SiUS04-702 Control Specification (09/12 Class)
Function and Control 37
3.3 Controls at Mode Changing / Start-up
3.3.1 Preheating Operation
Outline Operate the inverter in the open phase operation with the conditions including the preheating
command from the discharge pipe temperature.
Detail Preheating ON Condition
When the discharge pipe temperature is below 50ºF, inverter in open phase operation starts.
(The power consumption of compressor during preheat operation is 35 W.)
OFF Condition
When the discharge pipe temperature is higher than 54ºF, inverter in open phase operation
stops.
3.3.2 Four Way Valve Switching
Outline Heat Pump Only
During the heating operation current must be conducted and during cooling and defrosting current
must not be 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 delay switch of the four way valve must
be carried out after the operation stopped.
Detail The OFF delay of four way valve
Energize the coil for 160 sec after unit operation is stopped.
3.3.3 Four Way Valve Operation Compensation
Outline Heat Pump Only
At the beginning of the operation as the four way valve is switched, acquire the differential pressure
required for activating the four way valve by having output the operating 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 operating mode changes to cooling from heating.
3. When starting compressor for rushing defrosting or resetting.
4. When starting compressor for the first time after the reset with the power is ON.
5. When starting compressor for heating next to the suspension of defrosting.
6. When starting compressor next to the fault of switching over cooling / heating.
Set the lower limit frequency to 68 (model by model) Hz for 45 seconds with any conditions 1
through 6 above.
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