Carrier AQUASNAP JUNIOR 30RA015 Скачать руководство пользователя страница 38

Страница: 38 / 48

Chiller location

Do not locate near sound sensitive areas without proper
acoustic consideration. Pad isolated from building rooftop
mounting requires consideration for structure-borne trans-
mission. Unit must be level within

-in. per ft when

installed to ensure proper oil return to the compressors.
Clearances must be provided around chillers for airflow,
service and local code requirements. See dimensional
drawings for specific unit clearance requirements. Chiller
fan discharge must be at or above adjacent solid walls.
Installation in pits is not recommended.

Oversizing chillers

Oversizing chillers by more than 15% at design conditions
must be avoided as the system operating efficiency is
adversely affected (resulting in greater or excessive electri-
cal demand). When future expansion of equipment is
anticipated, install a single chiller to meet present load
requirements and add a second chiller to meet the addi-
tional load demand. It is also recommended that 2 smaller
chillers be installed where operation at minimum load is
critical. The operation of a smaller chiller loaded to a
greater percentage over minimum is preferred to operating
a single chiller at or near its minimum recommended value.
Minimum Load Control should not be used as a means to
allow oversizing chillers. Minimum Load Control should be
given consideration where substantial operating time is
anticipated below the minimum unloading step.

Cooler fluid temperature

1. Maximum leaving chilled fluid temperature (LCWT)

for unit is 60 F (16 C). Unit can start and pull down
with up to 95 F (35 C) entering-fluid temperature. It is
recommended that entering-fluid temperature not
exceed 70 F (21 C).

2. Minimum LCWT for standard unit is 40 F (3.3 C). For

leaving-fluid temperatures from 34 to 39.9 F (1° to
3.28 C) a 20% anti-freeze solution, or greater is
required. Application of chiller within the 39.9 to
15 F (3.3 to –9.4 C) range is possible by ordering the
factory-installed ‘brine’ option.

NOTE: Water flowing through cooler should not exceed
100 F (38 C).

Cooler flow/range

Ratings and performance data in this publication are for a
cooling temperature rise of 10° F (6° C), and are suitable
for a range from 5 to 20 F (2.8 to 11.1 C) temperature rise
without adjustment. The 30RA chillers may be operated
using a different temperature range, provided flow limits
are not exceeded. For minimum flow rates, see Minimum
and Maximum Cooler Flow Rates table. High flow rate is
limited by pressure drop that can be tolerated. Use the
Packaged Chiller Builder Program to obtain the rating if a
temperature rise other than 10° F (6° C) is used.

Minimum cooler flow (maximum cooler tempera-
ture rise) —

The minimum cooler flow for standard units

is shown in Minimum and Maximum Cooler Fluid Flow
Rates table. When system design conditions require a
lower flow (or higher rise) than the minimum allowable
cooler flow, follow the recommendations below.

1. Multiple smaller chillers may be applied in series, each

providing a portion of the design temperature rise.

2. Cooler fluid may be recirculated to raise the flow rate

to the chiller. However, the mixed temperature enter-
ing cooler must be maintained a minimum of at least
5° F (2.8° C) above the LCWT.

NOTE: Recirculation flow is shown below.

Maximum cooler flow —

The maximum cooler flow

(approximately 5° F [2.8° C] rise) results in a practical max-
imum pressure drop through cooler.

Return fluid may bypass the cooler to keep the pressure

drop through the cooler within acceptable limits. This per-
mits a higher delta T with lower fluid flow through cooler
and mixing after the cooler.
NOTE: Bypass flow is shown below.

MINIMUM AND MAXIMUM COOLER FLOW RATES

ENGLISH

30RA

SIZE

MIN. FLOW

RATE (Gpm)

MAX. FLOW

RATE (Gpm)

010

015

018

022