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receiving and installation
1 RECEIPT OF EQUIPMENT
1.1 INSPECTION
All equipment should be carefully checked for damage or shortages
as soon as it is received. Each shipment should be carefully
checked against the bill of lading. If any damage or shortage is
evident, a notation must be made on the delivery receipt before
it is signed and a claim should then be filed against the freight
carrier. Inspection and claims are the responsibility of the recipient..
1.2 LOSS OF GAS HOLDING CHARGE
Each copper, steel, and stainless steel tube STC unit is leak
tested, evacuated to remove moisture and then shipped with a
gas holding charge. Absence of this charge may indicate a leak
has developed in transit. The system should not be charged with
refrigerant until it is verified that there is no leak, or the source of
the leak is located. If the unit contains aluminum tubes or flanged
refrigerant connections, the unit is leak tested and evacuated but
a gas holding charge is not provided.
2 ASSEMBLY OF COMPONENTS
2.1 SHIPPED LOOSE PARTS
Dielectric Flange Union with required bolts, nuts, and gaskets
(if the coil contains aluminum tubes); TEV supply shipped loose.
2.2 DIELECTRIC FLANGE UNION
Aluminum tube evaporators have aluminum flanged refrigerant
connections. A dielectric flange union to attach steel pipe to the
aluminum evaporator flange is provided in a separate box. The box
should contain dielectric bolt gaskets, bolts, nuts, flange gasket,
and mating steel socket weld flange. To avoid material damage
during assembly, preweld a length of refrigerant pipe to the steel
flange before assembly to the aluminum flange. See Section 6.2
for the aluminum to steel flange assembly drawing .
2.3 REFRIGERANT DISTRIBUTOR NOZZLE
For a direct expansion system, the STC Series units already have
the distributor nozzle installed. As a check, see that the nozzle is
in the distributor, or the auxiliary hot gas tee for direct expansion
halocarbon with hot gas defrosts, before installing the thermal
expansion valve to the distributor or auxiliary hot gas tee.
2.4 EXPANSION VALVE (Optional Item)
Before hanging a unit with a direct expansion design, install the
expansion valve and connect the equalizer tube. The expansion
valve should be installed directly to the distributor body or as close
as possible with no elbows or bends. Steel expansion valves for
ammonia requires the removal of the discharge tube. Locate the
expansion valve bulb on a horizontal length of suction line closer
to the connection stub. Position the bulb in a 3, 4, 8, or 9 o'clock
position. Do not position the bulb on the top or the bottom of the
pipe. Clamp the bulb down flush and tight against the pipe and
insulate. Never locate the bulb on a trap or downstream from a trap.
Expansion valves are NOT adjusted at the factory prior to shipment.
It is important that the operation of the expansion valve be checked
after the system has balanced out at the desired room temperature.
If the coil is being starved it is necessary to reduce the superheat
setting of the valve by turning the adjusting stem counter-clockwise.
If the superheat is too low it is necessary to increase the superheat
setting of the valve by turning the adjusting stem clockwise. It is
recommended that for a 10°F to 12°F T.D. system, the valve be
adjusted to maintain 5°F to 6°F of superheat.
3 RIGGING INSTRUCTIONS
An STC unit tends to be a long and heavy object with two coils.
Jobsite requirements will affect the method of moving and lifting
the unit into place. Carefully consider the support that is required
to lift and move the unit. To ensure that the unit is not bowed
or damaged when being lifted into place from above, all leg or
hanger points should be used. If the unit is being lifted into place
from underneath, a level support directly under all of the shipping
legs is required to adequately steady the unit as it is lifted to the
hanger rods..
4 UNIT LOCATION AND MOUNTING
4.1 UNIT LOCATION
Unit must be located to provide good air circulation to all areas.
Space around the unit should allow for free airflow into and out
of the unit. Light fixtures, shelving, ceiling structures, and product
boxes must be located so that they do not block the air discharge
from the unit.
On all units a space should be provided for the possible future
replacement of the electric defrost heaters if heaters have been
furnished. Table 1 specifies the recommended access dimensions
that are needed to remove the heater rods on one or both ends
of the unit.
4.2 MOUNTING
The STC units are ceiling hung or floor mounted (12" legs). Ceiling
hung units should be suspended with 1/2" diameter threaded
STEEL hanger rods. Do not use nylon-threaded rods. Rods should
have double nuts on the top and bottom. Adequate support must
be provided to hold the weight of the unit. Refer to the unit drawing
supplied with the unit or the catalog for the approximate unit weight
and hanger locations. All hanger holes on the coil support angle
should be used to support the unit. Do not temporarily support a
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