Ariston STI 125 INDIRECT User manual

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Installation
Instructions
Type C Boilers
G.C.N: 41-116-04
LEAVE THESE INSTRUCTIONS
WITH THE END-USER
Country of destination: GB

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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 User’s Manual.
1. GENERAL
INFORMATION
2
TABLE OF CONTENTS 1. GENERAL INFORMATION
1.1 GENERAL INSTRUCTIONS
1.2 OVERALL VIEW
2. INSTALLATION
2.1 REFERENCE STANDARDS
2.2 SITING THE APPLIANCE
2.3 OVERALL DIMENSIONS
2.4 CLEARANCES
2.5 MOUNTING THE APPLIANCE
2.6 ELECTRICAL CONNECTION
2.7 GAS CONNECTION
2.8 WATER CONNECTIONS
2.9 FLUE CONNECTION
2.10 ROOM THERMOSTAT CONNECTION
2.11 ELECTRICAL DIAGRAMS
2.12 GAS AND WATER CIRCUITS
3. D.H.W. STORAGE CYLINDER
3.1 2 PORT AND 3 PORT VALVE INSTALLATIONS
3.2 DOMESTIC HOT WATER PRIORITY KIT
4. COMMISSIONING
4.1 INITIAL PREPARATION
4.2 CONTROL PANEL
4.3 REMOVING THE FRONT PANEL
4.4 INITIAL START UP
4.5 OPERATIONAL ADJUSTMENTS
4.6 COMBUSTION ANALYSIS
4.7 FUME DISCHARGE MONITORING
4.8 DRAINING THE SYSTEM
5. GAS ADJUSTMENTS
GAS ADJUSTMENT TABLE
5.1 CHANGING THE TYPE OF GAS
6. MAINTENANCE
7. TECHNICAL INFORMATION

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1.1 GENERAL INSTRUCTIONS Read the instructions and recommendations in these Installation 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 our
Servicing Centre technicians or your installer may need to consult it in the future.
This is an appliance for the production of central heating (C.H.).
This appliance must be used only for the purpose for which it is 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 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.
If you are going away for a long period of time, remember to shut the mains gas tap
or the gas cylinder valve.
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 Centre and request the use of
original spare parts. For in-guarantee repairs contact MTS (GB) Limited.
Check the following at least once a year:
1 - Check the seals for the water connections; replace any faulty seals.
2 - Check the gas seals;replace any faulty gas seals.
3 - Visual check of the entire unit.
4 - Visual check of the combustion process or analysis of combustion by-products
(see section 4.5) and cleaning of the burner if needed.
5 - If called for by point.3, dismantling and cleaning of the combustion
chamber.
6 - If called for by point.4, dismantling and cleaning of the burner jets.
7 - Visual check of the primary heat exchanger:
- check for overheating in the blade assembly;
- clean the exhaust fan if needed.
8 - Adjustment of the flow rate of the gas:flow rate for lighting, partial load and full
load.
9 - Check of the heating safety systems:
- safety device for maximum temperature (overheat thermostat);
- safety device for maximum pressure (safety valve).
10- Check of the gas safety systems:
- safety device for lack of gas or flame ionisation (detection
electrode);
- safety device for gas cock.
11- Check of the electrical connection (make sure it complies with the instructions
in the manual).
12- General check of the combustion by-products of the discharge/ventilation
system.
13- Check of the general performance of the unit.

