch
N/A
SA
SB
SF
SL
SW
T1
T2
TA
TIS
VZ
Low Water Pressure Warning Light
Lock-Out Warning Light
Flue Warning Light
Power On indication
Summer / Winter Switch
Boiler Control Thermostat Stage 2
Boiler Control Thermostat Stage 1
Room Thermostat (Optional)
Transformer
N/A

- 16 -
Figure 17 Mital Max Internal Wiring Diagram
AE
CR
DV
E1
E2
E3
EA
ER
F
F1
FT
H
IG
Control Box
Rectifier (SIT Only)
Diverting Valve
Gas Safety Solenoid
Gas Solenoid Modulation
Main Gas Solenoid
Ignition Electrode
Flame Detection Probe
Fuse
Fuse
Electrical Filter
High Limit Thermostat
Boiler On / Off Switch
IW
M1, 2 & 3
MO
MR
MV
OP
PB
PC
PF
PW
RS
RW
Hot Water Switch
Hot Water Priority Switch
Permanent Live for Time Clock
Terminal Strip
Fan Motor
Heating Timer Connections
Lock-Out Reset Button
Pump
Air Pressure Switch
Water Pressure Switch
4 Contact Relay
1 Contact Relay
S1
S2
SA
SB
SF
SL
SW
T1
T2
TA
TIS
TL
Hot Water Control Thermostat Stage 2
Hot Water Control Thermostat Stage 1
Low Water Pressure Warning Light
Lock-Out Warning Light
Flue Warning Light
Power On indication
Summer / Winter Switch
Boiler Control Thermostat Stage 2
Boiler Control Thermostat Stage 1
Room Thermostat (Optional)
Transformer
Hot Water Limit Thermostat

- 17 -
14.0 Commissioning
The heating system including the radiators and
domestic hot water circuit must be thoroughly
flushed. The system should be completely filled and
‘cold flushed’ without the boiler in-situ. The boiler
should then be connected, electrical and gas safety
tests/checks completed and passed. The system
should then be refilled, brought to temperature and a
‘hot flush’ carried out.
The system can then be refilled and all air locks
removed and the system checked for water leaks.
Dependant upon location it may be necessary for the
system water and the mains feed water (Mital, Mital
plus & Mital max ONLY) to be treated to protect the
boiler from scale and sludge formation. The Local
Water Authorities should be consulted. If required the
following products are recommended:
System water treatment - Fernox MB-1 if steel
radiators are used & Fernox Copal when aluminium
is present in the system i.e. radiators.
Mains water treatment - Fernox Quantomat (Mital,
Mital plus & Mital max only).
Operation of the boiler and controls should be
checked.
Check gas valve is correct for fuel supply (GPL =
LPG & Methano = Methane), then check the burner
pressure.
Inlet
pressure
mbar
Outlet
pressure
High Fire
mbar
Outlet
pressure
Low Fire
mbar
Natural
Gas 20 10 2.5
L.P.G. 37 35 10
If the gas pressure at the burner (injector) does not
correspond to the values shown above, commission
the unit as follows :-
Mital & Montreux.
To check the pressure at the burner, connect a
pressure gauge to the burner pressure test point 11
(Figure-18) after having slackened the internal screw
by a few turns and remove yellow plastic cap 5.
Figure. 18 - Honeywell V4600 Gas Valve.
KEY
1 Thermocouple connection.
2 Gas valve inlet.
3 Gas inlet pressure test point.
4 Gas valve control knob.
5 Adjustment screw cover.
6 High gas pressure adjustment nut.
7 Low gas pressure adjustment screw.
8 Modulating solenoid electrical
connections.
9 Pilot burner adjustment screw.
10 Pilot burner connection.
11 Burner pressure test point.
12 Gas valve outlet.
•To adjust the High fire pressure turn the boiler on
(as per section 16.0 Users Instructions) and with it
operating on high fire adjust nut 6with a 8mm
spanner to the correct pressure (turning the nut
clockwise increases the burner pressure).
•To adjust the Low fire pressure, turn the boiler off
at the mains and disconnect the electrical
connections 8from the modulating solenoid
(WARNING - these connections will become live
when the boiler is switched on, cover the ends
with electrical tape while low fire pressure is
adjusted). Switch the boiler on and adjust screw 7
to the correct pressure while keeping nut 6locked
off with the spanner (turning the screw clockwise
increases the burner pressure).
•Turn off the boiler and re-connect electrical
connections for the modulating solenoid and
check the High and Low fire pressure values,
readjust if required and then re-fit Yellow plastic
cap 5.
•Check that the pilot flame length is correct i.e.
covering the thermocouple bulb, if adjustment is
required turning the screw 9clockwise decreases
the burner pressure.

