Carrier 30GB060 - Manual (Page 4)

Application data (cont)
per ton (6.5 to 10.8 liters per kW). To achieve this volume,
it is often necessary to install a tank in the loop. Tank
should be baffled to insure that there is no stratification
and that water (or brine) entering tank is adequately mixed
with liquid in the tank.
GOOD
GOOD
Cooler fouling factor used to calculate tabulated ratings
was 0.0005 ft2. hr. °F/Btu (0.000088 m^. K/W). As fouling
factor is increased, both unit capacity and compressor
power decrease. Standard ratings should be corrected
using following multipliers:
FOULING FACTOR
CAPACITY
MULTIPLIER
COMPRESSOR
POWER
MULTIPLIER
ENGLISH
((F . hr. °F/Btu)
SI
(m*. K/W)
0.0005 0.000088 1.00 1 00
0.001 0.000176 0.97 0.98
0.002 0.000352 0.91 0.91
Cooler protection in form of ethylene glycol (or other
suitable brine) is recommended when operating in areas
which experience temperatures below 32 F (0°C) to
protect cooler should there be a loss of cooler heater
power. Even though unit cooler is protected with insula­
tion and an electric heater that protects the cooler down
to 10 F (-12 C), it does not protect water piping external
to unit. 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.
Draining cooler and outdoor piping is recommended if
system is not to be used during freezing weather condi­
tions. See section below for low-ambient operation.
Condenser
Altitude correction factors must be applied to standard
ratings at altitudes above 2000 ft (610m) using following
multipliers:
ALTITUDE
CAPACITY
MULTIPLIER
COMPRESSOR
POWER
MULTIPLIER
ENGLISH
(ft)
SI
(m)
0 0 1 00 1.00
2000 610 0 99 1.01
4000 1220 0 98 1.02
6000 1830 0,97 1.03
8000 2440 0.96 1.04
10000 3050 0.95 1.05
Condenser airflow restrictions 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 shown below.
EXTERNAL
STATIC
RESISTANCE
CAPACITY
MULTIPLIER
COMPRESSOR
POWER
MULTIPLIER ENGLISH
(in. wg)
SI
(Pa)
0.0 0.0 1 00 1.00
0.1 25 0 986 1 01
0.2 50 0 968 1.03
High-ambient temperature — Standard 30GB chillers
can operate to 115 F (46 C) ambient temperature.
Low-ambient operation
Flotronic^“ 30GB chillers with electronic expansion valves
(EXV) will start and operate at ambients down to 0°F
(-18 C) with following field provisions:
Wind baffles must be added for operation below 32 F (0°C).
A WARNING
Operation at low ambient is not recommended if
minimum load on chiller is below minimum step of
unloading.
Protection against freeze-up — It is recommended
that field-installed chilled water piping be protected at
lower ambient temperatures by wrapping with field-supplied
heating cable and covering with 2-in. (50-mm) thick closed­
cell insulation.
Antifreeze solution must be added to water loop to
protect loop down to 15 F (8 C) below minimum operating
ambient temperature.
For operation of EXV-equipped chillers below 0°F
(-18 C) and for operation of TXV-equipped (factory-
installed option) chillers below 32 F (0°C), down to -20 F
(-29 C), the Carrier Motormaster® condenser head pres­
sure control and its associated components must be
added. Consult your local Carrier representative for
complete details.
Provide sufficient volume in the chilled water loop — At
least 6 gallons per ton of refrigerant (6.5 liters per kilowatt)
is recommended minimum, provided there is a moderate
system load.
Capacity Correction (Antifreeze)
Ethylene glycol (or other suitable brine) should be used in
installations where subfreezing temperatures are ex­
pected. Unit performance data must be corrected for
the addition of ethylene glycol as shown in following
example. Correction factors may be derived from follow­
ing curves.
Example: Where a 5 F outdoor temperature is anticipated,
determine concentration of ethylene glycol to protect
system to -10 F ambient temperature at zero flow.
Enter the solution crystallization point curve at -10 F,
read 40% concentration of ethylene glycol is required to
prevent crystals from forming in solution.
Consider the 30GB060 unit from the Selection Pro­
cedure (Water) example (refer to correction curves at
40% solution).