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The technical information and instructions provided herein below are intended for the
installer so that the unit may be installed correctly and safely.
The installation and initial start up of the boiler must be by a CORGI Registered
Installer in compliance with the installation standards currently in effect, as well as
with any and all local health and safety standards i.e. CORGI .
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 current Gas Safety (installation & use) Regulations, the Local
Building Regulations, the current I.E.E. Wiring Regulations, the byelaws of the local
water authority, and in Scotland, in accordance with the Building Standards
(Scotland) Regulation and Health and Safety document No. 635 “Electricity at work
regulations 1989”.
Installation should also comply with the following British Standard Codes of Practice:
2.1 REFERENCE STANDARDS
2. INSTALLATION
1.2 OVERALL VIEW
FIG. 1.0
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 5440-1:1990 Flues
BS 5440-2:1989 Air supply
BS 5449:1990 Forced circulation hot water systems
BS 6789:1987 Installation of gas fired hot water boilers of rated
input not exceeding 60kW
BS 6891:1989 Installation of low pressure gas pipe up to 28mm
BS 7671:1992 IEE wiring regulations
BS 4814:1990 Specification for expansion vessels
BS 5482:1994 Installation of LPG
LEGEND:
1. Flue connector
2. Fan
3. Combustion chamber hood
4. Main heat exchanger
5. Safety thermostat
6. Combustion chamber
7. Combustion chamber insulation panel
8. Detection electrode
9. Ignition electrodes
10. Burner
11. Regulation thermostat
12. Frost thermostat
13. Pump pressure switch
14. Safety valve (3 bar)
15. Automatic By-pass
16. Gas valve
17. Spark generator
18. Boiler drain valve
19. Circulation pump with automatic air release valve
20. Expansion vessel
21. Air pressure take-off point
22. Air pressure switch
23. Combustion analysis points

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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.
Fasten the boiler in place using the template and anchors supplied with the unit. It is
highly recommended that a spirit level be used to position the boiler so that it is
perfectly level.
For additional information, please consult the instructions contained in the
connection kit and the flue kit.
2.6 ELECTRICAL CONNECTION
2.5 MOUNTING THE APPLIANCE
132 132
CE
400 mm
300 mm
60 mm
450 mm
LEGEND:
A= Central Heating Flow (3/4”)
C= Gas Inlet (3/4”)
E= Central Heating Return (3/4”)
mm = Clearances
2.3 OVERALL DIMENSIONS
In order to allow for access to the interior of the boiler for
maintenance purposes, the boiler must be installed in
compliance with the minimum clearances indicated in FIG. 2.1
2.4 CLEARANCES
FIG. 2.1
5
2.2 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 appliance in a room containing a bath or
shower.
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.
The location must permit adequate space for servicing and air circulation around the
appliance as indicated in paragraph 2.4.
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, permanent wall to prevent access from the rear.

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The boiler operates with alternating current, as indicated in the
technical information table in section 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 under the
inspection cover (see the servicing manual for further
information)
IMPORTANT!
In the event that the power supply cord must be changed, replace it with one with the
same specifications. Make the connections to the terminal board located within the
control panel, as follows:
- The yellow-green wire should be connected to the terminal marked with the “”
symbol;
- The blue wire should be connected to the terminal marked “N”;
- The brown wire should be connected to the terminal marked “L”.
Note:The diagrams for the electrical system are indicated in section 2.12.
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 microSYSTEM range of boilers are supplied for connection to a 230 V~ 50 Hz
supply.
The supply must be fused at 3 A.
The method of connection to the electricity supply 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 (see section 2.2).
E
L
N
FIG. 2.2
2.8 WATER CONNECTIONS
2.7 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 should not be used.
FIG. 2.4
VIEW OF THE BOILER CONNECTIONS
FIG. 2.3
A
D
LEGEND:
A= Central Heating Flow
C= Gas Inlet
E= Central Heating Return
F= Safety Valve
G= Pump transportation screw
(remove before igniting the boiler)
H= Automatic By-pass pipe
F
BC
E
SC004A

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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
collecting 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 radiator valves within the
system.
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.
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 6 litre (1.3 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.
MAINS WATER FEED - CENTRAL HEATING:
There must be no direct connection to the mains water supply even through a
non-return valve, without the approval of the Local Water Authority.
FILLING:
A temporary method for initially filling the system and replacing lost water during
servicing and initial filling (in accordance with current Water Regulations), is provided
as an integral part of the connection kit (see FIG. 2.4). The flexible hose must be
removed once the system has been filled.
RESIDUAL HEAD OF THE BOILER

