When a remote air cooled condenser is installed
outdoors, it will be subjected to varying
temperatures. Within many areas, winter to
summer annual temperatures swings can be as
high as 120
impact on the performance of the condenser. As the
ambient temperature drops, the condenser capacity
increases due to the wider temperature difference
between ambient and condensing. As this happens,
the condensing temperature also drops as the
system finds a new balance point. Although the
overall system capacity will be higher at lower
condensing temperatures, other problems can
occur. The capacity of an expansion valve is
affected by both the liquid temperature entering the
valve and the pressure drop across it. As the
condensing temperature decreases, the pressure
drop across the metering device also decreases. A
lower pressure drop decreases the capacity of the
valve. Although lower liquid temperatures increase
the capacity of the metering device, the increase is
not large enough to offset the loss due to the lower
pressure drop.
The following three sections cover the various
options used to control condensing temperatures.
(i) Fan Cycling
Cycling of the condenser fans helps control the
condensing temperature. With this approach to
solving low ambient problems, fans are taken
off-line either one at a time, or in pairs. It is not
recommended that multiple fan condensers cycle
more than two fans per step. The reason for this is
that the pressure in the condenser will increase
drastically as several fans are taken off-line at the
same time. This will result in erratic operation of the
refrigeration system and applies additional stress to
the condenser tubes. It is preferable to control the
condensing temperature as smoothly as possible.
Fans should be cycled independently on a
condenser where the fans are all in a single row .
On two row condensers, the fans should be cycled
in pairs.
o
F (48.9 oC) which will have a major
prevent short cycling of the fans. Constant short
cycling will produce a volatile condensing pressure
while decreasing the life of the fan motors.
For recommended fan cycling switch settings, refer
to Table 2. Differential settings on fan cycling
temperature controls should be about 5
o
F (2.8 oC).
On fan cycling pressure controls, a differential of
approximately 35 psig is recommended.
Fans closest to the inlet header should be run
continuously whenever the compressor is running.
If these initial fans are wired through a cycling
control, the life of the condenser may be shortened
due to the additional stress placed on the tubes and
headers. Table 1 shows the fan cycling options
available for all condenser models.
(ii) Variable Motor Speed Control
If additional head pressure control is required beyond
the last step of fan cycling, variable fan motor speed
may be used. V ariable motor speed is optional on all
condenser models. A varying motor speed may be
accomplished using a modulating pressure control.
A variable speed controller can be an electronic or
solid state device which varies the voltage going to
the motor depending on the pressure of the medium
being sensed.
(iii) Refrigerant Regulating Controls
Pressure regulating controls are available from a
number of valve manufacturers. The purpose of this
control is to regulate the refrigerant flow in such a
way as to maintain a pre-selected condensing
pressure. In lower ambient temperatures, these
valves throttle to maintain the desired pressure and
in doing so, flood the condenser with liquid
refrigerant.
The larger the condenser surface is, the higher its
capacity will be. When a condenser is flooded, its
useful condensing surface is reduced. This is
because the refrigerant occupies the space which
would otherwise be used for condensing.
Ambient temperature sensing controls can be set to
bring on certain fans when the outdoor temperature
reaches a predetermined setpoint. Pressure
sensing controls are set to bring on certain fans
when the condensing pressure reaches the setpoint
on the control. Temperature or pressure setpoints
and differentials should be set in such a way as to
Some control/check valve combinations will
regulate refrigerant flow depending on the pressure
at the inlet of the condenser.These are of ten referred
to as inlet regulators. As the valve closes, hot gas
bypasses the condenser through a differential check
valve to increase the pressure at the receiver.
- 12 -
LOW AMBIENT OPERATION
CONDENSER
ORI
VALV E
LIQUID RECEIVER
CONDENSER
SINGLE VALVE
HEAD
PRESSURE
CONTROL
LIQUID RECEIVER
SINGLE V ALVE CONDENSER PRESSURE CONTROL
(Regulates inlet pressure or outlet pressure depending on valve design)
ORD
DIFFERENTIAL
CHECK VA LVE
ORI / ORD CONDENSER PRESSURE CONTROL
This will flood the condenser until the condensing
pressure increases to a point which will again open
the valve. Other valves regulate the refrigerant at the
outlet of the condenser to provide a similar effect.
These are commonly referred to as outlet regula-tors. There are also combination inlet/outlet
regulators with a differential check valve or other
type of condenser bypass arrangement incorporated within the valve.
Controls which regulate the flow of refrigerant based
on condenser inlet pressure are typically used in
conjuction with a check valve having a minimum
opening differential across the condenser. Outlet
regulators typically require a check valve with a fixed
pressure differential setting of between 20 and 35
psi. The differential is needed to compensate for
pressure drop through the condenser during flooding and associated discharge piping.
Systems equipped with a condenser flooding
arrangement should always use a receiver having
sufficient liquid holding capacity . Additional liquid
required for flooding is only required during the
winter low ambients and must be stored somewhere in the system at the higher ambients. Failure
to use an adequately sized receiver will result in
liquid back-up in the condenser during the warmer
summer months. This will cause the system to
develop very high pressures in the high side resulting in a high pressure safety control trip.
Determining Additional Flooded
Refrigerant Charge
Additional charge will vary with the condenser
design TD and the coldest expected ambient
temperature. Condensers designed for low TD
applications (low temperature evaporators) and
operating in colder ambients will require more
additional charge than those designed for higher
TD applications (high temperature evaporators)
and warmer ambients.
Refer to tables on pages 15 & 16 to determine
the required added refrigerant charge at the
selected TD and ambient temperatures.
These charges are based on condensers using Fan
Cycling options with their last fan (Single Row Fan
Models) running or last pair of fans running (Double
Row Fan models).
WARNING: Do not over charge when charging by a
sightglass. Liquid lines feeding the TXV at the
evaporator must have a solid column of liquid (no
bubbles) however bubbles at the sightglass (located
adjacient to the receiver) may be normal due to the
result of a higher pressure drop at that point. Bubbles
could also appear in the glass whenever the
regulating valves start to flood the condenser .
Always record the number of drums or the weight of
refrigerant that has been added or removed in the
system. Overcharged systems may result in
compressor failure as well as other serious
mechanical damage to the system components.
- 13 -
LOW AMBIENT OPERATION
Table 1 - Fan Cycling Control Schedule
FAN ARRANGEMENT
SINGLE ROW
1 FAN
HEADER END
FAN
1
CONTROL
PANEL END
2 FAN
FAN
1
FAN
2
3 FAN
FAN
1
FAN
2
FAN
3
FANS CYCLED
1 ST AGE
2’ND STAGE
1’ST STAGE
FANS A VAILABLE
FOR VARIABLE
SPEED CONTROL
Table 2 - Ambient Fan Cycling Thermostat Settings
SNAFFOREBMUN
RESNEDNOCNO
SLEDOMWORELGNISEGATSts1EGATSdn2
F°.D.TNGISED)C°(
FANS IN CONST ANT
OPERA TION
F°*SGNITTESTATSOMREHT)C°(
03)7.6
1(
52)9.31(
2
02)1.11(
51)3.8(
01)6.5(
03)7.61(
52)9.31(
3
02)1.11(
51)3
.8(
01)6.5(
06)6.51(
56)3.81(
07)1.12(
57)9.32(
08)7.62(
06)6.51(
56)3.81(
07)1.12(
57)9.32(
08)7.62(
04)4.4(
55)8.21(
06)6.51(
56)3.81(
57)9.32(
* NOTE: These are typical settings. Further adjustments may be necessary to suit actual field conditions.
A thorough inspection of the equipment, including all
component parts and accessories, should be made
immediately upon delivery . Any damage caused in transit,
or missing parts, should be reported to the carrier at once.
The consignee is responsible for making any claim for
losses or damage. Electrical characteristics should also
be checked at this time to ensure that they are correct.
LOCATION
Before handling and placing the unit into position a review
of the most suitable location must be made. This
condenser is designed for outdoor installation.
A number of factors must be taken into consideration
Horizontal Air Discharge
(Standard Shipping Configuration)
when selecting a location. Most important is the provision
for a supply of ambient air to the condenser, and removal
of heated air from the condenser area.
Higher condensing temperatures, decreased
performance, and the possibility of equipment failure
may result from inadequate air supply .
Other considerations include:
1. Customer requests
2. Loading capacity of the roof or floor.
3. Distance to suitable electrical supply.
4. Accessibility for maintenance.
5. Local building codes.
6. Adjacent buildings relative to noise levels.
WALLS OR OBSTRUCTIONS
All sides of the unit must be a minimum of 4 feet
(1.25 m) away from any wall or obstruction. Overhead
obstructions are not permitted. If enclosed by three
walls, the condenser must be installed as indicated for
units in a pit.
4 ft
(1.25 m)
min.
LOUVERS/FENCES
Louvers/fences must have a minimum of 80% free area
and 4 feet (1.25 m) minimum clearance between the
unit and louvers/fence. Height of louver/fence
must not exceed top of unit.
MULTIPLE UNITS
A minimum of 8 feet (2.5 m) is required between
multiple units placed side by side. If placed end to end,
the minimum distance between units is 4 feet(1.25 m).
8 ft
(2.5 m)
min.
Note: Units shown without optional mounting legs
4 ft
(1.25 m)
min.
4 ft
(1.25 m)
min.
- 17 -
INSTALLATION
Vertical Air Discharge
(Requires Optional Mounting Leg Kit)
WALLS OR OBSTRUCTIONS
All sides of the unit must be a minimum of 4 feet
(1.25 m) away from any wall or obstruction. Overhead
obstructions are not permitted. If enclosed by three
walls, the condenser must be installed as indicated for
units in a pit.
4 ft
(1.25 m)
min.
UNITS IN PITS
The top of the condenser must be level with, or above the
top of the pit. In addition, a minimum of 8 feet(2.5 m) is required between the unit and the pit walls.
MULTIPLE UNITS
A minimum of 8 feet (2.5 m) is required between
multiple units placed side by side. If placed end to end,
the minimum distance between units is 4 feet(1.25 m).
8 ft
(2.5 m)
min.
LOUVERS/FENCES
Louvers/fences must have a minimum of 80% free area
and 4 feet (1.25 m) minimum clearance between the
unit and louvers/fence. Height of louver/fence
must not exceed top of unit.
8 ft
(2.5 m)
min.
8 ft
(2.5 m)
min.
PLACEMENT
Once a suitable location is selected ensure all the remote
mounting parts (legs and hardware) are available. Refer to
Fig.1b (P. 19) and the dimensional data on page 6 for the leg
mounting locations.
4 ft
(1.25 m)
min.
Note: Units shown with optional mounting legs
4 ft
(1.25 m)
min.
- 18 -
INSTALLATION
Fig. 1 - LIFTING / OPTIONAL LEG INSTRUCTIONS
Fig. 1a - LIFTING POSITIONS
FOR HORIZONTAL AIR FLOW
CONFIGURATION
Lower unit into vertical
air flow position, taking
care not to damage coil
surface under unt.
Optional horizontal
For horizontal air flow
configuration, Outlet
header connection
MUST be at the bottom.
leg kit shown.
Air cooled condensers are large, heavy mechanical
equipment and must be handled as such. A fully qualified
and properly equipped crew with necessary rigging should
be engaged to set the condenser into position. Lifting
brackets or holes have been provided at the corners for
attaching lifting slings. S preader bars must be used when
lifting so that the lifting force must be applied vertically .
Under no circumstances should the coil headers or
return bends be used in lifting or moving the condenser.
Ensure the unit is placed in a level position (to ensure
proper drainage of liquid refrigerant and oil). The legs
should be securely anchored to the building structure,
sleeper or concrete pad. The weight of the condenser is
not enough to hold in place during a strong wind, the legs
must be anchored.
Fig. 1b - LIFTING POSITIONS
FOR MOVING INTO VERTICAL
AIR FLOW POSITION
Legs are fastened to
end panel side flanges
usiing 5/16-18 bolts and
lock-nuts provided with
optional leg kit.
DISCHARGE LINES
Discharge lines should be designed to minimize
refrigerant pressure drop, since high pressure losses
increase the required compressor horsepower per ton of
refrigeration.
Discharge lines must be pitched away from the
compressor to ensure proper drainage of oil being carried
in the line.
A discharge check-valve at the bottom of a vertical riser
will prevent oil (and liquid refrigerant) from draining back to
the compressor during the off-cycle. When the vertical lift
exceeds 30 feet(9 m), insert close-coupled traps in the
riser at 30 feet(9 m) intervals.
An alternate method of handling the oil problem would be
the addition of an oil separator see Figure 3 (b).
REFRIGERANT PIPING
All refrigeration piping must be installed by a qualified
refrigeration mechanic. The importance of correct
refrigerant pipe sizing and layout cannot be overemphasized. Failure to observe proper refrigerant piping
practices can result in equipment failure which may not be
covered under warranty .
All air cooled condensers are supplied complete with
headers and refrigerant connections sized for connecting
to standard refrigeration tubing.These connections may
not be the same as the actual line sizes required for the
field installation. Refer to a recognized source (ASHRAE
charts, manufacturer’s engineering manuals etc.) for line
sizing.
A reverse trap should be installed at the top of all vertical
risers. The top of the reverse trap should be the highest
point in the discharge line and should have an access
valve installed to allow the reclaimation of non-condensible
gas from the system.
Pulsation of the hot gas in the discharge line is an inherent characteristic of systems utilizing reciprocating
compressors. The discharge line must be rigidly supported along its entire length to prevent transmission of
vibration and movement of the line.
CONDENSA TE LINES
The condensate line must be designed to allow free
drainage of refrigerant from the condenser coil to the
receiver. Refer to Fig. 4 for typical condensate line piping
when utilizing head pressure regulating valves.
- 19 -
Fig. 2 - 5
INSTALLATION
TYPICAL SYSTEM PIPING
Figure 2 - Single Circuit
Figure 4 - Single circuit regulator valve
head pressure control
Figure 3(a) - Single circuit with
double discharge riser
(may be required with
capacity control)
Figure 5 - Multiple circuits
Figure 3(b) - Single circuit with
Oil Separator (may be
required with capacity
control)
15
LEGEND
1 - Compressor
2 - Air Cooled Condenser
3 - Receiver
4 - Condensate Line
5 - Discharge Line
6 - Trap-minimum 18” (157 mm)
7 - Reverse Trap-minimum
All wiring and connections to the air cooled condenser
must be made in accordance with the National Electrical
Code and all local codes and regulations. Any wiring
diagrams shown are basic and do not necessarily
include electrical components which must be field
supplied. (see pages 7-10 for typical wiring diagrams).
Refer to the Electrical Specifications table on p age 3 for
voltage availability and entering service requirements.
SYSTEM ST ART-UP CHECKS
1. Check the electrical characteristics of all components
to be sure they agree with the power supply .
2. Check tightness of all fans and motor mounts.
3. Check tightness of all electrical connections.
4. Upon start-up, check fans for correct rotation. Air is
drawn through the condenser coil. T o change rot ation
on 3 phase units reverse any two (2) fan motor leads.
5. All system piping must be thoroughly leak checked
before a refrigerant charge is introduced.
MAINTENANCE
A semi annual inspection should be carried out by a
qualified refrigeration service mechanic. The main power
supply must be disconnected.
1. Check electrical components. Tighten any loose
connections.
2. Check control capillary tubes and lines for signs of wear
due to excessive vibration or rubbing on metal parts.
Secure if necessary .
3. Check tightness of all fans and motor mounts. Remove
any deposits which could effect fan balance. Note: Fan
motors are permanently lubricated and require only
visual inspection.
4. Clean the condenser coil using a soft brush or by
flushing with cool water or coil cleansers available
through NRP (National Refrigeration Products Inc.)
5. Update service log information (back page of service
manual)
The terms and conditions as described below in the General Warranty Policy cover all products
manufactured by National Refrigeration.
GENERAL WARRANTY POLICY
Subject to the terms and conditions hereof, the Company warrants all Products, including Service
Parts, manufactured by the Company to be free of defects in material or workmanship, under normal
use and application for a period of one (1) year from the original date of installation, or eighteen (18)
months from the date of shipment from the Company, whichever occurs first. Any replacement
part(s) so supplied will be warranted for the balance of the product’s original warranty. The part(s) to
be replaced must be made available in exchange for the replacement part(s) and reasonable proof of
the original installation date of the product must be presented in order to establish the effective date
of the warranty , failing which, the ef fective date will be based upon the date of manufacture plus thirty
(30) days. Any labour, material, refrigerant, transportation, freight or other charges incurred in connection with the performance of this warranty will be the responsibility of the owner at the current
rates and prices then in effect. This warranty may be transferred to a subsequent owner of the
product.
THIS WARRANTY DOES NOT COVER
(a) Damages caused by accident, abuse, negligence, misuse, riot, fire, flood, or Acts of God (b) damages
caused by operating the product in a corrosive atmosphere (c) damages caused by any unauthorized
alteration or repair of the system affecting the product’s reliability or performance (d) damages caused
by improper matching or application of the product or the product’s components (e) damages caused
by failing to provide routine and proper maintenance or service to the product (f) expenses incurred for
the erecting, disconnecting, or dismantling the product (g) parts used in connection with normal
maintenance, such as filters or belts (h) products no longer at the site of the original installation (i)
products installed or operated other than in accordance with the printed instructions, with the local
installation or building codes and with good trade practices (j) products lost or stolen.
No one is authorized to change this WARRANTY or to create for or on behalf of the Company any
other obligation or liability in connection with the Product(s). There is no other representation, warranty
or condition in any respect, expressed or implied, made by or binding upon the Company other than the
above or as provided by provincial or state law and which cannot be limited or excluded by such law , nor
will we be liable in any way for incidental, consequential, or special damages however caused.
The provisions of this additional written warranty are in addition to and not a modification of or subtraction
from the statutory warranties and other rights and remedies provided by Federal, Provincial or State
laws.
PROJECT INFORMATION
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- 23 -
“AS BUILT” SERVICE PARTS
04/14/2008
Service Parts ListService Parts List
Service Parts List
Service Parts ListService Parts List
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135 Little Nine Drive, Morehead City135 Little Nine Drive, Morehead City
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252-240-2829 • 1-800-24-BALL252-240-2829 • 1-800-24-BALL