Ariston 41-116-07 User Manual

Installation
Instructions
Type C Boilers

G.C.N: 41-116-06

41-116-07

LEAVE THESE INSTRUCTIONS
WITH THE END-USER

Country of destination: GB

2

TABLE OF CONTENTS

1. GENERAL INFORMATION

1.1 G

ENERAL I

NSTRUCTIONS

1.2 O

VERALL V

IEW

2. INSTALLATION

2.1 R

EFERENCE STANDARDS

2.2 SITING THE APPLIANCE

2.3 OVERALL DIMENSIONS

2.4 CLEARANCES

2.5 MOUNTING THE APPLIANCE

2.6 ELECTRICAL CONNECTION

2.7 GAS CONNECTION

2.8 W

ATER CONNECTIONS

2.9 F

LUE CONNECTION

2.10 R

OOM THERMOSTAT CONNECTION

2.11 ELECTRICAL DIAGRAMS

2.12 G

AS AND WATER CIRCUITS

3. D.H.W. STORAGE CYLINDER

3.1 2

PORT AND 3 PORT VALVE INSTALLATIONS

3.2 DOMESTIC HOT WATER PRIORITY KIT

4. COMMISSIONING

4.1 I

NITIAL PREPARATION

4.2 C

ONTROL PANEL

4.3 R

EMOVING THE FRONT PANEL

4.4 I

NITIAL START UP

4.5 OPERATIONAL ADJUSTMENTS

4.6 COMBUSTION ANALYSIS

4.7 FUME DISCHARGE MONITORING

4.8 DRAINING THE SYSTEM

5. GAS ADJUSTMENTS

GAS ADJUSTMENT TABLE

5.1 CHANGING THE TYPE OF GAS

6. MAINTENANCE

7. TECHNICAL INFORMATION

This manual is an integral and essential part of the product. It should be kept
with the appliance so that it can be consulted by the user and our authorised
personnel.

Please carefully read the
instructions and notices about the
unit contained in this manual, as
they provide important information
regarding the safe installation, use
and maintenance of the product.

For operating instructions please
consult the separate User’s Manual.

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

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

This is an appliance for the production of central heating (C.H.).
This appliance must be used only for the purpose for which it is designed.

The manufacturer declines all liability for damage caused by improper or
negligent use.

No asbestos or other hazardous materials have been used in the fabrication
of this product.

Before connecting the appliance, check that the information shown on the
data plate and the table in section 7 comply with the electric, water and gas
mains of the property.You will find the data plate on the reverse of the control
panel.
The gas with which this appliance operates is also shown on the label at the
bottom of the boiler.

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

Do not place objects on the appliance.
Do not allow children or inexperienced persons to use the appliance without

supervision.
If you smell gas in the room, do not turn on light switches, use the

telephone or any other object which might cause sparks.
Open doors and windows immediately to ventilate the room.
Shut the gas mains tap (at or adjacent to the gas meter) or the valve of the
gas cylinder and call your Gas Supplier immediately.
If you are going away for a long period of time, remember to shut the mains
gas tap or the gas cylinder valve.

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

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

Check the following at least once a year:

1 - Check the seals for the water connections; replace any faulty seals.
2 - Check the gas seals;replace any faulty gas seals.
3 - Visual check of the entire unit.

1. GENERAL
INFORMATION

3

1.1 GENERAL INSTRUCTIONS

4

4 - Visual check of the combustion process or analysis of combustion by-

products (see section 4.5) and cleaning of the burner if needed.

5 - If called for by point. 3, dismantling and cleaning of the combustion

chamber.
6 - If called for by point. 4, dismantling and cleaning of the burner jets.
7 - Visual check of the primary heat exchanger:

- check for overheating in the blade assembly;

- clean the exhaust fan if needed.

8 - Adjustment of the flow rate of the gas:flow rate for lighting, partial load

and full load.
9 - Check of the heating safety systems:

- safety device for maximum temperature (overheat thermostat);

- safety device for maximum pressure (safety valve).

10- Check of the gas safety systems:

- safety device for lack of gas or flame ionisation (detection
electrode);

- safety device for gas cock.

11- Check of the electrical connection (make sure it complies with the

instructions in the manual).

12- General check of the combustion by-products of the

discharge/ventilation system.

13- Check of the general performance of the unit.

LEGEND:

1. Flue connector

2. Air intake for twin pipe flue systems

3. Fan

4. Combustion chamber hood

5. Main heat exchanger

6. Safety thermostat

7. Combustion chamber

8. Combustion chamber insulation panel

9. Detection electrode

10. Ignition electrodes

11. Burner

12. Regulation thermostat

13. Frost thermostat

14. Pump pressure switch

15. Safety valve (3 bar)

16. Automatic By-pass

17. Gas valve

18. Spark generator

19. Boiler drain valve

20. Circulation pump with automatic air release valve

21. Expansion vessel

22. Air pressure take-off point

23. Air pressure switch

24. Combustion analysis points

1.2 O

VERALL VIEW

FIG. 1.0

5

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

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

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

The installation of this appliance must be in accordance with the relevant
requirements of the current Gas Safety (installation & use) Regulations, the
Local Building Regulations, the current I.E.E. Wiring Regulations, the
byelaws of the local water authority, and in Scotland, in accordance with the
Building Standards (Scotland) Regulation and Health and Safety document
No.635 “Electricity at work regulations 1989”.
Installation should also comply with the following British Standard Codes of
Practice:

The appliance may be installed in any room or indoor area, although
particular attention is drawn to the requirements of the current I.E.E. Wir ing
Regulations, and in Scotland, the electrical provisions of the Building
Regulations applicable in Scotland, with respect to the installation of the
appliance in a room containing a bath or shower.

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

The location must permit adequate space for servicing and air circulation
around the appliance as indicated in paragraph 2.4.
The location must permit the provision of an adequate flue and termination.
For unusual locations special procedures may be necessary.
BS 6798-1987 gives detailed guidance on this aspect.
A compartment used to enclose the appliance must be designed specifically
for this purpose. No specific ventilation requirements are needed for the
installation within a cupboard.
This appliance is not suitable for outdoor installation.

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

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

2.1 REFERENCE STANDARDS

2. INSTALLATION

2.2 SITING THE APPLIANCE

BS 7593:1992 Treatment of water in domestic hot water central

heating systems

BS 5546:1990 Installation of hot water supplies for domestic

purposes
BS 5440-1:1990 Flues
BS 5440-2:1989 Air supply
BS 5449:1990 Forced circulation hot water systems
BS 6789:1987 Installation of gas fired hot water boilers of rated

input not exceeding 60kW
BS 6891:1989 Installation of low pressure gas pipe up to 28mm
BS 7671:1992 IEE wiring regulations
BS 4814:1990 Specification for expansion vessels
BS 5482:1994 Installation of LPG

For safety purposes, have a competent person carefully
check the electrical system in the property, as the
manufacturer will not be held liable for damage caused by
the failure to earth the appliance properly or by anomalies
in the supply of power. Make sure that the residential
electrical system is adequate for the maximum power
absorbed by the unit, which is indicated on the rating plate.
In addition, check that the section of cabling is appropriate
for the power absorbed by the boiler.

The boiler operates with alternating current, as indicated in
the technical information table in section 7, where the
maximum absorbed power is also indicated. Make sure
that the connections for the neutral and live wires
correspond to the indications in the diagram. The
appliance electrical connections are situated on the
reverse of the control panel under the inspection cover
(see the servicing manual for further information)

IMPORTANT!

In the event that the power supply cord must be changed,
replace it with one with the same specifications. Make the
connections to the terminal board located within the
control panel, as follows:

- The yellow-green wire should be connected to the
terminal marked with the “”symbol;

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

- The brown wire should be connected to the terminal

6

Fasten the boiler in place using the template and anchors
supplied with the unit. It is highly recommended that a
spirit level be used to position the boiler so that it is
perfectly level.
For additional information, please consult the instructions
contained in the connection kit and the flue kit.

