Ariston ACO 35 Installation and Servicing Instructions

Country of destination: GB/IE

Installation and
Servicing
Instructions
Type C Boilers

ACO 35 MFFIG.C.N: 47-116-35

LEAVE THESE INSTRUCTIONS
WITH THE END USER

SERIES

2

TABLE OF CONTENTS

1. GENERAL INFORMATION

1.1. GENERAL INFORMATION 3

1.2. T

ECHNICAL INFORMATION 4

1.3. O

VERALL VIEW 6

2. INSTALLATION

2.1. REFERENCE STANDARDS 7

2.2. S

ITING THE APPLIANCE 7

2.3. O

VERALL DIMENSIONS 8

2.4. M

INIMUM CLEARANCES 8

2.5. M

OUNTING THE APPLIANCE 9

2.6. E

LECTRICAL CONNECTION 9

2.7. G

AS CONNECTION 9

2.8. W

ATE R CONNECTIONS 10

2.9. F

LUE CONNECTIONS 13

2.9.1 F

ITTING THE COAXIAL FLUE

(Ø 60 / 100 HORIZONTAL)14

2.9.2 F

ITTING THE 5” FLUE

(Ø 80 / 125 Horizontal/Vertical) 15

2.9.3 F

ITTING THE COAXIAL FLUE

(Ø 60 / 100 VERTICAL) 16

2.9.4 F

ITTING THE TWIN PIPE (Ø80 / 80) 17

2.10. F

ITTING THE MECHANICAL/DIGITAL

TIME CLOCK 20

2.11. S

ETTING THE MECHANICAL TIME CLOCK 22

2.11.1. S

ETTING THE DIGITAL TIME CLOCK 22

2.12. A

CCESSORY CONNECTION 24

2.13. E

LECTRICAL DIAGRAM 26

2.14. W

ATE R CIRCUIT DIAGRAM 28

3. COMMISSIONING

3.1. INITIAL PREPARATION 30

3.2. R

EMOVING THE CASING 32

3.3. C

ONTROL PANEL 33

3.4. I

NITIAL START-UP 35

3.5. D

ISPLAY: MESSAGES SHOWN DURING

NORMAL OPERATION 36

3.6. O

PERATING PARAMETERS 37

3.6.1. R

EGULATION MENU TABLE 37

3.6.2. S

ETTINGS DISPLAY 43

3.6.3. G

AS REGULATION CHECK 44

3.6.4. I

GNITION DELAY ADJUSTMENT 45

3.6.5. A

DJUSTING THE MAXIMUM HEATING

POWER 45

3.6.6. S

OFT LIGHT ADJUSTMENT 45

3.7. C

HANGING THE TYPE OF GAS 45

3.8. A

DJUSTING THE DOMESTIC HOT

WATER FLOW RAT E 45

3.9. B

ALANCING THE CENTRAL

HEATING SYSTEM 45

3.10. B

OILER SAFETY SYSTEMS 46

3.11. C

OMPLETION 47

3.12. D

RAINING 47

4. ZONE VALVES 48

5. SEQUENCE OF OPERATION 51

5.1 CENTRAL HEATING MODE 51

5.2 D

OMESTIC HOT WATE R MODE 51

6. MAINTENANCE 52

6.1. GENERAL REMARKS 52

6.2. C

LEANING THE PRIMARY EXCHANGER 52

6.3. C

LEANING THE CONDENSATE TRAP 52

6.4. O

PERATIONAL TEST 52

7. SERVICING INSTRUCTIONS 53

7.1. REPLACEMENT OF PARTS 53

7.2. T

O GAIN GENERAL ACCESS 53

7.3. A

CCESS TO THE COMBUSTION

CHAMBER 54

7.3.1. R

EMOVING THE FAN 54

7.3.2. R

EMOVING THE AIR PRESSURE SWITCH 55

7.3.3. R

EMOVING THE BURNER 55

7.3.4. R

EMOVING THE ELECTRODES 56

7.3.5. R

EMOVING THE HEAT EXCHANGER 56

7.3.6. R

EMOVING THE CONDENSATE

TRAP (TUBE)58

7.3.7. R

EMOVING THE CONDENSATE TRAP 58

7.4. A

CCESS TO THE GAS VALVE 59

7.4.1. R

EMOVING THE GAS VALVE 59

7.4.2. R

EMOVING THE SPARK GENERATOR 60

7.5. A

CCESS TO THE WATER CIRCUIT 60

7.5.1. R

EMOVING THE D.H.W.

(S

ECONDARY) EXCHANGER 60

7.5.2. R

EMOVING THE SAFETY VALVE 61

7.5.3. R

EMOVING THE AUTOMATIC AIR VENT 61

7.5.4. R

EMOVING THE DIVERTER VALVE

ACTUATOR 62

7.5.5. R

EMOVING THE DHW FLOW SWITCH

(MFFI ONLY)62

7.5.6. R

EMOVING THE PUMP 62

7.5.7. R

EMOVING THE PRESSURE GAUGE 63

7.5.8. R

EMOVING THE EXPANSION VESSEL 64

7.5.9. R

EMOVING THE D.H.W. TEMPERATURE

PROBE (N.T.C. - MFFI ONLY)64

7.5.10. R

EMOVING THE C.H. FLOW

TEMPERATURE PROBE (N.T.C.) 65

7.5.11. R

EMOVING THE C.H. RETURN

TEMPERATURE PROBE (N.T.C.) 65

7.6. A

CCESS TO THE CONTROL SYSTEM 66

7.6.1. C

HECKING THE FUSES 66

7.6.2. R

EMOVING THE PRINTED CIRCUIT

BOARDS 66

7.6.3. R

EMOVING THE TIME CLOCK 67

8. FAULT FINDING 68

8.1 FAULT FINDING GUIDE
(FLOW-CHARTS)68

9. SHORT SPARES PARTS LIST 72

10. ANNUAL MAINTENANCE CHECKLIST 76

11. BENCHMARK COMMISSIONING
CHECKLIST 78

12. SERVICE INTERVAL RECORD 79

PAGE PAGE

3

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.

1. GENERAL INFORMATION

Read the instructions and recommendations in these Installation
and Servicing Instructions carefully to ensure proper installation,
use and maintenance of the appliance.

Keep this manual in a safe place. You may need it for your own
reference while Servicing Technicians or your installer may
need to consult it in the future.

The ACO 35 MFFI is a combined appliance for the production of
central heating (C.H.) and domestic hot water (D.H.W.) and is
designed for domestic use only..

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.

MTS recommends the use of protective clothing when installing
and working on the appliance i.e. gloves.

Before connecting the appliance, check that the information
shown on the data plate and the table in Section 1.2 (page 4)
comply with the electric, water and gas mains of the property.
You will find the data plate on the inside of the casing.
The gas with which this appliance operates is also shown on the
label at the bottom of the boiler.

Do not install this appliance in a damp environment or close to
equipment which spray water or other liquids.

Do not place objects on the appliance.
Do not allow children or inexperienced persons to use the

appliance without supervision.

If you smell gas in the room, do not turn on or off light
switches, use the telephone or any other object which might
cause sparks.
Open doors and windows immediately to ventilate the room.
Shut the gas mains tap (at or adjacent to the gas meter) or the
valve of the gas cylinder and call your Gas Supplier immediately.

Always disconnect the appliance either by unplugging it from
the mains or turning off the mains switch before cleaning the
appliance or carrying out maintenance.

In the case of faults or failure, switch off the appliance and
turn off the gas tap. Do not tamper with the appliance.
For repairs, call your local Authorised Servicing Agent and
request the use of original spare parts. For in-guarantee repairs
contact MTS (GB) Limited.

1.1. GENERAL INFORMATION

4

Name
CE Certification
Flue Type

Heat Input max (Domestic Hot Water) kW
Heat Input max/min (Central Heating) kW
Heat Output max/min (Central Heating) kW
Heat Output max/min (Domestic Hot Water) kW
Efficiency of Nominal Heat Input (60/80°C) %
Efficiency of Nominal Heat Input (30/50°C) %
Efficiency at 30% of Nominal Heat Input (47°C) %
Efficiency at 30% of Nominal Heat Input (30°C) %
Efficiency at Minimum Input %
Efficiency (Dir. 92/42/EEC)**
SEDBUK Rating Band / %
Heat Loss to the Casing (∆T=50°C) %
Flue Heat Loss with Burner Operating %

General Info

Energy Performance

Max Discharge of Products of Combustion (G20) Kg/h
Temp. of exhaust fumes at nominal capacity °C
CO2 Content %
O

2 Content %

CO Content ppm
Nox Class

Emissions

Head Loss on Water Side (max) (∆T=20°C) mbar
Residual Head of System bar
Expansion Vessel Pre-load Pressure bar
Maximum Heating Pressure bar
Expansion Vessel Capacity l
Maximum Water Content of System l
Heating Temperature max/min (High temperature) °C
Heating Temperature max/min (Low Temperature) °C

Central Heating

Domestic Hot Water Temperature (approx) max/min °C
Specific Flow Rate (10 minutes/∆T 30°C) l/min
D.H.W. Flow Rate ∆T=25°C l/min
D.H.W. Flow Rate ∆T=35°C l/min
D.H.W. Minimum Flow Rate l/min
Pressure of Domestic Hot Water max/min bar

Domestic Hot Water

Nominal Pressure Natural Gas (G20) mbar
Consumption at Nominal Capacity(G20) m3/h
Gas Consumption after 10 Minutes* m

3

Gas

Electrical Supply V/Hz
Power Consumption W
Minimum Ambient Temperature °C
Protection Grade of Electrical System IP
Internal Fuse Rating

Electrical Data

Weight Kg
Casing Dimensions (D/W/H) mm

G.C. Number

ACO 35 MFFI

1312BQ4461

C13-C33-C43-C53-C83-B23-B33

44.6
62

9.4

3.8

109

5 (70 mg/kW/h)

200

0.2

0.7
3
7

130
82 / 46
75 / 25

56 / 36

16

18.84

13.5

2.5

6 / 0.2

20

3.17

0.37

3
4

230/50

145

+5

24D

2A Fast Fuse

43

310/450/750

47-116-35

* Calculated at 70% maximum output
** Calculated on Upper calorific value

Max. Condensate produced l/h
PH of condensate PH

1.2. TECHNICAL INFORMATION

37.2

33.3 / 7.4

29.4 / 6.5

33.3 / 7.4

88.2

94.6

92.5

97.4

87.3

A / 90.2

0.4

1.7

5

LEGEND:

1. Air Release Valve

2. Main Heat Exchanger (Stainless Steel)

3. Detection Electrode

4. Central Heating Flow Temperature Probe

5. Overheat Thermostat

6. Central Heating Return Temperature Probe

7. Air / Gas Mixer

8. Gas Valve

9. P.C.B. Box

10. Diverter Valve

11. Condensate Discharge

12. Condensate Trap

13. Low Water Pressure Switch

14. Domestic Hot Water Temperature Probe

1.3. OVERALL VIEW

FIG. 1.0

15. Secondary Heat Exchanger

16. Domestic Hot Water Flow Switch

17. Circulation Pump with Automatic Air Release Valve

18. Safety Valve (3 bar)

19. Automatic By-pass

20. Fan

21. Ignition Electrode

22. Silencer

23. Spark Generator

24. Expansion Vessel

25. Combustion Analysis Test Point

26. Flue Connector

26
25

1

24

23

22

2

21

3

4

5 6

20

7

8

19

9

18

10

11 1312 14 15 16

17

11

6

The technical information and instructions provided herein below
are intended for the installer / Servicing Technician so that the
unit may be installed and serviced correctly and safely.

In the United Kingdom the installation and initial start up of the
boiler must be by a CORGI Registered Installer in accordance
with the installation standards currently in effect, as well as with
any and all local health and safety standards i.e. CORGI.

In the Republic of Ireland the installation and initial start up of
the appliance must be carried out by a Competent Person in
accordance with the current edition of I.S.813 “Domestic Gas
Installations”, the current Building Regulations, reference should
also be made to the current ETCI rules for electrical installation.

This appliance must be installed by a competent installer in
accordance with current Gas Safety (installation & use)
Regulations.

The installation of this appliance must be in accordance with the
relevant requirements of the Local Building Regulations, the
current I.E.E. Wiring Regulations, the byelaws of the local water
authority, in Scotland, in accordance with the Building Standards
(Scotland) Regulation and Health and Safety document No. 635
“Electricity at work regulations 1989” and in the Republic of
Ireland with the current edition of I.S. 813, the Local Building
Regulations (IE).

C.O.S.H.H.

Materials used in the manufacture of this appliance are non­hazardous and no special precautions are required when
servicing.

