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W-2WAY ECO-i SYSTEM
Control Functions
(2) Heating control when outdoor unit heat exchanger is acting as an evaporator
Outdoor units
Indoor
units
* When the above operation is finished, normal operation starts at the horsepower determined by the indoor units
where thermostats are ON.
Control time
RAP valve kit
Fan
Minimum 1 min Maximum 10 min [until max (pressure sensor temp., E1)
35
°
C]
Valves at all indoor units operate at 250 pulses as a default.
Valve kits at all indoor units operate in heating mode (ON status).
Fan operates at the set fan speed, stops or operates at a very low speed,
depending on the indoor unit operation mode.
Electronic Thermostat
Expansion Valve
All outdoor units operate at the maximum horsepower.
In addition to ordinary heating and cooling operation, this system also includes the following 3 types of special con-
trols for control of the system as a whole.
1. 4-way Valve Adjustment Control
2. System refrigerant oil recovery control
3. Defrost control
4-1. 4-way Valve Adjustment Control
When the microcomputer is initialized immediately after power-ON, after warning output, and all outdoor units are
kept stopped for a preset period (standard = 60 minutes) , the 4-way Valve Adjustment Control will be performed.
This control is intended to changeover the 4-way valve of outdoor unit. When the unit has been stopped for long
period, and if refrigerant has accumulated somewhere in the tubing, recovery of the refrigerant is performed. This
control can also compensate for tubing thermal loss by radiation during heating start as well as for oil recovery.
(1) Cooling control when the outdoor unit heat exchanger is acting as a condenser
60 seconds
Outdoor Units
Indoor
units
* When the above operation is finished, normal operation starts at the horsepower determined by the indoor units where
thermostats are ON.
Control time
Electronic Thermostat
Expansion Valve
RAP valve kit
Fan
All outdoor units operate at the maximum horsepower.
Valves at all indoor units operate at a fixed pulse according to the indoor unit capacity.
Valve kits at all indoor units operate in Cooling mode (OFF status).
Fan operates at the set fan speed or stops, depending on the indoor unit operation
mode.
4-2. System Refrigerant Oil Recovery Control
4-2-1. System refrigerant oil recovery cycle
This control is performed using the cooling cycle during cooling operation and using the heating cycle during heat-
ing operation.
4-2-2. Start of System Refrigerant Oil Recovery Control
When the oil level in an operating compressor is detected as 0 (zero), the compressor stops in 120 seconds. If this
compressor repeats this operation 3 times and the oil level does not reach 2, system refrigerant oil recovery con-
trol is started.
* When the compressor has stopped because the oil level is 0, a count is added to the alarm counter. The counter
for this compressor is not cleared unless the oil level for that compressor reaches 2, or else alarm output occurs.
4. Special Controls
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