Heating Pump-Down Residual Operation - Daikin VRV R-407C PLUS Series Service Manual

Outline of Control (Outdoor Unit)

3.17 Heating Pump-Down Residual Operation

Conduct an operation during stop mode to discharge refrigerant from the low pressure side, since liquid
refrigerant remaining in the accumulator can be sucked into the compressor during startup and dilutes the
refrigerating machine oil in the compressor and lowers the lubricating performance.
[Residual operation starting condition]
DSHi : INV discharge pipe superheat degree
Th6-Te : Suction pipe temp. -Low pressure equivalent saturation temp.
[Description of movement]
Movement
∗ Receiver gas relief solenoid valve is open and liquid refrigerant is moved to liquid line for 60 seconds
[Ending condition]
66
Thermostat ON → OFF
& DSHi < 20˚C
OR
Th6 – Te < 10˚C
Compressor
67Hz+OFF
PI control when SHS = 10˚C
after entering pump-down residual operation.
However, this relief solenoid valve closes at Th6-Te < 0.
DSHi > 90˚C
Th6 – Te < 10˚C
& LP < 0.07MPa
Tc > 48.6˚C
10 min elapse
Outdoor unit
Motorized valve Solenoid valve for hot gas
Initial 2000 pls →
Indoor unit
Motorized valve
ON (equalization) 500 pls (all indoor unit)
Function R-407C PLUS Series
SiE 00-07