Hitachi RPI-0.8FSG1 Service Manual page 368

FIELD WORK INSTRUCTION
(3) Piping Length of Farthest Indoor Unit:
[Phenomenon]
During the simultaneous cooling and heating operation, the cooling capacity of the farthest indoor unit
is decreased when the farthest indoor unit is in cooling operation and the second farthest indoor unit is
in heating operation.
[Countermeasure]
It is recommended that the piping length between the multi-kit and the farthest indoor unit be within
5m. In case that the piping length between the multi-kit and the farthest indoor unit is longer than 5m,
use the T-branch at only the liquid pipe instead of liquid multi-kit. The direction of the T-branch is as
shown below. Purchase the T-branch locally for this piping work and prepare at each site. If the
diameter of the pipe between the outdoor unit and CH unit is different, use a reducer.
Outdoor Unit
(4) Start-Up in Simultaneous COOL/HEAT Operation Mode:
[Phenomenon]
In case of starting up in the simultaneous COOL/HEAT operation mode when the outdoor temperature
is low, the capacity increase time of the unit operation is longer in comparison with the only cooling or
heating operation mode (especially in starting up of small capacity operation; 1HP cooling and 1HP
heating [Example]).
[Countermeasure]
Do not install the unit where starting up in simultaneous COOL/HEAT operation mode is always
required. In case that the simultaneous COOL/HEAT operation is required, it is recommended that
individual refrigerant systems be applied for cooling and heating, or the starting up is performed in only
cooling or heating operation mode, and change over the operation mode to the simultaneous COOL/
HEAT mode when 10 to 20 minutes have passed after starting up operation.
5-8
Max. 30m
L (m)
Outdoor Unit
CH Unit
CH Unit
CH Unit
L (m) < 5m
...Multi-kit
L (m) > 5m
...T-branch at the
Liquid Pipe only
CH Unit
Horizontal