Selecting Outdoor Unit For Operation - Panasonic U-8MF2E8 Service Manual

2. Selecting Outdoor Unit for Operation

2-1. Outdoor Unit Operating Rules
All outdoor units in this system contain an inverter compressor. Therefore there is no order of priority for the
outdoor units.
2-2. Delayed Start of Outdoor Units
2-2-1. Delayed start of outdoor units in the same system
If it is necessary to operate the compressors simultaneously at multiple outdoor units, each outdoor unit will start
in order of unit No. every one second, beginning with unit No. 1.
This is in order to reduce the load on the power supply equipment.
Operation
starts
2-2-2. Delayed start for each system
When systems are linked with one communication cable and multiple systems are required to operate
simultaneously by the central control device, all main outdoor units will begin operating simultaneously. In this
situation, the load of the power supply equipment increases temporarily.
To prevent the overload, the start timing of each system can be delayed.
In order to enable this delay time, it must be set in the EEPROM for each system (Main outdoor unit). Those
systems (Main outdoor units) where this setting has been made will start after a delay according to their system
addresses.
To activate this delay start function, it is necessary to set it to EEPROM on main outdoor PCB.
EEPROM setting in main outdoor unit
CODE: 3E
Setting No
0 Delay start invalid (factory preset mode)
1 [System address * 8] seconds delay
2 [System address * 8] seconds delay
3 [System address * 8] seconds delay
* Delayed start for each system is not set in the factory preset mode.
2-3. Outdoor Unit Stop Rules
2-3-1. Stopping of All Outdoor Units
When all outdoor units must stop, the units stop at the same time. However, depending on the communications
timing, a difference of approximately 10 seconds may occur.
2-3-2. Stopping of Individual Outdoor Units According to Load of Air-Conditioning
When operating in cooling mode, all inverter compressors in the outdoor units operate and stop simultaneously.
* When ambient temperature is 10°C or more, inverter compressor may stop excluding one for short operating
time.
When operating in heating mode or mixed cooling/heating, the outdoor unit which has the inverter compressor
with the shortest amount of operating time continues to run and rest of the other outdoor units may be stopped
according to load of air-conditioning.
Main outdoor unit
( )
Unit No.1
Starts after 1 second Starts after 2 seconds
Delay time
1 - 3
Sub outdoor unit Sub outdoor unit
( )
Unit No.2
Starts after 3 seconds
3WAY SYSTEM
Control Functions
( )
Unit No.3
1