Ariston ACO 35 MFFI User manual

End User
Manual
ACO 35 MFFI COMBI
Country of destination: GB/IE

2
IMPORTANT!
Please read this manual carefully.
For additional information, please consult the “Installation and Servicing
Instructions.”
Make sure to keep the manuals provided with the appliance so that they
can be used by the end-user, installer or our authorised engineer.
Every attempt has been made to avoid errors of any kind in this manual,
the Management
invites customers to inform of any inaccuracies which they may find.
This will help to improve our service.
1. GENERAL INFORMATION page. 3
2. CONTROL PANEL page. 4
3. OPERATING INSTRUCTIONS page. 5
4. USEFUL INFORMATION page. 8
5. MECHANICAL TIME CLOCK page. 9
6. DIGITAL PROGRAMMER page. 10
TABLE OF CONTENTS
Dear Customer,
Thank you for choosing an ARISTON boiler.
Weguarantee that your boiler is a reliable and
technically sound product.
This manual provides detailed instructions and
recommendations for proper installation,
use and maintenance.
Remember to keep this manual in a safe place
for future reference i.e. by the gas meter.
Your local MTS Servicing Centre is at your
complete disposal for all requirements.
GUARANTEE
The guarantee on this appliance is
valid for 60 months from the first
day of installation,
subject to an annual service
carried out by a qualified
service engineer.
Repairs to the electric, water or
gas circuits may only be carried
out by your local authorised
MTS Servicing Centre.

3
1.GENERAL INFORMATION MTS (GB) Limited support the initiative. Your installer
will give you, and show you how to use, a Log Book which will give
you important information about your boiler, and heating system.
Please have this Log Book to hand whenever you contact a serv-
ice engineer or us.
All CORGI Registered Installers carry a CORGI ID card, and
have a registration number. Both should be recorded in your
boiler Log Book. You can check your installer is CORGI reg-
istered by calling CORGI direct on :- [phone].
The ACO MFFI range of boilers are combined appliances for the
production of Central Heating (C.H.) and Domestic Hot Water
(D.H.W.).
This appliance must be used only for the purpose for which it is
designed.
The manufacturer declines all liability for damage caused by
improper or negligent use.
Do not allow children or inexperienced persons to use the appli-
ance without supervision.
If you smell gas in the room, do not turn on light switches, use
the telephone or any other object which might cause sparks.
Open doors and windows immediately to ventilate the room.
Shut the gas mains tap (on the gas meter) or the valve of the gas
cylinder and call your Gas Supplier immediately.
If you are going away for a long period of time, remember to shut
the mains gas tap or the gas cylinder valve.
Before any intervention within the boiler it is first necessary
to isolate the electrical power supply by turning the external
switch to “OFF”.

4
2. CONTROL PANEL
Fig. 3.6
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 autho-
rised engineer.
Button Description
ON/OFF Switch
“COMFORT” Function Push-button
Reset Button/
Flue Test**/ scroll through Functions Menu
Menu Switch
Programming “+” key
Programming “-” key
Description
AGreen LED
(illuminated = burner on)
BTime clock
CSelector knob for Summer/Winter
Central Heating Temperature Adjustment Knob
DControl Panel Cover
EDomestic Hot Water Temperature Adjustment Knob
FHeating System Pressure Gauge
G“COMFORT” Function L.E.D
HRed LED
(illuminated = boiler lockout)
IMulti-function Display
35 MFFI