Installation should also comply with the following British
Standard Codes of Practice:

and in the Republic of Ireland in accordance with the following
Codes of Practice:

2. INSTALLATION

2.1. REFERENCE STANDARDS

BS 7593:1992 Treatment of water in domestic hot water

central heating systems

BS 5546:1990 Installation of hot water supplies for

domestic purposes
BS 5440-1:2000 Flues
BS 5440-2:2000 Air supply
BS 5449:1990 Forced circulation hot water systems
BS 6798:2000 Installation of gas fired hot water boilers

of rated input not exceeding 70kW
BS 6891:2005 Installation of low pressure gas pipe up to

28mm
BS 7671:2001 IEE wiring regulations
BS 4814:1990 Specification for expansion vessels
BS 5482:1994 Installation of L.P.G.

I.S. 813 Domestic Gas Installations

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 combined appliance in a
room containing a bath or shower, the location of the boiler in a
room containing a bath or shower should only be considered if
there is no alternative.

Where a room-sealed appliance is installed in a room
containing a bath or shower the appliance and any
electrical switch or appliance control, utilising mains
electricity should be situated so that it cannot be touched
by a person using the bath or shower, specifically in
accordance with current IEE Wiring Regulations.

The location must permit adequate space for servicing and air
circulation around the appliance as indicated in Section 2.4.
The location must permit the provision of an adequate flue and
termination.
For unusual locations special procedures may be necessary.
BS 6798-2000 gives detailed guidance on this aspect.
A compartment used to enclose the appliance must be designed
specifically for this purpose. No specific ventilation requirements
are needed for the installation within a cupboard.
This appliance is not suitable for outdoor installation.

The type C appliances (in which the combustion circuit, air
vent intake and combustion chamber are air-tight with
respect to the room in which the appliance is installed) can
be installed in any type of room.

Secondary ventilation is not required with this boiler. The boiler
must be installed on a solid, non-combustible, permanent wall to
prevent access from the rear.

7

2.3. OVERALL DIMENSIONS

In order to allow 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.

2.4. MINIMUM CLEARANCES

LEGEND:

A = Central Heating Flow (3/4”) (22mm Copper Tail)
B = Domestic Hot Water Outlet (1/2”) (15 mm Copper Tail)
C = Gas Inlet (3/4”) ( 22mm Copper Tail)
D = Domestic Cold Water Inlet (1/2”) (15mm Copper Tail)
E = Central Heating Return (3/4”) (22mm Copper Tail)
SV outlet = 1/2” Female BSP (Not Shown)

FIG. 2.0

FIG. 2.1

F

IG. 2.2

After removing the boiler from its packaging, remove the
template from the separate box containing the connection kit.
N

OTE: Pay particular attention to any test water that may spill

from the appliance.

Place the template in the position the appliance is to be
mounted and after ensuring it is hanging squarely, use it to mark
the holes for the hanging bracket, connection kit and flue pipe(s)
NB: For further information relating to the flue installation please
refer to Section 2.9 F

LUE CONNECTION. (If the appliance is to be

fitted on a wall of combustible material, the wall must

be
protected by a sheet of fireproof material).
If the appliance is to be fitted into a timber framed building,
guidance should be sought from the Institute of Gas Engineers
document REF: IGE/UP/7.

2.5.1. Drill the wall and plug using those supplied with the

connections kit, position the hanging bracket and
secure with the wall screws supplied, assemble the
connection kit and secure to the wall. N

OTE: It is highly

recommended that a spirit level be used to position the
appliance to ensure that it is perfectly level.

2.5.2. Position the appliance on the hanging bracket and

connect the connection kit to the boiler connections.
(see also Sections 2.7 Gas Connections, 2.8 Water
Connections & F

IG. 2.4).

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.

2.5.

MOUNTING THE APPLIANCE

785

310

450

450

130 130

225 225

143

750 35

93 65

F

67 67 65 93

100

120

water
gas

323

310

5

45

50

8

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
H = Condensate discharge
G = Condensate trap
F = Safety valve discharge

Central Heating

Detailed recommendations are given in BS 6798:2000 and BS
5449-1:1990, the following notes are given for general guidance.

P

IPEWORK

:

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.

S

YSTEMDESIGN

:

This boiler is suitable only for sealed systems.

D

RAINCOCKS

:

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.

VIEW OF THE BOILER CONNECTIONS

G

H

FIG. 2.4

2.6. ELECTRICAL CONNECTION

The boiler operates with alternating current, as indicated in the
technical data table (Section 1.2), where the maximum absorbed
power is also indicated. Make sure that the connections for the
neutral and live wires correspond to those indicated in Fig.2.3).
The appliance electrical connections are situated inside the
electrical box (see Section 2.12).

I

MPORTANT

!

In the event that the power supply cable 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 cable;

- The blue wire should be connected to the terminal marked “N”;

- The brown wire should be connected to the terminal marked “L”.

FIG. 2.3

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 must not be used.

Note: The diagrams for the electrical system are indicated in
Sections 2.12 and 2.13 (pages 22-24).

Warning, this appliance must be earthed.

External wiring to the appliance must be carried out by a
competent person and be in accordance with the current I.E.E.
Regulations and applicable local regulations.
The appliance is supplied with a fly-lead already connected, this
must be connected to a 240v supply fused at 3A and must
facilitate complete electrical isolation of the appliance, by the
use of a fused double pole isolator having a contact separation
of at least 3 mm in all poles or alternatively, by means of a 3 A
fused three pin plug and unswitched shuttered socket outlet both
complying with BS 1363.
The point of connection to the Electricity supply must be readily
accessible and adjacent to the appliance unless the appliance is
installed in a bathroom when this must be sited outside the
bathroom (see Section 2.2).
Should external controls be required, the design of the external
electrical circuits should be undertaken by a competent person,
see Sections 2.12 for further information.

F

9

RESIDUAL HEAD OF THE BOILER∆T20°C

FIG. 2.5

S

AFETYVALVEDISCHARGE

:

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.

C

ONDENSATEDISCHARGE

:

A flexible hose is supplied for connection to the condensate
discharge point H (Fig. 2.4). The condensate discharge hose
from the boiler must have a continuous fall of 2.5° and must
be inserted by at least 50 mm into a suitable acid resistant
tundish / pipe - e.g. plastic waste or overflow pipe. The
condensate discharge pipe must have a continuous fall and
preferably be installed and terminated within the building to
prevent freezing.

N

OTE:THE FLEXIBLE CONDENSE HOSE SUPPLIED WITH THE

APPLIANCE CAN BE EXTENDED BY PULLING THE TUBE OPENING THE

RIBBED PIPE

.

The discharge pipe must be terminated in a suitable position:

i) Connecting in to an internal soil stack (at least 450 mm

above the invert of the stack). A trap giving a water seal of
at least 75 mm must be incorporated into the pipe run,
there also must be an air break upstream of the trap.

ii) Connecting into the waste system of the building such as

a washing machine or sink trap. The connection must be
upstream of the washing machine/sink (If the connection
is down stream of the waste trap then an additional trap
giving a minimum water seal of 75 mm and an air break
must be incorporated in the pipe run, as above.

iii) Terminating into a gully, below the grid level but above the

water level.

iv) Into a soakway.

N

OTE: If any condensate pipe work is to be installed externally,

then it should be kept to a minimum and be insulated with a
waterproof insulation and have a continuous fall.

Some examples of the type of condensate drains can be
seen on this page.

2. External termination of condensate drainage pipe via
internal discharge branch (e.g. sink waste) and condensate
siphon

3. External termination of condensate drainage pipe via
internal discharge branch (e.g. sink waste - proprietary fitting).

1. Internal termination of condensate drainage pipe to
internal stack

800

700

600

500

400

[mbar]

300

200

100

0

0 200 400 600 800 1000 1200 1400 1600

[l/h]

10

4. External termination of condensate drainage pipe via
condensate siphon

AIRR

ELEASEPOINTS

:

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.

M

AINSWATE RFEED

- C

ENTRALHEATING

:

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.

F

ILLING

:

A method for initially filling the heating system is supplied with
the connection kit. The filling loop is connected between the
cold water inlet and the central heating flow connections, and
incorporates a non-return valve. To operate the filling loop, it
is necessary to open both quarter turn handles, once the
required pressure has been achieved, close both handles
and disconnect the hose in accordance with water
regulations. N

OTE: The installer should ensure that there are

no leaks as frequent filling of the heating system can lead to
premature scaling of the main exchanger and failure of
hydraulic components.

D

OMESTICWATE R

The domestic water must be in accordance with the relevant
recommendation of BS 5546:1990. Copper tubing to BS EN
1057:1996 is recommended for water carrying pipe work and
must be used for pipe work carrying drinking water, a scale
reducer should also be used to reduce the risk of scale
forming in the domestic side of the heat exchanger.

U

NDERFLOORHEATINGSYSTEMS

:

In the event of an under floor heating system, fit a safety
thermostat on the boiler flow (instructions for wiring the
thermostat to connection SP on the PCB can be found in
Section 2.12). This thermostat should be positioned at a safe
distance from the boiler to ensure the correct operation of the
same. If the thermostat is positioned too close to the boiler, the
water remaining in the boiler after domestic hot water has been
drawn will flow into the central heating system and may cause
the thermostat contact to open without there being any real
danger of the system being damaged, this would lead to a
boiler shutdown both in D.H.W. mode and C.H. mode, and the
error code “E08” would be displayed; boiler operation resumes
automatically when the thermostat contact closes on cooling.
Should the thermostat fail to be installed as recommended, the
under floor heating system can be protected by installing a
thermostatic valve upstream from the thermostat in order to
prevent the flow of excessively hot water towards the system.

WATER TREATMENT

The boiler is equipped with a stainless steel heat exchanger.

The detailed recommendations for water treatment are given
in BS 7593:1992 (Treatment of water in domestic hot water
central heating systems); the following notes are given for
general guidance;

If the boiler is installed on an existing system, any
unsuitable additives must be removed.

Under no circumstances should the boiler be fired before the
system has been thoroughly flushed; the flushing procedure
must be in line with BS7593:1992.

We highly recommend the use of a flushing detergent
appropriate for the metals used in the circuit. These include
cleansers produced by Fernox and BetzDearborn, whose

11

function is to dissolve any foreign matter that may be in the
system;

In hard water areas or where large quantities of water are in
the system the treatment of the water to prevent premature
scaling of the main heat exchanger is necessary.

The formation of scale strongly compromises the efficiency of
the thermic exchange because small areas of scale cause a
high increase of the temperature of the metallic walls and
therefore add to the thermal stress of the heat exchanger.

Demineralised water is more aggressive so in this situation it
is necessary to treat the water with an appropriate corrosion
inhibitor.

Any treatment of water by additives in the system for frost
protection or for corrosion inhibition has to be absolutely
suitable for all the metals used in the circuit.

The use of a corrosion inhibitor in the system such as Fernox
MB-1, BetzDeaborn Sentinel X100 or Fernox System Inhibitor
is recommended to prevent corrosion (sludge) damaging the
boiler and system;

If anti-freeze substances are to be used in the system, check
carefully that they are compatible with the metals used in the
circuit.

MTS suggests the use of suitable anti-freeze products such
as Fernox ALPHI 11, which will prevent rust and incrustation
taking place.

Periodically check the pH of the water/anti-freeze mixture of
the boiler circuit and replace it when the amount measured is
out of the range stipulated by the manufacturer ( 7 < pH < 8).
DO NOT MIX DIFFERENT TYPES OF ANTI-FREEZE

In under-floor systems, the use of plastic pipes without
protection against penetration of oxygen through the walls
can cause corrosion of the systems metal parts
(metal piping, boiler, etc), through the formation of oxides and
bacterial agents.

To prevent this problem, it is necessary to use pipes with an
“oxygen-proof barrier”, in accordance with standards DIN
4726/4729. If pipes of this kind are not used, keep the

system separate by installing heat exchanger

s of those

with a specific system water treatment.

IMPORTANT
Failure to carry out the water treatment procedure
will invalidate the appliance warranty.

12

2.9. CONNECTING THE FLUE

IMPORTANT!!

BEFORE CONNECTING THE FLUE, ENSURE THAT 1 LITRE OF

WATER HAS BEEN POURED INTO THE EXHAUST CONNECTION

TO FILL THE CONDENSATE TRAP

(FIG.2.7). SHOULD THE TRAP

BE EMPTY THERE IS A TEMPORARY RISK OF FLUE GASSES
ESCAPING INTO THE ROOM.

FIG. 2.7

Ø 60/100 mm

Fig. 2.9

FIG. 2.9

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 - From vertical drain pipes and soil pipes 75
E - From internal or external corners 300
F - Above ground on a public walkway or patio 2100
G - From a surface facing a terminal 2500
H - From a terminal facing a terminal 2500

I - Vertically from a terminal in the same wall 1500
J - Horizontally from a terminal in the same wall 300
K - Horizontally from an opening window 300
L - Fixed by vertical flue terminal

F

LUESYSTEM

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, it must also be located in a place not likely to cause

nuisance.

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 2.1 metres above a balcony, above ground

or above a flat roof to which people have access, then a

suitable stainless steel terminal guard must be fitted.

The minimum acceptable spacing from the terminal to

obstructions and ventilation openings are specified in Fig.

2.9.

