Ariston micro Genus 23 MFFI User manual

Installation Instructions
Type CBoilers
G.C.N: 41-116-01
47-116-08
47-116-09
47-116-13
LEAVETHESE INSTRUCTIONS
ADJACENTTOTHE GAS METER
Country of destination:GB

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TABLE OF CONTENTS
1. GENERAL INFORMATION
1.1 General Instructions
1.2 Technical Information
1.3 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 Diagrams
3. COMMISSIONING
3.1 Initial Preparation
3.2 Removing the Casing
3.3 Control 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 Ariston Unvented Cylinder

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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.
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 on pages 4-5 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 (on 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 carriyng 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 seal of water connections, replacing the gaskets if necessary.
2- Check the seal of the gas connections, replacing the gaskets if necessary.
1. GENERAL
INFORMATION
User’s
Manual
1.1 General Information

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23 MFFI 27 MFFI 27 RFFI SYSTEM 30 MFFI
CE Certification
Heat Input max/min kW 25.6/11.0 29.8/12.0 29.8/12.0 33.0/12.0
Heat Output max/min kW 23.1/9.2 27.3/10.1 27.3/10.1 30.3/10.2
Efficiency of Nominal Heat Input % 90.2 91.6 91.6 92.0
Efficiency at 30% of Nominal Heat Input % 87.8 88.3 88.3 88.6
Heat Loss to the Casing (³T=50°C) % 1.2 1.3 1.3 1.4
Flue Heat Loss with Burner Operating % 8.6 7.1 7.1 6.6
Flue Heat Loss with Burner Off % 0.4 0.4 0.4 0.4
Maximum Discharge of Fumes (G20-G25) Kg/h 59 62 62 61
Residual Discharge Head mbar 1.15 1.4 1.4 1.4
Consumption at Nominal Capacity (G20-G25) m3/h 2.72/3.32 3.16/3.86 3.16/3.86 3.49/4.05
Gas Consumption after 10 Minutes* m30.32/0.39 0.37/0.45 0.37/0.45 0.41/0.47
(15°C, 1013 mbar) (G30-G31) Kg/h 2.02/2.00 2.35/2.32 2.35/2.32 2.60/2.57
Temp.of exhaust fumes at nominal
capacity (G20-G25) °C 137 128 128 135
CO2 Content % 5.8 6.6 6.6 7.5
O2 Content % 9.2 8.0 8.0 8.0
CO Content ppm 32 34 34 49
Minimum Ambient Temperature °C +5 +5 +5 +5
Head Loss on Water Side (max) (³T=20°C) mbar 200 200 200 200
Residual Head of System bar 0.25 0.25 0.25 0.25
Heating Temperature max/min °C 82/42 82/42 82/42 82/42
Domestic Hot Water Temperature max/min °C 56/36 56/36 --- 56/36
D.H.W.Flow Rate ³T=35°C l/min 9.5 11.2 --- 12.3
D.H.W.Flow Rate ³T=35°C gal/min 2.1 2.5 --- 2.7
D.H.W.Flow Minimum Rate l/min 2.6 2.6 --- 2.6
Pressure of Domestic Hot Water max/min bar 6/0.2 6/0.2 --- 6/.02
Expansion Vessel Capacity l 7 7 7 7
Expansion Vessel Pre-load Pressure bar 1 1 1 1
Maximum Water Content in System l 145 145 145 145
Maximum Heating Pressure bar 3 3 3 3
Nominal Pressure Natural Gas (G20-G25) mbar 20-25 20-25 20-25 20-25
Liquid Gas (G30-G31) mbar 30-37 30-37 30-37 30-37
Electrical Supply V/Hz 230 / 50 230 / 50 230 / 50 230 / 560
Power Consumption W 150 190 190 190
Protection Grade of Electrical System IP X4D X4D X4D X4D
Internal Fuse Rating FAST 2 AT FAST 2 AT FAST 2 AT FAST 2 AT
Weight Kg 47 47 46.5 47
G.C. Number 47-116-08 47-116-09 41-116-01 47-116-13
1.2 Technical Information
3- Check the general condition of the appliance and of the combustion
chamber visually.
4- Visual check of the combustion: clean burners if necessary.
5- With reference to point 3, dismantle and clean the combustion chamber if
necessary.
6- With reference to point 4, dismantle and clean the injectors if necessary.
7- Visual check of the primary heat exchanger:
- check for overheating of the exchangers fins;
- clean the exhaust side of the exchanger and fan if necessary.
8- Regulate the gas pressure, ignition pressure, partial flame, maximum flame.
9- Check proper operation of the heating safety system:
- maximum safety temperature;
- maximum safety pressure.
10 - Check the proper operation of the gas safety system:
- gas or flame safety device;
- gas valve safety device.
11 - Check that the electrical connections have been made in compliance with
the instructions shown in the Installation Instructions.
12 - Check the efficiency of the hot water supply (flow and temperature).
13 - Check general operation of the appliance.
14 - Check the exhaust system for the combustion products.
*Calculated at 70% maximum output

