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4. Air flow rate: Reducing air flow through the tower causes the cold water
temperature to rise. This is the approved method by which to control leaving
water temperature.
If your tower is equipped with a single-speed motor, the motor may be shut
off when the water temperature becomes too cold. This will cause the water
temperature to rise. When the water temperature then becomes too warm
for your process, the motor can be restarted.
5. Fan cycling limits:
Considering the normal fan and motor sizes utilized on NC towers,
anticipate that approximately 4 to 5 starts per hour are allowable.
If your tower is equipped with a two-speed motor, you will enjoy greater op-
portunity for temperature control. When the water temperature becomes too
cold, switching the fan to half-speed will cause the cold water temperature
to rise—stabilizing at a temperature a few degrees higher than before. With
a further reduction in water temperature, the fan may be cycled alternately
from half-speed to off.
Do not start the motor more than four to five times per hour (each
low speed start and each high speed start count as one start).
If your tower consists of two or more cells, cycling of motors may be shared
between cells, increasing your steps of operation accordingly.
Multicell towers equipped with two-speed motors will maximize energy
savings and minimize sound levels if fans are staged so that all fans are
brought up to low speed before any fan goes to high speed.
For greater insight on cold water temperature control, please read
“Cooling Tower Energy and its Management”
,
Technical Report
#H-001-A
, available on our website
operation
Note
Note