E

E

4

120 mm

13

Warning

The exhaust gas ducts must not be in contact with or close to
inflammable material and must not pass through building
structures or walls made of inflammable material.
When replacing an old appliance, the flue system must be
changed.

Important

Ensure that the flue is not blocked.
Ensure that the flue is supported and
assembled in accordance with these
instructions.

2.9.1 FITTING THE COAXIAL FLUE
(Ø 60 / 100 HORIZONTAL)

Installation without extension

Installation with extension

Fig. 2.10

Fig. 2.11

Level

Level

C

ONTENTS

:

1

XSILICONE

O-R

ING

(60mm)

1XE

LBOW

(90O)

2XW

ALLSEALS(INTERNAL&EXTERNAL

)

1

XFLUEPIPE INCLUDINGTERMINAL

(1

METRE

- 60/100)

1XF

LUECLAMP

1XS

CREWS

1x Seal

Once the boiler has been positioned on the wall, insert the
elbow into the socket and rotate to the required position.

NOTE: It is possible to rotate the elbow 360

o

on its vertical axis.

Using the flue clamp, seals and screws supplied (Fig 2.12)
secure the elbow to the boiler.

The 1 metre horizontal flue kit (3318073) supplied is suitable
for an exact X dimension of 815mm.

Measure the distance from the face of the external wall to the
face of the flue elbow (X - Fig 2.9), this figure must now be
subtracted from 815mm, you now have the total amount to be
cut from the plain end of the flue.

Draw a circle around the outer flue and cut the flue to the
required length taking care not to cut the inner flue, next cut
the inner flue ensuring that the length between the inner and
outer flue is maintained. (Fig 2.12).

e.g.

X = 555mm
815-555 = 260mm (Length to be cut from the plain end of
the flue).

Once cut to the required length, ensure that the flue is free
from burrs and reassemble the flue. If fitting the flue from
inside of the building attach the grey outer wall seal to the
flue terminal and push the flue through the hole, once the wall
seal has passed through the hole, pull the flue back until the
seal is flush with the wall. Alternatively, the flue can be
installed from outside of the building, the grey outer seal
being fitted last.

120

* slope

150 mm

150 mm

* slope 5 mm per metre

14

Fig. 2.12

2.9.2 FITTING THE 5” FLUE
(Ø 80 / 125 HORIZONTAL/VERTICAL)

Should the flue require extending, the flue connections are
push fit, however, one flue bracket should be used to secure
each metre of flue.

N

OTE:SEE PAGE 19 FOR MAXIMUM AND MINIMUM FLUE RUNS.

Once the boiler has been positioned on the wall, it is
necessary to insert the Ø80/125 adaptor (F

IG. 2.13) for both

horizontal and vertical flue runs into the boiler flue socket (not
supplied with flue kit - Part No 3318095).

Push the adaptor onto the boilers flue connection, grease the
seals then add extensions or elbows as required, secure the
adaptor, using the clamp and screws provided.

To fit extensions or elbows it is first necessary to ensure that
the lip seal is fitted correctly into the inner flue, once verified,
it is simply necessary to push them together, no clamps are
necessary to secure the flue components.

Before proceeding to fit the flue, ensure that the maximum
flue length has not been exceeded (See the tables on Page

19) and that all elbows and bends have been taken into
consideration, the maximum flue length is 10 metres, for each
additional 90

o

elbow 1 metre must be subtracted from the

total flue length, and for each 45o0.5 metres must be
subtracted from the total flue length (the height of the

vertical adaptor and a 45obend can be seen in Fig. 2.14
and a 90

o

bend in Fig. 2.15).

N

OTE: DO NOT CUT THE VERTICAL FLUE KIT.

Screws

Clamp

Seal

Fig. 2.13

Fig. 2.14

Fig. 2.15

15

NOTE:SEE PAGE 19 FOR MAXIMUM AND MINIMUM FLUE RUNS.

C

ONTENTS

:

1

XSILICONE

O-R

ING

(60mm)

1

XCONICALADAPTOR

(60/100mm)

1XV

ERTICALFLUEKIT

(80/125mm)

3

XSCREWS

The vertical flue kit is supplied with a specially designed
weather proof terminal fitted, it can be used either with a flat
roof or a pitched roof.

The Vertical flue kits useable lengths with the pitched roof
flashings are indicated in Fig. 2.16.

Before proceeding to fit the flue, ensure that the maximum
flue length has not been exceeded (See the tables on Page

19) and that all elbows and bends have been taken into
consideration, the maximum flue length is 4 metres, for each
additional 90

o

elbow 1 metre must be subtracted from the

total flue length, and for each 45

o

0.5 metres must be

subtracted from the total flue length (the height of the

vertical adaptor and a 45

o

bend can be seen in Fig. 2.17).

Mark the position of the flue hole in the ceiling and/or roof
(see Fig. 2.15 for distance from wall to the centre of the flue).

Cut a 120mm diameter hole through the ceiling and/or roof
and fit the flashing plate to the roof.

DO

NOT

cut the vertical flue kit.

To connect the vertical flue kit directly to the boiler, place the
vertical starter kit (Part No. 3318079) (see Fig. 2.16) onto the
exhaust manifold and secure with the clamp, fit the vertical
adaptor onto the vertical starter kit (note: there is no need to
use a clamp to secure this as it is a push fit connection), the
vertical flue kit must then be inserted through the roof
flashing, this will ensure that the correct clearance above the
roof is provided as the terminal is a fixed height.

Should extensions be required, they are available in 1 metre
(Part No. 3318077), 500mm (Part No. 3318078) and 160mm
lengths, they must be connected directly to the vertical starter
kit before connecting the adaptor to allow the vertical flue kit
to be fitted. In the event that extension pieces need to be
shortened, they

must

only be cut at the male end and it must

be ensured that the inner and outer flue remain flush (Fig.

2.12)

When utilising the vertical flue system, action must be taken
to ensure that the flue is supported adequately to prevent the
weight being transferred to the appliance flue connection by
using 1 flue bracket per extension.

When the flue passes through a ceiling or wooden floor, there
must be an air gap of 25mm between any part of the flue
system and any combustible material. The use of a ceiling
plate will facilitate this. Also when the flue passes from one
room to another a fire stop must be fitted to prevent the
passage of smoke or fire, irrespective of the structural
material through which the flue passes.

2.9.3. FITTING THE COAXIAL FLUE
(Ø 60 / 100 VERTICAL)

Fig. 2.16

Fig. 2.17

16

2.9.4. FITTING THE TWIN PIPE (Ø80 / 80)

NOTE:SEE PAGE 19 FOR MAXIMUM AND MINIMUM FLUE RUNS.

Where it is not possible to terminate the flue within the
distance permitted for coaxial flues, the twin flue pipe can be
used by fitting a special adaptor to the flue connector and
using the aperture for the air intake located on top of the
combustion chamber.

Always ensure that the flue is adequately supported, using
one flue bracket per extension and avoiding low points. (MTS
supply suitable clamps as Part No. 705778).
To utilise the air intake it is necessary to:

1) Take the air intake cover off the top of the appliance

2) Assemble the flange on the header supplied with the boiler

3) Insert the header on the tube or the elbow up until the
lower stop (you do not have to use the washer).

4) Insert the elbow/header in the boiler air intake hole and
fasten it with screws.

The twin flue pipes can be fitted with or without additional
elbows and need no clamps, simply ensure that the red o-ring
is inserted in the female end of the flue pipe and push the
extension piece fully into the previous section of flue pipe or
elbow, check that the o-ring is not dislodged when
assembling the flue (greasing the seal will aid assembly).

Twin pipe can also be converted back to Coaxial flue to
enable vertical termination with a coaxial kit by using the pipe
bridge (Twin - Coaxial Adaptor - Part No. 3318089). When
running the twin flue pipe vertically.

It is not possible to terminate concentrically horizontally.
Termination is only possible with separate air and exhaust
terminals.

When siting the twin flue pipe, the air intake and exhaust
terminals must terminate on the same wall, the centres of the
terminals must

be a minimum of 280 mm apart and the air

intake must

not be sited above the exhaust terminal (refer to
Fig. 2.20). The air intake pipe can be run horizontally,
however, the terminal and the final 1 metre of flue must be
installed either horizontally or with a slight fall away from the
boiler to avoid rain ingress.

It is also strongly recommended that the air intake pipe run
be constructed of insulated pipe to prevent condense forming
on the outside of the tube.

The maximum permissible flue length for twin flue is
dependent on the type of run used.
For flue runs with the intake and exhaust pipes under the
same atmospheric conditions (T

YPE 4) the maximum length is

38 metres (27kW) and 48 metres (32kW), for runs with the
terminals under different atmospheric conditions (T

YPE 5) the

exhaust terminal must

extend 0.5 metres above the ridge of
the roof (this is not obligatory if the exhaust and air intake
pipes are located on the same side of the building). For T

YPE

5 also, the maximum permissible combined length is 51
metres (27kW) and 49 metres (32kW).

The maximum length is reached by combining the total
lengths of both the air intake and exhaust pipes. Therefore a
maximum length of 40 metres for example, will allow a flue
run of 20 metres for the air intake and 20 metres for the
exhaust pipes, also for each 90

o

elbow 2.2 metres must be

subtracted from the total length and for each 45

o

elbow 1.4

metres must be subtracted from the total flue length.

Some of the acceptable flue configurations are detailed on
page 20.

For further information relating to flue runs not illustrated,
please contact the Technical Department on 0870 241 8180.

17

Fig. 2.18

In the event that twin flue pipes are used, and the boiler has
a side clearance of less than 60mm from the wall, it is
necessary to cut a larger diameter hole for the flue pipe, this
should be ø10 cm, this will then allow for easier assembly of
the air intake elbow and the tube outside the wall (see Fig.

2.19).

Fig. 2.19

In the event that the air intake and exhaust are run to the left,
it will be necessary to reduce the height of the air intake by
cutting 20mm from the base of the air intake elbow (see Fig.

2.18)

Coaxial

Systems

Twin Pipe

Systems

Exhaust Type

Type 1
Type 1

Types 2 & 3

Type 4

Type 5

Maximum Extension

Exhaust/Air

(m)

4 (Horizontal)

16 (Horizontal)

4 (Vertical)

16 (Vertical)

54

(Air Intake & Exhaust

Equal Lengths (27

and 27 metres)

1+56 (Air Intake 1

Metre and Exhaust 56

Metres)

Diameter

of Pipes

(mm)

Ø 60/100
Ø 80/125

Ø 60/100
Ø 80/125

Ø 80/80

Ø 80/80

Reduction

45

o

(m)

0.5

0.5

0.5

0.5

0.25

0.25

Reduction

90

o

(m)

1
1

1
1

0.5

0.5

ø 100

60 mm

18

Fig. 2.20

NOTE: DRAWINGS ARE INDICATIVE OF FLUEING OPTIONS ONLY.

TYPE 1

TYPE 5

TYPE 4

TYPE 3

TYPE 2

Fig. 2.19

AIR INTAKE MUST NOT BE

FITTED ABOVE THE EXHAUST

AIR INTAKE

EXHAUST

AIR INTAKE

19

FIG. 2.22

FIG. 2.21

FIG. 2.23

DIGITAL

MECHANICAL

FIG. 2.20

C2

C2

C2

2.10. FITTING THE MECHANICAL / DIGITAL
CLOCK

The ACO MFFI boiler is supplied with a factory fitted
mechanical time clock. There is a digital clock available as
an optional extra (code: 706348).

To fit the digital clock it is necessary to proceed as follows:-

1. Remove the outer casing

2. Open the control panel (see fig. 2.20);

3. Unplug the electrical connection from the PCB and unscrew
the four screws (Fig. 2.21);

4. Remove the time clock (Fig. 2.22).

5. Connect the wires supplied with the clock to the digital time
clock as shown in Fig. 2.23;

6. Reassemble in reverse order.

N

OTE:THE MECHANICAL CLOCK HAS FOUR WIRES, THEREFORE THE

HARNESS WILL REQUIRE CHANGING ALSO

.

G

5

3

B

1

2

R

3

1

2

R

B

4

G

20

2.11. SETTING THE MECHANICAL TIME CLOCK

2.11.1. SETTING THE DIGITALTIME CLOCK

Fig. 2.24

1. General layout

The mechanical clock covers a 24 hour period. Each tappet
represents 15 minutes A (Fig. 2.25). An override switch is

located on the clock B (Fig 2.25).

2. To set the time

To set the time of day, grasp the outer edge of the dial and
turn slowly clockwise until the correct time is lined up with the
arrow C (Fig. 2.25).

3. To Set the "On" and "Off" times

The clock uses a 24hours system. e.g. 8 = 8.00 am and
18 = 6.00 pm. "ON" periods are set by sliding all tappets
between the "ON" time and the "OFF" time to the outer edge
of the dial.The tappets remaining at the centre of the dial are
the "OFF" periods.

4. For operation

Put the selector switch B to the symbol to control the
central heating by the clock. Put the switch B to «I» to select
permanent operation or to «0» to turn the central heating off
permanently.