2.6 ELECTRICAL CONNECTION

2.5 MOUNTING THE APPLIANCE

LEGEND:

A = Central Heating Flow (3/4”)
C = Gas Inlet (3/4”)
E = Central Heating Return (3/4”)
mm = Clearances

2.3 OVERALL DIMENSIONS

In order to allow for access to the interior of the boiler for
maintenance purposes, the boiler must be installed in
compliance with the minimum clearances indicated in F

IG. 2.1

2.4 CLEARANCES

F

IG. 2.1

F

IG. 2.2

132 132

C

400 mm

60 mm

450 mm

E

300 mm

N
L

E

VIEW OF THE BOILER CONNECTIONS

LEGEND:

A = Central Heating Flow
C = Gas Inlet
E = Central Heating Return
F = Safety Valve
G = Pump transportation screw

(remove before igniting the boiler)

H = Automatic By-pass pipe

CENTRAL HEATING

Detailed recommendations are given in BS 6798:1987 and BS 5449-1:1990,
the following notes are given for general guidance.

2.8 WATER CONNECTIONS

2.7 GAS CONNECTION

The local gas region contractor connects the gas meter to the service pipe.
If the gas supply for the boiler serves other appliances ensure that an
adequate supply is available both to the boiler and the other appliances
when they are in use at the same time.
Pipe work must be of an adequate size. Pipes of a smaller size than the
boiler inlet connection should not be used.

7

marked “L”.
Note:The diagrams f or the electrical system are indicated in section 2.12.

Warning,this appliance must be earthed.

External wiring to the appliance must be carried out by a competent person
and be in accordance with the current I.E.E. Regulations and applicable
local regulations. The microSYSTEM range of boilers are supplied for
connection to a 230 V

~

50 Hz supply.

The supply must be fused at 3 A.

The method of connection to the electricity supply must facilitate complete
electrical isolation of the appliance, by the use of a fused double pole
isolator having a contact separation of at least 3 mm in all poles or
alternatively, by means of a 3 A fused three pin plug and unswitched
shuttered socket outlet both complying with BS 1363.
The point of connection to the Electricity supply must be readily accessible
and adjacent to the appliance unless the appliance is installed in a bathroom
when this must be sited outside the bathroom (see section 2.2).

FIG. 2.3

F

IG. 2.4

F

A

D

B

C

E

SC004A

8

PIPE

WORK:

Copper tubing to BS EN 1057:1996 is recommended for water pipes.
Jointing should be either with capillary soldered or compression fittings.
Where possible pipes should have a gradient to ensure air is carried
naturally to air release points and water flows naturally to drain taps.
The appliance has a built-in automatic air release valve, however it should
be ensured as far as possible that the appliance heat exchanger is not a
natural collecting point for air.
Except where providing useful heat, pipes should be insulated to prevent
heat loss and avoid freezing.
Particular attention should be paid to pipes passing through ventilated
spaces in roofs and under floors.

B

Y-PASS

:

The appliance includes an automatic by-pass valve, which protects the main
heat exchanger in case of reduced or interrupted water circulation through
the heating system, due to the closing of thermostatic valves or radiator
valves within the system.

SYSTEM DESIGN:

This boiler is suitable only for sealed systems.

Drain Cocks:

These must be located in accessible positions to permit the draining of the
whole system and should be fitted at all low points.The taps must be at least
15mm nominal size and manufactured in accordance with BS 2870:1980.

S

AFETY VALVE DISCHARGE:

The discharge should terminate facing downward on the exterior of the
building in a position where discharging (possibly boiling water & steam) will
not create danger or nuisance, but in an easily visible position, and not
cause damage to electrical components and wiring.
The discharge must not be over an entrance or a window or any other type
of public access.

A

IR RELEASE

POINTS:

These must be fitted at all high points where air naturally collects and must
be sited to facilitate complete filling of the system.
The appliance has an integral sealed expansion vessel to accommodate the
increase of water volume when the system is heated.
It can accept up to 6 litre (1.3 gal) of expansion water. If the heating circuit
has an unusually high water content, calculate the total expansion and add
an additional sealed expansion vessel with adequate capacity. This should
be located on the return pipe work as close as possible to the pump inlet.

M

AINS WATER FEED - CENTRAL HEATING:

There must be no direct connection to the mains water supply even through
a non-return valve, without the approval of the Local Water Authority.

F

ILLING:

A temporary method for initially filling the system and replacing lost water
during servicing and initial filling (in accordance with current Water
Regulations), is provided as an integral part of the connection kit (see F

IG.

2.4).The flexible hose must be removed once the system has been filled.

RESIDUAL HEAD OF THE BOILER

Ø 60/100 mm

F

IG. 2.6

The boiler is designed to be connected to a coaxial flue discharge system.

9

2.9 FLUE CONNECTIONS

FLUE

SYSTEM

The provision for satisfactory flue ter mination must be made in accordance
with BS 5440-1.
The appliance must be installed so that the flue terminal is exposed to outside air.
The terminal must not discharge into another room or space such as an
outhouse or lean-to.
It is important that the position of the terminal allows a free passage of air
across it at all times.
The terminal should be located with due regard for the damage or
discolouration that might occur on buildings in the vicinity.
In cold or humid weather water vapour may condense on leaving the flue
terminal.
The effect of such “pluming”must be considered.
If the terminal is less than 2 metres above a balcony, above ground or above
a flat roof to which people have access, then a suitable terminal guard must
be fitted. When ordering a ter minal guard, quote the appliance model
number.
A suitable terminal guard is available from:

TOWER FLUE COMPONENTS
Morley Road
Tonbridge
Kent TN9 1RA

The minimum acceptable spacing from the terminal to obstructions and
ventilation openings are specified in F

IG. 2.5.

T

ERMINALPOSITION

mm

A - Directly below an openable window or other opening 300
B - Below gutters, soil pipes or drain pipes 75
C - Below eaves 200
D - Below balconies or car-port roof 200
E - From vertical drain pipes and soil pipes 75
F - From internal or external corners 300
G - Above ground or balcony level 300
H - From a surface facing a terminal 600

I - From a terminal facing a terminal 1200

J - From an opening in the car port

(e.g.door, window) into dwelling 1200
K - Vertically from a terminal in the same wall 1500
L - Horizontally from a terminal in the same wall 300

FIG. 2.5

HI

BC

F

D

J

A

E

F

G

K

L

G

Ø 80 mm

In addition, it is also possible to use a split (twin pipe)
system by fitting a special adaptor to the flue connector
and using the aperture for the air vent intake located on
the top part of the combustion chamber.
To utilise the air intake it is necessary to:

1. Remove the bottom of the air intake by cutting it with a
suitable knife (see F

IG. 2.7);

2. Insert the elbow into the air intake until it reaches the
lower end.(There is no need to use gaskets or sealing
compounds).

10

I

MPORTANT

!

For all flue systems, a restrictor
must always be inserted into the
boiler’s flue connector; the
restrictor must be Ø 46 or Ø 41 in
diameter depending on the length
of piping indicated inT

ABLE 2.1.

FIG 2.9 and FIG 2.10 illustrate some

of the various designs for coaxial or
twin pipe flue systems.
For further information on
discharge/ventilation accessories,
see the F

LUE PIPE ACCESSORIES

MANUAL.

COAXIAL SYSTEMS

F

IG. 2.7

F

IG. 2.8

F

IG. 2.9

L = Sum of the total length of exhaust + air intake piping.

