Product Design - Daikin ComfortNet DX18TC Service Instructions Manual

PRODUCT DESIGN

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.
DX16TC, DZ16TC, DX18TC, DZ18TC models are available in
2 through 5 ton sizes and use R-410A refrigerant. They are
designed for 208/230 volt single phase applications.
DX16TC, DZ16TC, DX18TC, DZ18TC R-410A model units use
the Copeland Scroll "Ultratech" Series compressors which
are specifically designed for R-410A refrigerant. These units
also have Copeland ® ComfortAlert diagnostics. The Copeland
ComfortAlert diagnostics are integrated into the unitary (UC)
control. These models are ComfortNet
There are a number of design characteristics which are
different from the traditional reciprocating and/or scroll com-
pressors.
"Ultractech" Series scroll compressors will not have a dis-
charge thermostat. Some of the early model scroll compres-
sors required discharge thermostat.
"Ultratech" Series scroll compressors use "POE" or
polyolester oil which is NOT compatible with mineral oil
based lubricants like 3GS. "POE" oil must be used if
additional oil is required.
The DX16TC, DZ16TC, DX18TC, DZ18TC series split system
units use a two-stage scroll compressor. The two-step
modulator has an internal unloading mechanism that opens
a bypass port in the first compression pocket, effectively
reducing the displacement of the scroll. The opening and
closing of the bypass port is controlled by an internal
electrically operated solenoid.
The ZPS two-step modulated scroll uses a single step of
unloading to go from full capacity to approximately 67%
capacity. A single speed, high efficiency motor continues to
run while the scroll modulates between the two capacity
steps.
A scroll is an involute spiral which, when matched with a
mating scroll form as shown, generates a series of crescent
shaped gas pockets between the two members.
During compression, one scroll remains stationary (fixed
scroll) while the other form (orbiting scroll) is allowed to orbit
®
(but not rotate) around the first form.
TM
ready.
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.
FIGURE A
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