Today's high efficiency electric chillers normally use
about 2.8 gpm of condenser water per ton. Pumps are purchased to produce
this flow for a given cooling tower height and total frictional resistance
in the piping and chiller system. Pump impellers exposed to sand and silt
can erode, and fouled or plugged condensers can significantly increase
pumping resistance. The combined result is reduced condenser flow. One of
the earliest warning signs of this problem shows up in the temperature rise
across the condenser. If it's higher than that specified in the chiller
design (commonly from 85°F to 95°F or a 10°F range), some form of flow
problem probably exists.
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