31
Unit Operation
Function of antifreezing in winter
When the unit is in the standby mode in winter and the water temperature is lower than the
set antifreezing temperature in winter, the unit automatically starts antifreezing operation, and
“
AP
”
is displayed. Thus, when the unit is in the standby mode in winter when it is easy to
freeze, the power supply of the unit shall be switched on.
Antifreezing of shell and tube heat exchanger
When the water temperature is lower than 3
℃
in the cooling mode, the compressor will be
turned off, the water pump continues to run, and
“
E3
”
is displayed.
Motor overload protection
•
Compressor motor overload and overheat protection.
•
Water pump motor overload protection.
•
Fan motor overload protection.
•
Temperature probe protection.
If the temperature probe fails, the system will give an alarm and stop.
*All alarm protection is manually reset. It is necessary to remove the fault and then press Reset
key or restart or shut down to recover the system.
Low suction pressure protection (cooling mode) ) (H Type Unit Only)
When the low pressure of any system is lower than 620kPa in the cooling mode, the system
shall be continuously detected for 60 seconds; if the low pressure is still below 620 kPa, the
compressor of this system shall be forcibly turned off, otherwise the compressor will continue to
run. Judgment is not performed in the first 3 minutes of initial operation of any compressor for
any system; judgment is not performed during the defrosting period.
This protection is allowed to occur once at most within 1 hour; if this protection occurs twice
within 1 hour, shut down and give an alarm, and display the code
“
78
”
(A system) or
“
7A
”
(B
system) on the single unit controller.
Suction anti-freezing protection
In the cooling mode, if the following conditions are met, the compressor will be turned off, the
electrical heater for the water circuit will be started, the water pump will continue to run, and the
code
“
E4
”
will be displayed on the single unit controller.
1. When the suction temperature of any system is lower than or equal to -3
℃
, start counting,
and meet the above conditions after 30 seconds;
2. When the water outlet temperature is higher than or equal to the refrigeration antifreezing exit
temperature (coil/plate type heat exchanger), the electrical heater for the water circuit is stopped.
When this fault occurs, the refrigeration plate type heat exchanger antifreezing locking time
is locked; after the refrigeration plate type heat exchanger antifreezing locking time is up, if all
suction temperature is higher than or equal to 3
℃
, this fault can be reset through the single unit
controller or the centralized controller. After reset, the water pump will still continue to run and
then shut down.
The low suction temperature protection will be shielded within 30 seconds after any compressor
is started.
High temperature protection(cooling mode) (H Type Unit Only)
In the cooling mode, if the fin temperature of any system is higher than 68
℃
for 5 seconds, the
fin temperature will be considered too high, and the unit will be shut down and give an alarm.
