Service
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135
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'10 • HM-T-149
Operation control function by the indoor unit controller
Protection control
Current protection
1) Maximum current limit control for the outdoor unit (by indoor unit control)
When the operation current of the outdoor unit comes close to the limit, request compressor speed is retained in order to keep the
current.
If the current exceeds the threshold set in Menu 9.1.10, request compressor speed is reduced.
2) Maximum current limit control for electric heater or other heat source
This function is available for 3phase connection only.
If the current on L1 or L2 exceeds the limit, heater output is reduced once every 5 seconds until the current drops to the normal level.
If the current on L3 exceeds the limit, compressor speed is reduced by 6rps every 30 seconds until the current drops to the normal
level.
Freeze protection of water heat exchanger
This function can be activated on Menu 9.3.17
(1) In cooling mode
Compressor speed is kept when the low pressure (BP4) reaches 7.5bar, and stopped when it reaches 6.5bar for 20 seconds. Operation
is automatically restarted when it reaches 8.3bar and the supply water temperature becomes 14°C or higher, but it will permanently
stop if the protection is activated for 3 times within an hour.
(2) In defrosting mode
Compressor stops when the low pressure (BP4) reaches threshold value depending on water temperature.
After stopping, the system automatically restarts with heating mode but the period to prohibit defrost is reduced to 15 minutes.
When the above action is repeated for 10 times, the system stops and error code is displayed.
Low condenser out
Compressor stops when the supply temperature (BT12) becomes below 5°C.
Compressor automatically restarts when the supply temperature (BT12) becomes above 14°C, but it will permanently stop if the
protection is activated for 3 times within an hour.
Operation control function by the indoor unit controller
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