V6-i VRF 50/60Hz 
    37 
4.3 Startup Control for Heating Operation 
Table 3-4.2: Component control during startup in heating mode 
Control functions and states 
Controlled  according  to  load  requirement, 
operating  frequency  increased  by  1  step  / 
sec 
Open once the four-way valve has opened, 
controlled  according  to  outdoor  ambient 
temperature and load requirement 
Electronic  expansion 
valve A 
Position (steps) from 0 (fully closed) to 480 
or  3000  (fully  open),  controlled  according 
to discharge superheat 
Electronic  expansion 
valve C 
Position (steps) from 0 (fully closed) to 480 
(fully  open),  controlled  according  to 
temperature  different  between  plate  heat 
exchanger inlet and outlet 
Solenoid  valve  (oil 
balance) 
Closed for 200 secs, open for 600 secs, then 
closed 
Solenoid  valve  (fast 
defrosting  (in  cooling) 
and  unloading  (in 
heating)) 
Open for 4 mins, then closed 
Solenoid  valve  (EXV 
bypass) 
Solenoid  valve  (indoor 
units bypass) 
Controlled according to load requirement 
Solenoid  valve  (inverter 
compressor  A  vapor 
injection) 
Controlled  according  to  inverter 
compressor A 
Solenoid  valve  (inverter 
compressor  B  vapor 
injection) 
Controlled  according  to  inverter 
compressor B 
Solenoid  valve  (inverter 
compressor  B  pressure 
balance) 
Open before compressor B startup