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2.10 Evaporator freeze protection
1. If the machine is idle during the winter, drain and rinse the evaporator and chilled water pipes with glycol. Drain and air
vent connections are included on the evaporator for this purpose.
2. We recommend adding glycol in proper proportion to the condenser cooling system. The freezing temperature, of the
water-glycol solution, must be at least 6° C lower than the expected minimum ambient temperature.
3. Insulate pipes especially chilled water ones to avoid condensation.
Damage caused by freezing is not covered by warranty, therefore, Daikin Applied Europe SpA
cannot be held liable.
2.11 Condenser protection and design considerations
If lake, river or ground water is used as the cooling fluid and the water valves have a leak, the condenser and liquid
refrigerant line temperatures could drop under room temperature when the machine is off. This problem occurs when cold
water circulates through the condenser and the unit remains off waiting load. If this happens:
1. Turn off the condenser water pump when the compressor is off.
2. Check that the liquid line expansion valve is working properly.
2.11.1
Condensation control with evaporative cooling tower
The minimum condenser inlet water temperature should not be less than 20° C at full water tower flow rate.
If the water temperature must be lower, even the water flow must be reduced proportionately.
To modulate the water flow to the condenser, install a three-way by-pass valve. The figure shows how the three-way valve is
applied to cool the condenser. The three-way valve can be activated by a pressure actuator which guarantees proper
condensing pressure in the case where the water temperature entering the condenser is less than 20° C.
In place of a valve with pressure actuator you might use a three-way servo-operated valve or a circulation pump controlled
by an inverter. Both of these two devices may be controlled by an analog 0-10 Vdc signal issued by the machine's electronic
controller according to the water temperature entering the condenser.
Figure 5-Condenser control scheme with cooling tower
2.11.2
Condensation control with well water
If ground water is used to cool the condenser, install a normally regulating control valve, direct drive, at condenser outlet.
This regulating valve must ensure an adequate condensing pressure in the case where the water temperature entering the
condenser is less than 20° C.
A service valve with pressure outlet is provided on the condenser sleeve for this purpose.
The valve must modulate its opening according to condensing pressure. When the machine shuts down, the valve will close
preventing the condenser from emptying.
1
Cooling tower
2
Condenser
1
2
