Thermostat - Control Principle - Lennox CLIMATIC 50 User Manual

THERMOSTAT - Control principle

Function
Adjust and hold the fluid outlet temperature as close as possible to the set point, by controlling the number of
compressor stages depending on the thermal load on the system.
Description
CLIMATIC 50 control constantly calculates the required capacity to reach the temperature set point.
TM
This variable is called "CAPACITY FACTOR" (CF) and its value can vary from 0 to 100%.
It is directly linked to the number of control stages of the unit.
i.e.: For ecologic WA 230D K STD with 6 control stages, the CF will start and stop a stage at the following
values:0-17-33-50-67-83-100
It then evolves following the principles detailed in the diagram below (This applies to a chiller):
Difference
between
Water outlet
Temperature
and SET POINT
In any Cases, for a chiller, if the Low Water temperature limit is reached, Compressors are stopped.
In order to anticipate, the reference point is recalculated each time the difference between water temperature
and set point reach a minimum or a maximum.
The rate of change of the Capacity Factor (CF) is determined by another parameter called "REACTIVTY"
and which value is in:
REACTIVITY for Cooling Mode can be adjusted in menu 3325
REACTIVITY for Heating Mode can be adjusted in menu 3335
CLIMATIC 50 user manual – Chillers ranges
+ 2°K
CF FROZEN
+ 1°K
+ 2°C
A
0°K
CF DECREASES
- 1°K
Capacity Stages)
- 2°K
FAST
% of CF / °C (Diff vs Set point) / min
(Removes
Water Outlet Temperature
Change Rate
SLOW
CL50-CHILLERS/IOM/1105-E
CF INCREASES
(Start more
Capacity Stages)
Zone
A
CF FROZEN
FAST
SLOW
15
15