Daikin RZQ100B8V3B Service Manual page 143

ESIE05-03
3.4.1 Expansion Valve Control at Startup
Outline Before going to the general expansion valve control, the expansion valve opening will be limited in
order to avoid the risk of liquid back and allow quick build up of pressure difference.
Details During startup, the opening degree is determined by both the compressor frequency & the suction
superheat. During startup, it is not possible to use only the value of the suction superheat because the
operation is not stable yet. As a consequence also the SH value will not be stable.
Graph
Expansion valve On RZQ71 units (using double swing compressor) the expansion valve will be fully opened (to 480
opening during pulses) for pressure equalisation before compressor start-up. Just before compressor start up, the
pressure expansion valve opening will be set to 65 pulses, same as for the 100~140 class.
equalization
Ending condition The starting control will be terminated when the low pressure value < 6 bar or when the maximum
starting time of 10 minutes has been reached in case the low pressure value stays > 6 bar.
Part 2 – Functional Description
Pressure
equalizing
start
Pressure equalizing
control before
compressor start
Compressor
Motorized valve
Outdoor Unit Functional Concept
Pressure Starting
equalizing control
complete complete
Starting control
RZQ71: 73 Hz
RZQ100 & 125: 107 Hz
15 s
RZQ71: 480 pls
RZQ100~140:
65 pls
1
2
3
4
5
2–59