Baltimore Aircoil Company 3000 Series Operating And Maintenance Instructions Manual Download Page 9

9

Winter Operation

T

he Series 3000 and Series 1500 Cooling Towers
can be operated at ambient temperatures below
freezing provided proper operating methods are

established and diligently followed. Precautions that must
be taken to insure satisfactory operation include:

• Freeze protection of the water in the cold water basin

when tower is idle.

• Elimination of water in the optional BALANCE CLEAN

®

Chamber and internal piping (Series 3000 only) when
the tower is idle.

• Elimination of water in the optional EASY CLEAN

®

Chamber and internal piping (Series 1500 only) when
the tower is idle.

• Control of ice formation during tower operation.

Freeze protection must be provided for the cold water
basin during shutdown 
since ice formation in the basin
can severely damage the cooling tower. A remote sump
located indoors in a heated space is an ideal method
since the water in the tower and connecting piping will
drain by gravity whenever the circulating pump is
stopped. Where a remote sump arrangement is
impractical, a form of cold water basin heat must be
provided in the tower itself. 
Electric immersion heaters
or steam coils, controlled by a thermostat in the cold
water basin, may be used. Consult your B.A.C.
Representative for details. Additionally, where a remote
sump is not used, all exposed make-up lines and
water piping that does not drain at shutdown should
be traced with electric heater tape and insulated.

Series 3000 Cooling Towers with Optional BALANCE-
CLEAN

® 

Chamber or Series 1500 Cooling Towers with

Optional EASY-CLEAN™ Chamber

Draining the water from the BALANCE CLEAN

®

or

EASY-CLEAN™ Chambers and internal piping is essential
whenever the potential for freezing temperatures exist.
This can be accomplished by utilizing the 1/2" NPT port
drain located on the inboard side of the BALANCE
CLEAN

®

or EASY-CLEAN™ Chamber. There are 3

recommended methods for draining the piping:

1. The preferred approach is to install a normally open
1/2" solenoid valve on the 1/2" drain connection of the
BALANCE CLEAN

®

or EASY-CLEAN™ Chamber. This

valve should be wired in the pump circuit such that it
closes when the pump is energized. The solenoid valve
must be selected to operate with a minimum pressure
differential of zero psi. The zero pressure differential valve
is required due to the limited static head imposed on the
valve from the water column.

or

2. A 1/2" manual valve can be installed on the 1/2" drain
connection of the BALANCE CLEAN

®

or EASY-CLEAN™

Chamber. The valve should be opened during cold
weather operation. CAUTION: The valve must be closed
during warm weather to obtain full thermal performance.

or

3. Remove the 1/2" plug from the 1/2" drain connection of
the BALANCE CLEAN

®

or EASY-CLEAN™ Chamber during

cold weather operation. CAUTION: The plug must be
reinstalled during warm weather to obtain full thermal
performance.

When the cooling tower is operated at wet bulb tempera-
tures below freezing, ice may form on wetted areas in
direct contact with the incoming air. Therefore, the inlet
louvers and outer face of the wet deck surface must be
inspected frequently so that if icing occurs, steps can be
taken to remove the ice before the tower is damaged or
system performance impaired.

When operating at subfreezing ambient temperatures, the
cooling tower will normally produce leaving water temper-
atures appreciably below design. However, low leaving-
water temperatures tend to promote ice formation.
Therefore, when operating in subfreezing ambient
temperatures, the leaving water temperatures should
be maintained as high as possible. The recommended
minimum water temperature in the cold water basin is
43˚F. Additionally, frequent visual inspections should
be performed to detect potential icing problems.

The first step in maintaining a high leaving water tempera-
ture is to ensure the tower operates with the maximum
possible heat load. Next, reduce the tower capacity by
cycling fans. Modulating the water flow rate to the tower is
not recommended as a method for cooling tower capacity
control. (CAUTION: Rapid on-off cycling can cause the
fan motor to overheat. It is recommended that controls
be set to allow a maximum of 6 on-off cycles per hour.)
If the tower is equipped with two-speed motors, operation
at low speed may be sufficient to prevent icing.

(Note: When two speed motors are used, the motor
starter should include a 15 second time delay when
switching from high to low speed.) 
However, it may also
be necessary to cycle fans off periodically to prevent ice
formation and/or to melt ice that accumulates on the
intake louvers and face of the wet deck surface. Again, it is
recommended that the controls be set to allow a
maximum of 6 on-off cycles per hour.

Under severe conditions where fan cycling is insufficient to
prevent icing, it may be necessary to operate the fan(s) in
reverse to remove any ice accumulation by forcing warm
air out to the intake louvers. WARNING: At such times,
DO NOT operate the fans in reverse any longer than is
necessary since extended reverse operation may
cause ice to form on the fan blades, fan stack, or elimi-
nators and damage the tower. 
Because of this possibility,
cooling towers using reverse fan operation for ice removal
should be equipped with a vibration cutout switch and
the duration of reverse operation should be limited to a
maximum of thirty minutes. A time delay of approximately
40 seconds between forward and reverse direction should
be incorporated into the motor controls.

Lastly, the importance of performing frequent visual
inspections and routine maintenance services during oper-
ation in subfreezing weather cannot be overemphasized.
These must be carried out on a routine basis to: 

Summary of Contents for 3000 Series

Page 1: ...ntenance be developed and carried out This bulletin is published as a guide to establishing such a program Included in the bulletin are the recommended services for start up operation and shutdown and...

Page 2: ...tent of impurities in the air and water determines the frequency of most maintenance services and also governs the extent of water treatment which can vary from a simple continuous bleed and biologica...

Page 3: ...r property damage All electrical mechanical and rotating machinery constitute a potential hazard particularly for those not familiar with the design construction and operation Accordingly adequate saf...

Page 4: ...to obtain even water distribution 13 Open the valve in the tower bleed line by others and adjust bleed to the recommended rate See Water Treatment page 10 continued 14 Check the voltage and current o...

Page 5: ...ically purge the EASY CLEAN Chamber of dirt and debris collected by the strainer The strainer should be cleaned periodically as shown in the Recommended Maintenance Schedule This is accomplished by un...

Page 6: ...f the thermal load is less than the design load at the time of unit start up the procedure may produce operating levels greater than that shown It may be necessary to re adjust the float in order to a...

Page 7: ...uch as one of those recommended for lubricating the fan shaft bearings BALTIDRIVE POWER TRAIN The BALTIDRIVE Power Train consists of a specially designed belt with corrosion resistant fan motor sheave...

Page 8: ...ies 3000 and Series 1500 Cooling Towers are con structed of corrosion resistant materials The wet deck sur face is made of an inert synthetic material which requires no protection against rot decay ru...

Page 9: ...eration CAUTION The plug must be reinstalled during warm weather to obtain full thermal performance When the cooling tower is operated at wet bulb tempera tures below freezing ice may form on wetted a...

Page 10: ...M per 100 tons of refrigeration Evaporation Rate Water Flow Rate x Range x 001 Example At a flow rate of 900 GPM and a cooling range of 10 F the evaporation rate is 9 GPM 900 GPM x 10 F x 001 9 GPM If...

Page 11: ...culating pump They should not be batch fed directly into the cold water basin 3 Acid water treatment is not recommended unless the unit s have been furnished with the BALTIBOND Corrosion Protection Sy...

Page 12: ...ment quality Local assistance with service problems The following is a list of retrofit options and accessories to further simplify maintenance access Internal Service Platform Ladder with Handrails E...

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