Tightening Evaporator Head Bolts; Inspecting/Cleaning Heat Exchangers; Evaporator Chilled Water Flow Switch; All Units - Carrier AquaForce 30XV140 Controls, Start-Up, Operation, Service And Troubleshooting Instructions

EVAPORATOR RETUBING — When retubing is required,
obtain the service of qualified personnel experienced in boiler
maintenance and repair. Most standard procedures can be fol-
lowed when retubing the evaporators. An 8% crush is recom-
mended when rolling replacement tubes into the tube sheet.
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 pre-
vent fluid from accumulating between the tube and the tube
sheet. New tubes must also be rolled into the center tube sheet
to prevent circuit to circuit leaks.

TIGHTENING EVAPORATOR HEAD BOLTS

Preparation — When reassembling evaporator heads,
always check the condition of the O-rings first. The O-ring
should be replaced if there are 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 / -in. Diameter Perimeter Bolts (Grade 5). . . . 200 to 225 ft-lb
4
1. Install all bolts finger tight.
2. Bolt tightening sequence is outlined in Fig. 56. 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 evaporator insulation.
10
6
13
3
1
16
8
12
Fig. 56 — Flooded Evaporator Unit Head
Recommended Bolt Torque Sequence
INSPECTING/CLEANING HEAT EXCHANGERS —
Inspect and clean evaporator tubes at the end of the first op-
erating season. Because these tubes have internal ridges, a rota-
ry-type tube cleaning system is necessary to fully clean the
tubes. Tube condition in the evaporator 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 re-
move any scale if found.
(271 to 305 N-m)
SINGLE
9
PASS
ONLY
5
15
2
4
14
7
11
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Hard scale may require chemical treatment for its preven-
tion or removal. Consult a water treatment specialist for
proper treatment procedures.
EVAPORATOR CHILLED WATER FLOW SWITCH —
A thermal-dispersion flow switch is factory-installed in the en-
tering water nozzle for all machines. See Fig. 57 and 58. Figure
58 shows typical installation. If nuisance trips of the sensor are
occurring, follow the steps below to correct:
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 evaporator. Use the
evaporator pressure drop curves on page 46 to calculate
the flow and compare this to system requirements. The
pressure drop curves are for water only.
L1
24 VAC
N
Fig. 57 — Chilled Water Flow Switch
OUT
FLOW SWITCH
(NOT TO SCALE)
Fig. 58 — Flow Switch Location

All Units

EVAPORATOR 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 treat-
ment program.
60
CAUTION
BRN 1
WHT
2
BLK 4
3
BLU
IN
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