92
JOHNSON CONTROLS
5276178-JIM-C-0118
Start-up
Verifying Compressor Rotation
This unit uses scroll compressors,
which will only operate in one direc
-
tion. Failure to observe these steps
could lead to compressor failure.
Check for proper compressor rotation. Series 40
units are properly phased at the factory. If the blower,
condenser fan, or compressor, rotate in the wrong
direction at start-up, the electrical connection to the unit
is misphased. Change the incoming line connection
phasing to obtain proper rotation.
The Series 40
rooftop unit uses hermetic scroll
compressors, which only pump in one direction.
Therefore, it is necessary to verify proper rotation at
unit start-up. Operation of the compressor in the reverse
direction will not produce any capacity, and cause the
compressor to cycle on internal overload. Operating the
compressor in reverse for “extended” periods can result
in failure of the compressor.
To verify proper rotation, monitor the suction and
discharge pressures of the respective refrigerant circuit
while the compressor cycles ON. If the discharge
pressure increases and suction pressure decreases as
the compressor cycles ON, the compressor is properly
phased and operating in the correct rotation.
Suction and discharge pressure may be monitored with
the User Interface if the optional suction and discharge
pressure transducers are installed
(refer to the section
on Menu Navigation).
If the optional transducers are not
installed, pressures must be monitored with a manifold
gauge connected to the service valves located on the
suction and discharge lines.
Compressor Oil Level Check
The oil level can only be tested when the compressor is
running in stabilized conditions, to ensure that there is
no liquid refrigerant in the lower shell of the compressor.
When the compressor is running in stabilized conditions,
the oil level must be between 1/2 and 3/4 in the oil sight
glass.
Note: at shutdown, the oil level can fall to the
bottom limit of the oil sight glass.
12. Verify proper belt tension of supply fan, exhaust
fan or return fan
(refer to
“
Maintenance
”
section
of manual).
Belts must be checked after 24 hours
of initial operation.
13. Manually rotate condenser fan blades, supply
exhaust and return blower wheels and motors, to
assure freedom of movement.
14. Verify proper condensate drain trap installation
(refer to Figure 25).
Fill traps with water prior to
unit start-up.
15. If applicable, verify installation of air filters
(refer
to Installation section for size and quantity).
UNIT CHECKS – POWER APPLIED
1. Apply 3-phase power and verify its value. Voltage
imbalance should be no more than 2% of the aver-
age voltage.
2. Verify programmed units Setpoints
(refer to “Quick
Start-Up Guide”, Form 100.50-SU4).
3. Fan Rotation
Check for proper supply air blower rotation. If fans
are rotating backwards the line voltage to unit point
of power connection is misphased
(see Compressor
Rotation above.)
If the condenser fans are rotating
in the correct direction and the supply fan is not, it
will be necessary to switch leads on the output side
of the VFD, since changing phase on the input side
of a VFD does not change rotation on the output
side. If the VFD is equipped with a bypass, verify
that rotation is correct in the bypass mode.
If unit is equipped with power exhaust
fans, also check them for proper rota
-
tion.
VFD units with bypass must not have the bypass
activated unless all individual space dampers are
full open. It is the responsibility of the installer to
interconnect the bypass mode to the signal to open
all boxes on the circuit.
4. Insure proper compressor rotation -
see following
instruction on Verifying Compressor Rotation.
Содержание 40 25 TON
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