Stulz C2020 - Assisted Freecooling

EN/07.2013/58/48
When PI control is enabled (parameter M31 set to 3), 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+(M33/100)*S06+M39
U2 U2=S01+((M33+M36)/100)*S06 U2=The evaporator fan is till at M90 U2=S01+((M33+M36)/100)*S06+M39
The damper reaches its max aperture at the temperature:
T max_ap_u1 = S01 + (M33 / 100) * S06 + (M90 / 100) * M39
T max_ap_u2 = S01 + ((M33 + M36) / 100) * S06 + (M90 / 100) * M39
When 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.
4.4.2. Assisted freecooling
The parameters involved are:
• M31 FREECOOLING ENABLE/OPTIONS: pre-set = Temperature
• M46 FREECOOLING OFF IF COMPRESSOR ON: pre-set = YES
• M47 MIN HUMIDITY LIMIT FOR FREECOOLING (LHUM) : pre-set = 20%
• M48 MAX HUMIDITY LIMIT FOR FREECOOLING (HHUM) : pre-set = 80%
• M49 FREEC. START DELAY EXCEED. HUMID. LIMIT: pre-set = 2h
• M52 ASSISTED FREEC. MODE MIN TEMP. DIFFERENCE: pre-set = 2°C
• M53 ASSISTED FREEC. MODE MIN EXTERNAL TEMPERATURE: pre-set = 20°C
“Assisted freecooling ” is the use of freecooling together with the compressor when there aren’t the conditions to enable
the traditional freecooling.
Compressor and free cooling logic is the same as in the traditional free cooling control.
To enable the “assisted freecooling”, M46 has to be set as NO.
The conditions to obtain an “assisted freecooling” are the followings:
– (TI – TAE > M52) and (TAE > M53)
– HHUM (M48) < IRH < LHUM (M47).
– HHUM (M48) < ERH < LHUM (M47).
If the dehumidification is active, the external humidity probe has to be present.
When IRH or ERH humidity is below “LIMIT MIN” (M47) or exceeds “LIMIT MAX” (M48), freecooling will be disabled for
a settable time (M49). If M49=0, the disabled time is one minute. The freecooling will restart if after this time the humidity
value is re-entered into the limits.
Note that the assisted freecooling is automatically disabled when the freecooling is not enabled (parameter M31 set to
No enable).