5
CAUTION!!
In the United Kingdom installation, start-up, adjustments
and maintenance must be performed by a CORGI registered
installer in accordance with the installation standards cur-
rently in effect, as well as with any and all local health and
safety standards i.e. CORGI.
Inthe 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”, and the current Building Regulations,
reference should also be made to the current ETCI rules for
electrical installation.
Improper installation may cause damage or injury to individuals,
animals and personal property, for which the manufacturer will
not be held liable.
To ensure efficient and safe operation it is recommended that the
boiler is serviced annually by a competent person.
If it is known or suspected that a fault exists on the appliance, it
must not be used until the fault has been corrected by a compe-
tent person.
Helpful Suggestions
To get the most out of your boiler, we have provided you with some use-
ful advice on proper use and maintenance:
-Periodically check the system pressure using the pressure gauge “F”
and make sure that the pressure is between 1.0 and 1.5 bar when the
system is off and cool. If the pressure is below the minimum recom-
mended value, the pressure must be brought into the acceptable
range. To refill the system, connect the flexible hose to the cold water
inlet and central heating flow, open the two black handles connected
to the silver flexible hose, once the pressure gauge “F” reads 1.5 bar
close the valves again and disconnect the flexible hose.
If the pressure level drops on a frequent basis, it is likely that there is
awater leak in the system. If this is the case, your installer must
inspect the system.
-The outer panels of the boiler's case must only be cleaned with a
damp cloth, do not use abrasive cleaners. The control panel can be
wiped with either a damp or dry cloth. Spray polishes must not be
used on the control panel surface or knobs. Care must be taken in
preventing any liquid entering the appliance.
-If the water is exceptionally hard, install a water softener so that the
efficiency of the boiler remains the same over time, as this will con-
sume less gas.
-To improve comfort levels and take full advantage of the heat pro-
duced by the boiler,it is necessary that an external thermostat and an
outdoor sensor be installed.
-When the boiler is not in use for prolonged periods shut it down by
pushing the button to the offposition and close the gas and
water isolation valves.
(Important!) This will disable the anti-frost device (see page 9) - if the
period of disuse is very cold it will also be necessary to drain the heat-
ing system of water.
If you wish to leave the anti-frost device active, it is necessary to leave
the boiler on: this will not safeguard from possible interventions which
may impair this function.
-It is good practice to clean and service the appliance and Central
Heating System every year.
Call a CORGI registered gas installer.
F
3. OPERATING INSTRUCTIONS
O

6
Adjusting the heating
It is possible to set the temperature of the Central Heating system
by adjusting the knob “C”.By positioning the indicator some-
where between 1 and 6, a temperature may be obtained which
varies from approximately 38˚C to about 82˚C.
The water temperature in the primary circuit is shown on the dis-
play.
External (room) thermostat control
If an external (room) thermostat is installed, it is recommended
that the temperature of the Central Heating system be set by
means of the knob “C”,leaving it at max in order to obtain the
best performance from the boiler and to allow the regulation of the
room temperature to function efficiently.
Setting the hot water for domestic use
Both in the winter and summer mode, the temperature of the
Domestic Hot Water may be adjusted by using knob “E”.A deliv-
ery temperature for the water may be chosen in a range from 36˚C
to about 56˚C, depending on the flow rate of the water and the
position of the knob between the min. and max. settings.
To increase water temperature, turn knob “E” to max. and reduce
the water flow rate at the tap.
The water temperature in the primary circuit is shown on the
display.
C
C
E
MNStart-up Procedure
Before starting the boiler, check the following:
-The water pressure on the pressure gauge “F” isbetween 1 and 1.5
bar;
-That the external gas cock “M” and “N” and the inlet for domestic
water are open.
These models are equipped with electronic ignition (there is no pilot
light).
To switch the boiler on, push the button. Turn the knob “C” to
the summer “ ” or winter position; a centralised electronic con-
trol unit will automatically light the main burner when needed without
any intervention from the outside (green LED “A” will illuminate when
the burner is on).
If the burner does not light within the pre-set safety time limit, the dis-
play will show an error code and the red LED “H” will illuminate.
To reset the ignition system, the reset button must be pressed.
Should the system fail to light a second time, check to make sure that
the gas cock is open. If the problem persists, contact one of our
Authorised Service Centres.
Winter and Summer Operating Modes
In the “winter”operating mode, the boiler will produce both
Central Heating and Domestic Hot Water. In the “summer”oper-
ating mode, the boiler will produce only Domestic Hot Water.
Using the knob on the control panel, the user can select “winter”
or “summer” operating mode. Keeping the knob “C” at the “ ”
position selects the “summer” operating mode. “Winter” operating
mode may be selected by positioning the knob “C” between the
min. and max. settings.
summer winter
CC
H
A

