Carrier 50FF Series Control Manual
Also see for 50FC Series: Installation, operation and maintenance instructionsControls, Start-Up, Operation and TroubleshootingUser manualService and maintenance instructionsInstallation, operation and maintenance instructions
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Contents
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2912 - COMPONENTS MANAGEMENT12.9. Outdoor air damperFor control of the outdoor air damper (optional), the control has aproportional output 0/10V (Y1).This will be activated for the following circumstances:Free-coolingThe operation of the free-cooling, in units with economizer, allowsthe outdoor air conditions to be taken advantage of when theseare more favourable than those of the return air.Note: the free-cooling function is not compatible with the activationof the rotary heat exchanger or the recovery circuit.After free-cooling, the first compressor of the main circuit will enterinto operation, if necessary.To check whether or not the conditions of the outdoor air aremore favourable than those for the return air, three procedurescan be used:Free-cooling in summer (COOLING mode)The free-cooling will be active when the following conditions aremet:● The unit is operating in COOLING or AUTO mode.● Free-cooling function summer authorised.● The outdoor temperature is less than the return temperatureminus the free-cooling differential.Free-cooling function depends on two parameters:● Offset: this defines the difference between the setpoint and theair return temperature at which the outdoor air damper beginsthe opening.● Differential: the opening of the outdoor air damper is carried outin accordance with the return air temperature.It’s possible to disable the compressors if it is considered thatthe difference between the return temperature and the outdoortemperature is sufficient with free-cooling.Free-cooling in winter (HEATING mode)Free-cooling in winter is useful, for example, in shopping centres,discos etc. where, during operation in winter, due to overheating,the temperature is always greater at the setpoint and cooling hasto be initiated instead of heating.This function will be active provided that these conditions are met:● The unit is operating in HEATING mode.● Free-cooling function winter authorised.● The outdoor temperature is less than the return temperatureminus the free-cooling differential.● The outlet temperature is above 10ºC.● For thermal free-cooling, the opening of the outdoor air damperis ordered when the temperature of the outdoor air is lower thanthat of the return air plus a differential. In this case, the controluses the outdoor and return air temperature probes.● For enthalpic free-cooling, the control calculates the enthalpyof the return air and of the outdoor air based on the temperatureand relative humidity readings of the return and outdoor air. Aftercalculating the enthalpies, carry out the following comparison:* Damper closed and (Hint-Hext) > enthalpy diff., damper opens.* Damper open and (Hint-Hext) ≤ enthalpy diff., damper closes.● For thermoenthalpic free-cooling, the opening of the outdoorair damper is performed when the enthalpy of the outdoor airis lower than that of the return air plus a differential and it alsomeets the condition that the outdoor temperature is lower thanthat of the return air by 1ºC, which allows the outdoor conditionsto be taken advantage of in a better manner.Specific humidity Specific humidity Specific humidityDry temperatureDry temperatureDry temperatureThermalfree-coolingEnthalpicfree-coolingThermoenthalpicfree-cooling Thermoenthalpicfree-coolingIt saves more energyC1 C2Zm/2BandTc TrDif_FCOff_FCDamper100% openSUMMERC1Damper100% openC2Zm/2BandTc TrDif_FCWINTER |
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