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5. Other Controls
5-1. Oil Control
5-1-1. Oil level
Oil level
Meaning
2
Sufficient
1
Slightly
low
1
0
Extremely
low
The compressor contains enough oil when the oil level is in the range between level 2 and until it has just become
1. Thus oil level 1 does not mean that the compressor is empty of oil. When the compressor reaches oil level 0
during operation, the system is likely to run out of oil within 5 to 10 minutes. Check for oil leaks and make sure that
refrigerant pipes are intact.
5-1-2. Oil level detection
Excess oil in the compressor is sent by bypass via a capillary tube to the low-pressure circuit. The temperature
detected by a temperature sensor is used to determine whether it is oil (warm) or refrigerant (cold).
5-1-3. Self-separator oil recovery control
* When a low oil level is detected, this control recovers the oil which has accumulated in that oil separator and
sends it to the compressor.
(1) Operation when oil level is 1
30 seconds after the oil level changes from 2 to 1, both the balance valve and recovery valve turn ON for up to
2 minutes.
However, if the oil level becomes 2 during these 2 minutes, this control is stopped.
When this control has been stopped, it will not restart for 3.5 minutes unless the oil level becomes 0.
(2) Operation when oil level is 0
Both the balance valve and recovery valve turn ON and remain ON.
5-1-4. Unit refrigerant oil recovery control – utilizing balance tubes
* If the low oil level continues, that outdoor unit (oil-receiving outdoor unit) receives a supply of oil from operating
outdoor units where the oil level is not low (oil-supply outdoor units).
(1) Control at the oil-supply outdoor unit begins 3 minutes after the oil level at the outdoor unit changes to 0 or 1.
Oil supply is performed for a maximum of 5 minutes from each unit.
(2) When oil supply is ended, oil supply from that outdoor unit will not occur again for a period of [(No. of outdoor
units – 1) x 5 minutes]. In addition, oil supply is ended if the oil-receiving outdoor unit oil level changes to 2, or if
the oil-supply outdoor unit oil level becomes low.
(3) The supply of oil is received from 1 unit at a time, in sequence, according to the order of priority of their inverter
compressors.
(4) Operation during unit refrigerant oil recovery
(A) Oil-receiving outdoor unit
The recovery valve turns ON and remains ON.
* Because self-separator oil recovery may occur simultaneously at the same unit, both the balance valve
and recovery valve turn ON at this time.
(B) Oil-supply outdoor unit
The balance valve turns ON and remains ON.
The bypass valve repeatedly turns ON and OFF according to a fixed cycle.
* When the balance valve is ON, the oil in the oil separator is discharged into the balance tube. The bypass
valve releases high-pressure gas which forces this oil toward the oil-receiving outdoor unit, and flushes out
the balance tubes.
The operation of this bypass valve allows oil to be supplied even when there is a difference in height
between the outdoor units.
5-1-5. Indoor unit refrigerant oil self-recovery control
Refer to the items concerned with indoor unit special control.
Oil state
There is more than an adequate amount of oil in the
compressor.
The compressor may contain an adequate amount of oil, but
it may also contain less than an adequate amount of oil.
There is not enough oil in the compressor.
This is the normal operating state
of the system and not a problem.
Check that oil control recovers oil.
Check that system oil recovery
control restores the oil level.
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3-WAY ECO-i SYSTEM
Control Functions
Assessment
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