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GENUS 23/27/30 MFFI
Legend:
1. Flue Connector
2. Combustion Chamber Hood
3. Main Heat Exchanger
4. Combustion Chamber Insulation Panel
5. Burner
6. Expansion Vessel
7. Overheat Thermostat
8. Spark Generator
9. Diverter Valve (MFFI)
Motorised Valve (RFFI)
10. Main Circuit Temperature Probe
11. Main Circuit Flow Switch
12. Domestic Hot Water Temperature Probe
13. Diverter Valve Microswitch
14. Filter Seat
15. Drain Valve
16. Secondary Heat Exchanger
17. Safety Valve (3 bar)
18. Circulation Pump with Automatic Air Release Valve
19. Gas Valve
20. Detection Electrodes
21. Ignition Electrodes
22. Fan
23. Venturi
24. Air Pressure Switch
GENUS 27 RFFI SYSTEM
Fig. 1.1
1.3 OverallView

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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 startup of the boiler must be by a CORGI Approved
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 the 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 regs. 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 boiler 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 an 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.
There are no limitations with respect to ventilation and the volume of the room
itself. The boiler must be installed on a solid, permanent wall to prevent access
to the electrical parts (when live) through the aperture on the back frame.
2. INSTALLATION
2.1 Reference Standards
2.2 Siting the Appliance
Low pressure
pipes BS 6891 1988
Boilers of rated input
not exceeding 60 kW BS 6798 1987
Forced circulation hot
water system BS 5449 1990
Installation of gas hot water
supplies for domestic purposes
( 2nd family gases) BS 5546 1990
Flues BS 5440-1 1990
Air supply BS 5440-2 1989

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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”)
F = Cylinder Flow (3/4”)
G = Cylinder Return (3/4”)
2.3 Overall Dimensions
890
385
(A-B-D-E)
(C)
465
99 99
132 67 65
85
155
208
30
49
(F - G)
(A-D-E)
(C)
AF CDGE
GENUS 23/27/30 MFFI
GENUS 27 RFFI SYSTEM
In order to allow for access to the interior of the boiler for maintenance purposes, the
boiler must be installed in compliance with the clearance requirements indicated in the
diagram below.
400
300
450
60 60
110197
160
2.4 Clearances
min 300 - ma x 350
GENUS 23/27/30 MFFI GENUS 27 RFFI SYSTEM
Fig. 2.1
Fig. 2.2

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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.
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 data
table (1.2), 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)
2.5 Mounting the Appliance
2.6 Electrical Connection
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
earth symbol; make sure to re-use the ferrule 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”.
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 qualified technician
and be in accordance with the current I.E.E. Regulations and applicable local
regulations.The Genus 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.
Fig. 2.3
2.7 Gas Connection
The local gas supplier 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.

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2.8 Water Connections
Legend
A = Central Heating Flow
B = Domestic Hot Water Outlet
C = Gas Inlet
D = Domestic Cold Water Inlet
E = Central Heating Return
F = Cylinder Flow
G= Cylinder Return
I = 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.
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 cock-type
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.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 downwards 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.
A
C
B D E
I
A
C
G
D E
I
F
GENUS 23/27/30 MFFI GENUS 27 RFFI SYSTEM
View of the Boiler Connections
Fig. 2.4
Fig. 2.5
Fitting the connection kit to the
Genus 27 RFFI System only.
It will be noted that the kit has two
connections not required for this boiler
i.e. the domestic cold inlet “E” and the
domestic hot water outlet “B” (see fig.
2.4)
.
Although the cold water main supply
must be connected to the isolation valve
for the purpose of operating the filling-
loop, the isolation valve is NOT
connected to the boiler and should be left
in the OFF position.
The D.H.W. outlet is capped-off on the
boiler, therefore not requiring the
isolation valve to be used.
The Genus 27 RFFI System has 2 x 3/4"
B.S.P. male threads for the cylinder flow
and return. It is recommended that 2 x
22mm x 3/4" female iron fittings (not
supplied) be used on these connections
(using P.T.F.E. tape), before the boiler is
mounted on the wall.

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Residual Head of the Boiler
27/30 kW
23 kW
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 value when the system is heated.
It can accept up to 7 l (1.5 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.
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 Water Supply Byelaw
14), is provided as an intergal part of the connection kit (see fig. 2.5) .The
flexible hose must be removed once the system has been filled.The D.H.W.
inlet valve on the connection kit has two postions, one for winter and one for
the summer.This enables the flow-rate through the appliance to be adjusted
so that a sensible D.H.W. temperature may be achieved throughout the year.
DomesticWater
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.
2.9 Flue Connections
Flue System
The provision for satisfactory flue termination must be made as described
in BS 5440-1.
The appliance must be installed so that the flue terminal is exposed to outdoor 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 “steaming” 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.