- 18 -
Mital plus, Mital max, Montreux plus &
Montreux max.
To check the pressure at the burner, connect a
pressure gauge to the burner pressure test point 3
(Figure - 19) after having removed the screw and
remove clear plastic cap C(Figure. 20).
Figure. 19 - SIT 836 Nova Gas Valve.
KEY
1 Gas valve inlet.
2 (E) Gas inlet pressure test point.
3 (A) Burner pressure test point.
4 High and Low gas pressure adjustment
(as per Figure - 20).
5 Modulating solenoid electrical plug
6 Gas valve outlet.
•To adjust the High fire pressure turn the boiler on
and with it operating on high fire adjust nut B
(Figure - 20) with a 10mm spanner to the correct
pressure (turning the nut clockwise increases the
burner pressure).
•To adjust the Low fire pressure, turn the boiler off
at the mains and disconnect the electrical plug 5
(Figure - 19) from the modulating solenoid
(WARNING - the plug will become live when the
boiler is switched on, take care not to poke inside
the plug). Switch the boiler on and adjust screw A
to the correct pressure while keeping nut Blocked
off with the spanner (turning the screw clockwise
increases the burner pressure).
•Turn off the boiler and re-connect electrical plug
for the modulating solenoid and check the High
and Low fire pressure values, readjust if required
and then re-fit clear plastic cap C.
Figure. - 20 SIT 836 Nova Gas Valve, High
and Low Gas Pressure Adjustment.
Mital, Mital plus & Mital max - the hot water flow rate
MUST be adjusted. The integral flow regulator (see
figure 10) is not a pressure reducer; therefore, high
pressure above 6 bar on the Mains water system has
to be reduced by means of an external pressure
reducer.
Check the position of the flue gate (see figure 9) is
correct for flue length etc. Ensure flue operation is
correct and clean, and that any condense or rain
water in the flue pipes are collected and drained
without reaching the equipment.
Ensure the cap on the automatic air release valve is
loose and the valve is functioning correctly.
IMPORTANT
After the unit has been commissioned, check :-
1. The electrical connections of the gas valve.
2. All gas lines should be re-checked for soundness
using leak detector solution.
3. All pressure test points are checked for
soundness.
4. The correct operation of all the control and safety
devices.
14.1 Handing Over
After completing the installation the installer should
demonstrate the operation of the boiler and any
system controls to the user.
ALL instruction MUST be handed to the user for
retention and advice given regarding the need for
annual servicing.

