Return Limit - Danfoss ECL Comfort 210 Installation Manual

Installation Guide

5.4 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.
Example, maximum return temperature limitation;
return temperature gets higher than limit
52 DEN-SMT/DK
ECL Comfort 210 / 310, application A260
Return temperature limitation
° C
High limit Y2
60
Low limit Y1
40
-15
Low T out X2 High T out X1
The calculated limit is shown in brackets ( ) in the monitoring display.
See the section "Monitoring temperatures and system components".
= Temperature
T
= Temperature
Y
= Time
X
# 1 # = Return temperature
# 2 # = Return temperature limit
# 3 # = Desired flow temperature
# 4 # = Action point
VI.LG.F2.02
Outdoor temp.
° C
15
Danfoss District Energy