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4. Water valve position For maximum cooling, open the water valve leading
to the hot water distribution basin and close the water valve leading to the
plume abatement coil. In plume abated mode/winter operation, fully open
the water valve leading to the plume abatement coil and completely close
the water valve leading to the hot water distribution basin.
It is not recommended that the plume abatement coil be operated
with partial flow and/or no heat loading during freezing weather.
Potential freezing may occur causing severe damage to the coil.
Check with your local Marley representative regarding minimum
flow allowed for your application.
5. 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 leav-
ing 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. If your tower is equipped
with a VFD, the system offers better temperature control by varying the fan
speed.
For the most effective plume reduction, it is recommended to op-
erate the fan at full speed when the tower is operating in plume
abated mode.
If fans must be modulated to control temperature, lock all fans together
and reduce speed on all fans the same for maximum plume abatement.
Fan Cycling Limits:
Considering the normal fan and motor sizes utilized on NCWD towers,
anticipate that approximately 4 to 5 starts per hour are allowable.
If your tower is equipped with a two-speed motor, greater opportunity for
temperature control is afforded to you. When the water temperature be-
comes 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. When fans are operated at less than full
speed, there will be a loss of plume abatement capability of the tower.
Caution
Note
Note
operation
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Summary of Contents for Marley NCWD
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