Operation; Sequence Of Operation; Dual Chiller Sequence Of Operation - Carrier AQUASNAP 30RB060-390 Controls, Start-Up, Operation, Service And Troubleshooting Instructions

FLOW RATE REQUIREMENTS — Standard chillers should
be applied with nominal flow rates within those listed in the
Minimum and Maximum Cooler Flow Rates table. Higher or
lower flow rates are permissible to obtain lower or higher
temperature rises. Minimum flow rates must be exceeded to
assure turbulent flow and proper heat transfer in the cooler. See
Table 34.
CAUTION
Operation below minimum flow rate could subject tubes to
frost pinching in the tube sheet, resulting in failure of the
cooler.
Consult application data section in the Product Data
literature and job design requirements to determine flow rate
requirements for a particular installation.

OPERATION

Sequence of Operation —
the chiller, the cooler pump will start. After verifying water
flow, the control will monitor the entering and leaving water
temperature. At any time that a compressor is not operating, its
crankcase heater is active. If the need for mechanical cooling is
determined, the control decides which circuit and compressor
to start. The compressor will deenergize the crankcase heater as
it starts. Compressors will be staged with minimum load
control (if equipped and configured) to maintain LWT set
point.
Shutdown of each circuit under normal conditions occurs in
increments, starting with the minimum load control (if
MINIMUM
30RB COOLER
SIZE FLOW RATE
(gpm)
060 72
070 84
080 96
090 108
100 120
110 132
120 144
130 156
150 180
160 192
170 204
190 228
210 252
225 270
250 300
275 330
300 360
MINIMUM COOLER
FLOW RATE
30RB
(gpm)
SIZE
Module A Module B
315 192 192
330 192 204
345 204 204
360 204 228
390 228 228
With a command to start
Table 34 — Minimum and Maximum Cooler Flow Rates
SIZES 060-300
MINIMUM
MAXIMUM
LOOP
FLOW RATE
VOLUME
(gpm)
(gal.)
288 180
336 210
384 240
432 270
480 300
528 330
576 360
624 390
720 450
768 480
816 510
912 570
1008 630
1080 675
1200 750
1320 825
1440 900
SIZES 315-390
MAXIMUM COOLER
FLOW RATE
(gpm)
VOLUME
Module A Module B
768 768
768 816
816 816
816 912
912 912
equipped) and finishing with the last running compressor. Once
minimum load control is disabled, one compressor is
shut down. Eight seconds later the next compressor will
shut down. The process will continue until all of the compres-
sors are shut down. The EXV will close completely, 1 minute
after the last compressor has shut down. There are several
abnormal conditions that, if detected, will shut down the circuit
immediately. In this case, minimum load control and all
compressors are turned off without an 8-second interval
between them. The cooler pump will remain ON for 20 sec-
onds after the last compressor has been turned OFF.
Dual Chiller Sequence of Operation —
command to start the chiller, the master chiller determines
which chiller will become the lead chiller based on Configura-
 
tion RSET LLBL and Configuration
The lead chiller is always started first and the lag chiller is held
at zero percent capacity by the master chiller forcing the lag de-
mand limit value to 0%. The lead chiller's water pump will be
started. The lag chiller's water pump shall be maintained off if

Configuration RSET
lead chiller will control capacity of the lead chiller.
If Lead Pulldown Time (Configuration
has been configured, the lead chiller will continue to operate
alone for that specified time. After the Lead Pulldown Time
timer has elapsed, if the lead chiller is fully loaded and either
all available compression is on or at the master demand limit
value, then the lag start timer (Configuration
LLDY) is initiated. When the pulldown timer and lag start
timer have elapsed and the Combined Leaving Chilled Water
Temperature is more than 3° F (1.7° C) above the set point,
then the lag chiller is started.
MINIMUM COOLER
FLOW RATE
(l/s)
5
5
6
7
8
8
9
10
11
12
13
14
16
17
19
21
23
MINIMUM COOLER
MIN
FLOW RATE
LOOP
(l/s)
(gal.)
Module A Module B
945 12 12
990 12 13
1035 13 13
1080 13 14
1170 14 14
45

RSET

LAGP=0. The internal algorithm of

RSET

MAXIMUM MINIMUM
COOLER LOOP
FLOW RATE VOLUME
(l/s) (liters)
18
21
24
27
30
33
36
39
45
48
51
58
64
68
76
83
91
MAXIMUM COOLER
FLOW RATE
(l/s)
Module A Module B
48 48
48 51
51 51
51 58
58 58
With a

LLBD.

LPUL)

RSET
681
795
908
1022
1136
1249
1363
1476
1703
1817
1931
2158
2385
2555
2839
3123
3407
MIN
LOOP
VOLUME
(liters)
3577
3748
3918
4088
4429