Table of Contents
Advertisement
8.6 - Capacity control
This function adjusts the capacity using the variable speed
compressor to keep the water exchanger temperature at its
setpoint. The control system continuously takes account of
the temperature error with respect to the setpoint, the rate
of change in this error and the difference between entering
and leaving water temperatures in order to determine the
optimal moment at which to add or withdraw capacity.
Compressors are started and stopped in a sequence designed
to equalise the number of start-ups (value weighted by their
operating time). For more information about compressors
sequence, see section 8.14.
8.7 - Night mode
Night mode allows users to configure the unit to operate with
specific parameters in a pre-defined time period.
The night period is defined by a start time and an end time
that are the same for each day of the week. During the night
period the unit capacity is limited.
The Night mode settings or the maximum capacity value can
be configured via the Configuration menu (GEN_CONF –
General Configuration).
8.8 - Low noise mode
The low noise function is used to reduce the noise level by
limiting the speed of the fans during a predefined period of time.
The "low noise" mode is defined by a start time and an end time
that are the same for each day of the week. Low noise settings
as well as the maximum fan speed can be configured via the
Configuration menu (GEN_CONF – General Configuration).
The "low noise" mode is different from the "low noise" option
(15LS). Low noise mode and Low noise option are compatible.
The configuration needs to be done carefully to avoid problems
caused by too low fan speed.
8.9 - Head pressure control
The condensing pressure of each circuit is controlled by
variable speed fans. The fan speed is controlled in each circuit
based on the outdoor air temperature, water exchanger fluid
temperature and circuit capacity.
8.10 - Refrigerant gas leak detection (option 159)
The control permits refrigerant leak detection. Two additional
sensors that detect the refrigerant concentration in the air
must be installed on the unit.
If one of these sensors detects an abnormal refrigerant level
for more than one hour, the alarm will be triggered, but the
unit will continue to operate.
32
8.11 - Automatic refrigerant leak detection
As standard the controller has the functionality allowing for
detecting lack of refrigerant. Whenever the system detects
the possible refrigerant shortage, the alarm informing about
the necessity of service intervention will be triggered (10110
for circuit A and 10111 for circuit B).
The refrigerant leak detection control is based on an algorithm
that monitors several operating parameters, including
refrigerant pressure and temperature.
The effectiveness of the detection algorithm is not guaranteed
when circuit capacity is lower than 50% and when leaving
water temperature is below 7°C.
8.12 - BACnet (option 149)
The BACnet/IP communication protocol is used by the
building management system or the programmable
controllers to communicate with the Touch Pilot control.
NOTE: BACnet option can be installed only by Carrier
service technicians.
8.13 - Circuit lead/lag selection
This function determines the lead and lag circuit on dual-
circuit units. It controls the start/stop sequence of the
refrigeration circuits called circuit A or circuit B.
The circuit authorised to start first is the lead circuit. Lead
circuit is used first for capacity increases and at the same time
should be decreased last when decreasing capacity.
The lead/lag circuits can be selected manually or automatically
according to the unit configuration (GEN_CONF).
• Automatic lead/lag circuit determination: The control
system determines the lead circuit to equalise the
operating time of each circuit (value weighted by
the number of start-ups of each circuit). As a result,
the circuit with the lowest number of operating hours
always starts first.
• Manual lead/lag circuit determination: Circuit A or B
selected as the lead circuit. The selected circuit is always
the leader. It is the first to start and the last to stop.
To set lead/lag circuit
1. Navigate to the Configuration menu.
2. Select General Configuration (GEN_CONF).
3. Set Cir Priority Sequence [prio_cir].
Cir Priority Sequence [prio_cir]
0 = Automatic lead/lag selection
1 = Circuit A priority
2 = Circuit B priority
Advertisement
Table of Contents
