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Alternately, an air distribution plenum must be field fabricated with supply grilles to distribute
the air. If a common plenum is utilized to connect the supply air for distribution from multiple
units, it is recommended that isolation backdraft dampers be installed on the discharge end of
the unit or somewhere prior to the common plenum to prevent cold discharge air from entering
units that may be on standby. Alternatively, we offer an AireSeal option which keeps the EC
fans running at a selectable speed between 20-50% when the unit is in standby to prevent air
from entering the units from the common plenum. Units are shipped with Electronically
Commutated (EC) motors often referred to as “plug fans”. Fan speed is factory set based on
order. Fan speed can be changed in 1% increments through the Data Alarm Processor (dap4)
microprocessor controller, by several different methods. See the dap4 User Manual for details
and recommended settings.
WARNING: Do not operate upflow units without installing a plenum,
ductwork or guard over the fan opening(s) on the top surface of the
cabinet. Ductwork must be connected to the fan(s), or a plenum must be
installed on the top of the cabinet for protection from rotating blower
wheel(s) on upflow units. Risk of high-speed moving parts can cause
injury or death. Disconnect all local and remote electric power supplies
before working in the unit.
NOTE: Seal openings around piping and electrical connection to prevent air
leakage. Failure to do so could reduce the unit’s cooling performance.
Piping
• All refrigerant piping should be is Type L Air Conditioning Refrigeration (ACR) hard
drawn copper pipes. Soft copper is unacceptable.
• When brazing refrigerant lines, an inert gas should be passed through the line at low
pressure to prevent scaling and oxidation inside the tubing. Dry nitrogen is preferred. No
soldering allowed.
• Completely de-burr and clean tube end and inside surface of piping.
• Use only a suitable silver alloy on suction and liquid lines. Limit the flux to the minimum
required to prevent contamination of the joint internally. Flux only the male portion of the
connection, never the female. After brazing, remove excess flux.
• All refrigeration piping materials are subject to changes in temperature and will expand
and contract with temperature change. Installation techniques must allow for expansion
and contraction changes for piping connections, this will prevent stresses which may
buckle and rupture the copper tube piping or joints.
• Proper piping practices should be employed to ensure adequate oil return, even under
minimum load conditions with special consideration given to the size and proper slope
of the tubing coming from the evaporator. See section 2.14 Recommended Line Sizing,
Air Cooled Units for more information on line sizes.
• Tubing returns from the evaporator should be designed so as not to trap oil and to
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