PRODUCT DESIGN
7
This section gives a basic description of cooling unit opera-
tion, its various components and their basic operation.
Ensure your system is properly sized for heat gain and loss
according to methods of the Air Conditioning Contractors
Association (ACCA) or equivalent.
CONDENSING UNIT
The condenser air is pulled through the condenser coil by a
direct drive propeller fan. This condenser air is then dis-
charged out of the top of the cabinet. These units are
designed for free air discharge, so no additional resistance,
like duct work, shall be attached.
The suction and liquid line connections on present models
are of the sweat type for field piping with refrigerant type
copper. Front seating valves are factory installed to accept
the field run copper. The total refrigerant charge for a normal
installation is factory installed in the condensing unit.
The DX16 models are available in 1 1/2 through 3 1/2 ton sizes
and uses R-410A refrigerant. They are designed for 208/230
volt single phase and 380V 3-phase applications. Model
sizes, refrigerant, and electrical specs vary by country.
Please check with your local dealer for information related to
your country. All model units use the Copeland Scroll ZPK5
& ZPK6 series, which are specifically designed for R-410A
refrigerant and use 3MA POE oil which is NOT compatible
with mineral based lubricants like 3GS. "POE" oil must be
used if additional oil is required.
As this motion occurs, the pockets between the two forms
are slowly pushed to the center of the two scrolls while
simultaneously being reduced in volume. When the pocket
reaches the center of the scroll form, the gas, which is now
at a high pressure, is discharged out of a port located at the
center.
During compression, several pockets are being compressed
simultaneously, resulting in a very smooth process. Both the
suction process (outer portion of the scroll members) and the
discharge process (inner portion) are continuous.
Some design characteristics of the Compliant Scroll com-
pressor are:
• Compliant Scroll compressors are more tolerant of liquid
refrigerant.
NOTE: Even though the compressor section of a Scroll
compressor is more tolerant of liquid refrigerant, contin-
ued floodback or flooded start conditions may wash oil
from the bearing surfaces causing premature bearing
failure.
• Compliant scroll compressors perform "quiet" shutdowns
that allow the compressor to restart immediately without
the need for a time delay. This compressor will restart
even if the system has not equalized.
NOTE: Operating pressures and amp draws may differ
from standard reciprocating compressors. This informa-
tion can be found in the unit's Technical Information
Manual.
COOLING
The refrigerant used in the system is R-410A. It is a clear,
colorless, non-toxic and non-irritating liquid. R-410A is a
50:50 blend of R-32 and R-125. The boiling point at atmo-
spheric pressure is -62.9°F.
A few of the important principles that make the refrigeration
cycle possible are: heat always flows from a warmer to a
cooler body. Under lower pressure, a refrigerant will absorb
heat and vaporize at a low temperature. The vapors may be
drawn off and condensed at a higher pressure and tempera-
ture to be used again.
The indoor evaporator coil functions to cool and dehumidify
the air conditioned spaces through the evaporative process
taking place within the coil tubes.
NOTE: The pressures and temperatures shown in the
refrigerant cycle illustrations on the following pages are for
demonstration purposes only. Actual temperatures and pres-
sures are to be obtained from the "Expanded Performance
Chart".
Liquid refrigerant at condensing pressure and temperatures,
(270 psig and 122°F), leaves the outdoor condensing coil
through the drier and is metered into the indoor coil through
the metering device. As the cool, low pressure, saturated
refrigerant enters the tubes of the indoor coil, a portion of the
liquid immediately vaporizes. It continues to soak up heat and
vaporizes as it proceeds through the coil, cooling the indoor
coil down to about 48°F.
Heat is continually being transferred to the cool fins and tubes
of the indoor evaporator coil by the warm system air. This
warming process causes the refrigerant to boil. The heat
removed from the air is carried off by the vapor.
As the vapor passes through the last tubes of the coil, it
becomes superheated. That is, it absorbs more heat than is
necessary to vaporize it. This is assurance that only dry gas
will reach the compressor. Liquid reaching the compressor
can weaken or break compressor valves.
