SPX Cooling Technologies MARLEY AV 98-1514E - Manual (Page 16)

16
Note
Wintertime Operation:
The Marley fill system used in the AV Series cooling tower has air entrance
louvers that are molded integrally as part of the fill. This feature makes
these towers very forgiving of cold weather operation, even at the low
temperature and reduced load conditions encountered in free cooling
and other low temperature applications. Nevertheless, during operation
in subfreezing weather the opportunity exists for ice to form in the colder
regions of the tower.
Slushy, transitory ice forms routinely in the colder regions of the fill
of low temperature towers, and is visible through the tower louvers.
Such ice normally has no adverse effect on tower operation, but
its appearance should be a signal to the operator to undertake ice
control procedures.
It is the operator's responsibility to prevent the formation of destruc-
tive (hard) ice on the cooling tower fill. Certain guidelines should be
followed:
1. Do not allow the tower’s leaving water temperature to drop below a
minimum allowable level—say 36°F to 40°F (2°C to 4.5°C). If such
low temperature operation is necessary or beneficial to your process,
establish the minimum allowable level as follows:
During the coldest days of the first winter of operation, observe whether
any ice is forming on the louver face, particularly near the bottom
part of the louver face. If hard ice is present on the louvers, you must
increase the allowable cold water temperature. If the coldest possible
water is beneficial to your process, ice of a mushy consistency can
be tolerated—but routine periodic observation is advisable.
If the minimum allowable cold water temperature is established at
or near minimum heat load, it should be safe for all operating condi-
tions.
Having established the minimum allowable cold water temperature, main-
taining that temperature can be accomplished by fan manipulation, as
outlined in
item 4 under Tower Operation. However, in towers of more
than one cell, where fans are manipulated sequentially, please realize
that the water temperature will be significantly lower in the cell or cells
operating at the highest fan speed than the net cold water temperature
Caution
Operation