Application data (cont)
Minimum fluid-cooled condenser flow —
This value
(maximum rise) is shown in Minimum Cooler and Con-
denser Fluid Flow Rates and Minimum Loop Volume table
on page 13. Condensers may be piped in series. Ensure
leaving fluid temperature does not exceed 104 F (40 C).
Variable cooler flow rates —
These rates may be applied
to standard chillers. However, the unit will attempt to main-
tain a constant leaving chilled fluid temperature. In such cases,
minimum flow must be in excess of minimum flow given in
the Minimum Cooler and Condenser Fluid Flow Rates and
Minimum Loop Volume table, and flow rate must change
in steps of less than 10% per minute. Apply 6 gal per ton
(6.5 L per kW) fluid loop volume minimum if flow rate
changes more rapidly.
Chilled fluid loop volume —
The volume in circulation
must equal or exceed 3 gal per nominal ton of cooling
(3.25 L per kW) for temperature stability and accuracy in
normal air conditioning applications. See Minimum Cooler
and Condenser Fluid Flow Rates and Minimum Loop Vol-
ume table on page 13. (For example, a 30HR100 would
require 294 gal [1112.8 L] in circulation in system loop —
see Minimum Cooler and Condenser Fluid Flow Rates and
Minimum Loop Volume table on page 13.) For process jobs
where accuracy is vital, or for operation at ambient tem-
perature below 32 F (0° C) with low unit loading conditions,
there should be from 6 to 10 gal. per ton (6.5 to 10.8 L
per kW). To achieve this volume, it is often necessary to
install a tank in the loop. Tank should be baffled to ensure
there is no stratification, and that water (or brine) entering
tank is adequately mixed with liquid in the tank.
NOTE: Tank installation is shown below.
Fouling factor —
The fouling factor used to calculate tabu-
lated ratings was 0.00025 ft
2
•
hr
•
F/Btu (0.000044 m
2
•
KW). As fouling factor is increased, unit capacity decreases
and compressor power increases. Standard ratings should
be corrected using following multipliers:
FOULING FACTOR CORRECTION
FOULING FACTOR
COOLER
CONDENSER
English
SI
Cap.
Power
Cap.
Power
0.0005
0.000088
0.995
1.000
0.990
1.005
0.001
0.000176
0.980
1.000
0.969
1.033
0.002
0.000352
—
—
0.908
1.098
Rating tables are based on 10° F (5.6° C)
D
T in the cooler and 0.00025
ft
2
•
hr
•
F/Btu (0.000044 m
2
•
K/W) fouling factor in both cooler and con-
denser. Also, 10° F (5.6° C)
D
T in condenser for 3-pass parallel, 20° F
(11.1° C)
D
T for 6-pass parallel, and 40° F (22.2° C)
D
T for 6-pass se-
ries circuiting arrangements.
PERFORMANCE CORRECTIONS
1. Corrected Cooling Capacity = Rated Cooling Capacity x all correc-
tion factors.
2. Corrected Compressor Power Input = Rated Power Input x all cor-
rection factors.
Cooler and fluid-cooled condenser freeze
protection
If chiller or fluid lines are in an area where ambient con-
ditions fall below 32 F (0° C), it is recommended that an
antifreeze solution be added to protect the unit and fluid
piping to a temperature 15° F (8.3° C) below the lowest
anticipated temperature. Corrections to performance as in-
dicated in Capacity Correction and Selection Procedure sec-
tions on pages 15 and 17 must be applied.
Use only antifreeze solutions approved for heat exchanger
duty. Use of automotive antifreezes is not recommended
because of the fouling that can occur once their relatively
short-lived inhibitor breaks down.
If not protected with an antifreeze solution, draining cooler
and outdoor piping is recommended if system is not to be
used during freezing weather conditions.
30HS condenser requirements
1. Ensure each refrigerant circuit has its own head pres-
sure control.
2. Condenser must provide 15° F (8.3° C) subcooling, a
maximum of 40° F (22.2° C) difference between satura-
ted condensing temperature and outdoor ambient
temperature (to prevent overload at high ambient
temperatures), and a minimum of 20° F (11.1° C) dif-
ference (to assure subcooling).
3. Do not manifold independent refrigerant circuits into a
single condenser.
4. Condenser should not be located more than 50 ft
(15 m) below chiller to maintain subcooling.
5. Design discharge and liquid piping according to Carrier
System Design Manual.
TANK INSTALLATION
14
