18
Warning
Warning
Warning
Caution
Therefore, if excessive ice forms on the louvers, stop the fan for a few
minutes. With the fan off, the water flow will increase in the vicinity of the
louvers and reduce the ice buildup.
3. Under extended extreme cold conditions, it may be necessary to operate
the fan in reverse. This forces warm air out through the louvers, melting
any accumulated ice—adequate heat load must be available. Reversal
of fan should only be done at half speed or less. Reverse operation of
the fan should be used sparingly and should only be used to control ice,
not
to prevent it. Reverse fan operation should not need to exceed 1 or
2 minutes. Monitoring is required to determine the time required to melt
accumulated ice.
Operating the fan in reverse at half speed for prolonged periods
during subfreezing weather can cause severe damage to fans and
fan cylinders. Ice can accumulate inside fan cylinders at fan blade
plane of rotation and fan blade tips will eventually strike this ring of
ice, damaging the fan blades or cylinder. Ice can also accumulate
on fan blades and be thrown off, damaging fan cylinder or blades.
Allow a minimum of 10 minute delay between reverse operation
and forward operation during subfreezing weather to permit ice to
dissipate from fan blades and fan cylinders. See Fan Drive Caution
note on page 9 for fan speed change and reversing precautions.
Intermittent Freezing Weather Operation:
If periods of shutdown (nights, weekends, etc.) occur during freezing weather,
measures must be taken to prevent the water in the cold water basin—and
all exposed pipework—from freezing. Several methods are used to combat
this, including automatic basin heater systems and pump freeze protection
systems available from Marley.
Basin heaters systems will not prevent the coil from freezing.
Unless some means of freeze prevention is incorporated into your
system, the fluid cooler basin and exposed pipework should be
drained at the beginning of each wintertime shutdown period.
If fluid cooler basin is drained, verify that all basin heaters have
been shut off either by automatic cutoff or disconnect switch.
operation
