Page 18
PCA Series Chillers
3 Sequence
of
Operation
IMPORTANT!
•
The PCA unit has a leaving water temperature range of 30°F (-1°C) to 65°F
(18°C). Do not attempt to run the PCA unit outside this temperature range or
damage to the unit may occur.
•
When operating the PCA unit between 30°F (-1°C) and 40°F (5°C), you must
use a solution of 75% water and 25% industrial-grade ethylene glycol with a
suitable corrosion inhibitor to protect the PCA unit from freeze-up. See
Figure 6 on page 16 for more information.
Such damage is not covered by the AEC, Inc. warranty.
3-1 Chilled Water Circuit
Figure 9, Figure 10, and Figure 11
;
Process cooling water supply and return connections are made at the pipe stubs at
the rear of the chiller.
;
Warm water returns from the process and enters the reservoir tank.
;
The process water is pumped through the evaporator where it is cooled.
;
The coolant flows to the process and returns to repeat the cycle.
;
A chilled water bypass assembly (patent pending) between the supply and return
lines guarantees a constant flow through the evaporator during intermittent low or
no-flow conditions.
;
A flow switch in units without pumps will prevent the compressor from running
without adequate flow through the evaporator
3-2 Refrigeration
Circuit
;
Liquid refrigerant from the condenser passes through a filter/dryer which removes
moisture and other contaminants.
;
The refrigerant then passes through the thermal expansion valve which allows the
refrigerant to expand and cool the inside of the heat exchanger. The refrigerant
flows through the suction line to the compressor.
;
The refrigerant gives up its heat as it re-condenses to a liquid in the condenser and
the cycle starts over again.