- 19 -
15.0 Maintenance
1. Removal of Burner
•Isolate both the electrical and gas supply to the
boiler.
•Open the boiler control cover.
•Remove the two self tapping screws at bottom of
front case.
•Pull the front case forward, at the bottom and lift.
•Remove the ten self tapping screws from the
outer combustion chamber cover.
•Remove the self tapping screws from the inner
combustion chamber cover (Mital plus, Mital max,
Montreux plus and Montreux max) and remove.
•Disconnect and remove ignition probe and either
pilot burner or flame detection probe.
•Remove the four burner fixing screws and pull
assembly forward as per Figure. 21.
•Check the injectors for damage or blockage.
•Inspect the burner gas ways for damage or
blockage. Vacuum or blow out any lint or dirt.
•Check the burner plaques for signs of cracking,
distortion or leaking. Replace if damaged.
•Gently brush the top of the burner with a soft
brush and blow away any deposits.
•Inspect the combustion chamber insulation for
signs of charring or damage. Replace if required.
•Check the fan assembly for signs of wearing, over
heating or distortion.
•Remove fan assembly and inspect for damage.
Remove any dust and replace.
Figure. - 21 Burner Fixing Screws.
2. Pilot Burner (Mital and Montreux)
•Check the injectors for damage or blockage.
•Inspect the burner gas ways for damage or
blockage.
•Vacuum or blow out any lint or dirt.
3. Clean Flueways
•Cover the controls and burner injectors with a
waterproof sheet.
•Remove flue hood by removing the three fixing
screws and disconnecting the electrical wires for
the fan.
•Remove all loose deposits from the heat
exchanger, particularly between the fins, working
from above and below the heat exchanger, using
a suitable brush.
•Once clean reassemble burner, fan, and pilot.
4. After Service Checks
•Check the distance between burner or pilot head
and the ignition and detection electrodes are
3mm.
•Check pilot burner or flame detection probe are
correctly aligned.
•Complete re-assembly of boiler and case.
•Turn ON both the gas and electrical supply.
•Check boiler ‘LIVE’ light is illuminated.
•Set controls to ‘calling’.
•Observe lighting sequence, ensuring quiet burner
ignition.
•Check burner & pilot pressure and adjust if
required.
•Observe flame picture of both pilot and burner.
15.1 Fault Finding
On the following page is a fault finding guide.
•Column 1 Fault, states the current fault.
•Column 2 Warning Lights, the Mital plus, Mital
max, Montreux plus and Montreux max have a
enhanced control panel to assist with fault finding.
You should look down the Warning Lights column
to find the sequence of lights which is displayed
on the boiler with reference to the fault.
•Column 3 Consequences, relates to the
secondary faults.
•Column 4 Possible Causes, of the fault in column
1.

- 20 -
15.2 Fault Finding Guide.
Fault Warning Lights Consequences Possible Causes
Burner fails to light green light off - No power
- Main switch off
- Main fuse blown
- appliance fuse blown
water gauge around 0 bar - low system pressure
- faulty system water pressure switch
fan functions - faulty air pressure switch
- blocked flue
- pressure switch tubes blocked /
disconnected
- flue too long
- boiler flue gate set in the wrong position
fan not working - faulty air pressure switch
- faulty fan
Boiler partially
working hot water only - room thermostat set too low
- faulty room thermostat
- faulty programmer / timer
heating only - HWS control thermostat set too low
- faulty HWS control thermostat
- faulty diverter valve micro switches
- faulty diverter valve
Improper operation burner noisy - reddish flame - gas pressure wrong
burner noisy on ignition - ignition source poorly aligned
- faulty burner delay
boiler keeps switching off and on - radiators shut down
- pump speed too low
- by-pass wrongly adjusted
- air lock
- system too small
Radiators cold boiler kettling - pump speed too low
- system incorrectly balanced
- air in system
Boiler locks out locks out after a few seconds - ionisation probe misalign
- ionisation probe wire disconnected or
broken
- poor electrical earth
- phase and neutral swapped
- Ignition card faulty
- power supply out of phase
boiler sparks but fails to light - gas supply turned off
- ignition probe misalign
- poor gas pressure
- faulty gas valve
locks out during normal operation - faulty heating control thermostat
- faulty hot water control thermostat
- pump blocked
- blocked heat exchanger
- system blocked
Safety valve leaks pressure gauge above 1.5 bar (cold) - system pressure too high
pressure gauge above 3 bar (hot) - faulty expansion vessel
pressure gauge normal - faulty safety valve
HWS lukewarm radiators hot when hot water is being drawn - diverter blocked
fluctuating HWS temperature - HWS control thermostat wrongly calibrated
- gas valve not calibrated
- fluctuating gas pressure
- faulty gas valve modulator
hot primary pipe - flow regulator misadjusted
- scale build up in HWS exchanger
boiler off diverter valve working - faulty HWS control thermostat
= Light NOT on = Light ON