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Ø60/100 mm
FIG. 2.6
A
BC
D
E
F
G
J
K
HI
L
GF
The boiler is designed to be connected to a coaxial flue discharge system.
2.9 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.
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.
A suitable terminal guard is available from:
TOWER FLUE COMPONENTS
Morley Road
Tonbridge
KentTN9 1RA
The minimum acceptable spacing from the terminal to obstructions and ventilation
openings are specified in FIG. 2.5.
T
ERMINAL P OSITION
mm
A - Directly below an openable window or other opening 300
B - Below gutters, soil 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 75
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
FIG. 2.5

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Exhaust
Type
C12 (xx)
C32 (xx)
C42 (xx)
Restrictor
ø44 mm
L min = 0.5 m
L max = 1 m
Maximum
Extension
Exhaust/Air
L = 5 m
Risk of Condensation Forming
Coaxial
Systems
ø60/100
Piping not insulated
ø44 restrictor NO restrictor
NONE NONE
Piping insulated
ø44 restrictor NO restrictor
NONE NONE
TABLE 2.1
10 RFFI
To connect a room thermostat and/or time clock, it is necessary
to:
1. - Open the control panel as indicated in section 4.3;
2.- Remove screws “A” and remove the inspection cover from
the reverse of the control panel;
3.- For the room-thermostat connect the thermostat switching
wires to the position 5 and 6 and remove the wire link (for
three-wire thermostats connect the neutral to terminal N);
4. - For the time clock connect the clock switching wires to the
positions 3 and 4 and connect the clock motor electrical
supply to the terminals marked Land N.
Note: A frost thermostat is built-in to the appliance.
For connection to control systems with zone valves
for hot water cylinders see section 3.
2.10 ROOM THERMOSTAT
CONNECTION
A
9
IMPORTANT!
For all flue systems, a restrictor must
always be inserted into the boiler’s
flue connector; the restrictor must be
Ø 44 in diameter depending on the
length of piping indicated in TABLE
2.1.
FIG 2.9 and FIG 2.10 illustrate some of
the various designs for coaxial or twin
pipe flue systems.
For further information on
discharge/ventilation accessories, see
the FLUE PIPE ACCESSORIES MANUAL.
COAXIAL SYSTEMS
FIG. 2.9

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2.11 ELECTRICAL DIAGRAM
10
FIG. 2.12
Legend: A - On/Off Switch
B - On/Off L.E.D.
C - Heating Switch
D - Heating L.E.D.
E - Reset Button
F - Ignition Failure (Lockout) L.E.D.
A01 - Pump Pressure Switch
A02 - Frost Thermostat
A03 - Modulator
A04 - Circulation Pump
A05 - Regulation Thermostat
A06 - External Control System
A07 - Time Clock Connector
A08 - External (Room) Thermostat
A09 - Air Pressure Switch
A10 - Fan
A11 - Overheat Thermostat
A12 - Spark Generator/Gas Valve Supply
A13 - Detection Electrode
Colours: Wh - White
Bl - Blue
Gry - Grey
Brn - Brown
Blk - Black
Rd - Red
Grn/Yll-Yellow/Green

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1
2
3
4
5
6
7
8
9
10
11 12
13
14
15
16
17
LEGEND:
1. Fan
2. Main heat exchanger
3. Overheat thermostat
4. Burner
5. Ignition electrodes
6. Detection electrode
7. Regulation thermostat
8. Frost thermostat
9. Gas valve
10. Pump pressure switch
11. Safety valve (3 bar)
12. Boiler drain valve
13. Automatic by-pass
14. Pressure gauge
15. Circulation pump with automatic
air release valve
16. Expansion vessel
17. Air pressure switch
A. Central Heating Flow
B. Inlet Gas
C. Central Heating Return
2.12 GAS AND WATER CIRCUITS
FIG. 2.14
FIG. 2.13