7
G
C
Comfort Function
The supply of water for domestic use can become more conven-
ient by means of the “COMFORT” function, which maintains the
secondary exchanger at a preset temperature when the boiler is
not running; thereby allowing a quicker delivery of domestic water
when required. This function is activated by pressing
the button on the control panel. When the function is on, a
yellow L.E.D. “G” onthe control panel will illuminate.
Note: If the “COMFORT” function is on during the pump overrun
period, it will be temporarily deactivated. The yellow L.E.D. “G”
will remain on to indicate that the boiler will resume the “COM-
FORT” mode once the pump overrun period is complete.
Periodic operation of the appliance will occur regardless of
demand on the boiler. This function is normal operation
Turning Off the Heating
Installation without an external thermostat:
To turn off the heating, turn the selector knob “C” to “ ”.The
boiler will still provide domestic hot water.
Installation with an external thermostat:
To turn off the heating, turn the selector knob “C” to “ ”.The
boiler will still provide hot water for domestic use. With an exter-
nal room thermostat, turn the dial of the thermostat down to the
frost setting.
Turning off the boiler
To turn the boiler off, push the button ; the display will go
off.
Display: Viewing Normal Functions
When the system is operating, i.e. while the boiler is fulfiling its normal
functions, the left-hand display will show a letter indicating the fol-
lowing functions:
0
0No Request for Heat (Stand By)
C
CCentral Heating
c
cPump Overrun for Heating
d
dWater for Domestic Use
h
hPump Overrun for Water for Domestic Use
The right-hand display (two-digit) shows:
- in heating mode: temperature of heating system flow;
- in domestic hot water mode: temperature of the DHW leaving
the boiler
LEFT RIGHT

8
Boiler Shutdown
The boiler is equipped with safety devices which intervene in
certain situations to shutdown the boiler. Some of these situa-
tions are signalled by the boiler and can be corrected by the
user.
Shutdown Due to Ignition Failure
This anomaly is indicated by “A01” on the display. To reset the
boiler, press and then release the reset button .
At this point, the electronic ignition system will attempt to light the
burner again.
Should the boiler fail to ignite a second time, check that the
external gas cock is open. If the problem persists, contact an
Authorised Service Centre.
Shutdown Due to Overheating
This anomaly is indicated by “A 03” on the display. The boiler has
shutdown because the safety thermostat detected that the boiler
temperature has exceeded the maximum limit.
To reset this state, wait until the boiler has cooled and press
the button.
If the safety thermostat operates on a frequent basis, contact an
Authorised Service Centre.
Shutdown Due to Insufficient Water Circulation
This anomaly is indicated by “A 02” on the display.
One of the possible causes of this shutdown situation could be the
lack of water in the boiler or water circulation failure in the primary
heating circuit.
Check the system pressure on the pressure gauge “F” and, if it is
less than 0.5 bar, try bringing the system pressure up to a mean
value of 1.0 bar by opening the water inlet valve (see page 4 for
further instructions). Then reset by pressing the button.
Other Shutdown Situations
Should a shutdown situation indicated on the left display by the
letter E (E 04, E 05, E06, .....etc. ), contact an Authorised Service
Centre.
If instead the display shows one of the shutdown situations indi-
cated by the following letters and figures, A 07, A 33, A 97, A 98,
A 99, try resetting the boiler by pressing the reset button . If
the boiler shuts off again, contact an Authorised Service Centre.
Anti-frost device
The boiler is fitted with a device which, in the event that the water
temperature falls below 8
˚C the pump activates and runs until a
temperature of 18˚C is attained. In the event that the water tem-
perature falls below
3 ˚C, the diverter valve switches to Domestic
Hot Water and the burner fires and runs on minimum power until
a temperature of 33˚C is attained.
This device is only activated when the boiler is operating perfect-
ly and:
- the system pressure is sufficient;
- the boiler is powered electrically;
- gas is being distributed.
IMPORTANT!
DUE TO THE HIGH EFFICIENCY NATURE OF THE APPLIANCE, TJE FLUE WILL
PRODUCE PLUMES OF CONDENSED WATER VAPOUR, THIS IS NORMAL OPER-
ATION FOR A CONDENSING BOILER.
4. USEFUL INFORMATION

