Installation Guide
ECL Comfort 310, application A376
5.3 Return limit
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 outdoor temperature coordinates are set in 'High T out X1'
and 'Low T out X2'. The return temperature coordinates are set in
'High limit Y2' and 'Low limit Y1'.
The controller automatically changes the desired flow temperature
to obtain an acceptable return temperature when the return
temperature falls below or gets higher than the calculated limit.
This limitation is based on a PI regulation where P ('Infl.' factor)
responds quickly to deviations and I ('Adapt. time') responds
slower and over time removes the small offsets between the
desired and actual values. This is done by changing the desired
flow temperature.
Return temperature limitation
High limit Y2
Low limit Y1
°
C
15
40
-15
60
° C
Outdoor temp.
Low T out X2 High T out X1
Influence
‘Infl. - min.’ > 0
‘Limit’
‘Infl. - max.’ > 0
Return temperature
‘Infl. - max.’ < 0
‘Infl. - min.’ < 0
If the ‘Infl.’ factor is too high and / or the ‘Adapt. time’ too low, there is
a risk of unstable control.
High T out X1 (return temp. limitation, high limit, X-axis)
11031
Circuit
Setting range
Factory setting
1
-60 ... 20 °C
15 °C
Set the outdoor temperature for the low return temperature limitation.
The corresponding Y coordinate is set in 'Low limit Y1'.
Low limit Y1 (return temp. limitation, low limit, Y-axis)
11032
Circuit
Setting range
Factory setting
1
10 ... 150 °C
40 °C
Set the return temperature limitation referring to the outdoor temperature
set in 'High T out X1'.
The corresponding X coordinate is set in 'High T out X1'.
Low T out X2 (return temp. limitation, low limit, X-axis)
11033
Circuit
Setting range
Factory setting
1
-60 ... 20 °C
-15 °C
Set the outdoor temperature for the high return temperature limitation.
The corresponding Y coordinate is set in 'High limit Y2'.
Danfoss District Energy
VI.GU.B1.02
DEN-SMT/DK
79
