CeilAir CW series Návod k obsluze stáhnout pdf (Strana 35)

(©July, 2008)

CeilAiR OHS Series Installation, Operation & Maintenance Manual

ir Technology Systems, Inc.

4. Loosen the set screw in the side of the sheave

with an Allen wrench.

5. Remove the sheave key.

6. Adjust the blower speed by closing the sheave

one half turn to increase speed or opening the

sheave one half turn to decrease speed.

7. Replace the sheave key and tighten set screw.

8. Proper belt tension is achieved when the belt has

a deflection of ¾ inch per foot of span between the

blower and motor pulleys, with a firm pressure

placed on the side of the blower belt. Adjust the

blower belt tension by raising (to tighten) or

lowering (to loosen) the nuts on the adjustment

rods of the motor base.

CAUTION

If the belt tension is too tight, it will cause pre-

mature blower and/or motor bearing failure. If the

belt is too loose, the belt will slip and cause belt

squeals and eventual belt failure.

9. Restore power to system.

10. Check the current draw on the blower motor to

make sure it does not exceed the nameplate

rating of the motor.

11. If current draw exceeds nameplate rating of motor

repeat steps 1 through 9 to decrease blower

speed. If the motor pulls too much current, slow

the blower down by opening the adjustable sheave

one half turn at a time until the motor current is at

or below the nameplate FLA.

12. Check the motor overload on the blower starter to

confirm its setting is correct for the FLA of the motor.

2.9.6 Thermal Expansion Valve

All

CeilAiR

units utilizing thermal expansion valves

(TEV) control the flow of refrigerant entering the

evaporator to maintain a constant superheat of the

refrigerant vapor at the outlet of the evaporator. Super-

heat is the difference between the refrigerant vapor

temperature and its saturation temperature at that

pressure. By controlling superheat, the TEV keeps

nearly the entire evaporator surface active while not

permitting liquid refrigerant to return to the compressor.

The standard super-heat is factory set at 12-15°F and

should not need adjustment.

2.9.7 Hot Gas Reheat (Optional)

The hot gas reheat option incorporates a hot gas

reheat solenoid valve and a hot gas reheat coil. Under

normal operation when no reheat is required, the hot

gas reheat valve is de-energized and hot gas flows

directly from the compressor discharge to the con-

denser. When there is a call for reheat, the controller

energizes the hot gas reheat solenoid valve. The hot

gas reheat solenoid valve diverts hot gas to the reheat

coil, mounted directly downstream of the evaporator

coil, before it travels to the condenser. No adjustment

to the valve is necessary.

2.9.8 Hot Gas Bypass (Optional)

The two most common systems provided by SATS for

hot gas bypass are snap acting and full floating

described as follows.

2.9.8.1 Snap Acting Hot Gas Bypass

The snap acting hot gas bypass system provides for

some modulated capacity control and freeze protec-

tion. The hot gas bypass system includes a discharge

bypass valve that allows some hot gas from the

compressor discharge line to pass into the evaporator

coil to maintain a preset suction pressure. The

compressor cycles on demand from the controller.

The snap acting hot gas bypass system also provides

freeze protection for the evaporator coil by limiting the

minimum refrigerant pressure, preventing the surface

temperature of the evaporator coil from dropping below

32°F.

2-24

Figure 13- Belt Drive Blower

1 2 ... 30 31 32 33 34 35 36 37 38 39 40 ... 59 60

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