EN/07.2013/58/46
4.4. Freecooling
The parameters involved are:
• S01 COOLING SET POINT (CS) : pre-set = 25°C
• S06 COOLING BAND : pre-set = 5°C
• M31 FREECOOLING ENABLE/OPTIONS: pre-set = Temperature
• M32 MIN IN-OUT ENTHALPY DIFF. FOR FREECOOLING: pre-set = 15KJ/Kg
• M33 START FREECOOLING UNIT 1 : pre-set = 0%
• M34 FREECOOLING UNIT 1 MAX VALUE: pre-set = 75%
• M36 FREECOOLING UNIT 2 OFFSET VALUE: pre-set = 40%
• M41 MIN IN-OUT TEMP. DIFF. FOR FREECOOLING: pre-set = 10°C
• M42 MIN EXTERNAL TEMP. ENABLE FREECOOLING (LTAEM) : pre-set = -25°C
• M43 MAX EXTERNAL TEMP. ENABLE FREECOOLING (HTAEM) : pre-set = 60°C
• 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
• M51 FREECOOLING REGULATION: pre-set = Damper
• M83 EXTERNAL AMBIENT PRESSURE: pre-set = 1013mbar
• M90 MIN EVAPORATOR FAN SPEED: pre-set = 30%
• M92 MAX EVAPORATOR FAN SPEED: pre-set = 100%
Important Note: TAE controlled for free cooling is the last TAE sampled with the condenser fan on.
Enable conditions
Special parameters involved:
• M31 FREECOOLING ENABLE/OPTIONS: pre-set = Temperature
• M35 ENABLE FREECOOLING FOR 2 UNIT: pre-set= YES
Freecooling is selectable. If it’s enabled, two options will be available: enthalpic control or control based on temperature,
on one or two units, selected by M31 and M35 setup parameters.
Temperature
When temperature based freecooling is chosen (M31 = Temp) the conditions to enable freecooling are the following:
Conditions to enable freecooling: Condition to disable freecooling:
TI- TAE > OFFSET (by default is 10°C), TI - TAE > M41 TI - TAE ≤ OFFSET (by default is 10°C), TI - TAE ≤ M41
LTAEM (M42) < TAE < HTAEM (M43)
If the ERH probe is present then: LHUM (M47) < ERH < HHUM (M48)
If the IRH probe is present then: LHUM (M47) < IRH < HHUM (M48)
Enthalpic control with freecooling
Condition to enable freecooling: Condition to disable freecooling:
Internal Enthalpy - External Enthalpy > OFFSET (15)
Internal Enthalpy - External Enthalpy > M32.
Internal Enthalpy - External Enthalpy ≤ OFFSET (15)
Internal Enthalpy - External Enthalpy ≤ M32.
LTAEM (M42) < TAE < HTAEM (M43)
LHUM (M44) < ERH < HHUM (M48)
The pressure of the external ambient can be set, by parameter M83, to adapt the enthalpy calculation to the altitude.
The pressure of the external ambient depends on the altitude (meters above the sea level) of installation, so the
pressure will decrease if the altitude increases.
To Next Page
Loading...
Need help?
General