9
5.TIME CLOCK
NOTE: the time clock is for central heating control only.
The time clock is provided with 96 switches, called riders, each of
which covers a time interval of 15 minutes (four per hour).
When a rider is switched from the inside (off setting) to the outside
of the clock border (on setting), the circuit is closed (switch on) for
a period of 15 minutes and then the boiler starts if the room ther-
mostat (if installed) or the heating thermostat require heat (heat-
ing function on).
EXAMPLE
To set the heating of your home in the time interval from 7.00
am to 8.00 am and from 7.00 pm to 10.00 pm every day (see
diagram):
-rotate the outer ring of the clock in a clockwise direction until the
correct time of day (24h) lines up with the arrow on the clock (at
approx. 2 o’clock position);
-under no circumstances should the minute hand be moved
manually;
- make sure all the switches, i.e. the riders, are placed on the
inside of the clock border;
- pull outward the riders for 7.00 am and 8.00 am, and then all rid-
ers between these two;
- repeat this for 7.00 pm and 10.00 pm.
Other heating intervals may be set in the same way.
The clock is provided with a selector switch with three positions
(see figure):
1.Position “I” CONSTANT: in this position, the clock circuit is
always closed (switch on), therefore the boiler will constantly be
on and will only shut off upon the request of the room thermo-
stat (if installed) or the heating thermostat;
2.
Position “O” HEATING OFF: in this position, the clock circuit is
always open (switch off) and the boiler will therefore never ignite
for heating;
3. “Central” Position PROGRAMMING ACTIVE: in this position,
the programming set by the user is active.

10
P
r
o
g
.
Day
Manual switch
Summer and
winter time
setting
Reset
Enter
weekday/s
Enter
the hours
Week-
days
flash
Enter
minutes
Enter
switching
times
Imput
time
Status
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.
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 carried out by using the “Day” key.
When the day seIection is left bIank, the programmed switch-
ing 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
6. DIGITAL PROGRAMMER
Selection of single days: 1 = Mon. .............. 2 =Tues.
Save the switching time with the “ ” key.
The time switch enters the automatic operating mode and dis-
plays 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 com-
pleted, and you return the time clock to the current time dis-
play 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 switch-
ing instructions in the memory in real time, it will correctly acti-
vate 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 loca-
tions 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 automati-
cally 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.

11
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 sec-
onds. 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 dis-
play switches into the AM/PM mode.

Commercial subsidiaries: MTS (GB) Limited MTS Heating Limited
MTS Building Damastown Industrial Park
Hughenden Avenue Damastown Avenue
High Wycombe Mulhuddart
Bucks HP13 5FT Dublin 15
Telephone: [phone] Telephone: [phone]
Fax: [phone] Fax: [phone]
Internet: www.mtsgroup.com/uk Internet: www.mtsgroup.com/ie
E-mail: [email protected] E-mail: [email protected]
Technical Advice: 0870 241 8180 Technical Advice: [phone]
Customer Service: 0870 600 9888 Customer Service: [phone]
Manufacturer: Merloni TermoSanitari SpA - Italy
420010001101