28
(7)Clean up the pipeline.
8.11 Freeze Protection
When the flow passage of the shell-and-tube heat exchanger is frozen up, it would cause
serious damage to the heat exchanger, such as cracking and leakage which are out of
warranty, therefore, the user should take measures stated below for freeze protection：
(1)In order to make sure the unit can automatically perform defrosting under low
temperature, the water pump must be interlocked with the unit.
(2)(1) Under subzero condition, when the unit is required to perform cooling, anti-freeze
liquid should be added into the water system based on the table below.
(3)Under subzero condition, when the unit is not required to perform cooling for a short
term, the unit should be powered on; when the unit is not required to perform cooling
for quite a long term, disconnect the power supply and then drain the shell and tube
completely.
Table 8.11.1 Thermal and Physical Properties of the Glycol Solution
Quality Concentration Initial Freezing Temperature Density
16 -7 1020
19.8 -10 1025
23.6 -13 1030
27.4 -15 1035
31.2 -17 1040
35 -21 1045
38.8 -26 1050
42.6 -29 1055
46.4 -33 1060
Notes:
(1)This table is cited from Design Manual for Practical Refrigeration Engineering
published by China Architecture Industry Press. If physical data of the glycol has been
provided by the manufacturer, it always prevails.
(2)Once the glycol is taken as the second refrigerant, its initial freezing temperature of the
glycol solution should be 2~3℃ lower than the lowest environment temperature.
8.12 Rountine Maintenance
Routine maintenance shall be performed periodically by the qualified technician so as to
extend the service life of the unit and lower the possibility of occurrence of faults.
Record weekly the running status of the unit to facilitate troubleshooting for the servicemen.
■ Daily Maintenance
(1)Check the circulating water pump and the flow rate.
(2)Check the voltage and power supply.
A Series Inverter Modular Air-cooled Chiller (Heat Pump)
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