29
The 30MPA units that use air-cooled or evaporative con-
densers must have adequate means for head pressure control
when operating below 65°F (18.3°C) ambient.
The 30MPA remote condenser requirements are as follows:
• If multiple units are connected to a single condenser,
ensure each refrigerant circuit has its own head pressure
control
• Condenser must provide 15°F (8.3°C) subcooling, maxi-
mum of 40°F (22.2°C) difference between saturated
condensing temperature and outdoor ambient tempera-
ture (to prevent overload at high ambient temperatures),
and a minimum of 20°F (11.1°C) difference (to ensure
subcooling).
• Do not manifold multiple refrigerant circuits into a
single condenser.
• If air-cooled condenser is located below chiller, refer to
condenser manufacturer’s performance data for avail-
able liquid lift.
• Refer to condenser installation instructions for location
guidelines.
Carrier recommends that a field-supplied pressure relief de-
vice be installed in each discharge line of 30MPA units. Most
local codes require the discharge line relief valve to be vented
directly to the outdoors. The vent
must not
be smaller than the
discharge line relief valve outlet.
The 30MPA units are shipped with a discharge line loop to
facilitate factory testing. Relieve the pressure caused by the ni-
trogen holding charge. Cut the discharge line loop as close as
possible to the elbow. This will leave approximately 2-in.
(50 mm) of straight tubing for liquid line connection. Uncap
the discharge line. Be sure to connect the discharge line to the
larger line. Do not leave the reducing coupling in place.
30MPW UNITS WITH NITROGEN CHARGE — For
30MPW units with the factory nitrogen charge option, re-
lieve the pressure caused by the nitrogen holding charge
and proceed to the Evacuation and Dehydration section.
It is best practice to minimize the amount of time the sys-
tem is exposed to ambient air.
EVACUATION AND DEHYDRATION — Because the
30MP compressor oil can absorb moisture, it is important to
minimize the amount of time that the system interior is
exposed to the atmosphere. Minimizing the exposure time of
the oil to the atmosphere will minimize the amount of moisture
that needs to be removed during evacuation.
Once all of the piping connections are complete, leak test
the unit and then pull a deep dehydration vacuum. Connect the
vacuum pump to the charging valve in the suction line and to
the liquid line service valve. For best results, it is recommended
that a vacuum of at least 500 microns (0.5 mm Hg) be
obtained.
Afterwards, to ensure that no moisture is present in the sys-
tem, perform a standing vacuum-rise test. With the unit in deep
vacuum (500 microns or less), isolate the vacuum pump from
the system. Observe the rate-of-rise of the vacuum in the sys-
tem. If the vacuum rises by more than 50 microns in a 30-min-
ute time period, continue the dehydration process. Maintain a
vacuum on the system until the standing vacuum requirement
is met. This will ensure a dry system.
By following these evacuation and dehydration procedures,
the amount of moisture present in the system will be
minimized.
30MPW CONDENSER DESCRIPTION — All 30MPW
units use a brazed-plate heat-exchanger-type condenser.
These heat exchangers are made of embossed plates of
acid-resistant stainless steel. Every other plate is reversed
so that the ridges of the herringbone pattern intersect one
another on adjacent plates, forming a lattice of contact
points. These plates are vacuum-brazed together to form a
compact and pressure-resistant heat exchanger.
After brazing, the impressions in the plates form 2 separate
systems of channels where the refrigerant and water flows are
counterflow. The number of plates varies depending on unit
capacity. The condensers provide approximately 10° to 12°F
(6° to 8°C) liquid subcooling at the standard Air-Conditioning,
Heating and Refrigeration Institute (AHRI) rating condition.
30MPW CONDENSER — When facing the unit control
box, the condenser is the uninsulated heat exchanger located on
the left-hand side. The water connections are on the right-hand
side of the heat exchanger with the LIQUID-IN connection at
the bottom, and the LIQUID-OUT connection at the top. For
30MPW units with water manifold option, refer to manifold
Victaulic spacer fitting kit accessory installation instructions.
A strainer with a minimum of 40 mesh must be installed
within 10 ft (3 m) of the chiller closest to the water header
inlet to prevent debris from clogging or damaging the
chiller’s heat exchangers.
To install the Victaulic coupling (see Fig. 29):
1. Use Victaulic couplings designed for use on IPS dimen-
sioned materials; for example, Style 75, Style 77, Quick
Vic Style 107, or Style 177.
2. Lubricate the gasket lips and stretch the gasket over the
end of the heat exchanger coupling. Avoid twisting the
gasket when installing.
3. Bring the pipe and heat exchanger coupling ends together
into alignment. Slide the gasket so that it is centered over
the ends. Apply a light film of lubricant to the gasket, or
to the outside diameter of the pipe. Avoid twisting the
gasket during installation.
4. Install the inside coupling half over the gasket and then
install the outer half. Connect with nuts and bolts. Tighten
the nuts equally on both sides. Ensure there is no gap be-
tween the two halves of the coupling.
Fig. 2
8
— Double Discharge Riser
Construction Detail
a30-1245
TO
CONDENSER
B
RED.
TEE
90 DEGREE
STR ELLS
FROM
CHILLER
45 DEGREE
STR ELLS
A
LEGEND
RED. TEE
—
Reducing Tee
STR ELLS —
Street El
b
ows
a30-1979ef
1118
