Controlling Bc Controller - Mitsubishi Electric CITY MULTI PUHY-P108 Service Handbook

[ VII Control ]

[3] Controlling BC Controller

1. Control of SV A, SV
SV A, SV B, and SV
SV A
Port SV B
SV C
2. Control of SVM1
SVM turns on or off depending on the operation mode.
Operation
Cooling only
mode
SVM1 ON
*1. Pressure differential control: The detected differential pressure (PS1 and P3) is controlle every minute so
as to be within a certain range.
3. Control of LEV
LEV opening (sj) is controlled as follows depending on the operation mode.
Operation mode
LEV1
LEV2
NU-G, (only for NU-GA
NU-GA model)
model
LEV3
NU-GB
LEV3a
model
*1. Liquid level control: The liquid level detected by the liquid inlet temperature (TH11 sensor) is controlled so as to be within
a certain range.
*2. Pressure differential control: The detected differential pressure (PS1 and P3) is controlle every minute so as to be within
a certain range.
*3. Can be 110 or more due to pressure rise on the liquid side (PS1).
*4. Superheat control: The amound of superheat that is calculated on the bypass inlet and outlet temperature (NU-G, NU-GA:
TH12,TH15, NU-GB: TH22, TH25) is controlled every minute so as to be within a certain range.
4. Control of SVM2 (only for NU-GA model)
Operation
Cooling only
mode
SVM2 OFF
*1. Pressure differential control: The detected differential pressure (PS1 and P3) is controlled every minute so
as to be within a certain range.
B, and SV C
C turn on or off depending on the operation mode of the branch.
Cooling Heating
ON OFF
OFF ON
ON OFF
Cooling main Heating only
Pressure dif-
ferential con- OFF
*1
trol
Cooling
Cooling only
main
Liquid level
2000
control
Pressure
differential
Superheat control
*4
control
Superheat Superheat
*4
control control
Cooling main Heating only
Pressure
OFF differential
*1
control
- 164 -
Mode
Stopped Defrost
OFF OFF
OFF OFF
OFF OFF
Heating main Defrost
OFF ON
Heating
Heating only
main
*3
110 110
*1
Pressure Pressure
*2
differential differential
*2
control control
60 60
*4
Heating main Defrost
Pressure
differential OFF
*1
control
Stopped
OFF
Defrost Stopped
2000 1200
NU-G: 1000
60
NU-GA: 2000
*2
60 60
Stopped
OFF