Stulz C2020 User Manual

EN/07.2013/58/47
4.4.1. Function description
The parameter involved is:
• I30 SELECT RELAY FREECOOLING: pre-set = NO CONN.
There are two control methods to do “freecooling” function: with damper or with damper and evaporator fan partialization.
It’s possible to choose the control algorithm by the parameter M51
if 0 = only by damper;
if 1 = damper + evaporator fan.
It’s possible to associate the freecooling status to a relay by parameter I30.
if ( FC status > 0 ): Relay associated to FC status On, else: Relay associated to FC status Off
Damper regulation
The damper regulation is done in the following way with 2 units at the same time, if enabled by M35 setup parameter.
The conditions to start/stop the freecooling on unit 1 and 2 are:
Start Freecooling Max Freecooling
Unit 1
U1 = CS + 0% B
U1 = S01 + M33 * S06
U1 = CS + 75% B
U1 = S01 + M34 * S06
Unit 2
U2 = CS + 40% B = START FRC. U1 + OFFSET
U2 = S01 + (M33 + M36)* S06
U2 = CS + (75% + 40%) B = MAX FRC. U1 + OFFSET
U2 = S01 +(M34 + M36)* S06
If IRH or ERH is below “LIMIT MIN” (M47) or exceeds “LIMIT MAX” (M48) or if IRH probe is absent and humidity switch
is active, freecooling will be disabled for a settable time M49. The freecooling will restart if, after this time, the humidity
value is re-entered into the limits. If M49=0, the disabled time is one minute.
If the dehumidification is active and the external humidity probe ERH is absent, the freecooling will be disable.
The evaporator fan speed is at its maximum value (M93).
Fan speed and damper regulation
It’s possible to control both damper and evaporator fan speed to obtain a noiseless regulation.
In damper regulation, the evaporator fan speed doesn’t change and temperature is controlled by the damper aperture.
In this case (fan speed and damper regulation), to obtain a lower noise when the damper is opened, the evaporator fan
speed is decreased and the damper reaches its max aperture before than under “damper regulation”.
In particular, when the damper reaches its max aperture, the evaporator fan speed will increase from its minimum to its
maximum speed up to the situation of max cooling.
When the damper is closed and the dehumidification is disabled, the evaporator fan speed will be at its minimum value.
When P control is enabled (parameter M31 set to 1), the conditions are:
Start Freecooling Max damper aperture Max Freecooling
U1 U1 = S01 + (M33 / 100) * S06 U1 = The evaporator fan is till at M90 U1 = S01 + (M34 / 100) * S06
U2 U2 = S01 + ((M33 + M36) / 100) * S06 U2 = The evaporator fan is till at M90 U2 = S01 + ((M34 + M36) / 100) * S06
The damper reaches its max aperture at the temperature:
T max_ap_u1 = S01 + ((M33 + M36) / 100) * S06 + (M90 / 100) * (S06 * (M34 - M33) / 100)
T max_ap_u2 = S01 + ((M33 + M36) / 100) * S06 + (M90 / 100) * (S06 * (M34 - M33) / 100)

Stulz C2020 Specifications

General

Brand	Stulz
Model	C2020
Category	Controller
Language	English