The grey
side of the
ECL Card
Ex
tended ser
vic
e
The grey
side of the
ECL Card
Ex
tended ser
vic
e
32f
Service parameter(s) 31-34
Service parameter(s) 35
32g
31-34
Return temperature limitation
The return temperature limitation is based on the outdoor
temperature. Typically in district heating systems a
higher return temperature is accepted at a decrease in
outdoor temperature. The relationship between the return
temperature limits and outdoor temperature is set in two
coordinates.
The upper limit coordinate is set in lines 31 and 32 and the
lower limit coordinate in lines 33 and 34.
80
60
40
20
-15
0
+15
T
return
Line 34
Line 32
Lower limit
Upper limit
Line 33
Line 31
T
out
31 Return temperature limitation - upper limit (X-axis)
Circuit
Setting range
Factory setting
I / II
-30 ... 15 °C
15 / 15 °C
Set the outdoor temperature value (see drawing).
Set the outdoor temperature value (X coordinate)
for the upper limit.
(The corresponding Y coordinate is set in line 32).
32 Return temperature limitation - upper limit (Y-axis)
Circuit
Setting range
Factory setting
I / II
10 ... 110 °C
40 / 40 °C
Set the return temperature limitation referring to the outdoor
temperature value set in line 31 (see drawing).
Set the return temperature (Y coordinate) for the
upper limit.
(The corresponding X coordinate is set in line 31).
33 Return temperature limitation - lower limit (X-axis)
Circuit
Setting range
Factory setting
I / II
-30 ... 15 °C
-15 / -15 °C
Set the outdoor temperature value (see drawing).
Set the outdoor temperature value (X coordinate)
for the lower limit.
(The corresponding Y coordinate is set in line 34).
34 Return temperature limitation - lower limit (Y-axis)
Circuit
Setting range
Factory setting
I / II
10 ... 110 °C
60 / 60 °C
Set the return temperature limitation (see drawing).
Set the return temperature (Y coordinate) for the
lower limit.
(The corresponding X coordinate is set in line 33).
35 Return temperature influence - max. limitation
Circuit
Setting range
Factory setting
I / II
-9.9 ... 0 ... 9.9
-2.0 / -2.0
Set the influence from the return temperature on the desired flow
temperature.
Set the influence of the max. return temperature
limitation (set in line 30 or lines 31-34).
Influence higher than 0:
The desired flow temperature is increased, when
the return temperature gets higher than the set
limit.
Influence lower than 0:
The desired flow temperature is decreased, when
the return temperature gets higher than the set
limit.
0
Influence
Max. limitation > 0
Return limit
Return temp.
Max. limitation < 0
Example
The return limit is active from 50 °C.
The influence is set to -2.0.
The actual return temperature is 2 degrees too high.
Result:
The desired flow temperature is changed by -2.0 x 2 = -4 degrees.
Normally, the setting in line 35 is lower than 0 in district heating
systems to avoid a too high return temperature.
Typically, the setting in line 35 is 0 in boiler systems because a
higher return temperature is acceptable (see also line 36).
