Carrier 50FF Series Control Manual

Also see for 50FC Series: Installation, operation and maintenance instructions Controls, Start-Up, Operation and Troubleshooting User manual Service and maintenance instructions Installation, operation and maintenance instructions

Contents

Carrier 50FF Series Control Manual Manual pdf 33 page image

3313.1. Control of the supply air temperatureControl in summer (COOLING mode)The control of the minimum temperature limit in the supply airprevents excessively significant drops in the ambient temperature.This setting is important for units with automatic switching betweenCOOLING and HEATING mode, with low outdoor temperaturesand hot water coil, to avoid the risk of freezing of the coil if theunit starts to operatue in COOLING mode.In COOLING mode, the control is activated when the supplytemperature is included between the maximum and minimumsetpoint, and the difference with the ambient temperature is lowerthan the offset set:● Minimum setpoint in COOLING mode: 10ºC● Maximum setpoint in COOLING mode: 22ºC● Offset with regard to the ambient temperature measured: 15ºC● Control band (differential): 5ºCFor example:Ambient T: 30,5ºC - Offset: 15ºC = 15,5ºC -> control OnAmbient T: 24,0ºC - Offset: 15ºC = 9,0ºC -> control OffThe compressors will gradually disconnect to avoid an excessivelylow supply temperature.The following components could be used as “backup” to increaseit: hot water coil (V3V), compressors in HEATING mode (C) andelectrical heaters (R).The control of supply is activated when two circumstances arefulfilled:● The supply temperature is included between the maximum andminimum values of supply setpoints.● The difference between the supply temperature and the ambienttemperature is lower than the offset set. The ambient probeimproves the supply temperature control, limiting the differencebetween both temperatures. It increases the thermal comfortlevel of the installation.13 - OPTIONAL FUNCTIONS OF CONTROLSUMMER3-WVBand Tc i Supply T• Only hot water coil100%0%C2-2 C2-1 C1-2 C1-1Band Tci• Only compressorsSUMMERSupply TR2 R1Band Tci• Only electrical heatersSUMMERSupply TV3VBandTci• Compressors + hot water coil100%0%2 stages 2 stagesC2-2 C2-1 C1-2 C1-1BandTci• Compressors + electrical heaters2 stages 2 stagesC2-2 C2-1 C1-2 C1-1R2 R1SUMMERSupply TSUMMERSupply TWhere:supply temperature setpointSupplyT: supply temperatureTc s :Control in winter (HEATING mode)The control of the maximum temperature limit in the supply airavoids the stratification of the hot air masses.In HEATING mode, the control is activated when the supplytemperature is included between the maximum and minimumsetpoint and the difference with the ambient temperature is higherthan the offset set:● Minimum setpoint in HEATIING mode: 30ºC● Maximum setpoint in HEATIING mode: 45ºC● Offset with regard to the ambient temperature measured: 22ºC● Control band (differential): 5ºCFor example:Ambient T: 17,5ºC + Offset: 22ºC = 39,5ºC -> control OnAmbient T: 24,0ºC + Offset: 22ºC = 46,0ºC -> control OffThe backup stages and the compressors will be disconnected(always starting with the electric heaters) within the control band(by default 5ºC).Note: when the control of supply is activated, on the screensP01 and P02 of the Group F. MODES the text “LIMIT” appearsintermittently.The control of the minimum temperature limit in the supply airactives compresors in HEATING mode, hot water auxiliary coil orelectrical heater (in the order of entry established for HEATINGmode), to prevent a drop of supply temperature bellow the ambientetemperature setpoint in HEATING mode (by default 21ºC).This control avoid the risk of freezing of the coil, for units with lowoutdoor temperatures and hot water coil.If the unit is working in HEATING mode, when there is demand offree-cooling in winter, the control of minimun supply temperaturechanges and it is carried out as a fonction of the setpoint ofminimun supply temperature in COOLING mode (10ºC by default).The control band is divided among the authorized components.The hot water coil is equivalent to 2 control stages, the total numberof compressors to another 2 and each electrical heater to 1 stage.