Daikin EWWQ-AJYNN Service Manual page 8

Introduction
Head pressure
control, well water
system
Temperature and
waterflow
limitations
Evaporator freeze
protection
vi
When using city or well water for condensing refrigerant, install a normally closed direct acting water
regulating valve in the outlet piping of the condenser. This regulating valve will assure an adequate
condensing pressure if the inlet condenser water temperature falls below 15 °C. The condenser
service valve provides a pressure tap for the regulating valve. The valve can modulate in response to
head pressure. On shutdown, the valve closes, preventing water from siphoning out of the condenser.
Siphoning causes condenser waterside drying and accelerates fouling. If a valve is not used, Figure 2
illustrates the recommendation of a loop at the outlet. Size the loop height (H) to offset the negative
pressure caused by the siphoning effect. A vacuum breaker may be required.
Cooling Tower
Condenser
EWWQ-AJYNN units are designed to operate in conditions from -8 °C to +15 °C leaving water
temperature on the evaporator side and +15 °C to +55 °C entering water temperature on the
condenser side. Glycol in the evaporator is required on all applications below +4 °C leaving evaporator
fluid temperature. The maximum allowable water temperature to the cooler in a non-operating cycle is
40 °C. The non-operating leaving condenser water temperature maximum is 46 °C. Flow rates below
the minimum values shown in the evaporator and condenser pressure drop curves may cause
freeze-up problems, scaling and poor control. Flow rates above the maximum values shown in the
evaporator and condenser pressure drop curves will result in unacceptable pressure drops, excessive
nozzle and tube erosion and possibly cause tube failure.
When freeze protection is a concern, do the following:
■ If the unit will not be operated during the winter, drain and flush the evaporator and chilled water
piping with glycol. Drain and vent connections are provided on the evaporator.
■ When using a cooling tower, add glycol solution to the chilled water system. Freeze point should
be approximately 6°C below minimum design ambient temperature.
■ Insulate field water piping, especially on the chilled water side.
Note: Freeze damage is not considered a warranty failure and is not the responsibility of Daikin.
Loop required when no
regulating valve is used
H
To drain
Direct acting water
regulating valve
ESIE 07-05
From main
condenser
pump