Inter-Bp Units Gas Pipe Isothermal Control - Daikin FTX25JVEA9 Service Manual

System control
3.35

Inter-BP Units Gas Pipe Isothermal Control

Purpose of the This function ensures appropriate refrigerant distribution to each BP unit when many room units
are operating in the cooling mode.
Function
Outline The gas pipe temperatures of operating room units are detected by the gas pipe thermistors,
and the opening degrees of the motorized valves are corrected so as to equalize the gas pipe
temperatures of the room units.
In this control, the following conditions are also effective.
When the difference between the gas pipe temperature of each room unit and the average
value is small, no correction is provided.
The temperature difference ∆ DCG1 between the min. value of the heat exchanger temperatures
Details
of BP units and the min. gas pipe temperature is calculated. If it is lower than the average value
of total temperature difference (-5°C), open the motorized valve of the applicable BP unit.
164
When gas pipe temperature is higher than average gas pipe temperature → Opens the valve
of that room unit
When liquid pipe temperature is lower than average gas pipe temperature → Closes the
valve of that room unit
→
Judged as stable. (Set as PI control prohibit zone to prevent hunting)
The motorized valve opening degree correction of this function is restricted to prevent the
valve closing past a certain level.
→
For improvement of stability and convergibility performance
Si18-201
Main Functions