Control Specification
SiUS12-928_B
57
Function and Control
3.3
Controls at Mode Changing / Start-up
3.3.1 Preheating Operation
Outline
The inverter operation in open phase starts with the conditions of the outdoor temperature and the
preheating command from the indoor unit.
Detail
ON Condition
When the outdoor temperature is below 50.9°F (10.5°C), the inverter operation in open phase
starts.
OFF Condition
When the outdoor temperature is higher than 53.6°F (12°C), the inverter operation in open
phase stops.
3.3.2 Four Way Valve Switching
Outline
In heating operation, current is conducted, and in cooling and defrosting operation, current is not
conducted. In order to eliminate the switching sound, as the four way valve coil switches from ON to
OFF when the heating is stopped, the OFF delay switch of the four-way valve is carried out.
Detail
OFF delay switch of four-way valve:
The four-way valve coil is energized for 150 seconds after the operation is stopped.
3.3.3 Four Way Valve Operation Compensation
Outline
At the beginning of the operation as the four-way valve is switched, the pressure difference to
activate the four-way valve is acquired by having output frequency which is more than a certain
fixed frequency, for a certain fixed time.
Detail
Starting Conditions
1. When starting the compressor for heating
2. When the operation mode changes from the previous time
3. When starting the compressor for defrosting
4. When starting the compressor for the first time after resetting with the power ON.
The lower limit of frequency keeps
A
Hz for 70 seconds with any conditions 1 through 4 above.
3.3.4 3-Minute Standby
Turning on the compressor is prohibited for 3 minutes after turning off.
(Except when defrosting.)
A
(Hz)
Cooling
Heating
18 class
40
55
24/32 class
28