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3. D.H.W. STORAGE
CYLINDER The microSYSTEM can be connected to a storage cylinder (both open-vented and
unvented) for the production of domestic hot water (D.H.W.). Cylinders of different
capacities can be used depending on site requirements (see TABLE 3.1 for a
selection of ARISTON unvented cylinders).
FIG. 3.2
3 port valve installation
FIG. 3.1
2 port valve installation
3.1 2 PORT AND 3 PORT VALVE
INSTALLATIONS
Wiring to 2 port valve installation
using an external 2 channel
programmer
Type Danfoss FP715
Type Honeywell ST6400C
FIG. 3.3

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Technical Data Capacity Coil C.H.W. D.H.W. Max Heating Heat Ioss
Surface Flow/rate Flow/rate Output
MODEL It. m2m3/h It/h kW kWh/24h
Contract STI 125 Indirect 125 0.75 0.5 194 11.3 2
1 266 15.5
2 340 19.8
Comfort STI 125 Indirect 125 0.75 0.5 256 14.9 2.2
Contract STI 150 Indirect 150 0.93 1 353 20.5
2 451 26.2
Comfort STI 150 Indirect 150 0.93 0.5 256 14.9 2.4
Contract STI 210 indirect 200 0.93 1 353 20.5
2 451 26.2
Comfort STI 210 Indirect 200 0.93 0.5 256 14.9 2.9
Contract STI 300 Indirect 300 0.93 1 353 20.5
2 451 26.2
SB 125 Indirect 125 1 0.5 190 11 1.72
1 318 18.5
2 496 28.8
SB 150 Indirect 150 1 0.5 190 11 1.75
1 318 18.5
2 496 28.8
SB 200 Indirect 200 1.3 0.5 190 11 2.1
1 318 18.5
2 496 28.8
TABLE 3.1
Wiring to 3 port valve installation
using an external 2 channel
programmer
Type Danfoss FP715
Type Honeywell ST6400C
FIG. 3.4 NOTE:When using a 3 port valve installation in conjunction with an unvented cylinder it will be
necessary to use a 2 port valve on the cylinder flow connection in addition to the 3- port
valve to satisfy Building Regulations.

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MTS (GB) Limited support the initiative. Within the information pack you will
find a copy of the logbook. It is important that this is completed in the
presence of your customer, they are shown how to use it, and it is signed by them.
Please instruct your customer that they must have their logbook with them
whenever they contact a service engineer or us.
Preliminary electrical system checks to ensure electrical safety must be carried out
by a competent person i.e. polarity, earth continuity, resistance to earth and short
circuit.
FILLING THE HEATING SYSTEM:
Remove the panels of the case and lower the control panel (see section 3.3 for
further information).
Open the central heating flow and return cocks supplied with the connection kit
(there are two isolation points on the return connection).
Unscrew the cap on the automatic air release valve one full turn and leave open
permanently.
Close all air release valves on the central heating system.
Gradually open valve(s) at the filling point (filling-loop) connection to the central
heating system until water is heard to flow, do not open fully.
Open each air release tap starting with the lowest point and close it only when
clear water, free of air, is visible.
Purge the air from the pump by unscrewing anticlockwise and removing the
pump plug and also manually rotate the pump shaft in the direction
indicated by the pump label to ensure the pump is free.
Refit the pump plug.
Continue filling the system until at least 1.5 bar registers on the pressure gauge.
Inspect the system for water leaks and remedy any leaks discovered.
GAS SUPPLY:
Inspect the entire installation including the gas meter, test for soundness and
purge the supply as described in BS 6891:1988.
Open the gas cock (supplied with the connection kit) to the appliance and check
the gas connections on the appliance for leaks.
When the installation and filling are completed turn on the central heating system
(section 4.4) and run it until the temperature has reached the boiler operating
temperature.The system must then be immediately flushed through.
The flushing procedure must be in line with BS 7593:1992 code of practice for
treatment of water in domestic hot water central heating systems.
During this operation, we highly recommend the use of a central heating flushing
detergent (Fernox Superfloc or equivalent), whose function is to dissolve any foreign
matter that may be in the system.
Substances different from these could create serious problems to the pump or
other components.
The use of an inhibitor in the system such as Fernox MB-1 or equivalent is strongly
recommended to prevent corrosion (sludge) damaging the boiler and system.
Failure to carry out this procedure may invalidate the appliance warranty.
4. COMMISSIONING
4.1 INITIAL PREPARATION
Boiler microSYSTEM
10 RFFI
Cylinder
Possible
Possible
The microSYSTEM is able to be connected to a specially designed kit for the
management of D.H.W. production.This kit gives priority to production of D.H.W.unlike
traditional systems where the boiler power is split between C.H. and D.H.W. This
generally enables a smaller storage cylinder to be chosen as the boiler’s full output
will be channelled into the cylinder allowing for a quick heat-up.
The kit (ARISTON part number 706329) can be obtained from an ARISTON supplier.
The kit consits of:
1) Electronic module able to plug into the boiler’s P.C.B;
2) 3-way priority valve with actuator for connection to the boiler’s flow outlet;
3) A limit thermostat (80˚C) to check the water temperature of the heating flow to the
cylinder, to be installed within the boiler;
4) Pipes and accessories.
Contract STI 125 Indirect
Comfort STI 125 Indirect
TABLE 3.2
3.2 DOMESTIC HOT WATER
PRIORITY KIT

