Capacity - Carrier AQUAFORCE 30XA080-500 Product Data

Application data (cont)
Altitude correction factors
Correction factors must be applied to standard ratings
at altitudes above 2000 ft (609.6 m) using the following
multipliers:
ALTITUDE CORRECTION FACTORS
ALTITUDE
(ft) (m)
2,000 609.6
4,000 1219.2
6,000 1828.8
8,000 2438.4
10,000 3048
Condenser airflow — Airflow restrictions on units with
standard fans will affect the unit capacity, condenser head
pressure, and compressor power input. Correction factors
to be applied for external static restrictions up to 0.2 in. wg
(50 Pa) are as follows:
EXTERNAL STATIC
in. wg Pa
0.0 0.0
0.1 25
0.2 50
Multiple chillers
Where multiple chillers are required, or where standby
capability is desired, chillers may be installed in parallel.
Units may be of the same size or different sizes. However,
cooler flow rates must be balanced according to the recom-
mendations for each chiller to ensure proper flow.
Unit software is capable of controlling two units as a sin-
gle plant. Refer to the Controls, Start-Up, Operation, Ser-
vice, and Troubleshooting guide for further details.
Dual chiller control
The ComfortLink™ controller allows 2 chillers (piped in
parallel or series) to operate as a single chilled water plant
with standard control functions coordinated through the
master chiller controller. This standard ComfortLink fea-
ture requires a communication link between the 2 chillers.
There are several advantages to this type of control:
• Redundancy (multiple circuits)
• Better low load control (lower tonnage capability)
• Lower rigging lift weights (2 machines rather than
1 large machine)
• Chiller Lead-Lag Operation (evens the wear between
the two machines)
Parallel dual chiller operation — Parallel Chiller Oper-
ation is the recommended option for Dual Chiller Control.
In this case, each chiller must control its own dedicated
pump or isolation valve. Balancing valves are recom-
mended to ensure proper flow in each chiller. Two field-
supplied and installed dual chiller leaving water tempera-
ture sensors are required, one for each module, for this
function to operate properly.
Consider adding additional isolation valves to isolate
each chiller to allow for service on a machine, and still
allow for partial capacity from the other chiller.
Series dual chiller operation — Series Chiller Opera-
tion is an alternate control method supported by the
ComfortLink control system. Certain applications might
48

CAPACITY

COMPRESSOR POWER
MULTIPLIER MULTIPLIER
0.99 1.01
0.98 1.02
0.97 1.03
0.96 1.04
0.95 1.05
CAPACITY COMPRESSOR
MULTIPLIER POWER MULTIPLIER
1.000 1.00
0.986 1.01
0.968 1.03
require that the two chillers be connected in series. For
nominal 10 F (5.6 C) cooler ranges, use the Minus 1 Pass
Cooler arrangement to reduce the fluid-side pressure drop.
Use the standard cooler pass arrangement for low flow,
high cooler temperature rise applications. Two field-
supplied and installed dual chiller leaving water tempera-
ture sensors are required, one for each module, for this
function to operate properly.
Consider adding additional piping and isolation valves to
isolate each chiller to allow for service on a machine, and
still allow for partial capacity from the other chiller.
Condenser coil protection (Enviro-Shield™)
Refer to the Environmental Corrosion Protection white
paper for more information.
Pre-coated aluminum-fin coils have a durable epoxy-
phenolic coating applied to the fin prior to the fin stamping
process to provide protection in mildly corrosive coastal
environments. Pre-coated coils have an inert barrier
between the aluminum fin and copper tube. This barrier
electrically disconnects the dissimilar metals to minimize
the potential for galvanic corrosion. This economical
option provides substantial corrosion protection beyond
the standard uncoated coil construction.
Copper-fin coils provide increased corrosion resistance
in moderate coastal environments where industrial air pol-
lution is not present. All copper coils eliminate bimetallic
construction to eliminate the potential for galvanic corro-
sion. Application in industrial environments is not recom-
mended due to potential attack from sulfur, sulfur oxide,
nitrogen oxides, carbon and several other industrial air-
borne contaminants. In moderate seacoast environments,
copper-fin coils have extended life compared to standard
or pre-coated aluminum-fin coils.
E-coated aluminum-fin coils have an extremely flexible
and durable epoxy coating uniformly applied to all coil
surfaces. Unlike brittle phenolic dip and bake coatings,
E-coat provides superior protection with unmatched flexi-
bility, edge coverage, metal adhesion, thermal perfor-
mance and most importantly, corrosion resistance.
E-coated coils provide this protection since all coil surfaces
are completely encapsulated from environmental contami-
nation. Specify E-coated aluminum-fin coils for industrial
environments with high levels of air pollution. This option
also provides better protection compared to standard or
pre-coated aluminum-fin coils in industrial environments.
E-coated copper-fin coils have the same flexible and
durable epoxy coating as E-coated aluminum-fin coils.
However, this option combines the natural salt and envi-
ronmental resistance of all-copper construction with the
highest level of corrosion protection. Specify E-coated
copper-fin coils in the harshest combination of coastal and
industrial environments.
Electrical/utility interests
Energy management — Use of energy management
practices can significantly reduce operating costs, espe-
cially during off-peak modes of operation. Demand limiting
and temperature reset are two techniques for accomplish-
ing efficient energy management. See Demand Limiting
(also called load shedding) section below for further details.