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

9

6

12

A

C

B

Fig. 2.25

Operating the time switch

The steps marked with the symbol “ ” are necessary to carry
out a switching program.

Preparing for Operation

Activate the “Res” switch (=RESET) to reset the time switch
to its default setting (activate using a pencil or similar
pointed instrument). Do this:

- every time you wish to “reset” the time switch

- to erase all switching times and the current time of day.
After approximately two seconds the following display
appears: “– – : – –”.

Enter current time and weekday

- Keep the “ ” key pressed down
During the summer time period press the +/- 1h key once.
Enter the hour using the “h” key
Enter the minutes using the “m” key
Enter the day using the “Day” key

1 = “Monday”..............7 = Sunday

- Release the “ ” key.

1

12

6

13

24

14

23

15

22

16

21

20

I

19

18

17

2

3

4

5

6

7

9

8

9

10

11

12

21

Entering the switching times

You have 20 memory Iocations available. Each switching
time takes up one memory location.
Keep pressing the “Prog” key until a free memory location is
shown in the display “– –:– –”.
Programme ON or OFF with the “ ” key:
“ ”= OFF; “ ”= ON
Enter the hour using “h”
Enter the minutes using “m”
If a switching command is to be carried out every day (1 2 3
4 5 6 7) then store using the “ ” key, otherwise select the
day(s) it is to be carried out by using the “Day” key.
When the day seIection is left bIank, the programmed
switching instruction operates at the same time every day
1 2 3 4 5 6 = Monday – Saturday
1 2 3 4 5 = Monday – Friday
6 7 =Saturday – Sunday

Selection of single days: 1 = Mon. .............. 2 =Tues.

Save the switching time with the “ ” key.
The time switch enters the automatic operating mode and
displays the current time of day.
Begin any further entry of a switching time with the “Prog”
switch. If your entry is incomplete, the segments not yet
selected will blink in the display. After programming is
completed, and you return the time clock to the current time
display with the “ ” key, the time clock will not activate any
switching instruction required for the current time. You may
need to manually select the desired switching state with the
“ ” key. Thereafter, as the unit encounters further
switching instructions in the memory in real time, it will
correctly activate all subsequent switching instructions.

Manual Override Switch “ ”

With the “ ” you can change the current setting at any time.
The switching program already entered is not altered.

Reading the programmed switching times

Pressing the “Prog” key displays the programmed switching
times until the first free memory location appears in the display
“– – : – –”.

If you now press the “Prog” key once again, the number of free
memory Iocations will be displayed, e.g. “18”. If all memory
locations are occupied, the display “00” appears.

Changing the programmed switching times

Press the “Prog” key repeatedly until the switching time you
want to change is displayed. You can now enter the new data.
See point “Entering the switching times”.

Notes on storing switching times:

If you end your entry of the switching times by pressing the
“Prog” key, then the switching time you have entered will be
stored and the next memory location displayed.

In addition, a complete switching command is stored
automatically after around 90 seconds provided no other key
is pressed. The time switch then enters the automatic operating
mode and displays the current time again.

Deleting individual switching times

Press the “Prog” key repeatedly until the switching time you wish
to delete is shown in the display. Then set to “– –” using the “h”
or “m” key and keep the “ ” key pressed down for around 3
seconds. The switching time is now erased and the current time
is displayed.

AM / PM time display

If you press the “+/-1h” and “h” keys at the same time, the time
display switches into the AM/PM mode.

22

2.12. ACCESSORY CONNECTION

IMPORTANT!!
Before carrying out any repairs to the appliance always
ensure that the external power supply has been isolated.
The boiler will remain live even when the ON/OFF knob is
in the “O”(off) position.

IMPORTANT!!

Only remove the links from SP and TA if they are to be
connected to external controls.

TA

SP

FIG. 2.27

F

IG. 2.26

In order to gain access to the external control connections, it is
first necessary to remove the casing (as shown in Section 3.2 ­page 39) then proceed as follows:

1. Remove the cover of the main PCB box (Fig 2.26).

2. Access can now be gained to the following connectors (see
Section 2.13 - page 24):
CN10 - Safety thermostat for underfloor heating (SP)
CN 9 - Room Thermostat (TA)
CN 11 - Time clock
CN 6 - Interface PCB (

FIG. 2.28)

CONNECTION OF ROOM THERMOSTAT OR EXTERNAL

TIME CLOCK

a. - Insert the thermostat cable through the cable grommet

and fasten it by means of the cable-clamp provided.

b. - Connect the thermostat wires to the terminal block

CN9 (Fig. 2.27 - Diagram A).

c.- If a remote time clock is to be fitted, supply 240V from

the same spur as the boiler for the clock motor supply,
disconnect the integral time clock from the P.C.B.
CN11

d. - Using a volt-free switching time clock, connect the

switching wires from the time clock following points A­C above (Fig. 2.27 - Diagram B).

e. - If using an external time clock and room thermostat,

these must be connected in series as points A-D
above (Fig. 2.27 - Diagram C).

N

OTE:ENSURE LOW VOLTAGE AND HIGH VOLTAGE CIRCUITS ARE

CABLED SEPARATELY TO AVOID INDUCED VOLTAGES IN THE LOW

VOLTAGE CIRCUITS

.

23

FIG. 2.28

FITTING THE EXTERNAL SENSOR (code. 3318888)

The external sensor is supplied with the interface PCB
(Fig. 2.28).

The external sensor should be sited no more than 50 m from the
boiler and on an external north facing wall, between 2.5 and 3
metres above the ground. It should also be ensured that the
external sensor is positioned out of direct sunlight.

To connect the external sensor, plug the interface PCB into
connector CN6 on the main PCB (see Fig. 2.28 and 2.29).

To connect between the interface PCB and the external sensor,
it will be necessary to use 2x 0.5mm

2

cable, connected to the

two terminals on the external sensor and to Terminal B

(SE)

(Fig. 2.28) on the interface PCB.

Instructions on the activation and setting of the outdoor sensor
are detailed on pages 37 and 38.

Parameter P activates the external sensor, Parameter P 6
modifies the thermal curve and Parameter P 5 selects the
specific thermal curve for the type of system installed.

24

2.13. ELECTRICAL DIAGRAM

The P.C.B. is fitted with 2 fuses, on the live and the
neutral.
The fuse holder contains:

- 5 x 20mm “3.15A Slow” glass fuses

FIG. 2.29

C

B

N

F

O

FLOOR

12 1

ROOM

2

34

1

2

TIMER

CN11

CN10

CN9

A

CN6

G

I

L

M

E

H

D

Underfloor

Heating Safety

thermostat

Optional

CN9 CN10

123456789

1

10 11 12

89
7

CN8 CN11

Bl
Pnk

Gry
Blk

Gry
Wh

Rd
Bl

Pnk

.

g

o

r

P

Room

thermostat

Day

Optional

D.H.W.

temperature

probe

D.H.W.

flow

C.H. Return

temperature

probe

switch

1

CN12

12345

101112

CN8

6

1

1

CN7

O

123456789

1011

12

2

L

N

L

1

CN5

N

CN16

CN4

Wh
Wh
AZ

Overheat

thermostat

C.H. Flow

temperature

probe

Az

Low

water

pressure

CN1

switch

BlK

CN2

10 11 12

89
7

Blk
Pnk
Gry

Wh
Bl

Brn
Blk

Rd

Spark

generator

Diverter

valve

Circulation

pump

Brn

1

FUSE

Bl

Az

Gas valve

Wh

CN1 CN12CN5

Rd
Brn

Blk

Fan

FUSE

CN3

Bi

25

Legend:

A-ON/OFF button
B-Multifunction display
C-Reset button
D-Green LED (Indicates burner on)
E-Comfort function LED (yellow)
F-Red LED (indicates lockout)
G-COMFORT button
H-Central Heating temperature adjustment
I-Programming key +
L-Programming key -
M-Menu button
N-Domestic Hot Water temperature adjustment
O-EEPROM key

CN1 = FAN

1:

Start of coil (black)

2: End of coil (brown)
3: “Hall” sensor power supply 12V (red)
4: “Hall” sensor input (white)
5: “Hall” sensor neutral (blue)
6: Not used

CN2 = FLAME SENSOR

CN3 = Earth

CN4 =

POWER SUPPLY

1: Live (brown)
2: Neutral (blue)

CN5 =

EQUIPMENT
CONNECTIONS

1: Gas valve neutral (blue)
2: Gas valve live (brown)
3: Not used
4: Pump (V1) live (red)
5:

Pump (V2) live (black)

6:

Pump (ON/OFF) live (brown)

7:

Pump neutral (blue)

8: 3-way valve (C.H.) (red/black)
9: 3-way valve (D.H.W.)(brown)
10:

3-way valve Neutral (blue)

11: Spark generator Neutral (black)
12: Spark generator live (black)

CN6 = INTERFACE PCB

(OPTIONAL - see Section 2.12)

Accessories:
External sensor
Remote Control CLIMA MANAGER
Secondary outlet (see Section. 2.12)

CN7 = DISPLAY

1: Power 5V
2: Display return
3: Display transmission
4: Earth

CN8 = SENSOR CONNECTOR

1: Central Heating flow sensor (white)
2: Central Heating return sensor (white)
3: Not used
4: DHW flow switch (grey)
5: DHW sensor (grey)
6: Not used
7: Not used
8: DHW flow switch earth (grey)
9: DHW sensor earth (grey)
10: C.H. flow sensor earth (white)
11: C.H. return sensor earth (white)
12: Not used

CN9 = ROOM THERMOSTAT
(OPTIONAL - see Section 2.12)

CN10 = UNDERFLOOR HEATING

SAFETY THERMOSTAT
(OPTIONAL - Section 2.12)

CN11 = TIME CLOCK

(see Section 2.12)

CN12 = SENSOR CONNECTOR

1: Not used
2: Not used
3: Low water pressure switch
4: Low water pressure switch earth
5: Overheat thermostat
6: Overheat thermostat

26

2.14. WATER CIRCUIT DIAGRAM

L

EGEND

:

1 - Air release valve
2 - Main heat exchanger
3 - Burner
4 - Fan
5 - Air / Gas Mixer
6 - Gas valve
7 - Overheat thermostat
8 - Central heating flow temperature probe
9 - Secondary heat exchanger
10 - Motorised valve
11 - Low water pressure switch
12 - Domestic hot water temperature probe
13 - Condensate Trap
14 - Drain valve
15 - Automatic By-pass

16 - Domestic hot water flow switch
17 - Pressure gauge
18 - Safety valve
19 - Circulation pump with automatic

air release valve
20 - Central heating return temperature probe
21 - Expansion vessel

A - Central Heating Flow
B - DHW Outlet
C - Gas Inlet
D - Cold Water Inlet
E - Central Heating Return
F - Safety valve discharge

G - Condensate trap

H - Condensate discharge

FIG. 2.30

1

2

10

11

3

21

4

5

6

20

7

8

9

19

18

17

bar

16

15

14

12

ABC

D

E

F

G

H

13

27

3. COMMISSIONING

3.1. INITIAL PREPARATION

MTS (GB) Limited support the initiative. In Sections 11
and 12 of this manual you will find the commissioning
checklist (page 70) and the service interval record (Page 71), It
is important the commissioning checklist 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 this manual 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.

F

ILLING THEHEATINGSYSTEM

:

Remove the case and lower the control panel (see section 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 lowest point and
close it only when clear water, free of air, is visible.

Purge the air from the pump by unscrewing the pump
plug and also manually rotate the pump shaft in the
direction indicated by the pump label to ensure the pump
is free.

I

MPORTANT!!

O

PEN THE MANUAL AIR VENT AND ENSURE THAT THE PRIMARY

EXCHANGER IS FREE OF AIR. (See FIG. 3.0)

Refit 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.

F

ILLING OF THE

D.H.W. S

YSTEM

:

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

GASS

UPPLY

:

Inspect the entire installation including the gas meter, test for
soundness and purge, all as described in BS 6891:2005.
Open the gas cock (supplied with the connection kit) to the
appliance and check the gas connector on the appliance for
leaks.

W

ATE RTREATMENT

:

The boiler is equipped with a stainless steel heat exchanger.

The detailed recommendations for water treatment are given
in BS 7593:1992 (Treatment of water in domestic hot water
central heating systems); the following notes are given for
general guidance;

If the boiler is installed on an existing system, any
unsuitable additives must be removed.

Under no circumstances should the boiler be fired before the
system has been thoroughly flushed; the flushing procedure

Manual Air Vent

FIG. 3.0

28

must be in line with BS7593:1992.
We highly recommend the use of a flushing detergent
appropriate for the metals used in the circuit. These include
cleansers produced by Fernox and BetzDearborn, whose
function is to dissolve any foreign matter that may be in the
system;
In hard water areas or where large quantities of water are in
the system the treatment of the water to prevent premature
scaling of the main heat exchanger is necessary.