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B
4
5
In order to access the inside of the boiler, it is necessary to
unscrew the fastening screws “A” of the control panel located on
the lower part of the panel itself.
The control panel moves downward and when pulled forward
rotates on two lateral hinges.
The panel stays in a semi-horizontal position, which allows
access to the inner parts of the boiler.
In order to increase the manoeuvring space, it is possible to raise
the control panel and rotate it to a fully horizontal position.
15
4.3 REMOVING THE
FRONT PANEL
1
2
3
A
LEGEND:
A- On/Off button
B- On/Off L.E.D. green (frost protection active)
C- Central Heating button
D- Cental Heating active L.E.D. green
E- Ignition failure (lockout) and/or overheat reset button
F- Ignition failure (lockout) and/or overheat L.E.D. red
G- Central heating temperature adjustment
H- Energy Saving System (ESS)
I- Knock-out for time clock
J- Heating system pressure gauge
4.2 CONTROL PANEL
FIG. 4.1
To dismantle the front casing panel it is necessary to:
1 - Remove the two screws “B”;
2 - Move the front casing panel up and lift forward.

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The flue connector has two apertures, readings can be taken for
the temperature of the combustion by-products and of the
combustion air, as well as of the concentrations of O2and CO2,
etc. .
To access these intakes it is necessary to unscrew the front
screw and remove the metal plate with sealing gasket.
To achieve the best test conditions, turn the central heating
adjustment knob “G”to the “max”position and remove the
electrical connection to the heating sensor (see section 6.). This
will allow the appliance to operate at the maximum heating
power.
4.5 COMBUSTION ANALYSIS
4.4 INITIAL START-UP THE CHECKS TO BE RUN BEFORE INITIAL START-UP ARE AS FOLLOWS:
1. Make sure that:
-the screw on the automatic air valve has been loosened when the
system is full;
- If the water pressure in the system is below 1.5 bar, bring it up to the appropriate
level;
-Ensure that the gas cock is closed;
-Make sure that the electrical connection has been made properly and that the
earth wire is connected to an efficient earthing system;
-Supply power to the boiler by pushing the On/Off button “A” (see FIG.4.1) - the
L.E.D. “B” will illuminate. Then push the button “C” in for central heating - the
L.E.D. “D” will illuminate.This will start the circulation pump. After 7 seconds, the
boiler will signal a shutdown due to ignition failure. Leave the boiler as it is until
all of the air has been bled from the system.
-Loosen the cap on the head of the pump to eliminate any air pockets;
-Repeat the procedure for bleeding the radiators of air;
-Check the system pressure and, if it has dropped, open the filling loop
again to bring the pressure back up to 1.5 bar.
2. Make sure that all gate valves are open;
3. Turn on the gas cock and check the seals on the connections with an approved
soap solution and eliminate any leaks.
4. Press the reset button “E” for the lighting system; the spark will light the main
burner. If the burner does not light the first time, repeat the procedure.
5. Check the minimum and maximum pressure values for the gas going to the
burner; adjust it if needed using the values indicated in the table in
section 5 (See the relative section for burner pressure adjustment within the
servicing manual).
FIG. 4.2
In the boiler, it is possible to monitor the correct operation of
the flue exhaust/air intake, checking for a loss of general
pressure in the system. Through the use of a differential
manometer connected to the test points of the combustion
chamber, it is possible to detect the ∆P of operation of the air
pressure switch.
The value detected should not be less than 0.5 mbar under
conditions of maximum thermal power in order for the boiler
to function properly and without interruption.
4.6 FUME DISCHARGE
MONITORING
FIG. 4.3

