Hitachi RAS-4-HNPE - Not Cooling Well Due to Insufficient Installation Space for the Outdoor Unit

12. Maintenance notes
458
SMGB0079 rev.0 - 01/2013
12.1.5 Alarm code “31”
Question and answer for the eld work
Example 4: Alarm code “31”
Phenomenon Alarm code “31” sometimes occurred and the system stopped.
Cause
The combination of the indoor units and the outdoor unit was the following.
ON
OFFON ON ON ON
Power
Source
This system was used in a tenant building. One of tenant’s customers turned off the main switch for the indoor unit while
other indoor units are running. This results in a different setting of the total indoor unit capacity in the same refrigerant
cycle.
Countermeasure All the main switches for the indoor units were always ON.
12.1.6 Not cooling well due to insufcient installation space for the outdoor unit
Question and answer for the eld work
Example 5: Not cooling well due to insufcient installation space for outdoor unit
Phenomenon
Cooling operation was well performed through the intermediate season. However the cooling operation was not well avai-
lable when the outdoor temperature was higher than 35 °C.
Cause
As the outdoor units were installed without a sufcient installation space the hot discharge air from other outdoor units was
circulated.
In this case though the outdoor temperature was 35 °C the actual suction air temperature was nearly 50 °C and protection
system from excessively high suction pressure was activated the frequency of the compressor was decreased and the
cooling capacity was also decreased accordingly.
As the outdoor units in-line were installed back to back with a distance of 600 mm between each outdoor unit’s back the
hot discharged air from other outdoor units was circulated.
Countermeasure Ensure that sufcient space should be secured for multi-row and multiple-installation.
Example
Keep a distance of more than 15 mm between other units
and do not put obstacles on the right and left sides. Dimen-
sion B is as shown below.
For detailed information please refer to Unit Installation
chapter.
L A B
0 < L < 1/2H 600 or more 300 or more
1/2H < L < H 1400 or more 350 or more
N O T E
• IfLislargerthanHmounttheunitsonabasesothatHisgreaterorequaltoL.
• Inthissituationensurethatthebaseisclosedanddoesnotallowtheairowtoshortcircuit.
• Whenthemark*dimensionissecuredbesuretomounttheairowguide.