Danfoss ECL Comfort 310 Operating Manual page 91

Operating Guide
If you want to tune the PI regulation precisely, you can use the following method:
• Set the 'Tn' (integration time constant) to its max. value (999 sec.).
• Decrease the value for the 'Xp' (proportional band) until the system starts hunting (i.e. gets unstable) with a constant amplitude (it
might be necessary to force the system by setting an extreme low value).
• Find the critical time period on the temperature recorder or use a stop watch.
This critical time period will be characteristic for the system, and you can evaluate the settings from this critical period.
'Tn' = 0.85 x critical time period
'Xp' = 2.2 x proportional band value in the critical time period
If the regulation seems to be too slow, you can decrease the proportional band value by 10%. Make sure there is a consumption
when you set the parameters.
Danfoss District Energy
ECL Comfort 310, application A368
Temp.
Critical time period
VI.LG.J3.02
Time
DEN-SMT/DK 91