Specifications

Control Specification SiUS12-928_A
47 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 preheating command from the
indoor and outdoor temperatures, and the discharge pipe temperature.
Details ON Condition
 When the outdoor temperature and the discharge pipe temperature are below 10.5°C (51°F),
the inverter operation in open phase starts.
OFF Condition
 When the outdoor temperature or the discharge pipe temperature is higher than 12°C (54°F),
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, current is not conducted.
In order to eliminate the switching sound when heating is stopped, as the four-way valve coil
switches from ON to OFF, the OFF delay switch of the four-way valve is carried out after the
operation stopped.
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, acquire the differential pressure
to activate the four-way valve by having an output frequency which is more than a certain fixed
frequency, for a certain fixed time.
Detail Starting Conditions
1. When starting compressor for heating.
2. When the operation mode changes from the previous time.
3. When starting compressor for defrosting or resetting.
4. When starting compressor for the first time after the reset with the power is ON.
Set the lower limit frequency to around Hz for 70 seconds with any of the above conditions
.
(Hz)
Cooling Heating
18 class 40 55
24/32 class 28 28