11

Exhaust

Type

C12 (xx)
C32 (xx)
C42 (xx)

Restrictor

ø 46 mm

L min = 0.5 m

L max = 1 m

Maximum
Extension
Exhaust/Air

L = 4 m

Risk of Condensation Forming

Coaxial

Systems

ø 60/100

Piping not insulated

ø 46

restrictor NO restrictor

NONE NONE

Piping insulated

ø 46

restrictor NO restrictor

NONE NONE

Exhaust

Type

C12 (xx)
C32 (xx)
C42 (xx)

Restrictor

ø 41 mm

L min = 0.5 m

L max = 1 m

Maximum
Extension
Exhaust/Air

L = 4 m

Risk of Condensation Forming

Coaxial

Systems

ø 60/100

Piping not insulated

ø 41

restrictor NO restrictor

NONE NONE

Piping insulated

ø 41

restrictor NO restrictor

NONE NONE

TABLE 2.1

Exhaust

Type

C12 (xy)
C32 (xy)
C42 (xy)

C52 (xy)
C82 (xy)

Restrictor

ø 41 mm

L max = 38 m

L max = 34 m

Maximum
Extension
Exhaust/Air

62 m
62 m
62 m

54 m

Risk of Condensation Forming

Twin Pipe

Systems

ø 80/80

Piping not insulated

ø 41

restrictor NO restrictor

8 m 11 m

8 m 11 m

Piping insulated

ø 41

restrictor NO restrictor

19 m 31 m

19 m 31 m

21 RFFI

28 RFFI

Exhaust

Type

C12 (xy)
C32 (xy)
C42 (xy)

C52 (xy)
C82 (xy)

Restrictor

ø 46 mm

L max = 25 m

L max = 22 m

Maximum

Extension
Exhaust/Air

34 m
34 m
34 m

31 m

Risk of Condensation Forming

Twin Pipe

Systems

ø 80/80

Piping not insulated

ø 46

restrictor NO restrictor

3.0 m 4.5 m

3.3 m 4.8 m

Piping insulated

ø 46

restrictor NO restrictor

12.5 m 16.0 m

14.0 m 17.8 m

21 RFFI

28 RFFI

TWIN PIPE

SYSTEMS

FIG. 2.10

In calculating the lengths of the pipes, the
maximum length “L” must also take into
consideration the values for the
exhaust/air intake end terminals, as well
as 90° elbows for coaxial systems.
The C52 types must comply with the

following requirements:

1 - The exhaust/ air intake pipes must

have the same diameter of

ø 80 mm.

2 - If elbows are to be inserted into the

air intake and/or exhaust system, the
calculation of the overall length must
take into consideration the values for
each elbow, see the F

LUE PIPE

ACCESSORIES MANUAL.

3 - The exhaust pipe must protrude by at

least 0.5 m above the top of the roof
in the event that it is located on the
opposite side of the building to the
side with the air intake (this condition
is not obligatory when the air intake
and exhaust are located on the same
side of the building).

12

To connect a room thermostat and/or time clock, it is necessary to:

1. - Open the control panel as indicated in section 4.3;

2.- Remove screws “A”and remove the inspection cover from the reverse of the control
panel;

3. - For the room-thermostat connect the thermostat switching wires to the position 5 and
6 and remove the wire link (for three-wire thermostats connect the neutral to ter minal
N);

4. - For the time clock connect the clock switching wires to the positions 3 and 4 and
connect the clock motor electrical supply to the terminals marked L and N.

Note: A frost thermostat is built-in to the appliance.

For connection to control systems with zone valves for hot water cylinders
see section 3.

2.10 ROOM THERMOSTAT
CONNECTION

A

2.11 ELECTRICAL DIAGRAM

13

FIG. 2.12

LEGEND:

A - On/Off Switch
B - On/Off L.E.D.
C - Heating Switch
D - Heating L.E.D.
E - Reset Button
F - Ignition Failure (Lockout) L.E.D.

A01 - Pump Pressure Switch
A02 - Frost Thermostat
A03 - Modulator
A04 - Circulation Pump
A05 - Regulation Thermostat
A06 - External Control System
A07 - Time Clock Connector
A08 - External (Room) Thermostat
A09 - Air Pressure Switch
A10 - Fan

A11 - Overheat Thermostat
A12 - Spark Generator/Gas Valve Supply
A13 - Detection Electrode

Colours:
Wh -White
Bl -Blue
Gry -Grey
Brn -Brown
Blk -Black
Rd -Red
Grn/Yll-Yellow/Green

14

LEGEND:

1. Fan

2. Main heat exchanger

3. Overheat thermostat

4. Burner

5. Ignition electrodes

6. Detection electrode

7. Regulation thermostat

8. Frost thermostat

9. Gas valve

10. Pump pressure switch

11. Safety valve (3 bar)

12. Boiler drain valve

13. Automatic by-pass

14. Pressure gauge

15. Circulation pump with automatic
air release valve

16. Expansion vessel

17. Air pressure switch

A. Central Heating Flow
B. Inlet Gas
C. Central Heating Return

2.12 G

AS AND W

ATER CIRCUITS

F

IG. 2.14

FIG. 2.13

1

2
3

4
5

6
7

8
9

10

17

16

15
14

13

11

12

15

3. D.H.W. STORAGE
CYLINDER

The microSYSTEM can be connected to a storage cylinder (both open-vented and
unvented) for the production of domestic hot water (D.H.W.). Cylinders of different
capacities can be used depending on site requirements (see T

ABLE

3.1 for a

selection of ARISTON unvented cylinders).

F

IG. 3.2

3 port valve installation

F

IG. 3.1

2 port valve installation

3.1 2

PORT AND 3 PORT VALVE

INSTALLATIONS

Wiring to 2 port valve installation
using an external 2 channel
programmer
Type Danfoss FP715
Type Honeywell ST6400C

FIG. 3.3

16

TABLE 3.1

Wiring to 3 port valve installation
using an external 2 channel
programmer
Type Danfoss FP715
Type Honeywell ST6400C

FIG

. 3.4

NOTE: When using a 3 por t valve installation in conjunction with an unvented cylinder it

will be necessary to use a 2 por t valve on the cylinder flow connection in addition
to the 3- port valve to satisfy Building Regulations.

Technical Data Capacity Coil C.H.W. D.H.W. Max Heating Heat Ioss

Surface Flow/rate Flow/rate Output

MODEL It. m
Contract STI 125 Indirect 125 0.75 0.5 194 11.3 2

Comfort STI 125 Indirect 125 0.75 0.5 256 14.9 2.2
Contract STI 150 Indirect 150 0.93 1 353 20.5

Comfort STI 150 Indirect 150 0.93 0.5 256 14.9 2.4
Contract STI 210 indirect 200 0.93 1 353 20.5

Comfort STI 210 Indirect 200 0.93 0.5 256 14.9 2.9
Contract STI 300 Indirect 300 0.93 1 353 20.5

2

m3/h It/h kW kWh/24h

1 266 15.5
2 340 19.8

2 451 26.2

2 451 26.2

2 451 26.2

SB 125 Indirect 125 1 0.5 190 11 1.72

1 318 18.5
2 496 28.8

SB 150 Indirect 150 1 0.5 190 11 1.75

1 318 18.5
2 496 28.8

SB 200 Indirect 200 1.3 0.5 190 11 2.1

1 318 18.5
2 496 28.8

17

MTS (GB) Limited support the initiative.Within the information pack
you will find a copy of the logbook. It is important that this is
completed in the presence of your customer, they are shown how to use it,
and it is signed by them. Please instr uct your customer that they must have
their logbook with them whenever they contact a service engineer
or us.

Preliminary electrical system checks to ensure electrical safety must be
carried out by a competent person i.e. polarity, earth continuity, resistance to
earth and short circuit.

F

ILLING THE HEATING SYSTEM:

Remove the panels of the case and lower the control panel (see section

3.3 for further information).
Open the central heating flow and return cocks supplied with the
connection kit (there are two isolation points on the return connection).
Unscrew the cap on the automatic air release valve one full turn and leave
open permanently.
Close all air release valves on the central heating system.
Gradually open valve(s) at the filling point (filling-loop) connection to the
central heating system until water is heard to flow, do not open fully.
Open each air release tap starting with the lowest point and close it only
when clear water, free of air, is visible.

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

Refit the pump plug.
Continue filling the system until at least 1.5 bar registers on the pressure
gauge.
Inspect the system for water leaks and remedy any leaks discovered.

