Carrier AQUASNAP JUNIOR 30RA015, Данные о продукции, Страница: 41 / 48

41
Cooler fouling factor
The fouling factor used to calculate tabulated ratings was
0.00010 ft
2
⋅
hr
⋅
°F/Btu (0.000018 m
2
⋅
°C/W). As foul-
ing factor is increased, unit capacity decreases and com-
pressor power increases. Standard ratings should be
corrected using the multipliers in the following table.
FOULING FACTORS
Cooler and hydronic system freeze protection
Freeze protection for down to –20 F (–28.9 C) for the
cooler and hydronic package is available as a factory-
installed option. Since power is sometimes lost for extend-
ed periods during winter storms, freeze protection provid-
ed by heater tapes will be effective only if a back-up power
supply can be assured for the unit’s control circuit, heater
and cooler pump. If not protected with an antifreeze solu-
tion, draining the cooler and outdoor piping is recom-
mended if the system will not be used during freezing
weather conditions.
Two conditions that must be considered when determin-
ing antifreeze concentration are leaving water set point
and ambient freeze conditions. Both of these parameters
can help determine the recommended concentration level.
Higher concentration must be used to adequately protect
the machine.
NOTE: Use only antifreeze solutions approved for heat ex-
changer duty.
For applications in which the leaving water temperature
set point is less than 40 F (4.4 C), a suitable inhibited anti-
freeze solution must be used. The solution concentration
must be sufficient to protect the chilled water loop to a
freeze protection (first crystals) concentration of at least
15° F (8.3º C) below the leaving water temperature set
point.
If the chiller refrigerant or fluid lines are in an area where
ambient conditions fall below 34º F (1º C), it is required
that an antifreeze solution be added to protect the unit and
fluid piping to a temperature of 15º F (8.3º C) below the
lowest anticipated ambient temperature.
Select concentration based on either burst or freeze pro-
tection as dictated by the application. If the chiller does not
operate during the winter, nor is a start-up expected, a
burst protection concentration is recommended. This con-
centration may not be high enough to pump the fluid
through the unit. Burst protection is typically a lower con-
centration that will provide better performance from the
machine. If the chiller does operate during winter, a freeze
protection concentration is recommended. This
concentration will be high enough to keep the fluid in a
condition that it can be pumped at low ambient conditions.
Consult glycol fluid manufacturers for burst protection
recommendations and fluid specifications.
High ambient temperature operation
High outdoor ambient chiller start-up and operation (fully
loaded) is possible for standard 30RA chillers at ambient
temperatures up to 120 F (50 C) at nominal voltage.
Low ambient temperature operation
Units will start and operate down to 45 F (7.2 C) (sizes
010-018) and 32 F (0° C) (sizes 022-055) as standard.
Operation to –20 F (–29 C) requires optional Motor-
master ® V condenser head pressure control as well as wind
baffles, minimum load control, and the accessory liquid line
solenoid. Inhibited propylene glycol or other suitable corro-
sion-resistant anti-freeze solution must be field supplied
and installed in all units for unit operation below 32 F
(0° C). Solution must be added to fluid loop to protect loop
down to 15° F (8° C) below minimum operating ambient
temperature. Concentration should be based on expected
minimum temperature and either “Burst” or “Freeze” pro-
tection levels. At least 6 gal. per ton (6.5 L per kW) of fluid
volume is the recommended minimum for a moderate sys-
tem load.
NOTE: In order for a chiller to operate at –20 F (–29 C)
ambient temperature, the minimum load on the chiller
must be above the minimum step of unloading.
NOTE: As an alternative to requiring a glycol solution, the
cooler may be remotely located. Burying refrigerant lines is
never permitted.
Altitude correction factors
Correction factors must be applied to standard ratings
at altitudes above 2000 ft (610 m) using the following
multipliers:
ALTITUDE CORRECTION FACTORS
Freeze versus burst protection
If chiller operation is not required during winter/off season,
lower glycol concentrations based on “burst” protection
criteria should be considered. Often use of burst protection
results in lower fluid costs and has less impact on chiller
cooler capacity and flow rate. Consult glycol fluid manufac-
turers for burst protection recommendations and fluid
specifications.
FOULING
FACTOR
(English)
(ft
2
⋅
hr
⋅
F/Btu)
FOULING
FACTOR
(SI)
(m
2
⋅
C/kW
CAPACITY
MULTIPLIER
COMPRESSOR
POWER
MULTIPLIER
.00025 .000044 0.991 0.995
.00050 .000088 0.977 0.987
.00075 .000132 0.955 0.979
.00175 .000308 0.910 0.952
IMPORTANT: Glycol anti-freeze solutions are highly
recommended since heater tapes provide no protec-
tion in the event of a power failure.
ALTITUDE
(ft)
ALTITUDE
(m)
CAPACITY
MULTIPLIER
COMPRESSOR
POWER
MULTIPLIER
2,000 610 0.99 1.01
4,000 1220 0.98 1.02
6,000 1830 0.97 1.03
8,000 2440 0.96 1.04
10,000 3050 0.95 1.05