Stulz C2020 User Manual

EN/07.2013/58/56
T-ON = CS + [B / 3] and T-ON = S01 + [S06 / M04]
Where the offset is equal to: Offset = S06 / (number of units) = S06 / M04
4.8.6. Cooling with freecooling conditions
If freecooling is enabled and it’s necessary to cool, before switching on the compressor of the leader unit, the damper
of all units will be opened in according to the freecooling logic explained below.
There are two types of freecooling control methods, which can be chosen by the parameter M51:
• If 0 = only damper regulation;
• If 1 = damper + evaporator fan regulation.
Damper regulation
In a system where max number of units on is three (M04 = 3), the offset is equal to:
Offset = B / (2 * max number of units on) = S06 / (2 * M04) = S06 / (6)
The damper of the leader board (unit 1) starts to open and then it gets its maximum aperture at the temperatures
described in the table below. If the temperature increases, the second and then the third units will open the damper at
the conditions described below. If the temperature continues to increase, the third unit stays at its maximum aperture
and the compressor of the first unit will switch on; it will continues it this way with the compressors of the unit 2 and 3 if
the temperature continues to increase.
Damper starts to open at T: Damper max aperture at T: Compressor on: Compressor off:
Unit
1
T-START=CS+[0*B/6]
T-START=S01+[0*S06/(2*M04)]
T-MAX=CS+[1*B/6]
T-MAX=S01+[1*S06/(2*M04)]
T-ON=CS+[4*B/6]
T-ON=S01+[4*S06/(2*M04)]
T-OFF=CS+[3*B/6]
T-OFF=S01+[3*S06/(2*M04)]
Unit
2
T-START=CS+[1*B/6]
T-START=S01+[1*S06/(2*M04)]
T-MAX=CS+[2*B/6]
T-MAX=S01+[2*S06/(2*M04)]
T-ON=CS+[5*B/6]
T-ON=S01+[5*S06/(2*M04)]
T-OFF=CS+[4*B/6]
T-OFF=S01+[4*S06/(2*M04)]
Unit
3
T-START=CS+[2*B/6]
T-START=S01+[2*S06/(2*M04)]
T-MAX=CS+[3*B/6]
T-MAX=S01+[3*S06/(2*M04)]
T-ON=CS+[6*B/6]
T-ON=S01+[6*S06/(2*M04)]
T-OFF=CS+[5*B/6]
T-OFF=S01+[5*S06/(2*M04)]
In the next figure there’s an example:
If in a system the max number of units on is five (M04= 5), the offset will be equal to:
Offset = B / (2 * max number of units on) = S06 / (2 * M04) = S06 / (10)
Temp
Temp set point
1 OFFSET 2 OFFSET 3 OFFSET 4 OFFSET 5 OFFSET
BAND
ON
ON
ON
Leader board
compressor
Board 2
compressor
Board 3
compressor
OFF
OFF
OFF
OFF
6 OFFSET
Cooling
capacity
Opening
leader
damper
proportional
Opening
second
damper
proportional
Opening
third
damper
proportional

Stulz C2020 Specifications

General

Brand	Stulz
Model	C2020
Category	Controller
Language	English