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SIT 845 GAS Valve
Key:
1 - Coil
2 - Minimum power
adjustment screw
3 - Maximum power
adjustment nut
4
4 - Gas valve outlet pres-
sure point
1
5 - Gas valve inlet pres-
sure point
6 - Protection hood
5
3-3
Heating output.
e boiler also has electronic
modulation that adapts the boiler potentiality
to the e ective heating demand of the house.
en the boiler works normally in a variable
gas pressure eld between the minimum heating
output and the maximum heating output
depending on the system's heating load.
N.B.: the boiler is produced and calibrated in
the central heating phase at nominal output.
Approximately 10 minutes are needed to reach
the nominal heat output changeable using
parameter (P6).
N.B.: the selection of the "Minimum heating
output" and "Maximum heating output"
parameters, in presence of a heating request,
allows boiler ignition and power supply of the
modulator with current equal to the value of the
respective set value.
Minimum CH output
Range of values which can
Parameter
be set
from 0 % Imax. to 63 % Imax.
Maximum CH output
Range of values which can
Parameter
be set
from 0 % Imax. to 99 % Imax.
(Standard setting)
Timer setting. The boiler has an electronic
timing device that prevents the burner from
igniting too o en in the heating phase.
is supplied as per standard with a timer adjusted
at 3 minutes.
Central heating ignitions timer
Range of values which can
Parameter
be set
from 1 to 10
3 = 3 minutes (Standard set-
ting)
1 = 30 seconds
Central heating ramp timing. The boiler
performs an ignition ramp of about 10 minutes
to arrive from minimum power to nominal
heating power.
Central heating ramp timer
Range of values which can
be set
from 1 to 10
10 = 10 minutes (Standard
setting)
1 = 30 seconds
Boiler type. By selecting this parameter one
can select the operation of the type of boiler
being used: instantaneous monothermal boiler
(0), bithermal boiler (1) or monothermal with
boiler (2).
N.B.: according to the selection, also move the
jumper (JP1) on the circuit board (Fig. 3-2):
position 1-2 for bithermal boiler or position 2-3
for monothermal boiler.
Attention: the boiler is already adjusted when
P5
it leaves the factory, therefore this function is
only to be used in the event the circuit board
is replaced.
Boiler type
Range of values which can
be set
P6
from 0 to 2
0 = monothermal boiler (in-
stantaneous)
1 = bithermal boiler
e boiler
2 = monothermal boiler (with
boiler)
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)
P7
with preset duration. This prevents every
calibration or precision adjustment of the boiler
ignition phase in any conditions of use.
17
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 temperature safety thermostat and the
limit thermostat remain active. To activate the
chimney sweep function, press the Reset key
for at least 10 seconds. Its activation is indicated
by the flashing symbols (8 and 11 Fig. 2-1).
3
is function allows the technician to check
the combustion parameters. A er the checks
disable the function, switching the boiler o and
2
then on again or simply by pressing the button
(2 Fig. 2-1).
6
3.10 HEATING TIMER.
e boiler has an electronic timing device that
prevents the burner from igniting too o en in
the heating phase.
standard with a timer adjusted at 3 minutes. To
adjust the timer values, follow instructions for
parameter settings by selecting parameter (P7)
and set it with one of the values indicated on the
relative table.
3.11 PUMP ANTI BLOCK FUNCTION.
In the "summer" functioning mode (
boiler has a function that starts the pump at least
once every 24 hours for 30 seconds in order to
reduce the risk of the pump becoming blocked
Parameter
due to prolonged inactivity.
In the "winter" functioning mode (
has a function that makes the pump start at least
P8
once every 3 hours for 30 seconds.
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 a er the last boiler check/power supply. In
case of functioning in domestic hot water mode
the self-check starts within 10 minutes a er the
end of the withdrawing in progress, for duration
of approx. 10 seconds.
N.B.: during self-check, the boiler remains o ,
including signalling.
Parameter
P9
e boiler is supplied as per
) the
) the boiler
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