Immergas 3.018921, Instruction And Warning Booklet

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3.8  AUTOMATIC SLOW IGNITION 

FUNCTION WITH TIMED RAMP 

DELIVERY.

In the ignition phase the P.C.B. carries out an 

increasing gas delivery ramp (with pressure 

values that depend on the type of gas selected) 

with preset duration. This prevents every 

calibration or precision adjustment of the boiler 

ignition phase in any conditions of use.

3.9  "CHIMNEY SWEEP FUNCTION"

When activated, this function forces the boiler 

at max. output for 15 minutes.

In this state all adjustments are excluded and only 

the safety thermostat and the limit thermostat 

remain active. To activate the chimney sweep 

function it is necessary to position the main 

switch on Reset for a time between 8 and 15 

seconds without DHW or CH requests. Its 

activation is signalled by the simultaneous 

flashing of the LEDs (2) and (3). This function 

allows the technician to check the combustion 

parameters. After the checks, deactivate the 

function switching the boiler off and then on 

again.

3.10 PUMP ANTI-BLOCK FUNCTION.

The boiler has a function that starts the pump at 

least once every 24 hours for the duration of 30 

seconds in order to reduce the risk of the pump 

becoming blocked due to prolonged inactivity.

3.11 THREE-WAY ANTI-BLOCK 

FUNCTION.

Both in “domestic hot water” and in “domestic 

hot water-central heating” phase the boiler is 

equipped with a function that starts the three-

way motorised group 24 hours after it was last 

in operation, running it for a full cycle so as to 

reduce the risk of the three-way group becoming 

blocked due to prolonged inactivity.

3.12 RADIATORS ANTI-FREEZE 

FUNCTION.

If the system return water is below 4°C, the boiler 

starts up until reaching 42°C.

3.13 P.C.B. PERIODICAL SELF-CHECK.

During functioning in heating mode or with 

boiler in standby, the function activates every 18 

hours after the last boiler check/power supply. In 

case of functioning in domestic hot water mode 

the self-check starts within 10 minutes after the 

end of the withdrawing in progress, for duration 

of approx. 10 seconds.

N.B.:

 during self-check, the boiler remains off, 

including signalling.

3.14 YEARLY APPLIANCE CHECK AND 

MAINTENANCE.

The following checks and maintenance should 

be performed at least once a year.

- Clean the flue side of the heat exchanger.
- Clean the main burner.
-  Visually check the draught-breaker/anti-wind 

device for deterioration or corrosion.

- Check ignition and operation.
- Check correct calibration of the burner in 

domestic hot water and central heating phases.

- Check the operation of the appliance control 

and adjustment devices and in particular: 

  -  intervention of the main electrical switch on 

the boiler;

  - system control thermostat intervention;
  - domestic hot water control thermostat 

intervention.

- Check that the internal system is properly 

sealed according to specifications.

- Make sure the ionisation flame control gas 

supply failure safety device is working. It must 

start-up in less than 10 seconds.

- Visually check for water leaks or oxidation 

from/on connections.

-  Visually check that the water safety drain valves 

is not blocked.

- Check, after discharging the system pressure 

and bringing it to zero (read on boiler pressure 

gauge), that the expansion vessel charge is at 1.0 

bar.

- Check that the system static pressure (with 

system cold and after refilling the system by 

means of the filling valve) is between 1 and 1.2 

bar. 

- Visually check that the safety and control 

devices have not been tampered with and/or 

shorted, in particular:

  - over-temperature safety thermostat; 
  - system pressure switch;
  - flue thermostat.
- Check the condition and integrity of the 

electrical system and in particular:

  - electrical power cables must be inside the 

fairleads;

  - there must be no traces of blackening or 

burning.