25
ADJUSTING THE FUNCTIONAL PARAMETERS
Low load
The low load function prevents burner ignition and shut off in
the case of a low heat demand. The conditions for low load op-
eration activation is controlled in every Slave card that sends the
function activation request to the Master.
During normal operation, the setpoint of the active circuit (high
or low temperature circuit setpoint or DHW setpoint) is sent to
the Slave cards and is controlled by the temperature of the heat-
ing element by every Slave card:
if the modular system temperature > Setpoint – 8°C or
if the modular system temperature > 85°C - 8°C
consent for starting the burner is not given.
If the Slave board acquires a modular system temperature great-
er than 85°C for 3 times with the burner ignited, the heating el-
ement is turned off and the ignition procedure is started again.
Emergency function
In the case of a Master card fault, there are two methods for
manually controlling the Slave cards:
− With eBUS and with the manifold sensor
Disconnect the power supply from the system, disconnect
the BUS. Set the address 000000 on all slave cards (J10
and J17 OFF). Connect a power supply between 21 and 28
Vac to the BUS.
If the manifold temperature < Temp.Emergency (Par.40;
preset 70°C; can be set between 10 and 80°C) all the
burners will operate at maximum power.
If the manifold temperature > Temp.Eme 5°C all
burners are off.
− With PC
Disconnect the system power supply, disconnect the BUS
and connect the PC interface. The burner power can be
sent to the Slave card directly with the PC.
9
In the case of error, contact Technical Assistance Service.
R
.
Heat demand management for the high temperature circuit
with analogue input (Par. 14=2 or 3)
The room thermostat for the high temperature circuit is ignored
in the case of heat demand and the input signal is used for cal-
culating the system setpoint temperature or power.
The analogue input (see terminals 13-14 on the wiring diagram
on page 35) is only for the Master card and can also be used for
the low temperature circuit (Par.22). The analogue input cannot
be used for both circuits.
ANALOGUE POWER INPUT, Par. 14=2 (Par. 22=2 for low tempera-
ture circuits)
The following rules apply to high temperature (low temperature)
circuit demand:
0-2Vdc:
no demand by the high temperature (low temperature)
circuit
2-9Vdc:
the heat demand is converted into a power demand
for each Slave. A 2V input corresponds to minimum power, 9V to
maximum power (Par.15). The power is calculated linearly be-
tween 2V and 9V. Hysteresis for the end of demand is 0.2V and
therefore demand is present above 2V and stops below 1.8V.esta
è presente sopra i 2V e cessa sotto 1,8V.
Voltage (Volts)
0
1
2
3
4
5
6
7
8
9
10
Power (kW)
50
100
150
200
250
Figure 23
The burner ignited when:
− Delivery temp.
≤
Setpoint_ch_high (Par.1) – Ch_high_hist_
on (Par.19)
− (Delivery temp.
≤
Setpoint_ch_low (Par.3) – Ch_low_hist_
on (Par.26)
−
The burner shuts off when:
− Delivery temp. > Setpoint_ch_high (Par.1) + Ch_high_hist_
off (Par.20)
− (Delivery temp. > Setpoint_ch_low (Par.3) + Ch_low_hist_
off (Par.27)
ANALOGUE TEMPERATURE INPUT, Par. 14=3 (Par. 22=3 for low tem-
perature circuits)
The following rules apply to high temperature (low temperature)
circuit demand:
0-2Vdc:
no demand by the high temperature (low temperature)
circuit
2-9Vdc:
the heat demand is converted into a power demand
for each Slave, using the algorithm PID_CH_high (PID_CH_
low). 2V corresponds to a setpoint equal to T_Ch_high_
foot, Par. 18 (T_Ch_low_foot, Par. 24), 9V to a setpoint
equal to SetPoint_Ch_high, Par.1 (SetPoint_Ch_low, Par.3).
The setpoint is calculated linearly between 2V and 9V.
Hysteresis for the end of demand is 0.2V and therefore
demand is present above 2V and stops below 1.8V.
Voltage (V)
0
1
2
3
4
5
6
7
8
9
Setpoint
10
20
30
40
50
60
70
80
90
10
Figure 24
The burner ignited when:
− Delivery temp.
≤
Setpoint_ch_high (Par.1) – Ch_high_hist_
on (Par.19)
− (Delivery temp.
≤
Setpoint_ch_low (Par.3) – Ch_low_hist_
on (Par.26)
The burner shuts off when:
