SC3-600
March 2000
Part No. 25001301
Direct Drive
Fluid Coolers
Installation and
Maintenance Data
Table of Contents
Inspection
System Warranty
Installation ........................................2
Mixing Glycol and Water
Glycol Sludge Prevention
Fluid Circulating Pump....................................8
Rigging Instructions...........................3
Internal Volume and Weight ..............4
Start-up
Space and Location Requirements ............9-10
Typical Piping
In-Warranty Return Material Procedure..........11
Electrical Wiring ............................ 4-6
System Installation
Piping Installation
Replacement Parts ....................................... 12
Glycol Charge ...................................7
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Figure 1. Rigging Instructions.
similar distance should be maintained between adjacent units.
Sufficient free area should be left around and below unit to
avoid air restriction to coil.
Vertical airflow type units should be located no closer
than the width of the unit from a wall or other obstruction. It
two or more units are to be positioned in the same area, a
3
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Table 1. Fluid Cooler Internal Volume and Weight
Fluid
Cooler
Fan Configuration
Number
of
Fans
Number
of
Rows
Internal
Volume
Gallons
Approximate
Net Weight
(Lbs.)
1 x 2
1 x 2
1 x 2
1 x 3
1 x 3
1 x 4
1 x 4
1 x 5
1 x 5
2
2
2
3
3
4
4
5
5
2
3
4
3
4
3
4
3
4
6.7
9.2
1540
1590
1600
2360
2420
3150
2190
3510
3990
11.8
13.0
16.7
16.7
21.7
20.4
26.6
1 x 6
6
4
31.6
4790
2 x 2
2 x 2
2 x 2
2
2
2
2
3
4
13.5
18.5
23.5
1540
1620
1760
2 x 3
2 x 3
2 x 4
2 x 4
2 x 5
2 x 5
3
3
4
4
5
5
3
4
3
4
3
4
25.9
33.4
33.3
43.3
40.7
53.1
2420
2480
3230
3510
4040
4390
2 x 6
6
4
63.1
5270
Electrical Wiring
Electrical leads from each motor terminate at the unit
junction box. Field connections must be made from these leads
through a contactor, fuse and disconnect in accordance with
local, state and national codes.
The electrical installation should be in accordance with
National Electrical Code, local codes and regulations. Proper
overcurrent protection should be provided for the fan motors.
Wiring diagrams shown are only basic and do not show fuses,
disconnect switches, etc., which must be provided in the field.
Three-phase motors must be connected to three-phase
power of voltage to agree with motor and unit dataplate.
All standard motors have internal inherent overload
protectors. Therefore, contactors can be used instead of
starters requiring thermal protectors, eliminating the problem
of furnishing the proper heating elements.
The motors are wired into a common junction box. The
motors must be checked for proper rotation. Be sure to check
that motor voltage and control connection agree with electric
services furnished.
All dry coolers or units are furnished with either single-
phase or three-phase fan motors which are identified by the
unit dataplate.
4
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Diagram 1. Typical Fluid Cooler Wiring Diagram Without Fan Cycle Controls.
Single Row of Fans
Double Row of Fans
5
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Diagram 2. Typical Fluid Cooler Wiring Diagram With Standard Fan Cycle Controls.
Single Row of Fans
Double Row of Fans
6
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System Installation
tain the proper glycol-to-water ratio.
NOTE: All installation and maintenance are to be performed
only by qualified personnel who are familiar with local codes
and regulations, and experienced with this type of
equipment. CAUTION: Sharp edges and coil surfaces are
a potential injury hazard. Avoid contact with them.
Table 3 shows pressure drops for various pipe sizes at
flow rates commonly used with a typical dry cooler. These
pipe sizes are not necessarily always correct for the run from
the condenser to the dry cooler. Proper pipe size will depend
on available pump head. This can be determined by subtract-
ing from the total available pump head at design flow, the con-
denser pressure drop and the dry cooler pressure drop. Allow
some safety factor for last minute pipe fittings added to the
system and for eventual fouling of the system.
General
1. Structure supporting unit must be designed to support both
the unit and the fluid. Table 2 provides weight of fluid per
gallon. Tables 3 and 4 provide unit weight and volume
data. Provide suitable flashing of the roof, if this is a roof
installation. For ground level mounting, a concrete pad is
a. Glycol piping requires no insulation except when fluid tem-
perature will be below ambient dewpoint temperatures.
Dry coolers normally produce about 70° or higher fluid
temperatures.
recommended. Mounting holes permit the unit to be bolted b. Vents are required at all high points in the piping to bleed
down to withstand wind pressures. Provide adequate clear-
ance for unobstructed air flow to coils. See page 2 for
Space and Location requirements.
air when filling the system. If fluid coolers are at high
points, vent valves should be installed at each fluid cooler.
c. It is recommended that gate valves be installed on
both sides of the pump to prevent loss of fluid in the event
the pump should require repair or replacement. Shut-off
valves are also recommended at water cooled condensers
in case the condensing unit is to be moved or requires
maintenance involving the coolant system.
2. Level mounting is necessary to assure proper fluid distr-
Table 2. Fluid Weight Per Gallon
Percent Glycol
Pounds Per Gallon
0 (Water)
8.345
8.395
8.495
8.604
8.712
8.804
10
20
30
40
50
Table 3. Pressure Loss in Feet of Water
Pipe Type "L" Schedule 40 Steel Copper Tube Head
Size
Steel
O.D.
Head Ft./100 Ft. Head Ft./100 Ft.
Flow
GPM
15
20
25
25
30
35
40
40
45
60
60
Copper Equiv. Length
Equiv. Length
1
1
1
1
1
1
1
/
8
17.6
30.2
15.0
23.1
1
/
8
1
/
8
—
34.6
12.6
17.4
23.0
26.3
12.9
15.7
26.3
7.0
1 1/4
1 1/4
1 1/4
1 3/8
1 3/8
1 3/8
1 3/8
1 5/8
1 5/8
1 5/8
2 1/8
2 1/8
2 5/8
2 5/8
3 1/8
3 1/8
3 5/8
4 1/8
4 1/8
4 1/8
11.5
16.3
21.8
—
13.0
16.5
—
bution through the coil as well as flooded suction for the
pump.
3. Water piping must comply with local codes. Correct pipe
sizing will help reduce pumping power and operating costs.
—
1
1
1
/
/2
2
1
4.
In case of doubt, consult the manufacturer for the dry
cooler fluid pressure drop at the specific conditions on
your job.
—
2
7.9
80
2
13.7
12.0
100
150
200
250
300
300
350
400
2 1/2
2 1/2
3
8.5
6.1
12.9
9.1
13.7
9.2
5.
Provide sufficient valves and unions to permit easy ac-
cess to parts subject to wear and possible repair or re-
placement.
18.6
10.7
16.5
11.1
5.9
3
3 1/2
4
6. After fluid piping is completed, all joints should be leak
tested.
4.9
4
4
7.9
6.5
10.2
8.2
7. Where city water makeup is required, follow local codes,
making certain that disconnecting provisions are provided.
8. Select wire in accordance with nameplate data and local
codes.
Glycol Charge
The amount of ethylene glycol required depends upon
the following:
Piping Installation
a. The holding volume of the system which includes the hold-
ing capacity of the condenser, the holding capacity of the
interconnecting piping (Table 3) and the holding capacity
of the dry cooler (see Table 3).
The piping system should provide maximum leak pre-
vention. Weld or sweat joints should be used where possible
or tightly drawn Teflon tape threaded pipe joints should be made
if needed. The fact that glycol solutions or other heat transfer
fluids will leak where water will not, must be taken into ac-
count.
b. Percentage of glycol required by volume to provide pro-
tection at the design minimum outside temperature (see
Table 2).
The glycol system should not employ a pressure reduc-
ing valve. This is because a slight leak would lead to dilution
of the mixture. Any refill should be controlled so as to main-
7
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Table 4. Percentage of Ethylene Glycol to be Added by
Volume.
Fluid Circulating Pump
Mechanical seal type pumps must be used for glycol
systems. Gland type pumps would cause glycol waste and, if
used with a pressure reducing valve, will lead to dilution of the
glycol mixture and eventual freeze-up.
Percent %
20% 30% 40% 45% 50%
Minimum Outside Design
Temperature °F
+15 -3 -14 -23 -38
Table 4 is intended to be used as a guide only. Proper precautions need to
be taken to prevent freeze damage during low ambients. Consult glycol ven-
dor recommendations for specific freeze protection for your location.
Pump is selected for piping friction loss plus fluid pres-
sure drop through the dry cooler coil, plus pressure drop
through the heat source. No allowance for vertical lift is made
since in a closed system a counterhead acts on the pump suc-
tion.
Mixing Glycol and Water
With glycol solution the pump performance curve will
drift to the right from its design point, due to differences in
circuit design, control valve application, pressure drop calcu-
lations, etc. The pump should be selected high on the curve
so as to provide for the "drift". The pump curve should be
"flat" so that the pump will compensate for our inability to ex-
actly predict the final operating system flow condition and to
provide sufficient flow for satisfactory heat transfer and maxi-
mum protection against freezing at the far end of the circuit.
The pump motor should have sufficient power for operating
over the entire pump curve to prevent motor overload at re-
duced voltages. Paralleled pumps can also be used for good
power economy and continuous and automatic standby op-
eration. Properly applied parallel pumps will guard against
system breakdown caused by a simple pump failure. Certain
older systems have nonoperating standby pumps of equal
capacity to the operating unit. We recommend parallel pumps
in continuous operation because they provide practically the
same type of standby, in addition to being completely auto-
matic, at lower initial and operating cost.
Regardless of the strength of the mixture, you MUST
pre-mix the glycol and water prior to adding it to the system.
The chemical reaction between the two will release oxygen,
which is extremely undesirable in a close-loop system.
WARNING: For dry coolers operating without glycol
mixture, adequate freeze protection is
necessary during ambients below 32° F.
Glycol Sludge Prevention
Glycol systems may be subject to sludge formation in
coils, due to one or more of the following causes:
1. Reaction of the corrosion inhibitor with galvanized piping
(zinc).
2. Reaction of the glycol with chromate type water additives.
3. Reaction of the glycol with pipe dope, cutting oils, solder
flux, and other system dirt.
Glycol manufacturers offer a specially inhibited glycol
(formulated for snow melting systems) which does not react
with zinc. This glycol is also suitable for heat transfer sys-
tems. Glycol manufacturers also provide inhibitor check ser-
vices on a regular basis.
Consequently, good glycol system design requires the
following precautions:
1. No galvanized piping is to be used.
2. System piping must be thoroughly cleaned and flushed
with a heated trisodium phosphate solution before filling
wit the water/glycol mixture.
3. No chromate inhibitor treatment must be used.
4. The glycol manufacturer should provide inhibitor check
service and supply additional inhibitor as required.
8
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Start-up
1. Prestart:
Connect a pump and hose to the hose bibb away
from the pump and a hose to the hose bibb closest
to the pump. Begin pumping the glycol mixture into
the system at FULL PRESSURE. For the return
hose you should close the hose bibb so that you
get only a small flow of fluid or air. This is
necessary so you will build a head of fluid which will
force the air from the system. Once all the air is out
you will have a steady flow of only fluid. At this joint
you should close off the two hose bibbs and open
the shut off valve. See Diagram 3.
Check for correct dry cooler fan rotation. This can be done
by quickly jogging the fan contactor. Be sure that the fans
run freely. The same check is recommended for pumps.
2. Filling and Purging the System
The system should be pressure tested before adding glycol.
The system can be tested with air or water, however if the
ambient temperature is at or below freezing the use of air
is recommended. Test pressure should not exceed 60
PSIG.
a.
Roof Mounted Fluid Cooler
3.
4.
Flow Adjustment Procedure:
To fill the system, pour the premixed water and glycol
into the expansion tank. Fill the system until the
expansion tank is half full, then purge the air from
ALL vents. Operate the system for a minute, then
purge ALL vents again, and add glycol as required.
Repeat the purging of all vents after the first hour of
operation and again after several hours of operation.
Once the system is completely full of fluid, start the fluid
circulating pump. To assure proper fluid flow, adjust the
shut-off valve for required GPM by checking pump curve
and observing gauge pressure, or by using an in-line flow
meter.
Instruction Envelope:
b.
Ground Mounted Fluid Cooler
Keep wiring diagrams, instructions, list of spare parts, in
an envelope within easy reach of the installed dry cooler.
The fluid cooler may be lowest point in the system,
consequently the premixed water and glycol will have
to be pumped into the system. Close the shut off valve
and open the two hose bibbs installed in the piping
run on the leaving side of the pump, see piping
diagram.
Diagram 3.
Space and Location Requirements
Another consideration which must be taken is that the
The most important consideration which must be taken
into account when deciding upon the location of air-cooled
equipment is the provision for a supply of ambient air to the
condenser, and removal of heated air from the fluid cooler
area. Where this essential requirement is not adhered to, it
will result in higher head pressures, which cause poor operation
and possible eventual failure of equipment. Units must not be
located in the vicinity of steam, hot air or fume exhausts.
unit should be mounted away from noise sensitive spaces
and must have adequate support to avoid vibration and noise
transmission into the building. Units should be mounted over
corridors, utility areas, rest rooms and other auxiliary areas
where high levels of sound are not an important factor. Sound
and structural consultants should be retained for
recommendations.
9
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Walls or Obstructions
The unit should be located so that air may circulate freely room is left for maintenance work through access doors and
and not be recirculated. For proper air flow and access all panels. Overhead obstructions are not permitted. When the
unit is in an area where it is enclosed by three walls the unit
must be installed as indicated for units in a pit.
sides of the unit should be a minimum of “W” away from any
wall or obstruction. It is preferred that this distance be increased
whenever possible. Care should be taken to see that ample
Multiple Units
For units placed side by side, the minimum distance
between units is the width of the largest unit. If units are placed
end to end, the minimum distance between units is 4 feet.
Units in Pits
The top of the unit should be level with the top of the pit,
and side distance increased to “2W”.
If the top of the unit is not level with the top of pit, dis-
charge cones or stacks must be used to raise discharge air to
the top of the pit. This is a minimum requirement.
Decorative Fences
unit. If these requirements are not met, unit must be installed
as indicated for “Units in pits”.
Fences must have 50% free area, with 1 foot undercut,
a “W” minimum clearance, and must not exceed the top of
* “W” = Total width of the fluid cooler.
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Diagram 4. Typical Piping
In-Warranty Return Material Procedure
Material may not be returned except by permission of
authorized factory service personnel of Sterling, Inc. in
The return of a part does not constitute an order for
replacement. Therefore, a purchase order must be entered
New Berlin, Wisconsin. A “Return Goods” tag will be sent through your nearest Sterling, Inc. representative. The
to be included with the returned material. Enter the required
information on the tag in order to expedite handling at our
factories and prompt issuance of credits. All parts shall be
returned to the factory designated on the “Return Goods” tag,
transportation charges prepaid.
order should include part number, model number and serial
number of the unit involved.
Following our careful inspection of the returned part and if
it is determined that the failure is due to faulty material or
workmanship, credit will be issued on customer's purchase order.
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Sterling, Inc.
2900 S. 160th Street
New Berlin, WI 53151
262-641-8610 y Fax: 262-641-8653
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