SPX Cooling Technologies MH Fluid Cooler User Manual page 15

Note
Note
operation
Fan cycling limits:
Considering the normal fan and motor sizes utilized on MH Fluid
Coolers, anticipate that approximately 4 to 5 starts per hour are
allowable.
If your fluid cooler is equipped with a two-speed motor(s), you will have
an opportunity for process temperature control. When the process fluid
temperature becomes too cold, switching the fan to half-speed will cause
the cold process fluid temperature to rise—stabilizing at a temperature
a few degrees higher than before. With a further reduction in fluid tem-
perature, 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).
For greater insight on process fluid temperature control, please read
Marley Technical Report H-001 "Cooling Tower Energy Management",
available at spxcooling.com.
Pump cycling limits: Cycling the recirculating water pump(s) to control
process fluid temperature is not typically recommended. It is recommended
that while process fluid is being circulated through the coil the fluid cooler
recirculation water system always be in operation. If the recirculating water
pumps(s) are cycled as part of normal system operation, care must be
exercised — frequent wet/dry cycles may lead to premature scaling of
the coil surface.
Dampers: If equipped, the positive closure damper system is designed
to help prevent heat loss from the coil due to air movement caused by
convection or wind conditions when both the fan and pump are off.
Upon start-up of the fluid cooler fans, the damper actuator is energized
and rotates the damper assembly blades open. The actuator should be
wired into the control circuitry of the fan motor. Upon system shutdown
the damper actuator is de-energized and the spring return actuator returns
the damper blades to the closed position.
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