Table of Contents
Advertisement
NIGHT-TIME REDUCTION
the night-time reduction function is active when all the
following conditions exist contemporaneously:
- parameter C806 = 1 (function enable);
- there is an outdoor temperature sensor and it is work-
ing;
- no device is connected to the OpenTherm input;
- no device is connected to the 0-10Vdc input.
In this case, also outside the time band programming
the closure of the Ambient Thermostat input generates a
heat request. The set point is the one calculated from the
weather compensation curves, reduced by a value given
by the parameter H507.
WEATHER COMPENSATION
The weather compensation is activated if there is an
outdoor temperature probe; The delivery temperature set
point is calculated using the weather compensation curve
that is established in the following way:
The slop of the compensation curve is set using the
parameter H532, so as to adjust the delivery temperature
of the water in accordance with the outdoor temperature,
When the compensation curve is active the parameter
T_SET (H505) is added to the value calculated by the
weather curve, so as to be able to shift the curve verti-
cally.
Outdoor temperature Setpoint temperature
TE >= 0
TE < 0
TV = delivery setpoint temperature
TRw = ambient temperature setpoint
TE = outdoor temperature
s = weather curve slope
Korr = (20 – TRw) * (20 - TE) * s/120
The outdoor temperature used for the weather com-
pensation is that currently measured every 10 minutes
and averaged over a period of 10 hours. Based on the
temperature parameter for the passage from summer/
winter and winter/summer, the change of season occurs
automatically.
In this way the delivery setpoint temperature to be main-
tained is established.
SEQUENCE CONTROL STRATEGIES
The sequence control commands the flame control send-
ing a target output signal and operating with two different
strategies that can be selected using the parameter
C604:
20
GENERAL
TV = TRw + s(TRw - 8/9 TE) + Korr
TV = TRw + s(TRw - 0.7 TE) + Korr
Strategy A
= Simultaneous Ignition/Switching off of all
modules (C604=0)
Strategy B
= independent
Switching off (C604=1).
The control for managing the output at the flame controls
can be adjusted regarding frequency updating with the
parameter C607 (establishes every how many seconds
the command for varying the request output is sent) and
how much with parameter C608 (establishes the max-
imum output variation that can be adjusted with each
update).
Strategy A
The burners, in this sequence management mode, oper-
ate at the same time like a single burner and the same
command signal is passed to all of them simultaneously.
They switch on and modulate together to seek to main-
tain the collector temperature at the same value that has
been set.
The switching off and switching on of the burners take
place according to the logic presented in the diagram
below operating on the base of an offset value on the
delivery setpoint which is set at parameter H606.
Delivery temperature
Temperatura mandata
sequencer °C
sequenziatore °C
T_SPEG = T_SET + D_SPEG
T_SET
Each module, therefore, takes care of its own safety
working on the module probe in the following way:
if the water temperature exceeds the maximum value set
in parameter C517, the effective output of the module is
reduced with respect to the value requested by the boil-
er. If there is no temperature reduction and this exceeds
by a value equal to DELTA OFF the limit set above, the
flame control switches off the burner. The burner is then
restarted when the water temperature of the module has
dropped by a value equal to DELTA ON below the value
expressed in parameter C517.
Strategy B
In this control strategy the burners are ignited one after
the other.
In the event of a heat request, the first module (leader
module) comes on and the second module comes on
when the output percentage requested by the regulator
of the leader module reaches the value of the parame-
Simultaneous
Ignition/
T_ACC = T_SET + D_ACC
Time
Tempo
Hide quick links:
Advertisement
Table of Contents
