Si18-525B BP Unit Control
Function 129
6.2 BP Unit Electronic Expansion Valve Control
Purpose of the
Function
This function provides instructions regarding the absolute flow rate, relative flow rate and fully
closing from the outdoor unit to the BP unit in order to ensure outdoor unit compressor safety
and optimum refrigerating cycle of the system.
With the transmission a permit/prohibit flag for each distribution control in the BP unit, the
distribution control startup timing is controlled by the outdoor unit.
6.2.1 Electronic Expansion Valve Initial Opening Setting
Outline This function improves stability of the system to set initial opening of electronic expansion valve
at starting operation.
When the EV opening command from outdoor unit is lifted, the following opening setting is
performed.
During Cooling
Operation
Target EV opening = 2.5 × (DA - 14) + P5 - KEVOPC × (DOA - DA) pls
DA: room temperature, DOA: outdoor air temperature
During Heating
Operation
Target EV opening = 350 pls
6.2.2 Electronic Expansion Valve Flow Rate Restriction
This function prevents the deviation from the electronic expansion valve specification range by
restricting the electronic expansion valve flow rates of the operating and non-operating room
units during compressor operation. It also prevents the generation of abnormal noise such as
refrigerant flowing sound by restricting the circulation of refrigerant according to the operating
conditions (unit ON/OFF) of room units.
Outline Restriction of electronic expansion valve opening degrees of operating room units;
... Restriction of maximum and minimum flow rates based on constant
Restriction of electronic expansion valve opening degrees of non-heating room units;
... Restriction of minimum flow rate based on constant
... Maximum flow rate determined based on flow rates of operating room units
P5: KEVOPC:
Indoor unit capacity P5 KEVOPC
2.0 to 3.5 kW class 140 DOA
≤
DA 0
5.0 kW class 156 DA
<
DOA 2.5
6.0, 7.1 kW class 170
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