Ariston 24 MFFI ユーザーズマニュアル

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. 

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. 

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. 

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. 

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.