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2)
set-point temperature (T
I
): this is the temperature set up on the
chronothermostat by the user, i.e. the required room
temperature;
3)
thermal differential (d): the modulating power, on a percentage
basis, is calculated according to the T
A
room temperature and
the T
I
set-point temperature. In case the room temperature is
lower than or equal to (T
I
- d), the percentage of modulating
power is at its highest level (100%); in case the room
temperature is higher than or equal to T
I
, the percentage of
modulating power is zero (0%: heat demand OFF), as the
required temperature has already been reached/exceeded; in
case the room temperature is comprised between (T
I
- d) and
T
I
, the percentage of modulating power is calculated by means
of a specific formula which will be described later on;
4)
thermal hysteresis (i): any T
A
room temperature values next to
the T
I
set-point may generate a repeated sudden switch-on /
switch-off of the heat demand. The thermal hysteresis
parameter helps avoiding such unwanted occurrences: during
the T
A
increasing stage the burner switches off as soon as the
T
I
threshold is reached, while during the T
A
decreasing phase
the heat demand is activated again if the room temperature
drops below (T
I
- i);
5)
outside temperature (t
e
): if the system is equipped with an
outside temperature probe, this temperature value will influence
the final power percentage as shown in Fig. 5;
6) design min. outside temperature (t
ep
): if the system is equipped
with an outside temperature probe, the design min.
temperature, i.e. the min. outside temperature that can be
reached by the system, will influence the final power
percentage as shown in Fig. 5.
The type of temperature adjustment performed by the control unit
can be LOCAL, REMOTE or assisted by an outside temperature
probe: in the first case, an SA room temperature probe is used and
the temperature adjustment is totally managed by the control unit,
while the remote adjuster is only used to establish the set-point
temperature; in the second case, no SA room temperature probe is
connected and the temperature adjustment is totally controlled by
the chronothermostat type ENCRONO GA1; in the third case, an
outside temperature probe is used and the final power percentage
is influenced by this parameter.
The calculated/acquired modulation percentage affects the power
supplied to the EF fume extractor, to the FAN hot air blower and to
the current modulator(s) according to the min. and max. pre-set
values.
Fig. 5 shows the three types of temperature adjustment available in
the system.
Outside temp.
probe (SE)
available?
Temperature adjustment by an OUTSIDE
PROBE
The system type TC340 directly manages the
temperature adjustment by calculating the required
percentage of modulation power through the
following parameters:
-
the T
I
; set-point temperature;
-
the T
A
room temperature (measured by
an SA room temperature probe or a
chronothermostat type GA1);
-
the T
ep
design min. temperature (for further
details refer to the data sheets of the BRAHMA
remote adjuster type ENCRONO GA1);
-
the T
e
outside temperature.
Room temp.
probe
(SA) available?
LOCAL temperature adjustment
The system type TC340 directly manages the
temperature adjustment by calculating the required
percentage of modulation power through the
following parameters:
-
the T
I
; set-point temperature;
-
the T
A
room temperature (measured by
an SA room temperature probe);
-
the d
L
local thermal differential (adjustable
through serial interface);
-
the i
L
local thermal hysteresis (adjustable
through serial interface).
REMOTE temperature adjustment
The chronothermostat directly provides the system
type TC340 with the percentage of power to use for
the temperature adjustment, by using:
-
the T
I
set-point temperature;
-
the T
AR
room temperature directly measured;
-
the d
R
thermal differential set up through
BRAHMA ENCRONO GA1 (remote thermal
differential);
-
the i
R
thermal hysteresis set up through
BRAHMA ENCRONO GA1 (remote thermal
hysteresis).
Fig. 5 – Types of temperature adjustment
In case an outside temperature probe is used, the TC340 device
calculates the percentage of modulation power through the
following formula:
T
-
T
)
T
-
T
(
F
+
)
T
-
T
(
*
100
=
P
ep
I
A
I
C
e
I
%
NOTE: the F
C
coefficient (corrective factor) is a parameter which varies according to the
T
e
outside temperature and is directly calculated by the TC340 device.
To better understand the behaviour of the system type TC340 in
running status in case no outside temperature probe is connected,
please refer to the diagram of figure 6, assuming a set-point
temperature of 22°C, a thermal hysteresis of 0.4°C (in this way, in
case of room temperature decrease, the system re-ignition
threshold will be 21.6°C) and a thermal differentia l of 2.0°C (in this
way, the modulation area starting threshold will be 20°C). The
thermal hysteresis and differential can be of local or remote type
YES
NO
YES
NO
