Carrier 50FC - Roofcurb Dimensions and Duct Connections

16
7 - SELECTION OF THE OPERATING MODE
7.1. COOLING operating mode (summer)
The control will compare the temperature reading of the ambient (or
return) air probe with the value set by the COOLING setpoint and
with the value of the control band.
The unit will stop when the ambient (or return) temperature drops
below the setpoint + one-half of the dead zone value.
The input command of the various stages is the one featured on
the chart.
SUMMER
SUMMER
C1-1
C1-1
C2-1
C1-2 C2-1 C2-2
Zm/2
Zm/2
Band
Band
Tc
Tc
Tr
Tr
• 4 compressors (2 circuit)
• 2 compressors (1 circuit)
3WV
100%
0%
Dif_3WV
Off_3WV
3WV
100%
0%
Dif_3WV
Off_3WV
Tr: Control temperature
Tc: Cooling setpoint temp.
Zm: Dead zone
Banda: Control band
Illustrative example:
- Summer setpoint = 26.0ºC
- Di󰀨 erential band = 3.0ºC and Dead zone = 0ºC
- Unit without cold water coil.
• Units 2 compressors:
With the temperature below 26.0ºC, the compressors stop. If the
temperature starts to rise and exceeds 27.5ºC, compressor C1-1
starts. If it continues to rise and exceeds 29.0ºC, compressor C2-1
is also activated.
If the temperature drops below 27.5ºC compressor C2-1 stops. If it
continues to drop until reaching a value below 26.0ºC, compressor
C1-1 stops (the o󰀨 and on command for the compressors will
depend on whether the rotation is activated or not).
• Units 4 compressors:
The control band is divided between 4 compressors.
As backup cooling, these units can incorporate a cold water coil
(V3V). For the regulation of the coil, the control has a proportional
or on/o󰀨 output Y2 which controls the three-way valve.
For the input of the compressor stages, the control will use the
control band value, whilst for the water coil (optional), it will take
the di󰀨 erential into account.
The input command for the previous chart can be modifi ed using
parameters in order to give priority to the hot water coil.
Note: When the outdoor coil pressure of a circuit overcomes a
limit value (41,5 bar by default), one of the two compressors will
be stopped, thereby avoiding the stop of both compressors due to
the high pressure. This compressor will start working again if the
pressure drops below 36,5 bar.
7.2. HEATING operating mode (winter)
The control will compare the temperature reading of the ambient (or
return) air probe with the value set by the HEATING setpoint and
with the value of the control band.
As backup heating, these units can incorporate any of the following
components:
- a hot water coil (V3V).
- two stages of electrical heaters (R)
- a gas burner.
- a gas boiler.
An example of input command of the various stages is the one
featured on the chart.
Tr: Control temperature
Tc: Heating setpoint temp
Zm: Dead zone
Band: Control band
WINTER
WINTER
C2-2
C2-1
C2-1
C1-1
V3V
C1-2 C1-1
Zm/2
Zm/2
Band
Band
Tc
Tc
Tr
Tr
• 4 compressors (2 circuits) + hot water coil
• 2 compressors (1 circuit) + electrical heaters
100%
0%
Dif_V3V
Off_V3V
Off_R
R1R2
Dif_R
Forced disconnection of stages
It is possible to disconnect compressor or electrical heater stages,
by using parameters or mechanically using the digital inputs of the
expansion card c.pCOe with address 8.
This is useful for reducing electric consumption in time bands when
the electric price rate is high or in those cases where the electricity
consumption or the section of the electrical outlet are limited.
For the regulation of the hot water coil, the control has a proportional
or on/o󰀨 output Y2 which controls the three-way valve, and for the
regulation of the electrical heaters, there are two on/o󰀨 outputs
NO6- NO7.
The previous confi guration is typical for the options however the
control can also administer a proportional electrical heater stage in
the output Y2 and an on/o󰀨 water coil in output NO6
For the input of the compressor stages, the control will use the
control band value, whilst for the input of heaters and of the water
coil (optionals), it will take the respective di󰀨 erentials into account.
The input command for the previous chart can be modifi ed using
parameters in order to:
- Give priority to the hot water coil (by default).
- Activate the electrical heater stages without activating the
compressor(s) for cases of compressor breakdown or blocking
due to a low outdoor temperature.
Important: if this blocking is enabled, half of the compressors will
be disconnected at an outdoor temperature of -11’5ºC, and all
other compressors with a temperature of -14.5ºC. The recovery
compressor (optional) is authorized to operate.