Hitachi PC-ARF Technical Catalogue page 488

6 Building air conditioning controls
CSNET WEB (PSC-A160WEB1)
Auto cool/heat
The outdoor units of 2-tube systems are not designed to operate in the automatic Cool/Heat mode when more than one
indoor unit is connected to the same outdoor unit, but only in the cool or heat mode. Thus all indoor units connected to the
same outdoor unit should be changed from one mode to another at the same time. The same is applicable to the 3-tube
outdoor unit systems, for all indoor units connected to the same CH Box.
However, operation in the automatic Cool/Heat mode is available through CSNET WEB.
In temperate seasons, CSNET WEB calculates the main need of the indoor units for each of the outdoor units in the sys-
tems mentioned above, selects the mode needed for most of the units in the system and adjusts the remote controller
accordingly.
With the aim of giving the system time to be established in a particular mode, its requirements are checked for at least 20
minutes after the last change carried out. This process is continuous for as long as the indoor units are set to Auto.
If the systems are correctly designed, i.e. if all the indoor units of the same outdoor 2-tube unit have similar cooling and
heating demands, then it is possible to completely automate heating in the morning (for example), cooling in the afternoon
and heating once more at night.
Users maintain local control over the temperature in the room by the remote control.
There are two ways in which CSNET can decide whether the operation mode should be established in AUTO.
Description of the operation mode
In the automatic (Auto) Cool/Heat mode requested by the indoor units, CSNET WEB will check first whether the cooling
circuit to which the unit is connected is 2 tube or 3 tube before deciding to change the operating mode.
Next, CSNET WEB will calculate the difference to decide the best operation mode at that moment.
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TCGB0106 rev.0 - 12/2014