Ariston MICROCOMBI 23 MFFI User manual

Installation
Instructions
Type C Boilers
G.C.N: 47-116-16
LEAVE THESE INSTRUCTIONS
WITH THE END-USER
Country of destination: GB

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/SYSTEM DIAGRAMS
2.12 WATER CIRCUIT DIAGRAM
3. COMMISSIONING
3.1 INITIAL PREPARATION
3.2 CONTROL PANEL
3.3 REMOVING THE FRONT PANEL
3.4 INITIAL START UP
3.5 OPERATIONAL ADJUSTMENTS
3.6 COMBUSTION ANALYSIS
3.7 FUME DISCHARGE MONITORING
3.8 BOILER SAFETY SYSTEMS
3.9 DRAINING THE SYSTEM
4. GAS ADJUSTMENTS
GAS ADJUSTMENT TABLE
4.1 CHANGING THE TYPE OF GAS
5. MAINTENANCE
6. MISCELLANEOUS
6.1 WIRING DIAGRAM FOR TWO HEATING ZONES
6.2 WIRING DIAGRAM FOR CONNECTION TO AN ARISTON UNVENTED CYLINDER
7. TECHNICAL 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.
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 a combined appliance for the production of central heating (C.H.) and
domestic hot water (D.H.W.).
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 3.6) and cleaning of the burner if needed.
1. GENERAL
INFORMATION
3
1.1 GENERAL INSTRUCTIONS

4
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- Check of domestic hot water production efficiency (flow rate and temperature)
13- General check of the combustion by-products of the discharge/ventilation
system.
14- Check of the general performance of the unit.
LEGEND:
1. Flue connector
2. Air intake for twin pipe flue systems
3. Fan
4. Combustion chamber hood
5. “Twin-pass” heat exchanger
6. Domestic hot water temperature probe
7. Combustion chamber
8. Combustion chamber insulation panel
9. Burner
10. Detection electrode
11. Ignition electrodes
12. Gas valve
13. Spark generator
14. Pump pressure switch
15. Safety valve (3 bar)
16. Automatic By-pass
17. D.H.W. Flow switch
18. Domestic hot water inlet filter
19. Circulation pump with automatic air release valve
20. Safety thermostat
21. Main circuit temperature probe
22. Expansion vessel
23. Air pressure switch
24. Combustion analysis points
1.2 OVERALL VIEW
FIG. 1.0
IN016A

5
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:
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.
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.
2.1 REFERENCE STANDARDS
2. INSTALLATION
2.2 SITING THE APPLIANCE
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

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 table in section 6, 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 (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; make sure to re-
use the grommet mounted on the other supply cord;
- The blue wire should be connected to the terminal
marked “N”;
- The brown wire should be connected to the terminal
marked “L”.
6
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
250
LEGEND:
A = Central Heating Flow (3/4”)
B = Domestic Hot Water Outlet (1/2”)
C = Gas Inlet (3/4”)
D = Domestic Cold Water Inlet (1/2”)
E = Central Heating Return (3/4”)
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. 2.2
2.4 CLEARANCES
FIG. 2.1
FIG. 2.2
FIG. 2.3
QT002A
DM001A
VR001A

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
CENTRAL HEATING
Detailed recommendations are given in BS 6798:1987 and BS 5449-1:1990,
the following notes are given for general guidance.
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.
7
Note:The diagrams for the electrical system are indicated in section 2.11.
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 microCombi is 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).
FIG. 2.4
FIG. 2.5
KT003A
SC005A
FF

8
VR003A
RESIDUAL HEAD OF THE BOILER
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 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.
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 litres (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 in accordance with current Water Regulations and Byelaws
must be provided.
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.

Ø60/100 mm
FIG. 2.7
A
BC
D
E
F
G
J
K
HI
L
GF
The boiler is designed to be connected to a coaxial flue discharge system.
9
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. 2.6.
T ERMINAL P OSITION mm
A - Directly 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 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. 2.6 FU010A
FU003A
FU002A

Ø80 mm
The components marked * in FIG 2.9 are present or absent
depending on the type of flue system used by the installer.
In addition, it is also possible to use a split (twin pipe)
system by fitting a special adaptor to the flue connector
and using the aperture for the air vent intake located on
the top part of the combustion chamber.
To utilise the air intake it is necessary to:
1. Remove the bottom of the air intake by cutting it with a
suitable knife (see FIG.2.8);
2. Insert the elbow into the air intake until it reaches the
lower end.(There is no need to use gaskets or sealing
compounds).
10
IMPORTANT!
For all flue systems, a restrictor
may be be inserted into the
boilers flue connector; the
restrictor must be Ø43 in
diameter depending on the length
of piping indicated inTABLE 2.1.
FIG 2.10 and FIG 2.11 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. 2.8
FIG. 2.9
FIG. 2.10
FU005A
FU006A
FU004A
FU001A