Return Limit - Danfoss ECL Comfort 210 Installation Manual

Installation Guide

5.2 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.
High T out X1 (return temp. limitation, high limit, X-axis)
Circuit
1
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)
Circuit
1
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)
Circuit
1
Set the outdoor temperature for the high return temperature limitation.
The corresponding Y coordinate is set in 'High limit Y2'.
60 DEN-SMT/DK
ECL Comfort 210 / 310, application A231 / A331
11031
Setting range Factory setting
-60 ... 20 °C 15 °C
11032
Setting range Factory setting
10 ... 150 °C 40 °C
11033
Setting range Factory setting
-60 ... 20 °C -15 °C
Return temperature limitation
° C
High limit Y2
60
Low limit Y1
40
-15
Low T out X2 High T out X1
Influence
If the 'Infl. ' factor is too high and / or the 'Adapt. time' too low, there is
a risk of unstable control.
VI.LG.P1.02
Outdoor temp.
° C
15
'Infl. - min.' > 0
'Limit'
'Infl. - max.' > 0
Return temperature
'Infl. - max.' < 0
'Infl. - min.' < 0
Danfoss District Energy