G

AS SUPPLY:

Inspect the entire installation including the gas meter, test for soundness
and purge the supply as described in BS 6891:1988.
Open the gas cock (supplied with the connection kit) to the appliance and
check the gas connections on the appliance for leaks.

4. COMMISSIONING

4.1 INITIAL PREPARA TION

Boiler microSYSTEM microSYSTEM

21 RFFI 28 RFFI

Cylinder

= Ideal

= Possible

The microSYSTEM is able to be connected to a specially designed
kit for the management of D.H.W.production.This kit gives prior ity to
production of D.H.W. unlike traditional systems where the boiler
power is split between C.H. and D.H.W. This generally enables a
smaller storage cylinder to be chosen as the boiler’s full output will be
channelled into the cylinder allowing for a quick heat-up.

The kit (ARISTON part number

706329) can be obtained from an

ARISTON supplier.
The kit consits of:

1) Electronic module able to plug into the boiler’s P.C.B;

2) 3-way priority valve with actuator for connection to the boiler’s
flow outlet;

3) A limit thermostat (80˚C) to check the water temperature of the
heating flow to the cylinder, to be installed within the boiler;

4) Pipes and accessories.

Contract STI 125 Indirect
Comfort STI 125 Indirect
Contract STI 150 Indirect
Comfort STI 150 Indirect
Contract STI 210 Indirect
Comfort STI 210 Indirect
Contract STI 300 Indirect
SB 125 Indirect
SB 150 Indirect
SB 200 Indirect

TABLE

3.2

3.2 DOMESTIC HOT WATER
PRIORITY KIT

In order to access the inside of the boiler, it is necessary to
unscrew the fastening screws “A” of the control panel
located on the lower part of the panel itself.
The control panel moves downward and when pulled
forward rotates on two lateral hinges.
The panel stays in a semi-horizontal position, which allows
access to the inner parts of the boiler.
In order to increase the manoeuvring space, it is possible
to raise the control panel and rotate it to a fully horizontal
position.

18

4.3 R

EMOVING THE

FRONT PANEL

1

2

3

A

L

EGEND:

A - On/Off button
B - On/Off L.E.D. green (frost protection active)
C - Central Heating button
D - Cental Heating active L.E.D. green
E - Ignition failure (lockout) and/or overheat reset button
F - Ignition failure (lockout) and/or overheat L.E.D. red
G -Central heating temperature adjustment
H - Energy Saving System (ESS)
I - Knock-out for time clock
J - Heating system pressure gauge

4.2 C

ONTROL P

ANEL

F

IG. 4.1

When the installation and filling are completed turn on the central heating
system (section 4.4) and run it until the temperature has reached the boiler
operating temperature. The system must then be immediately flushed
through.
The flushing procedure must be in line with BS 7593:1992 code of practice for
treatment of water in domestic hot water central heating systems.
During this operation, we highly recommend the use of a central heating
flushing detergent (Fernox Superfloc or equivalent), whose function is to
dissolve any foreign matter that may be in the system.

Substances different from these could create serious problems to the
pump or other components.

The use of an inhibitor in the system such as Fernox MB-1 or equivalent is
strongly recommended to prevent corrosion (sludge) damaging the boiler and
system.

Failure to carry out this procedure may invalidate the appliance
warranty.

19

The flue connector has two apertures, readings can be

taken for the temperature of the combustion by-products
and of the combustion air, as well as of the concentrations
of O

2

and CO2, etc. .

To access these intakes it is necessary to unscrew the front
screw and remove the metal plate with sealing gasket.
To achieve the best test conditions, turn the central heating
adjustment knob “G” to the “max” position and remove the
electrical connection to the heating sensor (see section 6.).
This will allow the appliance to operate at the maximum
heating power.

4.5 COMBUSTION ANALYSIS

4.4 INITIAL START-UP

THE CHECKS TO BE RUN BEFORE INITIAL START-UP ARE AS FOLLOWS:

1. Make sure that:

- the screw on the automatic air valve has been loosened when the
system is full;

- If the water pressure in the system is below 1.5 bar, bring it up to the
appropriate level;

-Ensure that the gas cock is closed;

- Make sure that the electrical connection has been made properly and
that the earth wire is connected to an efficient earthing system;

- Supply power to the boiler by pushing the On/Off button “A” (see

F

IG.4.1) - the L.E.D. “B” will illuminate. Then push the button “C” in for

central heating - the L.E.D. “D” will illuminate. This will star t the
circulation pump. After 7 seconds, the boiler will signal a shutdown due
to ignition failure.Leave the boiler as it is until all of the air has been bled
from the system.

-Loosen the cap on the head of the pump to eliminate any air pockets;

-Repeat the procedure for bleeding the radiators of air;

- Check the system pressure and, if it has dropped, open the filling loop
again to bring the pressure back up to 1.5 bar.

2. Make sure that all gate valves are open;

3. Turn on the gas cock and check the seals on the connections with an
approved soap solution and eliminate any leaks.

4. Press the reset button “E” for the lighting system; the spark will light the
main burner. If the burner does not light the first time, repeat the
procedure.

5. Check the minimum and maximum pressure values for the gas going to
the burner; adjust it if needed using the values indicated in the table in
section 5 (See the relative section for burner pressure adjustment within
the servicing manual).

B

4

5

To dismantle the front casing panel it is necessary to:
1 - Remove the two screws “B”;
2 - Move the front casing panel up and lift forward.

FIG. 4.2

The boiler is fitted with the following devices (see section 4.2 for references).

1 - IGNITION FAILURE

:

This indicates ignition failure when a flame is not detected within 7
seconds of starting an ignition sequence. The L.E.D. “F” will illuminate
to signal the shutdown status.
The system can be reset by pressing and releasing the button “E” after
checking to make sure that the gas cock is open.

2 - I

NSUFFICIENT SYSTEM PRESSURE:

In the event of insufficient water pressure in the heating system, a
safety device will shutdown the boiler. Check the system pressure on
the pressure gauge “J” and if it is less than 0.4 bar refill the system to

1.5 bar. Once the system pressure is at the correct level the boiler will
ignite automatically.

3 - OVERHEATING:

This control shuts off the boiler in the case where the primary circuit
reaches a temperature in excess of 105°C.
The red L.E.D. “F” will illuminate to signal this shutdown status.
The system can be reset by waiting a few minutes for the primary
exchanger to cool down and then by pressing and releasing the “E”
button.

4. ANTI-FROST DEVICE:
The boiler is equipped with a device that, in the event of the water
temperature going below 6°C, the burner ignites at the minimum power
until the boiler water reaches a temperature of 16°C.
This device operates only if the boiler is functioning perfectly and:

- the system pressure is sufficient;

- the boiler is powered electrically - L.E.D. “B” illuminated;

- the gas is turned on.

5 - EXHAUST DISCHARGE ANOMALY SHUTDOWN:

The boiler is fitted with safety devices, which in the event of defective
discharge of exhaust fumes, automatically interrupts the gas supply,
thereby shutting off the boiler.
The shutdown of the boiler is temporary and when the discharge state
of exhaust fumes has returned to normal, the boiler automatically turns
back on

20

4.7 BOILER S

AFETY SYSTEMS

The heating system must be emptied as follows:

- Turn off the boiler;

- Attach a hose pipe and open the drain valve;

- Empty the system at the lowest points (where present). When the heating
system is unused for an extended period of time, it is recommended that you
add antifreeze with an ethylene glycol base to the water in the
heating lines and radiators if the ambient temperature drops below 0°C during
the winter.
This makes repeated draining of the entire system unnecessary.

4.8 D

RAINING THE SYSTEM

In the boiler, it is possible to monitor the correct operation of
the flue exhaust/air intake, checking for a loss of general
pressure in the system. Through the use of a differential
manometer connected to the test points of the combustion
chamber, it is possible to detect the ∆P of operation of the air
pressure switch.
The value detected should not be less than 0.55 mbar under
conditions of maximum thermal power in order for the boiler
to function properly and without interruption.