The formation of scale strongly compromises the efficiency of
the thermic exchange because small areas of scale cause a
high increase of the temperature of the metallic walls and
therefore add to the thermal stress of the heat exchanger.

Demineralised water is more aggressive so in this situation it
is necessary to treat the water with an appropriate corrosion
inhibitor.

Any treatment of water by additives in the system for frost
protection or for corrosion inhibition has to be absolutely
suitable for all the metals used in the circuit.

The use of a corrosion inhibitor in the system such as Fernox
MB-1, BetzDeaborn Sentinel X100 or Fernox System Inhibitor
is recommended to prevent corrosion (sludge) damaging the
boiler and system;

If anti-freeze substances are to be used in the system, check
carefully that they are compatible with the metals used in the
circuit.

MTS suggests the use of suitable anti-freeze products such
as Fernox ALPHI 11, which will prevent rust and incrustation
taking place.

Periodically check the pH of the water/anti-freeze mixture of
the boiler circuit and replace it when the amount measured is
out of the range stipulated by the manufacturer ( 7 < pH < 8).
DO NOT MIX DIFFERENT TYPES OF ANTI-FREEZE

In under-floor systems, the use of plastic pipes without
protection against penetration of oxygen through the walls
can cause corrosion of the systems metal parts
(metal piping, boiler, etc), through the formation of oxides and
bacterial agents.

To prevent this problem, it is necessary to use pipes with an
“oxygen-proof barrier”, in accordance with standards DIN
4726/4729. If pipes of this kind are not used, keep the

system separate by installing heat exchanger

s of those

with a specific system water treatment.

IMPORTANT
Failure to carry out the water treatment procedure

will invalidate the appliance warranty.

29

3.2. REMOVING THE CASING

To remove the front casing panel, follow these steps:

1. Remove the screws “A” (F

IG 3.1);

2. Remove the four screws from the case hooks (two at the top
and two at the bottom) and rotate (F

IG 3.2);

3. Lift and unhook the case panel (F

IG 3.3).

FIG. 3.2

F

IG. 3.3

F

IG. 3.1

A

A

30

3.3. CONTROL PANEL

FIG. 3.4

A

D

E

F

G

H

I

C

B

** IMPORTANT!!
The Flue Test function will cause the boiler to run continuously on
maximum power. This function must only be activated by an
authorised engineer.

Button Description

ON/OFF Button

“COMFORT” Function Push-button

Reset Button/
Flue Test**/ scroll through Functions Menu

Menu Button

Programming “+” key

Programming “-” key

Description

A

Green LED
(illuminated = burner on)

B

Time clock

C

Selector knob for Summer/Winter
Central Heating Temperature Adjustment Knob

D

Control Panel Cover

E

Domestic Hot Water Temperature Adjustment Knob

F

Heating System Pressure Gauge

G

“COMFORT” Function L.E.D

H

Red LED
(illuminated = boiler lockout)

I

Multi-function Display

35 MFFI (Combi)

31

3.4. INITIAL START-UP

1. Make sure that:

- the cap of the automatic air release valve is loosened;

- the system pressure is at least 1 bar on the
pressure gauge “F” (Fig. 3.4);

- the gas cock is closed (Fig. 3.7);

- the electrical connection has been carried
out in the correct manner.

To allow the air to escape from the system,

proceed as follows:

- push the On/off button and turn the
knob “C” (Fig. 3.5) to the “winter” position. The boiler pump will
start up and three consecutive attempts will be made to ignite
the burner. After the third attempt, the electronic system will
shutdown the boiler, because the supply of gas has been cut off.

The message “A01” will appear on the display and the red LED
“H” will illuminate;

- let the pump operate until all the air has escaped from the
system;

- repeat the procedure for bleeding the radiators of air;

- draw hot water for a short while;

- check the system pressure and, if it has gone down, fill it with
water until it returns to 1 bar.

2. Fill the boiler condensate trap with water (Fig. 3.6).
N.B. In the event of a prolonged period of system shutdown,
the condensate trap should be filled before any renewed
use. A shortage of water in the trap could temporarily lead
to a small leakage of fumes into the air.

3, Ensure that the flue is fitted correctly.

4. Turn on the gas cock (Fig. 3.8) and check

the seals on the connections, including the
one for the burner, making sure that the
meter does not signal the passage of gas.
Check the connections with a soap solution
and eliminate any leaks.

5. Press the reset button , the boiler will
attempt to light.
If the burner does not light the first time, repeat the procedure.
Note: Should the boiler fail to ignite check that no air is present
in the gas pipe.

The boiler is configured in the factory for the gas type in
question. To check the CO

2 setting, please refer to Section

3.6.3 (page 41).

6. Run the appliance in the DHW mode and check the correct

operation of the thermostat control.

7. Complete the commissioning checklist (page 70).

FIG. 3.5

C

H

FIG. 3.7

Fig. 3.8

FIG. 3.6

32

3.5. DISPLAY: MESSAGES SHOWN DURING
NORMAL OPERATION

During operation of the boiler, while it is carrying out its normal
operations, the left-hand display shows a series of characters that
refer to the operations indicated below:

0 No request for heat
C Heating
c Pump overrun for heating
d Domestic hot water
h Pump overrun for domestic hot water
F Frost Protection

The right-hand display (two-digit) shows:

- in CENTRAL HEATING mode: temperature of the Central Heating
system flow;

- in DOMESTIC HOT WATER mode: temperature of the Domestic Hot
Water.

FIG. 3.9

LEFT RIGHT

33

3.6. OPERATING PARAMETERS

The boiler has been designed to allow easy use of the operating
parameters.

3.6.1 REGULATION MENU TABLE

Summary of the functions accessed when the RESET button

and the menu button are pushed at the same time for
5 seconds.
On the display will appear the parameters indicated in table 3A.
To switch between the different parameters press the
button.
To modify the parameters push the programming keys and .

Fig. 3.10

Parameter Function Range Factory setting

1

Soft light
as % of maximum Heating Power
(NG)

from 00 to 99

(step: 1%)

58

2

Maximum Heating Power (%)

from 00 to 99

(step: 1%)

60

3

Ignition delay (minutes)

from 00 to 07

(step: 1 minute)

02

4

Central heating minimum
temperature

25°C if parameter r = 00
42°C if parameter r = 01

42

5

Central heating maximum
temperature

75°C if parameter r = 00
82°C if parameter r = 01

82

6

P∆T rpm (Check of the temperature
difference between the flow and
return sensors for twelve seconds on
initial start-up - D

O NOT ADJUST)

45

t/S

NOT USED

F

Boiler types

from O0 to 02

00

e

Secondary outlet function

from 00 to 03

00

p

Pump overrun (Central Heating ­mins)

from 01 to 15 or CO

02

c

Comfort function

from 00 to 01

00

p

Pump speed adjustment (modulating
or single speed)

U0 (single speed)

U1 (modulating)

U1

TABLE. 3A

34

Important!!
The parameters P5 and P6 are only enabled when the
outdoor sensor is activated (Parameter P - page 37-

38).

To return to the normal display, press the menu button .

Parameter Function Range Factory setting

r

selects low temperature systems
or standard systems

00 (Low temperature)
01 (Standard System)

01

p9

Temperature regulation controlled by
external sensor

90 (Disabled)

91 (Enabled)

90

p6

Correction of heat curve translation

from -20 to +20

P5

Curve incline

from 0_1 to 5_0

0_9

t

Test Function

A

Bus Address (Do not modify)

b 0

Set-point second heating zone

from 25 to 82

75

b 1

GSM value (Do not modify)

b 2

Heating delay after commutation in
DHW (from 0 to 30 minutes)

from 00 to 30

(step: 1 minute)

00

b 3

Post-ventilation in Heating mode

0 (Disabled)

1 (Enabled)

1

b 4

NOT USED

b 5

NOT USED

b 7

NOT USED

b 8

NOT USED

35

FIG. 3.11

Soft Light adjustment 1

The soft light can be adjusted between the maximum power
(shown on the display as “99”) and the minimum power (shown
on the display as “00”). The boiler is factory set to a value which
is suitable for the ignition with any type of gas.
The value set expressed as a percentage, can be displayed and
adjusted as indicated in

Section 3.6.1 (parameter 1)

FIG. 3.12

Maximum Heating Power adjustment 2

The maximum heating power can be adjusted between the
maximum power allowed by the boiler (29.4kW) and the
minimum recommended power (6.5 kW) indicated in the graph
below. The value is factory set to 70% of the maximum power.
The value set (expressed as a percentage) can be displayed
and modified as illustrated in Section 3.6.1 (parameter 2).
The display shows the value between 100% ("99" on the display)
and 1% ("00").

Use the graph below as a guide to set the boiler heating power to
suit the system load.

Display

Heat Output

Ignition Delay adjustment 3

The re-ignition delay for Central Heating can be adjusted to
between 0 and 7 minutes.
The delay is factory set to 2 minutes.
The value set can be displayed and modified as illustrated in
Section 3.6.1 (parameter 3)

FIG. 3.13

6.5

29.4

Secondary outlet Function E
(This parameter can be modified only with the
interface PCB connected)

With the interface PCB connected, it is possible to set the boiler
to operate with one of the following accessories, (see Section

2.12 for further information). The setting can be varied by
pushing the and keys, the following options are available:

00 zone valve -

factory setting -

(NOT USED IN UK)

01 N

OT USED

02 NOT USED
03 NOT USED

36

PUMP OVERRUN P

The pump overrun time may be adjusted (after the burner has been
turned off) by pressing the programming keys and .
The following modes are available:

01 1 minute of pump overrun
02 2 minutes of pump overrun - factory setting
03 3 minutes of pump overrun
04 4 minutes of pump overrun

..... .............................

15 15 minutes of pump overrun

FIG. 3.17

FIG. 3.16

Boiler types F

Factory setting:
00 - ACO 35 MFFI (COMBI)

T

HIS PARAMETER MUST NEVER BE ADJUSTED.

Maximum Central Heating temperature 5

This parameter allows the setting of the maximum temperature for
the central heating circuit. The value is factory set at 82°C and
can be adjusted as illustrated in Section 3.6.1 (parameter 5).

Minimum Central Heating temperature 4

This parameter allows the setting of the minimum temperature for
the central heating circuit. The value is factory set at 46°C and
can be adjusted as illustrated in Section 3.6.1 (parameter 4).

FIG. 3.15

FIG. 3.14

37

Pump Speed Adjustment P

By pressing the and keys it is possible to adust the
operation of the pump, the two options are as follows:

U0- Single Speed Pump
U1- Modulating Pump -

factory setting

FIG. 3.19

FIG. 3.18

Comfort Function (MFFI model - Combi only)

C

The boiler allows the convenience level to be increased in the output
of domestic hot water by means of the “COMFORT” function. This
function keeps the secondary exchanger warm during the periods in
which the boiler is inactive, thereby allowing the initial water drawn to
be at a higher temperature.
The function may be activated by pressing the key on the
control panel (see Section 3.3). When the function is active, a yellow
light “G” comes on, again located on the control panel.

The comfort function can be activated or deactivated by pressing
the and keys

00 Comfort function deactivated
01 Comfort function active for 30 minutes - factory setting.

It is possible to deactivate the comfort function by pressing the

button.

The yellow LED “G” will go out.

NOTE: During the overrun period of the pump, the “COMFORT”
function, if selected, is temporarily deactivated. The L.E.D. light
remains on to indicate that the boiler will return to the “COMFORT”
mode once the pump overrun has finished.

G

TEMPERATURE REGULATION CONTROLLED BY THE

EXTERNAL SENSOR

P

By pressing the and it is possible to make the following

adjustments:

“90” Temperature regulation controlled by the external sensor is

inactive (not installed).

“91” Temperature regulation controlled by the external sensor is

active (installed).

SETTING THE TEMPERATURE FIELD r

Using the programming keys and it is possible to make the

following adjustments:

“00” signifies that the flow temperature (which may be set by

means of the knob on the front control panel) may be
regulated from 25 to 75°C.

“01” signifies that the flow temperature (which also may be set by

means of the knob on the front control panel) may be

FIG. 3.20

FIG. 3.21

38

SETTING THE CURVE INCLINE P 5

(Only enabled when an outdoor sensor is installed)

When using an outdoor sensor, the microprocessor-controlled
P.C.B. calculates the most suitable flow temperature, taking into
account the external temperature and the type of system. The
microprocessor is capable of doing this because it is possible to
establish a link between the external temperature and the flow
temperature of the Central Heating system water. This link
translates into a "thermal curve".
The type of curve should be chosen in correspondence with the
planned temperature of the system and the nature of the heat loss
present in the building.

To select the type of curve access the Setting Menu by pressing the

and buttons for 5 seconds and proceed as follows;

1. Press the button four times to access Parameter 5;

2. P 5 will be shown on the left hand display;

3. Choose the curve required for the system from Fig. 3.26 and
select by pressing the and buttons.

FIG. 3.25

FIG. 3.24

ADAPTING THE HEAT CURVE “P 6”

(Only enabled when the outdoor sensor is activated)

Should the external sensor be fitted it will be necessary to set the
heating curve (see below) and may be necessary to adjust the parallel
shift depending on the performance of the heating system used.

