30Wga Unit Operation With A Remote Air-Cooled Condenser (Option 154); Operating Principle; Lead Fan; Communication To Control The Remote Condenser - Carrier AquaSnap 61WG Series Installation, Operation And Maintenance Instructions

15 - 30WGA UNIT OPERATION WITH A REMOTE AIR-COOLED CONDENSER
(OPTION 154)

15.1 - Operating principle

30WGA units have been specially designed to optimise the
operation of split installations, using air-cooled condensers as the
chiller heat rejection system. The installation of an operational
system is limited to the connection of the air-cooled condenser
inlet and outlet piping to the 30WGA unit.
The TouchPilot Junior control control system of the 30WGA
includes a logic to permit control the different fixed and variable-
speed fan variants.

15.2 - Lead fan

The physical position of the air-cooled condenser with fixed or
variable-speed fans depends on the position of the leaving liquid
refrigerant manifold. In all cases there is always a so-called lead
fan. This is the fixed or variable-speed fan that is physically the
closest to the leaving liquid refrigerant manifold.
This ensures optimum subcooling on the condenser outlet side,
especially at part load. This is the first fan to start in each circuit
and the last fan to stop. A fan configuration with fixed-speed fans
permits year-round system operation down to 0 °C outside
temperature.
A fan configuration with a variable-speed lead fan permits year-
round operation down to -10 °C outside temperature.
15.3 - Communication to control the remote
condenser
The electronic board specifically integrated in the control box of
the remote condenser( by an option selection on the manufacturer
condenser) and a communication LEN bus connected to the
microprocessor board of the unit are used for the overall system
control.
The option is supplied in the manufacturer condenser control box.
Connect the unit to board AUX1 in the condenser, using a
communication cable. The communication cable should be
connected to the plug with 3 points Wago type (5 mm spacing or
equivalent). The communication cable should be a shielded type.
The option includes an air temperature sensor installed on the
condenser.
TouchPilot Junior continuously optimises system operation to
obtain the best system efficiency by controlling the number of fans
required for any thermal load and outside temperature conditions.
15.4 - Configuration of the number of fan
stages and fan type based on the air-cooled
condenser model used in the installation
Please refer to the instructions in the TouchPilot Junior IOM units
to carry out the parameter setting of the air-cooled condenser
used in the installation:
- Use of speed variation on the lead fan(s)
- Number of fixed-speed fans
Based on the parameter setting used, the arrangement of the
digital and corresponding analogue outputs controlling the fans
will be activated by the control.
TouchPilot Junior controls the automatic switching of all fan stages,
based on operating time and number of start-ups of the different
stages. This function prevents fan motors from only running a little
or not at all and the shafts seizing up, especially during periods
with a low cooling demand, when the outside temperature is low.
Switching is often specified by the condenser manufacturers to
ensure a long operating life of the fan motors that are only used
a little or not at all in these particular operating conditions.
57