4.6 FUME DISCHARGE
MONITORING

FIG. 4.3

21

The boiler can be converted to use either methane (natural) gas (G20)
or LPG (G30 - G31) by an Authorised Service Centre.

The operations that must be performed are the following:

1. Replace the jets on the main burner (see table in section 5);

2. Adjust the maximum and minimum thermal capacity values for the boiler
(see table in section 5);

3. Replace the gas rating plate;

4. Adjust the maximum thermal power setting;

5. Adjust the soft-light feature (open the cover of the regulation screw on the

gas valve (see F

IG. 5.1). Rotate clockwise from min. to max. as per

installation requirements).

5.1 C

HANGING THE

T

YPE OF GAS

The outlet pressure of the gas cock is obtained by completely loosening the
screw on the solenoid. The maximum pressure of the gas to the burner will
be equal to the nominal delivery pressure minus the head loss within the
gas valve.

[1 mbar = 10,197 mmc.a.]

5. GAS ADJUSTMENTS

Lower Wobbe Index (15°C;1013mbar) MJ/m3h
Nominal Delivery Pressure mbar
Minimum Delivery Pressure mbar

21 RFFI

Main Burner: n. 12 jets (ø)mm
Consumption (15°C; 1013mbar) m

3

/h
Consumption (15°C; 1013mbar) Kg/h
Gas Burner Pressure:
max - min mbar

28 RFFI

Main Burner: n. 14 jets (ø)
Consumption (15°C; 1013mbar) m

3

/h
Consumption (15°C; 1013mbar) Kg/h
Gas Burner Pressure:
max - min mbar

CATEGORY II2H3+ Methane Gas

G20

Liquid Butane Gas

G30

Liquid Propane Gas

G31

45.67
20
17

1.30

2.4 - 1.05

----

8.5 - 1.7

1.30

3.15 -1.26

----

11.0 - 1.6

80.58
29
20

0.77

----

1.78 - 0.78

27.5 - 6.2

0.77

----

1.78 - 0.78

27.7 - 4.6

80.58
37
25

0.77

----

1.76 - 0.77

37.4 - 8.0

0.77

----

1.76 - 0.77

35.5 - 6.0

VG002Ab

TABLE 5.1

F

IG. 5.1

22

It is recommended that the following inspections be carried out on the
boiler at least once a year:

1 - Check the seals for the water connections; replace any faulty seals.
2 - Check the gas seals;replace any faulty gas seals.
3 - Visual check of the entire unit.
4 - Visual check of the combustion process or analysis of combustion by-

products (see section 4.5) and cleaning of the burner if needed.

5 - If called for by point. 3, dismantling and cleaning of the combustion

chamber.
6 - If called for by point. 4, dismantling and cleaning of the burner jets.
7 - Visual check of the primary heat exchanger:

- check for overheating in the blade assembly;

- clean the exhaust fan if needed.

8 - Adjustment of the flow rate of the gas:flow rate for lighting, partial load

and full load.
9 - Check of the heating safety systems:

- safety device for maximum temperature (overheat thermostat);

- safety device for maximum pressure (safety valve).

10- Check of the gas safety systems:

- safety device for lack of gas or flame ionisation (detection
electrode);

- safety device for gas cock.

11- Check of the electrical connection (make sure it complies with the

instructions in the manual).

12- General check of the combustion by-products of the

discharge/ventilation system.

13- Check of the general performance of the unit.

6. MAINTENANCE

23

Manufacturer: Merloni TermoSanitari SpA - Italy
Commercial subsidiary: MTS (GB) LIMITED

MTS Building
Hughenden Avenue
High Wycombe
Bucks HP13 5FT

Telephone:[phone]
Fax:[phone]
Internet: http://www.mtsgb.ltd.uk
E-mail: [e-mail]

Technical Service Hot Line: [phone]

23 99 84 1549 000 - Stampa: bieffe RECANATI

CE Certification
Heat Input max/min kW
Heat Output max/min kW
Efficiency of Nominal Heat Input %
Efficiency at 30% of Nominal Heat Input %
Heat Loss to the Casing (∆T=50°C) %
Flue Heat Loss with Burner Operating %
Flue Heat Loss with Burner Off %
Maximum Discharge of Fumes (G20) Kg/h
Residual Discharge Head mbar
Consumption at Nominal Capacity(G20) m

3

/h

Gas Consumption after 10 Minutes* m

3

(15°C, 1013 mbar) (G30-G31) Kg/h
Temp .of exhaust fumes at nominal capacity °C
CO2 Content %

O2 Content %
CO Content ppm

Minimum Ambient Temperature °C
Head Loss on Water Side (max) (∆T=20°C) mbar
Residual Head of System bar
Heating Temperature max/min °C
Expansion V essel Capacity l
Expansion Vessel Pre-load Pressure bar
Maximum Water Content of System l
Maximum Heating Pressure bar
Nominal Pressure Natural Gas (G20) mbar

LPG (G30-G31) mbar
Electrical Supply V/Hz
Power Consumption W
Protection Grade of Electrical System IP
Internal Fuse Rating
Weight Kg

G.C. Number

28 RFFI

6. TECHNICAL INFORMATION

63AU4549

22.7/10.0

21.0/8.7

92.8

90.8

1.2

6.0

0.2

46.2

0.70

2.4

0.32/0.39

1.78/1.76

117.2

6.81
9

20
+5

200

0.25

82/42

6
1

130

3

20

30-37

230/50

155

X4D

FAST 2 AT

39

41-116-06

63AU4549

29.8/12.0

27.8/10.5

93.5

90.7

0.2

6.3

0.4
60

1.60

3.15

0.37

2.34/2.31

128.8

6.9

8.1
48

+5

200

0.25

82/42

6
1

130

3

20

30-37

230/50

155

X4D

FAST 2 AT

39

41-116-07

21 RFFI

*Calculated at 70% maximum output

Servicing
Instructions
Type C Boilers

G.C.N: 41-116-06

41-116-07

LEAVE THESE INSTRUCTIONS
WITH THE END-USER

Country of destination: GB

2

1. SERVICING INSTRUCTIONS

1.1 REPLACEMENT OF PARTS

1.2 TO GAIN GENERAL ACCESS

- Removing the front panel

- Removing the sealed chamber front cover

- Removing the side panels

1.3 A

CCESS TO THE COMBUSTION CHAMBER

- Removing the combustion cover

- Removing the burner and jets

- Removing the electrodes

- Removing the main heat exchanger

- Removing the air pressure switch

- Removing the fan

1.4 S

ERVICING AND

REMOVAL OF THE GAS VALVE

- Setting the gas pressures

- Removing the spark generator

- Removing the gas valve

1.5 A

CCESS TO THE WATER CIRCUIT

- Removing the pump pressure switch

- Removing the safety valve

- Removing the automatic air vent

- Removing the pump

- Removing the pressure gauge

- Removing the expansion vessel

- Removing the overheat thermostat

- Removing the frost thermostat

- Removing the regulation thermostat

1.6 A

CCESS TO THE CONTROL SYSTEM

- Checking the fuses

- Removing the P.C.B.s

2. FAULT FINDING

2.1 FAULT FINDING GUIDE (FLOW-CHARTS)

3. ELECTRICAL DIAGRAMS

4. SHORT SPARE PARTS LIST

TABLE OF CONTENTS

2. The control panel moves downward and when pulled forward,

rotates on two lateral hinges; the panel stays in a semi­horizontal position, which allows access to the inner parts of
the boiler (F

IG. 1.2);

3. In order to increase the manouvering space, it is possible to
raise the control panel and rotate it to a fully horizontal position
(F

IG. 1.3);

4. Remove the screws “B”from the front panel bottom lip
(F

IG. 1.4);

5. Lift the front panel up and forward from the raised screws at the
the top of the casing (F

IG. 1.5).

FIG. 1.4

B

FIG. 1.5

3

1. SERVICING INSTRUCTIONS

The life of individual components varies and they will need
servicing or replacing as and when faults develop.
The fault finding sequence chart in chapter 2 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.