If the temperature in the house is too high, it will be necessary to
decrease the parallel shift, whereas if the temperature is too low it will
be necessary to increase the parallel shift as described below.

To set up the external sensor proceed as follows;

1. Access the settings menu by pressing the and buttons
for five seconds;

2. Press the button 5 times to access Parameter 6

3. P 6 will now appear in the left hand display

4. Adjust the parallel shift by turning the heating control knob
clockwise to increase or anti-clockwise to decrease as shown
below. The shift value can be read on the right hand display, from

-20 to +20 (Fig. 3.23).

Flow temperature (°C)

External temperature (°C)

FIG. 3.23

FIG. 3.22

100

6

-20 +20

60

20

+20

to increase the curve in parallel

the curve in parallel

to decrease

-20 +20

-20

39

Test Function t

The test function is used to enable the engineer/installer to check
the combustion rate (see Section 3.6.3).
The P.C.B. allows the boiler to be forced to the maximum or
minimum power. Enable the test function, two dashes will appear on
the right-hand display (see Fig. 3.27).

To select operation at maximum power, press the programming key

, two dashes will appear at the top of the right-hand display (see
Fig. 3.29).
This function is disabled when you press the reset key to quit the
adjustments menu.

To select operation at minimum power, press the programming key

, two dashes will appear at the bottom of the right-hand display

(see Fig. 3.28). This function is disabled when you press the reset
key “H” to quit the adjustments menu.

Note: The boiler can be forced to the maximum and minimum power

even without enabling the test function via the adjustments
menu:

a - by pressing the Reset key for 5 seconds, the boiler is

automatically forced to test mode and t-- will be displayed, the
boiler is now in the test mode for the maximum heating power, to
force the boiler to maximum output for hot water it is necessary
to press the and keys together, two dashes appear at the
top of the right-hand display (see Fig. 3.29). This function is
disabled by pressing the reset key .

b - by pressing the key, the boiler is forced to operate at

minimum power, two dashes appear at the bottom of the right­hand display (Fig. 3.28). This function is disabled by pressing
the reset key.

max power Central Heating

minimum power

FIG. 3.27

FIG. 3.28

With parameter P5 it is necessary to adjust the heat curve to one of
those shown in Fig. 3.26. By using the programming keys

and , the curve may be changed to select the required curve

for the system.

WARNING
If a curve is selected for an under-floor
heating a system safety thermostat must
be connected to the main terminal board
(see paragraph 2.12)

Fig. 3.26

max power DHW

FIG. 3.29

Flow temperature (°C)

External temperature (°C)

40

The boiler is designed to monitor some operating variables and
settings by means of the display on the front control panel. Keeping,
at the same time, the reset and the menu key pressed for over 10
seconds will allow access to the “readout” function of the main
system variables. By pressing the reset button repeatedly after that,
it is possible to read the following information in sequence:

Indication on the
left-hand display

U/1
U/2
U/3
U/4
U/6

E

A

Value read on right-hand display

Flow temperature of the Central Heating circuit (°C)

Return temperature of the Central Heating circuit (°C)

Domestic Hot Water output temperature (°C)

Outdoor temperature (°C)*

Fan speed (% rpm)

Last safety shut-off (see section 3.10.)

Last shutdown (see section 3.10.)

3.6.2 SETTINGS DISPLAY

To return to the normal display, press the menu key.
The boiler will automatically return to the normal display after no
buttons have been pressed for 2 minutes.

N

OTE 1: U/1 means that “U ” and “1” blink alternately on the display

N

OTE 2: the value 100% appears as “99” on the display

* = Only displayed when an external sensor is fitted.

41

SUPPLY PRESSURE (WORKING)

G20 methane 20 mbar

LPG 37 mbar

3.6.3 GAS REGULATION CHECK

Supply pressure check

1. Loosen screw “1” (Fig. 3.31) and connect the pressure gauge

connection pipe into the test point.

2. Turn the boiler on at maximum power, enabling the “test”

function (press the key for 5 seconds and then press the
programming keys and together ensuring the dashes are
at the top of the display (see Fig. 3.29). The supply pressure
should correspond to that shown for the type of gas the boiler is
designed for (see table below).

3. Disable the test mode by pressing the reset key.

4. When the check is over, tighten screw “1” and test for tightness.

N

OTE:IF THE WORKING PRESSURE IS INSUFFICIENT CHECK THE GAS

METER

, METER GOVERNOR, OR INSTALLATION PIPEWORK FOR

ERROR.

I

MPORTANT

!

D

O NOT PROCEED CHECKING AND ADJUSTING THE

CO

2

SETTINGS

UNLESS THE WORKING PRESSURE IS ADEQUATE

.

N

OTE

: A

LL SETTINGS ARE TO BE MADE WITH A

CO

2

METER WITH THE

PROBE FITTED TO THE FLUE GAS ANALYSIS POINT(FIG

. 3.30).

Setting the CO2 at minimum power

To check the air/gas ratio at minimum power, proceed as follows:

1. Connect the combustion analyser to the analysis point (Fig.

3.30) after removing the screw and cover.

2. Set the boiler to minimum power via the test function (see

paragraph 3.6.1) or by pressing the button for 5 seconds
and then pressing the button on the control panel, ensure
the dashes are at the bottom of the display (see Fig. 3.28).
Ensure the CO

2 value on the analyser corresponds with the

value indicated in table 4D. If this is not the case, adjust screw
“2” (Fig.3.31) with a screwdriver in small intervals, allowing the
reading to become stable before adjusting further, until you
obtain the correct CO2 reading. Allow the reading to become
stable for at least 4 minutes.

3. When the check is over, replace the cap on screw “2” (Fig. 3.31).

4. Disable operation at minimum power by pressing the key

or press the key to check the maximum value (dashes at top
of display see Fig. 3.29).

While the appliance is operating at maximum power, check
the gas rate of the appliance at the gas meter

Setting the CO2 at maximum power

To check the air/gas ratio at maximum power, proceed as follows:

1. With the combustion analyser already connected to the analysis

point, set the boiler to maximum power via the test function (see
paragraph 3.6.1) or by pressing the button for 5 seconds
and then the programming keys and ensuring the dashes
are at the top of the display (see Fig. 3.29).
Ensure the CO

2 value on the analyser corresponds with the

value indicated in table 4D. If this is not the case, adjust screw
“4” with a screwdriver in small intervals allowing the analyser
reading to stabilise before adjusting further (Fig. 3.31), until you
obtain the correct CO

2 reading. Allow the reading to become

stable for at least 4 minutes.

2. Disable the test mode by pressing the button.

The test mode is automatically disabled after 5 minutes.

3. Repeat the air/gas ratio at minimum power check (see

above).

4. Disconnect the analyser, remount the cover plate and check it is

securely in place.

While the appliance is operating at minimum power, check
the gas rate of the appliance at the gas meter

N

OTE:WHEN MAKING ADJUSTMENTS, ADJUST SMALL AMOUNTS AND

WAIT FOR THE ANALYSER TO STABILISE BEFORE MAKING

FURTHER ADJUSTMENTS

.

CO2 SETTING MAXIMUM VALUE

Calibration values check
CO

2 at maximum power G20 % vol 9.4 ±0.2

after 4 minutes of operation

LPG % vol 10.1 ±0.2

CO2 SETTING MINIMUM VALUE

Calibration values check
CO

2 at minimum power G20 % vol 8.7 ±0.2

after 4 minutes of operation

LPG % vol 8.6 ±0.2

SETTING THE GAS PRESSURES

FIG. 3.32

FIG. 3.31

TABLE 4D

FIG. 3.30

4

3

2

1

42

The soft light can be adjusted between the maximum power
(shown on the display as "99", i.e. 100%) and minimum power
(shown on the display as "00", i.e. 1%). The boiler is factory set to
a value which is suitable for ignition with any type of gas.
The value set (expressed as a percentage) can be displayed and
modified as illustrated in paragraph 3.6.1 (parameter 1).

The ignition delay can be adjusted to between 0 and 7 minutes.
The delay is factory set to 2 minutes.
The value set can be displayed and modified as illustrated in
paragraph 3.6.1 (parameter 3).

3.6.4 IGNITION DELAY ADJUSTMENT

3.6.5 ADJUSTING THE MAXIMUM HEATING POWER

3.6.6 SOFT LIGHT ADJUSTMENT

The maximum heating power can be adjusted between the
maximum power allowed by the boiler (29.4kW) and the minimum
power (6.5 kW) indicated in the graph. The value is factory set to
70% of the maximum power.
The value set (expressed as a percentage) can be displayed and
modified as described in paragraph 3.6.1 (parameter 2) using the
graph on Page 35.

3.7 CHANGING THE TYPE OF GAS

The boiler operation can be changed over from methane gas
(G20) to Liquid Gas (G31) or vice versa, an operation that must
be performed by a CORGI registered Gas Engineer.

To change the type of gas it is necessary to proceed as follows:

1. Before starting ensure both the gas and electrical supplies
to the boiler are isolated and the boiler is cool.

2. Remove the casing as indicated in Section 3.2.

3. Remove the silencer

4. Disconnect the electrical connection of gas valve and fan.

5. Remove the three torx screws of the air gas connections
(see Fig. 3.32) and loosen the nut under the gas valve
(see Fig. 3.33)

5. Remove all the mixer/fan/gas valve group (see Fig. 3.34)

6. Unscrew the four torx screws and disconnect the gas valve (see
Fig. 3.35).

7. Insert the diaphram into the gas valve (see Fig. 3.36)

8. Reassemble in reverse order.

9. Replace the gas label.

FIG. 3.32

FIG. 3.33

FIG. 3.34

43

3.8 ADJUSTING THE HOT WATER FLOW RATE

To adjust the hot water flow rate, it is necessary to first open the hot
water tap with the highest flow rate (normally the bath tap), adjust the
cold water inlet valve until the correct temperature rise is achieved at the
stated flow rate ( ACO 35 MFFI - ∆T@35°C = 13.5 l/min).

Alternatively, you can advise the customer to restrict the water flow
through each individual tap, by opening the tap and slowly closing it
until the water reaches the desired temperature.

3.9 BALANCING THE CENTRAL HEATING SYSTEM

To balance the central heating system it is first necessary to close
all radiator valves on the system, turn on the central heating, allow
the boiler to reach operating temperature and then starting at the
radiator furthest from the boiler, open the radiator valves until the
radiator becomes hot and move to the next radiator on the circuit,
working your way back to the radiator closest to the boiler.

10. Carry out check 3.6.3, verifying the inlet pressure is correct and
the CO2 values are as stated in Table 4D (page 41).

11. Check the gas connection for tightness.

12. Check that the ignition operates correctly and visually check the

burner flame.

13. Check that the domestic hot water is being correctly produced
by drawing hot water.

14. Check the flow rate and/or temperature of the water, depending
on the case.

15. Check that the condensate drips without difficulty into the
discharge.

FIG. 3.35

FIG. 3.36

LPG (G31)

Consumption at Nominal Capacity(G31) kg/h 2.33
Gas Consumption after 10 Minutes* kg 0,27

* Calculated at 70% maximum output

44

NOTE: When there is no ignition (A01), check that the gas cock is

open and gas is being supplied.

3.10 BOILER SAFETY SYSTEMS

The boiler is protected from malfunctioning by means of internal
checks by the P.C.B., which brings the boiler to a stop if necessary.
In the event of the boiler being shut off in this manner, a code
appears on the display which refers to the type of shut-off and the
reason behind it.
There are two types of shut-off:

-

SAFETY SHUTDOWN:

for this group of errors (characterised

on the display by the letter “E”) the situation is automatically
removed as soon as the cause behind it is resolved.
As soon as the origin of the shutdown disappears, the boiler
starts up again and returns to its normal operation.

-

SHUTDOWN:

(characterised on the display by the letter “A ”), is

not removed unless a manual intervention is made.
The boiler may return to operation only if reset, press the

button.
There follows a list of the shutdown modes and the respective
codes shown on the display.

Shutdown (“A ” type): if such a situation occurs, it is necessary to
reset the boiler using the appropriate key. If this shutdown occurs
frequently, your local Service Agent should be contacted.

Safety shutdown: In the event that a safety shutdown occurs, it is
necessary to contact an Authorised Service Centre.

DISPLAY CAUSE

A 01

Too many attempts to ignite on start up

A 03

The heating flow temperature exceeds 105°C
during operation

A 07

Too many failures to ignite in one period
during operation

A 33

Problem with the fan

A 97

Problem with the electronic monitoring

A 98

Problem with the electronic monitoring

A 99

Problem with the electronic monitoring

DISPLAY CAUSE

E 02

No water or no water circulation in central
heating system (for 40 sec.)

