Application topic: Exhaust and supply fans Control in a mechanical room.
Case description
Due to lack of space, the VRF outdoor units are placed sometimes inside closed
mechanical rooms. In those cases the air volume inside the room is circulated by an
exhaust and supply external fans.
The fan speed of VRF outdoor unit is always changing due to the capacity demand.
That’s the reason why the exhaust and supply air fans have to be able to change their
air flow. Usually they are controlled by a VSD that have to be controlled by the
required air volume change in the mechanical room.
In order to provide the required solution we connect CoolMaster in conjunction with
CoolEx. CoolMaster reads the exact fan speed from all outdoors at each point of time.
This data is translated by CoolEx to an analogical signal (0-10v) and is supplied to the
VSD of the exhaust fan.
Application topic: Backup Operation.
Case description
There is a need in certain spaces to have a 100% backup for the air conditioning. In
this case 2 indoor units installed in the required space. Only one works (never both at
the same time). Each indoor unit belongs to a different refrigerant circuit.
There are 2 operation tasks for such a system:
1. When one of the indoors is malfunctioning, the second indoor has to start
working automatically.
2. The master (or the leading system) has to be switched each certain period of
time. For example each month.
In order to provide the required solution we connect CoolMaster. One of its
commands enables to define backup of paired indoor units. Another command
changes the leading system after certain time period, which can be defined by the
Application topic: Electrical heaters control
Case description
There are some cases where there is a requirement for electrical heaters that must
work along with the indoor units and supply supplemental or backup heating. Original
VRF controls does not support this option.
End user must be able to operate the indoor unit in heating with electrical heater. In
this case, the indoor must work in the "Fan only" mode, and power, supplied to the
electrical heater must be controlled by the difference in the set point temperature and
the temperature measured in the room.
In this case we use CoolConverter that is connected to local thermostats by Modbus.
When "Auxiliary heating" mode is selected on local thermostat panel, the
CoolConverter changes the operation mode of the required indoor unit to a "Fan"
mode, and local control panel starts controlling the electrical heater. The local control
panel controls the heater (by on/off , analogical or PWM signals) due to the difference
between the measured temperature in the room and the user defined set point
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