1.1 R

EPLACEMENT OF PARTS

1.2 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.

1.2.1 Removing the front panel

1. Loosen the fastening screws “A”of the control panel located on

the lower part of the panel itself. (F

IG. 1.1);

A

FIG. 1.3

F

IG. 1.1

FIG. 1.2

To ensure efficient safe operation, it is recommended that the
boiler is 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 the Installation Manual
for further details).

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

4

1.2.2 Removing the sealed chamber front cover

1. Remove the screws “C”(FIG. 1.6);

2. Lift the sealed chamber front cover from the locating pins

(FIG. 1.7).

FIG. 1.6

C

C

FIG. 1.7

1.2.3 Removing the side panels

1. Remove the four screws “D” for each side panel (FIG.1.8);

2. Pull the panel away from the boiler at the base, then lift the

panel up and remove from the boiler.

D

D

D

FIG. 1.8

1.3.3 Removing the electrodes

Before carrying out this procedure, unscrew and slide the
burner forward (see previous section).

1. Remove rubber gasket “G” (F

IG. 1.12);

2. To remove the detection electrode disconnect the cable

at its connection point close to the P.C.B. (F

IG. 1.13);

FIG. 1.12

G

F

IG. 1.13

1.3.2 Removing the burner and jets

1. Remove the screws “F”from the burner (F

IG. 1.10);

2. Remove the burner (FIG. 1.11);

3. Disconnect the electrodes (see section 1.3.3);

4. Remove the jets using a No.7 socket spanner;

5. Replace in reverse order.

5

1.3.1 Removing the combustion cover

1. Remove the screws “E” (F

IG. 1.9);

2. Lift off the combustion cover.

1.3 ACCESS TO THE COMBUSTION CHAMBER

E

E

E

FIG. 1.9

FIG. 1.10

Fig. 1.11

F

F

6

3. Remove screw “H”(F

IG. 1.14);

4. Gently slide the electrode downward (FIG.1.15).

To replace, repeat the steps in reverse order, paying
particular attention to the following:
a -Centre the electrode in the positioning hole carefully,

otherwise the electrode may break;

b -Ensure that the left hand and right hand electrodes are

located the correct way round (facing each other), to
give the correct spark gap;

c -Check that the cables have been connected correctly;
d -Check that the rubber gasket cov ers the cable/ electrode

connection point completely.

F

IG. 1.14

FIG. 1.15

H

1. Drain the boiler of water;

2. Release the overheat thermostat sensor “I” (F

IG. 1.16);

3. Release the two connection nuts “J” connecting the
exchanger to the flow and return pipes (F

IG. 1.17);

4. Remove the heat exchanger by sliding forward (F

IG.

1.18).

1.3.4 Removing the main heat exchanger

FIG. 1.17

J

Fig. 1.16

I

FIG. 1.18

1. Disconnect electrical connections “N” and silicon pipe “O”
(F

IG.1.22);

2. Remove screw “P” and remove the fan collar clamp “Q”
(FIG

.1.23);

3. Remove screws “R” (F

IG.1.24);

4. Remove fan and mounting plate (FIG.1.25).

1.3.6 Removing the fan

1. Disconnect the electrical connections “K” and silicone

pipes “L” from their connection points (F

IG. 1.19);

2. Remove screws “M” on the top of the sealed chamber
(F

IG. 1.20);

3. Lift out the air pressure switch (F

IG. 1.21);

4. Unscrew to remove the switch from the plate.

FIG. 1.20

FIG. 1.19

7

1.3.5 Removing the air pressure switch

L

L

K

M

M

F

IG. 1.21

FIG. 1.24

R

R

F

IG. 1.23

P

Q

FIG. 1.22

N

O

F

IG. 1.25

8

1.4 SERVICING AND REMOVAL

OF THE GAS VALVE

1.4.1 Setting the gas pressures

1

2

3

4

A

B

C

F

G

D

Setting the minimum and the maximum power of the boiler

1. Check that the supply pressure to the gas valve is a minimum of 20 mbar
for natural gas.Turn off the gas supply at the isolation point under the
boiler

2. To do this, slacken the screw “A”.

Fit the pipe of the pressure gauge to the inlet pressure test point of the gas
valve “B”.

T urn on the gas suppl y at the isolation point under the boiler and with
the boiler running, read the inlet working pressure on the gauge.
When you have completed this operation, turn off the gas supply at the
isolation point under the boiler, remove the pressure gauge and tighten
the screw “A” securely into its housing to seal off the gas.T urn on the gas
supply at the isolation point under the boiler and test the screw for
gas escaping with an approved soap and water solution.

3. To check the pressure supplied by the gas valve to the burner, with the

boiler turned off, slacken the screw “C”.Fit the pipe of the pressure gauge
to the outlet pressure test point of the gas valve “D”.
Disconnect the compensation pipe “E”either from the gas valve or from
the sealed chamber.

4. Push the On/Off button to “ON”position -green light- and push the Heating
button to “ON” position -green light­Turn on the boiler by setting the external controls.
Adjust the 10mm nut “F” on the modureg to set the gas pressure Tur n the
nut clockwise to increase and anti clockwise to decrease the pressure until
the required pressure is achieved (see T

ABLE A page 9)

5. To set the minimum power, disconnect the supply cable from the modureg

and adjust screw “G” whilst holding nut “F”.
Turn the screw clockwise to increase the pressure and anticlockwise to
decrease the pressure until the required pressure is achieved (see T

ABLE

A page 9)

6. When you have completed the above operations, turn off the external

controls, re-connect the supply terminal to the modureg on the gas valve
and replace the cap on the screw of the modureg.

Setting pressure for soft ignition.

The soft light pressure is factory set.
If the ignition is not regular (e.g: not complete bur ner ignition or ignition
noise) check the soft light regulator position.
The soft light pressure will need adjusting as follows:

- Turn off electrical supply;

- referring to diagram 5, open the dust cap of the soft light regulator, by

unscrewing in clockwise direction the white screw;

- turn the adjustment screw one step in the direction max to increase or in

the direction min to decrease the soft light pressure;

- after each adjustment of the regulator, turn on the electrical supply and

recheck burner ignition (wait 20 seconds between each cycle to allow
the gas valves’internal servo system to reset). When the required level
is achieved, close the dust cap.

7. Remove the pipe from the pressure gauge and connect screw “C” to the
pressure outlet in order to seal off the gas.

8. Carefully check the pressure outlets for gas leaks (valve inlet and outlet).

IMPORTANT!

Whenever you disassemble
and reassemble the gas
connections, always check for
leaks using an approved soap
and water solution.

VG002Ac

VG002Ad

VG002Af

VG002Ae

E

VG002Ab

5

9

Regulating the heating power for

natural gas (G20)

Regulating the heating power for

butane gas (G30)

Regulating the heating power for

propane gas (G31)

TABLE A

21 kW

28 kW

21 kW

28 kW

21 kW

28 kW

CG004A

CG005A

CG006A

TB005A

GAS BURNER PRESSURE

GAS BURNER PRESSURE

OPERATING POWER

OPERATING POWER

GAS BURNER PRESSURE

21 RFFI

28 RFFI

2.4

1.05
20

8.5 3.3

1.7

3.15

1.26

11

1.6
14 x 1.30

84.7

37.0

0.7

111.1

44.5

4.3

0.6

OPERATING POWER

1.78 1.7662.8 62.1

0.78

27.5

6.2

2.34

0.94

27.7

4.6

27.5 27.2

10.7

2.4

82.6

33.2

10.8

1.8

14 x 0.77

0.77

37.4

8.0

2.31

0.93

35.5

6.0

14.6

3.1

81.5

32.8

13.8

2.3

14 x 0.77

10

F

IG. 1.28

FIG. 1.29

FIG. 1.30

U

V

V

1.4.3 Removing the gas valve

Impor

tant! Before removing the gas valve, ensure the gas

supply is turned off.