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The boiler is fitted with the following devices (see section 4.2 for references).
1 - IGNITION FAILURE:
This indicates ignition failure when a flame is not detected within 7 seconds of
starting an ignition sequence. The L.E.D. “F” will illuminate to signal the
shutdown status.
The system can be reset by pressing and releasing the button “E” after
checking to make sure that the gas cock is open.
2 - INSUFFICIENT SYSTEM PRESSURE:
In the event of insufficient water pressure in the heating system, a safety device
will shutdown the boiler. Check the system pressure on the pressure gauge “J”
and if it is less than 0.4 bar refill the system to 1.5 bar. Once the system
pressure is at the correct level the boiler will ignite automatically.
3 - OVERHEATING:
This control shuts off the boiler in the case where the primary circuit reaches a
temperature in excess of 105°C.
The red L.E.D.“F” will illuminate to signal this shutdown status.
The system can be reset by waiting a few minutes for the primary exchanger to
cool down and then by pressing and releasing the “E”button.
4. ANTI-FROST DEVICE:
The boiler is equipped with a device that, in the event of the water temperature
going below 6°C, the burner ignites at the minimum power until the boiler water
reaches a temperature of 16°C.
This device operates only if the boiler is functioning perfectly and:
- the system pressure is sufficient;
- the boiler is powered electrically - L.E.D.“B” illuminated;
- the gas is turned on.
5 - EXHAUST DISCHARGE ANOMALY SHUTDOWN:
The boiler is fitted with safety devices, which in the event of defective discharge
of exhaust fumes, automatically interrupts the gas supply, thereby shutting off
the boiler.
The shutdown of the boiler is temporary and when the discharge state of
exhaust fumes has returned to normal, the boiler automatically turns back on
17
4.7 BOILER SAFETY SYSTEMS
The heating system must be emptied as follows:
- Turn off the boiler;
- Attach a hose pipe and open the drain valve;
- Empty the system at the lowest points (where present). When the heating system
is unused for an extended period of time, it is recommended that you add
antifreeze with an ethylene glycol base to the water in the
heating lines and radiators if the ambient temperature drops below 0°C during the
winter.
This makes repeated draining of the entire system unnecessary.
4.8 DRAINING THE SYSTEM

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18
The boiler can be converted to use either methane (natural) gas (G20)
or LPG (G30 - G31) by an Authorised Service Centre.
The operations that must be performed are the following:
1. Replace the jets on the main burner (see table in section 5);
2. Pay attention to put the gas restrictor if convert the boiler from NG to
GPL and to take it out when pass from LPG to NG;
2. Adjust the maximum and minimum thermal capacity values for the boiler
(see table in section 5);
3. Replace the gas rating plate;
4. Adjust the maximum thermal power setting;
5. Adjust the soft-light feature (open the cover of the regulation screw on the
gas valve (see FIG. 5.1). Rotate clockwise from min. to max. as per
installation requirements).
5.1 CHANGING THE
TYPE OF GAS
The outlet pressure of the gas cock is obtained by completely loosening the screw on the solenoid.The
maximum pressure of the gas to the burner will be equal to the nominal delivery pressure minus the
head loss within the gas valve.
[1 mbar = 10,197 mmc.a.]
5. GAS ADJUSTMENTS
CATEGORY II2H3+ Methane Gas
G20 Liquid Butane Gas
G30 Liquid Propane Gas G31
45.67
20
17
1.30
---
1.22
----
8.3
80.58
29
20
0.77
2.9
----
0.91
22.9
80.58
37
25
0.77
2.9
----
0.90
29.5
VG002Ab
TABLE 5.1
FIG. 5.1
Lower Wobbe Index (15°C;1013mbar) MJ/m3h
Nominal Delivery Pressure mbar
Minimum Delivery Pressure mbar
10 RFFI
Main Burner: n. 8 jets (ø)mm
Restrictor ø
Consumption (15°C; 1013mbar) m3/h
Consumption (15°C; 1013mbar) Kg/h
Gas Burner Pressure:
max - min mbar

