Ariston 28 MFFI - Manual (Page 6)

If instead the display shows one of the shutdown situations indicated by the following
letters and figures, A64, A97, A98, A99, try resetting the boiler by pressing the reset
button “D”. If the boiler shuts off again, contact one of our Authorised Service Centres.
A NTI - 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 temperature 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 perfectly and
- the system pressure is sufficient;
- the boiler is powered electrically;
- gas is being distributed.
4. MAINTENANCE Schedule an annual maintenance check-up for the boiler with a CORGI registered
Service Engineer.
Correct maintenance always results in savings in the cost of running the system.
5. CHANGE OF GAS TYPE Our boilers are designed to function either with Natural Gas (methane) or L.P.G. gas. If
you need to changeover from one gas to the other, one of our Authorised Service Centres
should be contacted.
6. MECHANICAL TIME CLOCK
N OTE : 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 thermostat (if installed) or the heating thermostat require heat (heating
function on).
EXAMPLE
To set the heating of your home in the time interval from 7.00 am to 9.30 am and from
7.00 pm to 10.00 pm every day:
- 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 9.30 am, and then all riders between these two;
- repeat this for 7.00 pm and 10.00 pm.
UT011Ap
Other heating intervals may be set in the same way.
The timer has approximately 150 hours of battery back up for power failure.
The clock is provided with a selector switch with three positions (see figure):
UT014A
UT014A
UT014A
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 thermostat (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.
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