1. Disconnect all the cables from the solenoid and
modureg;

2. Remove the spark generator (see previous section);

3. Release the top nut “U” (F

IG. 1.28);

4. Remove the screws “V” from the bottom of the gas valve
pipe (FIG. 1.29);

5. Remove the gas valve (F

IG. 1.30).

1.4.2 Removing the spark generator

1. Disconnect ignition leads “S” by pulling upward

(F

IG. 1.26);

2. Remove the screw “T”(FIG. 1.27);

3. Remove the spark generator by pulling forward from the

gas valve.

FIG. 1.27

FIG. 1.26

S

T

11

1. 5. 2 Removing the safety valve

1. Loosen nut “Y” (F

IG. 1.33);

2. Disconnect the discharge pipe work from below the
boiler;

3. Unscrew and remove the valve.

1.5.3 Removing the automatic air vent

1. Unscrew valve top “Z” (FIG. 1.34);

2. Remove valve complete with float (F

IG 1.35).

FIG. 1.33

FIG. 1.34

Y

Z

FIG. 1.35

Impor

tant!

Before any component is removed, the boiler

must be drained of all water.

1.5 ACCESS TO THE WATER CIRCUIT

FIG. 1.31

W

FIG. 1.32

X

1.5.1 Removing the pump pressure switch

1. Remove the cable of the pump pressure switch “W”

(Fig. 1.31);

2. Unscrew the pump pressure switch by using a spanner
on the nut “X”(F

IG. 1.32);

3. Remove the pump pressure switch.

12

1.5.4 Removing the pump

1. Remove the U-clips “ A1” and “B1” (F

IG. 1.36);

2. Remove the retaining clip “C1” (FIG. 1.37);

3. Release the nut “D1” (FIG. 1.38);

4. Remove the pipe “E1” (F

IG. 1.39);

5. Remove the screw “F1” (FIG. 1.40);

6. Remove the pump (FIG. 1.41).

FIG.1.37

FIG.1.36

F

IG.1.38

C1

A1

B1

FIG

. 1.39

FIG. 1.40

FIG. 1.41

D1

E1

F1

13

1.5.6 Removing the expansion vessel

1. Release nuts “H1” and remove the gas pipe (F

IG. 1.44);

2. Release nut “I1” (FIG. 1.45);

3. Remove lock-nut “J1” (FIG. 1.46);

4. Remove the expansion vessel (F

IG. 1.47).

1.5.5 Removing the pressure gauge

1. Remove the U-clip “G1” and remove the pressure gauge

coupling (F

IG. 1.42);

2. Push the pressure gauge through the control panel from

the rear (F

IG. 1.43).

FIG. 1.42

FIG. 1.44

G1

F

IG. 1.43

H1

I1

F

IG. 1.45

F

IG. 1.46

FIG. 1.47

H1

J1

14

1.5.6 Removing the overheat thermostat

1. Disconnect the overheat thermostat electrical

connections “K1” (F

IG. 1.48);

2. Then remove the thermostat from its mounting by

releasing the securing clip (F

IG. 1.49).

1.5.7 Removing the frost thermostat

1. Disconnect the frost thermostat electrical connection

“L1” (F

IG. 1.50);

2. Then remove the thermostat from its mounting by

releasing the securing clip (F

IG. 1.51).

1.5.8 Removing the regulation thermostat

1. Remove the regulation thermostat sensor from its

mounting by releasing the securing clip “M1” (F

IG. 1.52);

2. Separate the facia panel from the rear of the control
panel (see section 1.6.2);

3. Remove the electrical connections “N1 from the
regulation thermostat (F

IG. 1.53);

4. Pull the regulation knob from the spindle of the
thermostat;

5. Remove the thermostat from the control panel facia by
unscrewing the mounting screws.

FIG. 1.48

FIG. 1.49

K1

F

IG. 1.52

FIG. 1.51

M1

L1

FIG. 1.50

FIG. 1.53

N1

15

1.6.2 Removing the P.C.B.s

1. Isolate electricity;

2. Remove the screws “O1” (F

IG. 1.56);

3. Separate the facia panel from the rear of the control
panel;

4. Unplug all electrical connections from the P.C.B. and
remove the screws “P1” and remove the P.C.B. (F

IG.

1.57).

F

IG. 1.56

O1

O1

O1

O1

O1

P1

P1

P1

P1

O1

F

IG. 1.57

1.6.1 Checking the fuse

1. Remove the inspection cover on the reverse of the

control panel (F

IG. 1.54);

2. Remove the fuse mounted on the reverse of the
inspection cover (F

IG. 1.55).

1.6 ACCESS TO THE CONTROL SYSTEM

F

IG. 1.54

FIG. 1.55

Important! Isolate the electrical supply to the boiler before
accessing the control panel.

16

B063

2. FAULT FINDING

P

RELIMINARY CHECKS

MAKE SURE THAT

:

IS

THE SUPPLY

L.E.D. ILLUMINATED?

IS

THE L.E.D.

ILLUMINATED?

NO

NO

NO

YES

NO

1 - CHECK THE FUSES
2 - CHECK THERE IS POWER

SUPPLIED TO THE

P.C.B.S

3 - CHECK/REPLACE THE P.C.B.

(CT1)

1 - C

HECK THE INTEGRITY

OF THE

L.E.D.

2-C

HECK/REPLACE THE P.C.B.

(CT1)

P

RESS THE

ON

/

OFF BUTTON

P

RESS THE CENTRAL

HEATING BUTTON

FROST

PROTECTION IS

ACTIVATED <5¡C. IS THE

FROSTPROTECTION

REQUESTED?

IS

TIME CLOCK/

PROGRAMMER

AND/OR ROOM

CALLING FOR

HEATING?

THE

THERMOSTAT

A

1 - THERE IS SUFFICIENT

WATER IN THE SYSTEM

2 - THE GAS IS TURNED ON
3 - THE ELECTRICAL SUPPLY

IS TURNED ON

YES

YES

YES

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

2.1 FAULT FINDING GUIDE
(FLOW-CHARTS)

FC002Aa

17

B063

A

FC002Ab

IS THE PUMP

RUNNING?

YES

IS THE FAN

RUNNING?

NO

POWER TO

THE PUMP?

YES

1 - CHECK THE OPERATION

OF THE PUMP

2 - RELEASE/REPLACE THE

PUMP

NO

NO

1 - CHECK THE PUMP CABLE
2-CHECK/REPLACE P.C.B.

(CT1)

3 - CHECK THE SYSTEM

PRESSURE GAUGE IS AT

1.5 BAR

YES

B

BOILER

SHUTDOWN?

NO

INTERNAL

P.C.B. PROTECTION

ACTIVATED?

NO

POWER TO

THE FAN?

YES

1 - REPLACE THE FAN

YES

YES

NO

1 - RESET THE BOILER

1 - CHECK/REPLACE AIR

PRESSURE SWITCH
AND CABLE

2 - CHECK IF THE RESET

IS JAMMED

3 - CHECK/REPLACE

DETECTION ELECTRODE

1 - CHECK/REPLACE FAN

CONNECTION CABLE

2 - CHECK/REPLACE P .C.B.
3 - C

HECK/REPLACE AIR

PRESSURE SWITCH

18

B063

B

NOISEY OPERATION

DECREASE/INCREASE OF HEATING CIRCUIT

PRESSURE

REPEATED SHUTDOWNS

REPEATED OPERATION OF SAFETY THERMOSTAT

INSUFFICIENT RADIATOR TEMPERATURE

- MAIN HEAT EXCHANGER FAULTY OR BLOCKED

WITH LIME-SCALE DEPOSITS

- LOW HEATING SYSTEM WATER PRESSURE

- CHECK GAS PRESSURES

- CHECK HEATING THERMOSTAT

- CHECK FAN

- CHECK PUMP

- CHECK FOR LEAKS ON THE HEATING CIRCUIT

- FAULTY FILLING LOOP

- FAULTY EXPANSION VESSEL

- F

AULTY DETECTION ELECTRODES

- C

HECK GAS PRESSURES

- C

HECK FLAME DETECTION ELECTRICAL CIRCUIT

- F

AULTY HEATING THERMOSTAT

- F

AULTY OVERHEAT THERMOSTAT

- P

RESENCE OF AIR IN THE HEATING CIRCUIT

- C

HECK BURNER PRESSURES

- C

HECK EXCHANGER FLUEWAY

- CHECK HEATING THERMOSTAT

- CHECK BY-PASS

- CHECK GAS PRESSURE

FC002Ac

IS THE

AIR PRESSURE SWITCH

ACTIVATED?

