Specifications

71
Table 47 — Condenser (Sizes 325-400) Tube
Components
LEGEND
NOTE: Tubes replaced along heat exchanger head partitions must
be flush with tube sheet (both ends).
RETUBING — When retubing is required, obtain service of
qualified personnel experienced in boiler maintenance and
repair. Most standard procedures can be followed when retub-
ing the coolers. An 8% crush is recommended when rolling
replacement tubes into the tubesheet.
Place one drop of Loctite No. 675 or equivalent on top of
tube prior to rolling. This material is intended to “wick” into the
area of the tube that is not rolled into the tube sheet, and prevent
fluid from accumulating between the tube and the tube sheet.
New tubes must also be rolled into the center tubesheet to
prevent circuit to circuit leaks.
TIGHTENING COOLER HEAD BOLTS
Preparation
— When reassembling cooler heads, always
check the condition of the O-rings first. The O-ring should be
replaced if there is visible signs of deterioration, cuts or
damage. Apply a thin film of grease to the O-ring before
installation. This will aid in holding the O-ring in the groove
while the head is installed. Torque all bolts to the following
specification and in sequence:
3
/
4
-in. Diameter Perimeter Bolts (Grade 5). . . . 200 to 225 ft-lb
(271 to 305 N-m)
1. Install all bolts finger tight.
2. Bolt tightening sequence is outlined in Fig. 55. Follow
the numbering or lettering sequence so that pressure is
evenly applied to O-ring.
3. Apply torque in one-third steps until required torque is
reached. Load all bolts to each one-third step before pro-
ceeding to next one-third step.
4. No less than one hour later, retighten all bolts to required
torque values.
5. After refrigerant is restored to system, check for refriger-
ant leaks using recommended industry practices.
6. Replace cooler insulation.
INSPECTING/CLEANING HEAT EXCHANGERS — In-
spect and clean cooler tubes at the end of the first operating
season. Because these tubes have internal ridges, a rotary-type
tube cleaning system is necessary to fully clean the tubes. Tube
condition in the cooler will determine the scheduled frequency
for cleaning, and will indicate whether water treatment is
adequate in the chilled water/brine circuit. Inspect the entering
and leaving water thermistor wells for signs of corrosion or
scale. Replace the well if corroded or remove any scale if
found.
WATER TREATMENT — Untreated or improperly treated
water may result in corrosion, scaling, erosion or algae. The
services of a qualified water treatment specialist should be
obtained to develop and monitor a treatment program.
CHILLED WATER FLOW SWITCH — A factory-installed
flow switch is installed in the entering water nozzle for all ma-
chines. See Fig. 56 and 57. This is a thermal-dispersion flow
switch. Figure 57 shows typical installation. If nuisance trips of
the sensor are occurring, follow the steps below to correct:
When power is supplied to the device, a warm-up period is
initiated. The warm-up period may take up to 30 seconds.
When enough flow is detected, the switch contacts will close.
The switch closure does not indicate minimum flow require-
ments have been met for the machine.
1. Check to confirm that all strainers are clean, valves are
open and pumps are running. For the case of variable
frequency drive (VFD) controlled pumps, ensure the
minimum speed setting has not been changed.
2. Measure the pressure drop across the cooler (evaporator).
Use the cooler pressure drop curves in Fig. 27-43 to cal-
culate the flow and compare this to system requirements.
3. If the contacts do not close with sufficient flow, then
check the wiring connection to the MBB. If the input sig-
nal is not closed, then the switch needs to be replaced.
CONDENSER WATER FLOW SWITCH AND THERMIS-
TORS — A condenser water flow switch and entering and
leaving water thermistors are factory-installed for all heat ma-
chines and chillers with optional medium temperature brine.
See Fig. 56 and 57. This is a thermal-dispersion flow switch.
Figure 57 shows typical installation.
COMPONENT
SIZE
in. mm
Tube Sheet Hole Diameter 1.000 to 1.008 25.40 to 25.60
Tube OD 0.992 to 0.998 25.20 to 25.35
Tube ID after Rolling
(includes expansion due to
clearance.)
0.918 to 0.935 23.32 to 23.75
ID — Inside Diameter
OD — Outside Diameter
Fig. 54 — Elliott Tube Plug
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CAUTION
Hard scale may require chemical treatment for its preven-
tion or removal. Consult a water treatment specialist for
proper treatment procedures.
CAUTION
Water must be within design flow limits, clean and treated
to ensure proper machine performance and reduce the
potential of tubing damage due to corrosion, scaling, and
algae. Carrier assumes no responsibility for cooler damage
resulting from untreated or improperly treated water.
Fig. 55 — Cooler Head Recommended
Bolt Torque Sequence
1
20
8
6
19
16
15
3
23
10
12
24
14
13
17
5
7
18
2
4
21
9
11
22
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