(5) Operation data during emergency operation
During emergency operation, no communication is performed with the indoor unit, so the data items needed for operation
are set to the following values:
Operation data
Intake temperature (TH1)
Indoor liquid pipe temperature (TH2)
Indoor 2-phase pipe temperature (TH5)
Set temperature
Outdoor liquid pipe temperature (TH3)
Outdoor discharge pipe temperature (TH4)
Outdoor comp. surface temperature (TH32/TH33)
Outdoor 2-phase pipe temperature (TH6)
Outdoor ambient temperature (TH7)
Temperature difference code
(room temperature - set temperature) (∆Tj)
Discharge superheat (SHd)
Sub-cool (SC)
*1. If the thermistor temperature data is normal (not open/short), that data is loaded into the control as valid data.
When the unit enters emergency operation and TH values are mismatched, set the thermistors to open/short.
And the unit runs emergency operation with the values listed above.
*2. If one thermistor is set to open/short, the values for SHd/SC will be different from the list above.
[Example] When liquid temperature thermistor (TH3) has an open or short circuit.
Thermistor
TH3
TH6
Regard normal figure as effective data.
TH4/TH32
Regard normal figure as effective data.
TH5
TH2
Discharge superheat (SHd)
Cooling = TH4 (or TH32/TH33) − TH6 = Tc − Ta
Heating = TH4 (or TH32/TH33) − TH5 = Td − 50
Degree of subcooling (SC)
Cooling = TH6 − TH3 = Ta − 45
Heating = TH5 − TH2 = 50 − 45 = 5°C
OCH774A
COOL
HEAT
45°C
5°C
Ta
Tb
Tc
Td
5°C
50°C
5°C
45°C
Operation mode
COOL
HEAT
27°C
20.5°C
5°C
45°C
5°C
50°C
25°C
22°C
45°C
5°C
80°C
80°C
50°C
5°C
35°C
7°C
5
5
30°C
30°C
5°C
5°C
56
Remarks
-
-
-
-
*1
*1
*1
*1
-
*2
*2