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19
It is recommended that the following inspections be carried out on the boiler at
least once a year:
1 - Check the seals for the water connections; replace any faulty seals.
2 - Check the gas seals;replace any faulty gas seals.
3 - Visual check of the entire unit.
4 - Visual check of the combustion process or analysis of combustion by-products
(see section 4.5) and cleaning of the burner if needed.
5 - If called for by point.3, dismantling and cleaning of the combustion chamber.
6 - If called for by point.4, dismantling and cleaning of the burner jets.
7 - Visual check of the primary heat exchanger:
- check for overheating in the blade assembly;
- clean the exhaust fan if needed.
8 - Adjustment of the flow rate of the gas:flow rate for lighting, partial load and full load.
9 - Check of the heating safety systems:
- safety device for maximum temperature (overheat thermostat);
- safety device for maximum pressure (safety valve).
10- Check of the gas safety systems:
- safety device for lack of gas or flame ionisation (detection electrode);
- safety device for gas cock.
11- Check of the electrical connection (make sure it complies with the instructions
in the manual).
12- General check of the combustion by-products of the discharge/ventilation system.
13- Check of the general performance of the unit.
6. MAINTENANCE

Supplied By www.heating spares.co Tel. [phone]
Manufacturer: MerloniTermoSanitari SpA - Italy
Commercial subsidiary: MTS (GB) LIMITED
MTS Building
Hughenden Avenue
High Wycombe
Bucks HP13 5FT
Telephone: [phone]
Fax: [phone]
Internet: http://www.mtsgb.ltd.uk
E-mail: inf[email protected]
Technical Service Hot Line: [phone]
23 99 84 1581 000 -Stampa: bieffe RECANATI
CE Certification
Heat Input max kW
Heat Output max kW
Efficiency of Nominal Heat Input %
Efficiency at 30% of Nominal Heat Input %
Heat Loss to the Casing (∆T=50°C) %
Flue Heat Loss with Burner Operating %
Flue Heat Loss with Burner Off %
Maximum Discharge of Fumes (G20) Kg/h
Residual Discharge Head mbar
Consumption at Nominal Capacity(G20) m3/h
Gas Consumption after 10 Minutes* m3
(15°C, 1013 mbar) (G30-G31) Kg/h
Temp. of exhaust fumes at nominal capacity °C
CO2 Content %
O2 Content %
CO Content ppm
Minimum Ambient Temperature °C
Head Loss on Water Side (max) (∆T=20°C) mbar
Residual Head of System bar
Heating Temperature max/min °C
Expansion Vessel Capacity l
Expansion Vessel Pre-load Pressure bar
Maximum Water Content of System l
Maximum Heating Pressure bar
Nominal Pressure Natural Gas (G20) mbar
LPG (G30-G31) mbar
Electrical Supply V/Hz
Power Consumption W
Protection Grade of Electrical System IP
Internal Fuse Rating
Weight Kg
G.C. Number
6. TECHNICAL INFORMATION
0063BL4994
11.6
10.5
81.3
79.2
3.2
6.1
0.2
23.7
0.3
1.22
0.13
0.91/0.90
121.7
6.94
8
31.5
+5
200
0.25
82/42
6
1
130
3
20
30-37
230/50
105
X4D
FAST 2 AT
30
41-116-04
10 RFFI
*Calculated at 70% maximum output