26
ADJUSTING THE FUNCTIONAL PARAMETERS
− 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)
MIX VALVE MANAGEMENT
The mix valve is controlled by the parameters:
− Mix_valve_step_open_time: Par.28 preset to 5s
− Mix_valve_step_close_time: Par.29 preset to 7s
− Mix_valve_interval_time: Par.30 preset to 5s
− Mix_valve_p_hyst: Par.31 preset to 2°C
− Mix_valve_still_hyst: Par.32 preset to 2°C
−
Before opening or closing, the valve waits the period of time set
in Par.30.
Opens if:
T_mandata_bassa < Setpoint_low – Par32
Closes if:
T_mandata_bassa > Setpoi Par32
Within the interval, the valve remains in its current position.
If:
T_mandata_bassa < Setpoint_low – Par31
opens for a period of time equal to half the value set in Par. 28
If:
T_mandata_bassa > Setpoi Par31
closes for a period of time equal to half the value set in Par. 29.
Time(s)
Collector temperature
Figure 25
Temperature Flow Mix (° C)
20
30
40
50
60
Closing - Opening Valve (s
)
-4
-3
-2
-1
0
1
3
25
35
45
55
2
Open
Close
default
Par. 31 = 10
Figure 26
Safety functions of the Slave cards
If the delivery temperature > 90°C for 5s, the slave card is blocked
(no. 46).
If the return temperature > 80°C for 5s, the slave card is blocked
(no. 47).
If the flue gas temperature > 80°C for 5s, the slave card is blocked
(no. 48) and the fan operates for 10 minutes at maximum.
The Slave card is able to protect the primary exchanger from the
hazards of low water circulation both using a flow switch as
well as checking the difference between the delivery and return
temperatures.
Checking
∆
T uses the parameter
∆
T_max (preset to 35°C) and lim-
its the burner power as follows:
− if
∆
T_max -5°C >
∆
T >
∆
T_max –10°C = burner modulated
− if
∆
T_max >
∆
T >
∆
T_max –5°C = burner at minimum
− if
∆
_T >
∆
_T_max = burner off.
Furthermore, the presence of a sensor stops the exchanger if the
pressure inside the combustion unit goes below 0.5 bar.