TERMINAL POSITION mm
A - Directly below an open 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 below 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
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A
BC
D
E
F
G
J
K
HI
L
GF
Fig. 2.6
Ø 60/100 mm
The boiler is designed to be connected to a coaxial flue discharge system.
Fig. 2.7
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

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A
Ø 80 mm
Ø 80 mm
In addition, it is also possible to use a split system by fitting a special adapter to
the flue discharge collar and using one of the apertures for the air vent intake
located on the top part of the combustion chamber (A).
A
A
Fig. 2.8
This procedure must be done as follows:
1- Remove the air vent intake you want to use, in the area indicated in
Fig. 2.9, by breaking the perforated ring.
2 - Use a tool to grasp the lid and remove it completely.
3 - Clean any burrs or sharp edges with a knife or an appropriate tool.
A
Fig. 2.9 Fig. 2.10

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In Fig. 2.11 below, several different types of flue systems are shown.
For additional information regarding the flue accessories, please consult the
Flue Pipe Accessories manual.
Fig. 2.11

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In calculating the lengths of the
pipes, the maximum length must also
take into consideration the values for
the exhaust/air intake end terminals,
as well as 90° elbows for coaxial
systems.
The C52 types must comply with the
following requirements:
1. The discharge/intake vent pipes
must have the same diameter of ø
80 mm.
2.The maximum combined flue
length is 17 m for Models Genus
23/27 MFFI/RFFI and 15 m for
Model Genus 30 MFFI. In this case
the minimum length for the air
intake pipe is 1 meter; the
maximum length of vertical
exhaust pipe must be a maximum
of 12 m.
3. If an elbow is inserted into the
discharge/ventilation system, the
calculation of the overall extension
must take into consideration the
values for each curve, as indicated
in the table.
4. The exhaust pipe must extend at
least 0.5 m above the ridge of the
roof if it is located on a side other
than that for the air intake (this is
not obligatory if the exhaust and air
intake pipes are located on the
same side of the building).
4 m 4 m 4 m
3 m 3 m 3 m
Maximum Extension
Exhaust/Air
23 kW - 27 kW 30kW
ExhaustType Diameter of
Pipes
(mm)
Use of Restrictor on Discharge Side
42 mm 45 mm
23kW 27 kW 30 kW
Risk of Condensation Forming
23kW 27 kW 30 kW
C12 (xx) C32 (xx) C42 (xx) C12 (xy) C32 (xy) C42 (xy) C52 (xy)
Coaxial
Systems
Twin Pipe
Systems
23 kW
54 m 54 m 54 m 17 m
27 kW
46 m 46 m 46 m 17 m
30 kW
50 m 50 m 50 m 15 m
ø 60/100 ø 60/100 ø 60/100
ø 80 ø 80 ø 80 ø 80
L * < 0.5 m L * < 0.5 m L * < 0.5 m
L < 7 m L < 7 m L < 7 m L < 7 m
L * < 0.5 m L * < 0.5 m L * < 0.5 m
L < 5 m L < 5 m L < 5 m L < 5 m
L * < 0.5 m L * < 0.5 m L * < 0.5 m
L < 7.5 m L < 7.5 m L < 7.5 m L < 7.5 m
L > 4.9 m L > 4.9 m L > 4.9 m L > 4.9 m
L > 6.5 m L > 6.5 m L > 6.5 m L < 5.3 m
L > 4.5 m L > 4.5 m L > 4.5 m L > 4.5 m
(*) L = Length of Piping

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4Remove the grommet “E” shown in the photo 4, make a hole in it and pass
the room thermostat wire through.
5Remove the link located in the terminal block and connect the wire.
6Replace the grommet and the terminal block to their original positions, close
the cover on the grommet compartment and fasten the wire-clamp “D” in
place.
7If a remote time clock is to be fitted, disconnect the integral time clock plug
from the P.C.B.
8Using a volt-free switching time clock, connect the switching wires from the
time clock following points 1-6 above.
9If using a time clock and room thermostat, these must be connected in
series as per points 1-8 above.
Note: Only a two-wire type room thermostat can be used.
For details on fitting the D.H.W. probe (Genus 27 RFFI only),
please consult the separate instruction sheet supplied with the
probe.
An anti-frost device is built-in to the appliance’s electronic
regulation system.
2.10 RoomThermostat
Connection
In order to perform this procedure, remove the boiler casing as indicated in
section 3.2.Then proceed as follows:
1Remove the two screws “A” in order to remove the cover, release the two
clips “B” and lift and rotate down the control panel box.
2Open the cover “C” on the left hand side of the compartment.
3Insert the wire for the connection of the room thermostat into the cable
clamp “D”, as indicated in photo 3.
12
A
B3
456
E
D
C
D

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2.11 Electrical Diagram
Legend:
AT = High Voltage P.C.B.
BT = Low Voltage P.C.B.
A = Remote Connector Kit
B = Flame Failure L.E.D.
C = Insufficient Water Pressure L.E.D.
D = WaterTemperature Indicator L.E.D.s
E = Overheat Thermostat Warning L.E.D.
F = System Reset Button
G = Selector Knob for Operating Mode
H = Domestic Hot Water Temp. Adjustment
I = Central Heating Temp. Adjustment
J = Wire Connector for Room Thermostat
K = Connector forTotal Check System
L = Selector for Local/Remote Control
M = Anti-cycling Device Adjustment for Heating
N = Soft-light Adjustment
O = Max Heating Temperature Adjustment
P = Time Clock Connection
Q = On/Off L.E.D.
R = On/Off Switch
S = Interface Wire for P.C.B.s
T = Relay Motorised Valve
U = Ignitor Relay
V = Gas Valve Relay
W = Fan Relay
X = Circulation Pump Relay
Y = Selector TCS2
Z = Link for Continuous Pump Run
Aa = Adaptor (British Gas use only)
A01= Air Pressure Switch
A02= Fan
A03 = Gas Valve
A04= Ignitor
A05 = Motorised Valve
A06= Circulation Pump
A07= Flame Detector
A08 = Earth Terminal
A09= Flame Detection Circuit
A10= Flame Indicator L.E.D.
A11= Transformer
A12= Filter
B01 = Over Heat Thermostat
B02 = External Thermostat
B03 = Gas Valve Modulator
B04= D.H.W. Probe Sensor Cylinder (RFFI SYSTEM models only)
B05= Heating Sensor
B06= Pressure Switch for Heating Circuit
B07= Microswitch for Diverter Valve (MFFI models only)
Colours
Gry = Grey
Rd = Red
Bl = Blue
Grn/Yll = Yellow/Green
Wh = White
Brn = Brown
Blk = Black
Wh/Rd = White/Red

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Aa
GENUS 23/27/30 MFFI
Aa
GENUS 27 RFFI SYSTEM

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CN202
P
GENUS 23/27/30 MFFI
P
GENUS 27 RFFI SYSTEM

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GENUS 23/27/30 MFFI
2.12 Water Circuit Diagram
Legend
1. Air Pressure Switch
2. Fan
3. Main Heat Exchanger
4. Burner
5. Electronic Ignitor and
Electronic Flame Detector
6. Gas Valve
7. Overheat Thermostat
8. Heating Sensor
9. Diverter Valve (MFFI)
Motorised Valve (RFFI)
10. Main Flow Switch Including
Safety Pressure Switch for
Primary Circuit
11. Automatic By-pass
12. Microswitch for Diverter Valve
13. Sensor for Domestic Hot Water
14. Secondary Heat Exchanger
15. Domestic Water Inlet Filter
16. Drain Valve
17. Safety Valve
18. Water Pressure Gauge
19. Circulation Pump with Automatic
Air Valve
20. Expansion Vessel
A. Central Heating Flow
B. Domestic Hot Water Outlet
C. Gas Inlet
D. Domestic Cold Water Inlet
E. Central Heating Return
F. Cylinder Flow
G. Cylinder Return
GENUS 27 RFFI SYSTEM

20
B004
3. COMMISSIONING
3.1 Initial Preparation
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 point 3.2. for
further information).
Open the central heating flow and return cocks supplied with the connection
kit.
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 lower point and close it only when
clear water, free of air, is visible.
Purge the air from the pump by unscrewing anticlockwise the pump plug and
also manually rotate the pump shaft in the direction indicated by the pump
label to ensure the pump is free.
Close the pump plug.
Continue filling the system until at least 1 bar registers on the pressure
gauge.
Inspect the system for water soundness and remedy any leaks discovered.
Filling of the D.H.W. System:
Close all hot water draw-off taps.
Open the cold water inlet cock supplied with the connection kit.
Open slowly each draw-off tap and close it only when clear water, free of
bubbles, is visible
Gas Supply:
Inspect the entire installation including the gas meter, test for soundness and
purge, all as described in BS 6891:1988.
Open the gas cock (supplied with the connection kit) to the appliance and
check the gas connector on the appliance for leaks.
When the installation and filling are completed turn on the central heating
system (sect. 3.4) 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 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.
To dismantle the front part of
the casing, proceed as follows:
1. Loosen the two screws “F”
located on the bottom part
of the boiler until the
first thread on the screws
appears;
1
F
3.2 Removing the Casing