NO

CHECK

P ON PRESSURE

∆

TEST POINT

∆

P mbar0.5

1 - CHECK AIR PRESSURE

SWITCH CABLE

2 - CHECK/REPLACE AIR

PRESSURE SWITCH

3 - CHECK/REPLACE P.C.B.

(CBM2)

YES

DOES

THE SPARK

SEQUENCE

START?

YES

IS THE BURNER

ALIGHT?

YES

HAS THE

BOILER SAFETY

SHUTDOWN BEEN

ACTIVATED?

NO

NO

NO

YES

PRESS THE RESET

BOILER

WORKING?

YES

∆

≤

P 0.5 mbar

HECK/REPLACE IGNITION

1 - C

ELECTRODES

2 - CHECK THE CABLES
3 - CHECK SPARK GENERATOR
4 - CHECK IGNITION ELECTRODE

CABLES

1 - CHECK POWER SUPPLY TO

THE GAS VALVE

2 - CHECK OPERATION OF THE

GAS VALVE

3 - REPLACE THE GAS VALVE

BUTTON

1 - CHECK IF THE FLAME

NO

2 - CHECK THE SOFT-LIGHT
3 - CHECK/REPLACE DETECTION

4-C

STRIKES THE DETECTION
ELECTRODE

GAS PRESSURE
ELECTRODE

1 - CHECK EXHAUST DISCHARGE
2 - CHECK VENTURI AND TUBES
3 - CHECK THE FAN EFFICIENCY
4 - REPLACE FAN

5-CHECK/REPLACE P.C.B. (CBM2)

HECK/REPLACE P.C.B. (CBM2)

4 - C

HECK/REPLACE

P.C.B. (CBM2)

IS

THERE STILL

A PROBLEM?

NO

NORMAL

OPERATION

NORMAL

OPERATION

NOISEY OPERATION

1

FAULT LIST

YES

DECREASE/INCREASE OF HEATING CIRCUIT

2

PRESSURE

REPEATED SHUTDOWNS

3

4

REPEATED OPERATION OF SAFETY THERMOSTAT

5

INSUFFICIENT RADIATOR TEMPERATURE

POSSIBLE CAUSES

- MAIN HEAT EXCHANGER FAULTY OR BLOCKED

- LOW HEATING SYSTEM WATER PRESSURE

- CHECK GAS PRESSURES

- CHECK HEATING THERMOSTAT

- CHECK FAN

- CHECK PUMP

- CHECK FOR LEAKS ON THE HEATING CIRCUIT

- FAULTY FILLING LOOP

- FAULTY EXPANSION VESSEL

- F

- C

- C

- F

- F

- P

- C

- C

- CHECK HEATING THERMOSTAT

- CHECK BY-PASS

- CHECK GAS PRESSURE

-SCALE DEPOSITS

WITH LIME

AULTY DETECTION ELECTRODES
HECK GAS PRESSURES
HECK FLAME DETECTION ELECTRICAL CIRCUIT

AULTY HEATING THERMOSTAT
AULTY OVERHEAT THERMOSTAT
RESENCE OF AIR IN THE HEATING CIRCUIT
HECK BURNER PRESSURES
HECK EXCHANGER FLUEWAY

19

B063

3. ELECTRICAL
DIAGRAMS

SE011A

L

EGEND:

A - On/Off Switch
B - On/Off L.E.D.
C - Heating Switch
D - Heating L.E.D.
E - Reset Button
F - Ignition Failure (Lockout) L.E.D.

A01 - Pump Pressure Switch
A02 - Frost Thermostat
A03 - Modulator
A04 - Circulation Pump
A05 - Regulation Thermostat

A06 - External Control System
A07 - Time Clock Connector
A08 - External (Room) Thermostat
A09 - Air Pressure Switch
A10 - Fan
A11 - Overheat Thermostat
A12 - Spark Generator/Gas Valve Supply
A13 - Detection Electrode

Colours:
Wh -White
Bl -Blue
Gry -Grey
Brn -Brown
Blk -Black
Rd -Red
Grn/Yll-Yellow/Green

20

B063

SF008A

21

B063

4. SHORT SPARE
PARTS LIST

microSYSTEM 21/28 RFFI

ES002A

11 1165676869 64

71 70

66

63 61

62

4

10
11

12

13
14

15
16

17

13

1

2

3

72

12

73

11

79

64

75

11

74

80

81
82

76

77

78

83

84

13

85

11

64

86

107

103

88
87

106

105

104

102

101

13

89

5
6

7
8
9

19

80

99

60

59

31

98

64

100

90

97

96
95

94

92

304

301 302 303

47

93

91

58

57

56
55

54

53
52
51

50

49
48

47
46

45

18

19
20

351

352

21 2322

353

33

354

1324 30 31 32 37 38

29

28272625

38 3839

44

42

4036 3733 34 35

41 43

21/28 RFFI

22

B063

998616
573521
573520
570760
998612
573528
998447
569390
998627
999542
574279
999475
998809
999476
998424
998836
999091
999577
999499
999245
998517
998484
571651
997182
998943
998489
999894
998620
998893
999538
998618
998669
998887
998939
998433
998434
999501
950030
998623
998622
998624
998644
998643
998738
998961
999207
998716
998717

Key

no.

G.C. part

no.

ARISTON

Part No.

Description

2

5
13
16
18
19
21
22
23
25
26
27
29
30
31

33AB

33CD

45
48
49
55

60AB

60CD

73
75

76AB

76CD

78AB

78CD

81

83A
83B
83C

83D
87AC
87BD

93
95
97
98

99
351
352
353

354AB

354CD

361
362

164 282
164 225

164 229
164 261

E03 818

E24 076
E24 075

Expansion vessel
Gasket 3/8"
Gasket 3/4"
Thermostat (frost)
Flow group
Gasket 1/2"
Safety valve (1/4" 3 bar)
Gasket 1/4"
Pump pressure switch
Spark Generator
Gasket
Gas valve
Auto air vent
Return group
O-ring
Pump
Pump
Thermostat (regulation)
P.C.B. (CBM2 AT-FFI2X)
Pressure gauge
Gasket
Air pressure switch
Air pressure switch
Gasket
O-ring (2.65 x 10.27)
Fan
Fan
Main exchanger
Main exchanger
Thermostat (overheat)
Burner 12 ramp (natural gas)
Burner 12 ramp (LPG)
Burner 14 ramp (natural gas)
Burner 14 ramp (LPG)
Burner jet (natural gas 1.30)
Burner jet (LPG 0.77)
P.C.B. (CT1)
Fast fuse 2AT
Electrode (ignition R.H.)
Electrode (ignition L.H.)
Detection electrode
O-ring (A.A.V.)
Auto air vent
Gasket (pump head)
Pump head
Pump head
Burner jet 1.30 full kit (natural gas)
Burner jet 0.77 full kit (LPG)

1
1

1
1
1

1
1
1
1
1
1
1
1
1
1
1
1
1

1
1

1
1

1
1
1

1
1
1
1
1
1
1
1
1
1
1
1

microSYSTEM 21/28 RFFI

23

B063

NOTES

23 99 84 1550 000 -

Manufacturer: Merloni TermoSanitari SpA - Italy
Commercial subsidiary: MTS (GB) LIMITED

MTS Building
Hughenden Avenue
High Wycombe
Bucks HP13 5FT

Telephone: [phone]
Fax:[phone]
Internet: http://www.mtsgb.ltd.uk
E-mail: [e-mail]

Technical Service Hot Line: [phone]