Pressure Equalizing Control - Daikin Super Multi NX FFQ25B8V1B Service Manual

SiBE121021_C
4.12.1 Fully Closing with Power on
The electronic expansion valve is initialized when the power is turned on. The opening position
is set and the pressure equalization is developed.

4.12.2 Pressure Equalizing Control

When the compressor is stopped, the pressure equalizing control is activated. The electronic
expansion valve opens, and develops the pressure equalization.
4.12.3 Opening Limit
Outline A maximum and minimum opening of the electronic expansion valve are limited.
Detail
The electronic expansion valve is fully closed in the room where cooling is stopped and is
opened at the fixed degree during defrosting.
4.12.4 Starting Operation Control / Changing Operation Room
The electronic expansion valve opening is controlled when the operation starts, and prevent the
superheating or liquid compression.
4.12.5 High Discharge Pipe Temperature
When the compressor is operating, if the discharge pipe temperature exceeds a certain value,
the electronic expansion valve opens and the refrigerant runs to the low pressure side.
This procedure lowers the discharge pipe temperature.
4.12.6 Oil Recovery Function
Outline The electronic expansion valve opening in the cooling stopped room is set as to open for a
certain time at a specified interval so that the oil in the cooling stopped room may not be
accumulated.
Detail During cooling operation, every 1 hour continuous operation, the electronic expansion valves in
the operation stopped room is opened by 80 pulses for specified time.
4.12.7 Gas Pipe Isothermal Control During Cooling
When the units are operating in multiple rooms, the gas pipe temperature is detected and the
electronic expansion valve opening is adjusted so that the temperature of the gas pipe in each
room becomes equal.
The temperatures are monitored every 40 seconds.
Function and Control
A maximum electronic expansion valve opening in the operating room: 450 pulses
A minimum electronic expansion valve opening in the operating room: 75 pulses
When the gas pipe temperature > the average gas pipe temperature, → open the electronic
expansion valve in that room
When the gas pipe temperature < the average gas pipe temperature, → close the electronic
expansion valve in that room
Control Specification
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