Schreiber Chillers 1055 New - Manual (Page 26)

allows the chiller to run, but water must be added immediately. Since the reservoir is open to the
atmosphere, a small amount of water may be lost due to evaporation. The local weather conditions
will dictate how often the reservoir should be topped off. If water needs to be added more than once a
month, there is a possibility of a leak in the system.
Flow Switch
There is a flow switch on each piping loop to protect the chilled water system. When the switch is
open (no flow) the pump on that loop will not run. If the flow switch is open on the GCHE loop, it will
also lock out the compressors to keep from freezing the evaporators. On pump startup, there is a
short time delay 15-25 seconds, to allow flow to be established before generating an error. When
running, there is a another time delay of 5-10 seconds to allow for flow disruptions caused by a
changed in valve position or bubbles in the system.
Backflow Kit
Since the chilled water reservoir is vented to the atmosphere, water in pipes above the water level of
the reservoir will flow back and overflow the reservoir when the pumps are shut off. To prevent this, a
backflow kit consisting of a solenoid valve on the return line on each loop , and a check valve on the
GCHE loop is provided. The solenoid valve is a normally closed valve that is energizes whenever the
pump contactor is energized.
The backflow kit also keeps the entire piping loop full of water during shut down. In some cases
(including startup) the pump will start when the pipe is not full. Since the flow switch is on the return
line, the pump may alarm on a flow error on pumped startup, because the time required to fill the
pipes and trigger the flow switch was longer than the time delay at pump startup. The alarm can be
reset, or the flow time delay temporarily increased to allow for pipe filling.
COMPRESSOR/EVAPORATOR SYSTEM
Refer to the following:_