E 06

Heating flow temperature probe in open circuit

E 07

Heating flow temperature probe in short-circuit

E 08

Heating return temperature probe
in open circuit

E 09

Heating return temperature probe
in short-circuit

E 10

Under floor heating temperature probe
in open circuit

E 20

Flame detected with gas valve closed

E 94

Problem within the electronic system

E 99

Problem within the electronic system

DISPLAY CAUSE

S 01

Ignition failure on 1st attempt

S 02

Ignition failure on 2nd attempt

S 04

Domestic hot water temperature probe
in open circuit

S 05

Domestic hot water temperature probe
in short circuit

S 06

Problem with rectification probe

S 30

Outdoor sensor open circuit

S 31

Outdoor sensor in short circuit

S 80

Remote Control CLIMA MANAGER room
sensor in open circuit or short circuit

45

The draining of the heating system must be carried out as follows:

- Turn off the boiler and isolate the electrical supply;

- Loosen the automatic air release valve;

- Open the system's discharge valve

- Empty out from the lowest points of the system (where
provided).

If the system is to be left active in areas where the room
temperature may go below 0°C during winter, it is recommended
that anti-freeze liquid be added to the water in the heating system in
order to avoid the need for repeated draining.

Draining the domestic hot water system
Every time that there is a danger of freezing, the domestic hot water
system must be drained as follows:

- close the water mains stop-cock;

- open all the hot and cold water outlets;

- empty out from the lowest points (where provided).

3.12 DRAINING

3.11 COMPLETION

D

AILYTEST

.
In order to prevent sticking components, the boiler carries out a self­diagnosing test every 21 hours: the pump runs for 15 seconds and
the diverter valve moves once.

A

NTI-FROSTDEVICE

.
The anti-frost function acts on the central heating flow temperature
probe, independently from other regulations, when the electrical
supply is turned on.
If the primary circuit temperature falls below 8°C the pump will run
for 2 minutes.
After the two minutes of circulation (fixed) the boiler will check the
following:
a) if the central heating flow temperature is > 8°C, the pump stops;
b) if the central heating flow temperature is between 3 and 8°C, the
pump will run for another two minutes;
c) if the central heating flow temperature is < 3°C, the burner will fire
(heating position) at minimum power until the temperature reaches
33°C, the burner will go out and the pump will continue to run for
two minutes.
If the flow temperature remains between 3-8°C the pump will
continue to run for two minutes for a maximum of 10 times unless a
temperature above 8°C is detected in the central heating flow, after
this the the burner will fire.
If lockout is caused by overheat the burner is kept OFF.

N

OTE: In all cases, the circulation takes place in the central

heating system.
The anti-frost device activates only when (with the boiler
operating correctly):

- the system pressure is correct;

- the boiler is electrically powered;

- there is a supply of gas.

A

NTI-SCALEDEVICE

.

When producing domestic hot water, the burner shuts off
whenever the output temperature of the hot water exceeds
61°C or the flow temperature of the primary circuit exceeds
78°C. It will not turn on if the temperature of the primary circuit
is greater than 78°C.

For the Republic of Ireland it is necessary to complete a
“Declaration of Conformity” to indicate compliance to I.S. 813. An
example of this is given in the current edition of I.S. 813. In addition
it is necessary to complete the commissioning checklist
(Section 11, page 70).

46

5. SEQUENCE OF OPERATION

Activation of the time clock and/or room thermostat starts the boiler.
The letter C is shown in the display followed by the flow

temperature.

With the boiler in rest, the diverter valve is in the domestic hot water
position, activation of the central heating changes the position of the
motorised valve head, moving the diverter valve into the central
heating position.

The start of the pump is delayed for 7 seconds to allow the
movement of the diverter valve.
The pump starts at speed 2, after the low water pressure switch
verfies water is present.
If the low water pressure switch does not verify water is present

after 40 seconds, error code E02, the boiler will resume operation

once the problem has been resolved.

Following the satisfaction of the low water pressure switch check the
fan starts and an ignition attempt is then made for 3 seconds after
the fan starts. The gas valve is energised and gas is delivered to
the burner fixed in relation to the fan. The ignition gas pressure (soft
light) is adjusted at Step 1 in the parameter adjustment mode (see
Section 3.6.1). This value is factory set. (1= minimum fan speed
and 00 = maximum fan speed). Soft light takes 4 seconds, the
electronics check for flame ionisation three times consecutively.

Failure on ignition results in the error code A01.

The boiler will modulate the burner according to the central heating
output. The burner can activate up to a maximum of the set point at
+4

o

C. Reignition of the burner occurs once it has thermostatically
turned off can be time delayed between 0 and 7 minutes, adjustable
in Step 3 (Section 3.6.1), the factory setting is 2 minutes.

Overheat safety is provided by a Klixon thermostat, the temperature
is set to 105 ±1

o

C, this thermostat remains active even when the
burner is off. In the event that the Klixon thermostat reads a
temperature value above 105 ±1oC the boiler will shut down and the

display will show A03, the fan will continue to run for 20 seconds.

After correct operation is proven the pump speed changes to speed
3 (if the system is cold), if the system is warm the pump remains at
speed 2.

5.1 CENTRAL HEATING MODE

5.2 DOMESTIC HOT WATER MODE

When a hot water tap is turned on the domestic hot water flow
switch is operated (if the diverter valve is in the central heating
position it will motor into the domestic hot water position and the

boiler starts. The letter d is shown in the display followed by the
temperature of the domestic hot water leaving the appliance.

The appliance will then follow the same operating logic as described
in Central Heating Mode.

In domestic hot water mode NTC1 limits the maximum temperature
to 78oC, reignition will occur at 74oC. The domestic hot water
temperature is limited to 61

o

C, reignition will occur at 60oC.

47

6. MAINTENANCE

6.1. GENERAL REMARKS

To ensure the validity of the 5 Year Guarantee, the boiler must be
serviced annually by a CORGI registered gas engineer.

MTS (GB) Limited will write to the householder as the boiler
becomes due for it’s annual service.

With the letter will also be sent a ‘Service Pack’, this will include the
annual maintenance checklist to be completed and signed by the
CORGI registered engineer, also included in this pack may be a
component which must be replaced and the old one returned with all
documentation included in the ‘Service Pack’ to MTS (GB) Ltd.

See Section 10 for annual maintenance requirements.

N

OTE:FAILURE TO COMPLY WITH THE ANNUAL SERVICE

REQUIREMENTS WILL RESULT IN THE

5 YEAR GUARANTEE

BECOMING VOID.

CLEANING THE EXHAUST SIDE
Access the combustion chamber (see section 7.3). Check that the
exhaust passages are clear; if there are deposits present, wash the
exchanger with compressed air, water or a vinegar-based detergent.
NOTE: it is possible to use a brush in order to mechanically remove
the residues.

Use of detergents:

- soak the blades well

- allow the detergent to act for about 20 minutes

- rinse with a strong jet of water to remove the deposits (the

control panel must be kept closed)

- make sure that there are no traces of detergents in the

exchanger.

CLEANING THE WATER SIDE
Use detergents that dissolve CaCO3. Leave to act for a short time
and then rinse. Make sure that the detergent does not remain inside
the exchanger.

To clean the condensate trap it is simply necessary to unscrew the
lower part of the condensate trap and clean it. Lastly, fill it with water
and replace the stopper.

6.2. CLEANING THE PRIMARY EXCHANGER

6.3. CLEANING THE CONDENSATE TRAP

6.4. OPERATIONAL TEST

After having carried out the maintenance operations, fill the
heating circuit to a pressure of approx. 1.5 bar and release the
air from the system. Also fill the domestic hot water system.

- Place the boiler in operation;

- If necessary, release the air again from the heating system.

- Check the settings and the correct functioning of all the

control, regulation and monitoring parts;

- Check the seal and the correct functioning of the system for

expelling fumes/drawing of combustion air;

- Check that the boiler ignites properly and carry out a visual

check on the burner flame;

- Check the CO2 values are correct (see Section 3.6.3)

IMPORTANT!!

If the boiler is not to be used for a prolonged period, the
condensate trap should be filled before operating the
boiler. A shortage of water in the trap will temporarily
risk flue gasses escaping into the room.

48

FIG. 7.1

7. SERVICING INSTRUCTIONS

The life of individual components vary and they will need servicing or
replacing as and when faults develop.
The fault finding sequence chart in Section 8 will help to locate which
component is the cause of any malfunction, and instructions for
removal, inspection and replacement of the individual parts are given
in the following pages.

7.1. REPLACEMENT OF PARTS

7.2. TO GAIN GENERAL ACCESS

All testing and maintenance operations on the boiler require the
control panel to be lowered. This will also require the removal of the
casing.

To lower the control panel and remove the casing,
proceed as follows:

1.

Remove the screws “A” (Fig. 7.1);

2.

Loosen the four screws ‘B’ from the case hooks (two
at the top and two at the bottom) and rotate (Fig. 7.2);

3.

Lift and unhook the case panel (Fig. 7.3);

4.

Lower the control panel (Fig. 7.4)

To ensure efficient safe operation, the boiler must be serviced
annually by a competent person.

Before starting any servicing work, ensure both the gas and
electrical supplies to the boiler are isolated and the boiler is
cool.

Before and after servicing, a combustion analysis should be made
via the flue sampling point (please refer to Section 3.6.3).

After servicing, preliminary electrical system checks must be carried
out to ensure electrical safety (i.e. polarity, earth continuity,
resistance to earth and short circuit).

A

A

FIG. 7.3

FIG. 7.2

B

49

7.3.1. REMOVING THE AIR/GAS ASSEMBLY

1.

Remove the three torx screws “C” (FIG. 7.5);

2.

Loosen the nut “D“ under the gas valve (FIG. 7.6);

3.

Disconnect electrical connections to gas valve and fan;

4.

Dismount the gas valve/mixer/fan group (FIG. 7.7);

5.

Reassamble in reverse order.

FIG. 7.5

FIG. 7.6

C

D

7.3. ACCESS TO THE COMBUSTION CHAMBER

FIG. 7.4

To gain better acess to certain components, it will be
necessary to remove the silencer.

50

FIG. 7.7

7.3.2. REMOVING THE BURNER

1.

Remove ther air/gas assembly see section 7.3.1;

2.

Slide the burner from its housing (FIG. 7.8);

3.

Reassemble in reverse order and check all seals are
undamaged and the burner is positioned correctly.

FIG. 7.8

FIG. 7.9

FIG. 7.10

FIG. 7.11

7.3.3. REMOVING THE DETECTION ELECTRODE

1.

Remove the two torx screws “E” (FIG. 7.9);

2.

Extract the electrode (FIG. 7.10);

3.

Disconnect the detection electrode cable (FIG. 7.11).

E

51

FIG. 7.12

FIG. 7.14

FIG. 7.13

7.3.4. REMOVING THE IGNITION ELECTRODE

1.

Remove the earth cable from the electrode (FIG. 7.12);

2.

Remove the electrode cable from the spark generator
(F

IG. 7.13);

3.

Unscrew the two screws “F” (FIG. 7.14).

F

1.

Remove ther air/gas assembly see section 7.3.1;

2.

Disconnect the air/gas connection unscrew the three

screws “G“ (FIG. 7.15);

3.

Remove the mixer by unscrewing the two screws “H” (FIG.

7.16).

4.

Remove the fan (FIG. 7.17).

7.3.5. REMOVING THE FAN

FIG. 7.16

H

H

FIG. 7.15

G

FIG. 7.17

52

FIG. 7.20

7.3.6. REMOVING THE HEAT EXCHANGER

1.

Drain the boiler;

2.

Remove the air/gas assembly see section 7.3.1;

3.

Remove the electrodes see section 7.3.3 - 7.3.4;

4.

Remove the condensate trap tube see section 7.3.7;

5.

Unplug the C.H. return and flow temperature probes
and the overheat thermostat (F

IG. 7.18);

6.

Unplug the pipe clips (FIG. 7.18);

7.

Loosen the nut “I” and remove the pipe (FIG. 7.19 - 7.20);

8.

Loosen the nut “J” and remove the pipe (FIG. 7.21 - 7.22);

9.

Loosen the nuts “K” and remove the exchanger
(FIG. 7.23 - 7.24).

FIG. 7.18

FIG. 7.22

FIG. 7.23

FIG. 7.21

FIG. 7.19

J

I

ATTENTION!!

When removing the heat exchanger, ensure that
no water can enter the electrical box containing
the PCB!

K

K

K

53

7.3.7. REMOVING THE CONDENSATE TRAP (TUBE)

1.

Unplug the clip “L” (FIG. 7.25);

2.

Unscrew the screw “M” (FIG.7.26);

3.

Remove the condensate tube (FIG. 7.27).

FIG. 7.27

FIG. 7.24

FIG. 7.25

FIG. 7.26

L

M

54

FIG. 7.28

FIG. 7.29

7.3.8. REMOVING THE CONDENSATE TRAP

1.

Remove the condensate trap tube - see section 7.3.7;

2.

Remove the condensate trap glass (FIG. 7.28);

3.

