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8. At this point the system is under-charged and may go
into a low-pressure situation in which the hot gas bypass
valve may open. To test if that valve is open, touch the
lines leading in and out of the valve. If both are the same
temperature then the valve is open. If the valve is open
then slowly add refrigerant in small increments until the
hot gas bypass valve closes and the incoming and
outgoing lines have different temperatures.
9. Allow the system to run for five to ten minutes so the
refrigerant pressures will stabilize. Measure the super-
heat.
NOTE: There is no ideal super heat temperature, but it
should be anywhere from 10° - 20°F (5.6° - 11.1°C),
depending on the load on the cooling units. On cool
days, it will be lower, and on hot days it will be higher.
10. Add refrigerant to reduce the superheat, or remove gas
to increase it. Do this in very small increments and allow
the system to stabilize before taking another superheat
reading.
11. Once the superheat is set properly, close the manifold
gauge valves, and backseat the discharge base valve.
Torque the stem-packing nut (gland nut) to 8 ft. lbs. or 96
in. lbs. Remove the manifold gauge hoses and replace
the service port caps.
Removing Refrigerant from the System
When adjusting the charge in the refrigerant system, some
refrigerant gas may need to be removed. It is a violation of
federal law to vent (release) refrigerant into the atmosphere,
and it is necessary to capture any refrigerant that is removed
from the system. There are two methods of doing this:
1. Use an approved refrigerant recovery unit and refillable
refrigerant container.
2. Allow refrigerant to escape from the high-pressure side
into a refillable refrigerant container.
L-0952 Installation
Initial Start Up
1. Open the seacock (seawater inlet valve).
2. Turn on all circuit breakers for the air conditioning
system: condensing unit, cooling units, and pump (pump
may or may not have its own c/b).
3. Set the system for cooling at the SMXir keypad, and
adjust temperature setting so the unit will turn on.
4. Verify that water is flowing from the overboard
discharge.
5. Allow unit to run for 10 minutes at high fan speed. Check
the temperature differential between discharge and
return air by placing an accurate thermometer in front of
the discharge grill and then in front of the return air grill.
In cooling, the difference between the discharge and
return should 15 - 20°F (8.3 - 11.1°C).
16
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