Remove the trap from the boiler (FIG. 7.29).

NOTE: Take care when removing the blanking cap to

place a container under the boiler as this will
release the contents of the condensate trap.

7.4 ACCESS TO THE GAS VALVE

FIG. 7.30

FIG. 7.31

1.

Remove the casing and lower the control panel as
instructed in Section 7.1.

2.

Press the release button “N” for the control panel (Fig.

7.30) and pull forward to remove from the boiler frame.

3.

Clip the control panel onto the frame of the boiler. (Fig.

7.31).

N

55

7.4.1. REMOVING THE GAS VALVE

1.

Remove the air/gas assembly see section 7.3.1;

2.

Remove the screws “O” from the bottom of the gas
valve (F

IG. 7.32);

3.

Remove the gas valve;

FIG. 7.32

O

7.4.2. REMOVING THE SPARK GENERATOR

1.

Disconnect the electrical connection from the spark
generator (FIG. 7.33);

2.

Remove the screws “P” from the bottom of the spark
generator (FIG. 7.34);

4.

Remove the spark generator.

FIG. 7.33

FIG. 7.34

P

P

4.

Reassemble in reverse order;

5.

The gas valve settings will need to be adjusted (see
section 3.6.3);

6.

Reinstate the gas supply and test for tightness on
reassembly.

56

7.5 ACCESS TO THE WATER CIRCUIT

7.5.1. REMOVING THE D.H.W. (SECONDARY) EXCHANGER

1.

Remove the two allen screws “Q” (FIG. 7.35 and 7.36);

2.

Push the exchanger towards the rear of the boiler, lift
upwards and remove from the front of the boiler (FIGS.

7.37, 7.38 and 7.39);

3.

Before replacing the exchanger ensure that the O-rings
are in good condition and replace if necessary.

Important!

Before any component is removed, the boiler

must be drained of all water.

FIG. 7.35

FIG. 7.37

FIG. 7.38

FIG. 7.39

Q

Q

FIG. 7.36

57

7.5.2. REMOVING THE SAFETY VALVE

1.

Loosen the nut “R” and remove the pipe (Fig. 7.40);

2.

Remove the valve (Fig. 7.41).

FIG. 7.40

FIG. 7.41

7.5.3. REMOVING THE AUTOMATIC AIR VENT

1.

Remove the U-clip “S” (FIG. 7.42);

2.

Remove the automatic air vent (FIG. 7.43).

FIG. 7.43

FIG. 7.42

S

R

58

7.5.6. REMOVING THE PUMP

1.

Unplug the electrical connection (FIG. 7.48);

2.

Unscrew the four screws “U” (FIG. 7.48);

3.

Remove the pump (FIG. 7.49).

FIG. 7.48

FIG. 7.49

7.5.5. REMOVING THE D.H.W. FLOW SWITCH

1.

Unplug the electrical connector (FIG. 7.46);

2.

Remove the D.H.W. flow switch (FIG. 7.47).

FIG. 7.46

FIG. 7.47

FIG. 7.44

7.5.4. REMOVING THE DIVERTER VALVE ACTUATOR

1.

Unplug the electrical connector and retaining clip “T”
(FIG. 7.44);

2.

Remove the diverter valve actuator (FIG. 7.45).

FIG. 7.45

T

T

T

T

T

59

7.5.8. REMOVING THE PRESSURE GAUGE

1.

Release U-clip “W” (FIG. 7.53 - 7.54);

2.

Ease the pressure gauge through the control panel
from the rear;

3.

Remove the pressure gauge.

FIG. 7.53

FIG. 7.54

W

7.5.7. REMOVING THE LOW WATER PRESSURE SWITCH

1.

Disconnect the electrical connection (FIG. 7.50);

2.

Loosen the nut “V” (FIG 7.51);

3.

Remove the low water pressure switch. (FIG 7.52).

FIG. 7.50

FIG. 7.51

FIG. 7.52

V

60

7.5.10 REMOVING THE D.H.W. TEMPERATURE PROBE (N.T.C.)

1.

Remove the electrical connector by pulling off and
loosening the nut “Z” (Fig. 7.58);

2.

Remove the D.H.W. temperature probe (FIG. 7.59).

FIG. 7.58

FIG. 7.59

7.5.9. REMOVING THE EXPANSION VESSEL

1.

Unscrew the screw “X” (FIG. 7.55);

2.

Loosen nut “Y” (FIG. 7.56);

3.

Remove the expansion vessel (FIG. 7.57).

X

FIG. 7.55

FIG. 7.56

FIG. 7.57

Y

Z

61

FIG. 7.60

7.5.10. Removing the C.H. Flow Temperature
Probe (N.T.C.)

1.

Unplug the C.H. Flow temperature probe (Fig. 7.60);

2.

Remove the electrical connection from the C.H. flow
temperature probe (FIG. 7.61).

FIG. 7.62

FIG. 7.63

7.5.11. REMOVING THE C.H. RETURN TEMPERATURE

PROBE (N.T.C.)

1.

Unplug the C.H. Return temperature probe (Fig. 7.62);

2.

Remove the electrical connection from the C.H. return
temperature probe (F

IG. 7.63).

FIG. 7.61

FIG. 7.64

7.5.10. Removing the Overheat Thermostat

1.

Unplug the overheat thermostat (Fig. 7.64);

2.

Remove the electrical connection from the overheat
thermostat (FIG. 7.65).

FIG. 7.65

62

7.6.1. CHECKING THE FUSES

1.

Remove the inspection cover of the PCB box (FIG. 7.66

- 7.67);

2.

Loosen the two screws “A1” and slide the PCB
forward before removing the screws (FIG. 7.68).

7.6 ACCESS TO THE CONTROL SYSTEM

FIG. 7.66

FIG. 7.67

FIG. 7.68

A1

A1

7.6.2. REMOVING THE P.C.B.S

1.

Remove the inspection cover of the PCB box (FIG.

7.66- SECTION 7.6.7);

2.

Unplug all the electrical connections and loosen the
screws “A1” (FIG. 7.68);

4.

Pull forward the main PCB (FIG. 7.69 & 7.70);

5.

Unscrew the screws “A2” (Fig. 7.71);

6.

Remove the cover of the control panel (FIG. 7.72);

7

. Unscrew the display P.C.B. mounting screws “A3” and

disconnect the P.C.B. connection cable “A4” (FIG. 7.73);

8.

Remove the display P.C.B. (FIG. 7.74);

9.

Replace either P.C.B. in reverse order.

FIG. 7.69

FIG. 7.70

FIG. 7.71

A2

A2

A2

63

FIG. 7.72

FIG. 7.73

FIG. 7.74

7.6.3. REMOVING THE TIME CLOCK

1.

Open the control panel (see the paragraph “

Removing

the P.C.B.s”);

2.

Unplug the electrical connection from the time clock
and unscrew the four screws (FIG. 7.75);

3.

Remove the time clock (FIG. 7.76).

FIG. 7.76

FIG. 7.75

A3

A3

A3

A3

A4

64

It is possible to detect and correct defects by using the standard fault
finding diagrams described in this chapter.

NOTE:THESE CHECKS ARE NOT EXHAUSTIVE

8.1. FAULT FINDING GUIDE
(FLOW-CHARTS)

8. FAULT FINDING

65

1. Check if there is air in
the system

2. Check the pressure on
the water gauge and fill
system to 1 bar

Push the RESET button

IS THE

LOW WATER

PRESSURE SWITCH

WORKING CORRECTLY?

E 02:does not close

66

67

9. SHORT SPARE PART LIST

35 MFFI

615

111

147

101

110

107

401

190

206

616

571

917

589

917
904

564

597

520

548

537

531

502

911

917

917

0101 MAIN EXCHANGER 65103385

BURNER 65103333

0107
0110

ELECTRODE (IGNITION) 65103358
ELECTRODE (DETECTION) 65103359

0111

0147

GASKET D:129.4 61306030
SPARK GENERATOR 65103516

0190

FAN ASSY 61314434

0206
0401

GAS VALVE 65103413

0502 MOTOR (3-WAY VALVE) 997147
0520

TEMPERATURE PROBE (D.H.W.) 998458

0529 PRESSURE GAUGE 65102220

531

AUTO AIR VENT + O-RING 9

0

SAFETY VALVE (1/2 3 BAR) 573172

0537
0538

KIT FOR REAR PUMP ATTACHMENT 65103500

0548

TEMPERATURE PROBE + CLIP 65103502
FLOW DETECTION KIT WITH MAGNET 65100540

0564

0571

LOW WATER PRESSURE SWITCH 995903

0589 SECONDARY EXCHANGER 65103501
0597

THERMOSTAT (OVERHEAT) 996065

P.C.B.(ACO-MCU) 65103508

0615
0616 P.C. B. (DISPLAY) 65102235
0901

FILLING LOOP PIPE 990737

0904 TAP (M/M 3/8 ) 65102016

TAP (M/M 3/8 - C.H. FLOW) 990742

0911

0917

GASKET 3/8 573521

95367

901

529

538

68

10. ANNUAL MAINTENANCE CHECKLIST

7.5.3. REMOVING THE AUTOMATIC AIR VENT

1.

Remove the U-clip “S”;

2.

Remove Auto Air Vent.

S

Annual Maintenance Check List

In order to maintain the 5 year manufacturers warranty, a similar sheet to this has been sent to the customer.
It must be completed in full by a CORGI registered engineer and returned with a replaced component if requested.
Note: These checks are not exhaustive, additional checks may be necessary

The flue has been checked to ensure it is:

Sited in accordance with the manufacturers instructions
Installed correctly
Is in good condition

The correct operation of the following components has been checked:

Air Pressure Switch
Thermostat Controls
Safety Valve
Ionisation (Flame Detection)

The following has been carried out:

Pressure in expansion vessel checked and corrected where necessary (0.7 bar)
Condensate system removed, cleaned and refilled
Auto Air Vent replaced and returned (see instructions over leaf)
DHW flow switch removed and cleaned (Combi Only)
Electrodes removed and cleaned (with emery cloth)
Burner and fan removed and cleaned (if necessary)
Primary heat exchanger checked and cleaned if necessary
All electronic parameters checked and set as required
Time clock and room thermostat checked for correct operation
Appliance settings made in accordance with manufacturers instructions
End user advised on the correct operation of the appliance

Please check the following information:

Gas inlet pressure
Gas rate
CO

2 setting (min/max)

DHW flow rate

(∆T @ 35 C)

o

CH output
Service Interval Record completed in Installation Instruction Manual

Gas working pressure
CO

2 ratio

DHW flow rate set to

69

11. BENCHMARK COMMISSIONING CHECKLIST

70

12. SERVICE INTERVAL RECORD

71

420010001200- 02/2006

MTS are continuously improving their products and therefore reserve the right to change specifications without prior notice and

accepts no liability for any errors or omission in the information contained in this document.

Manufacturer: Merloni TermoSanitari SpA - Italy

Commercial subsidiary: MTS (GB) Limited, MTS Building, Hughenden Avenue, High Wycombe, Bucks HP13 5FT

Please read these terms and conditions which are in
addition to any terms and conditions detailed in this book
or any registration card supplied with your appliance.

A charge will be made to the owner of the appliance if:

• The reason for any service visit is as a direct result
of a failure to install the appliance in accordance
with the manufacturer’s instructions.

• Your installer does not complete the necessary
commissioning process and procedure as detailed in
the Installation and Operating Instructions.

• Your appliance is not serviced on or before the 12
month anniversary of installation - this only applies to
appliances with a 2 and 5 year guarantee.

• Our service engineer calls as requested and the
failure is a non-manufacturing defect.

Failure to pay an invoice for any such occurence will be
assumed by MTS that you accept that your appliance
has not been installed correctly and understand that any
manufacturer’s guarantee has been withdrawn.

On the 12 month anniversary of the appliance
installation, you must have it serviced to continue any
guarantee offered into the following year. Failure to do
so will invalidate your guarantee and should an MTS
engineer be required to attend and no proof of service
documentation is made available, then MTS will charge.

As part of the commissioning process, it is a legal
requirement to register all boiler installations or
replacements with CORGI. Upon registration a
“Certification Number” will be issued followed by a
“Declaration of Safety” Certificate. MTS (GB) Ltd cannot
be called upon to carry out any work under the
manufacturer’s guarantee without proof of registration.
The registration number must be quoted when
requesting a service visit, and the “Declaration of Safety”
Certficate subsequently shown to the service engineer.
If the certificate is not made available, the engineer will
not work on the appliance and a wasted call charge will
be made.

TERMS AND CONDITIONS OF GUARANTEE

If you have a problem with commissioning on installation, please contact our

Technical Department on 0870 241 8180

Benchmark completed and customer advised

Customer advised on how to use and repressurise boiler

CORGI contacted for certification

Phone

Internet

Certification Number

CORGI will send Safety Certificate within 10 days to your customer

Date boiler installed

Serial Number

CORGI registration number (installer)

Installer details Name:

Address:

Phone:

For Customer Service please phone [phone]