Capacity Control - Comfortnet Models; Unloader Solenoid; Coils And Blower Coils; Dvptc Multi-Position Air Handler - Daikin ComfortNet DX16TC Series Service Instructions Manual

PRODUCT DESIGN
• 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, con-
tinued 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 information can
be found in the unit's Technical Information Manual.
CAPACITY CONTROL - COMFORTNET™ MODELS
During the compression process, there are several pockets
within the scroll that are compressing gas. Modulation is
achieved by venting a portion of the gas in the first suction
pocket back to the low side of the compressor thereby reduc-
ing the effective displacement of the compressor. See Figure
A. Full capacity is achieved by blocking these vents, increas-
ing the displacement to 100%. A solenoid in the compressor,
controlled by an external 24-volt ac signal, moves the slider
ring that covers and uncovers these vents. The vent covers
are arranged in such a manner that the compressor operates
somewhere around 67% capacity when the solenoid is not
energized and 100% capacity when the solenoid is energized.
The loading and unloading of the two step scroll is done "on
the fly" without shutting off the motor between steps. See
Figure C below. The unloaded mode default was chosen for
two reasons:
Molded Plug*
24 vdc
*Rectifier is integrated on the UC PCB
1. It is expected that the majority of run hours will be in the
low capacity, unloaded mode.
2. It allows a simple two-stage thermostat to control capac-
ity through the second stage in both cooling and possibly
heating if desired.
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Run Capacitor
Internal Unloader
Coil
FIGURE C

UNLOADER SOLENOID

A nominal 24-volt direct current coil activates the internal un-
loader solenoid. The input control circuit voltage must be 18 to
28 volt ac. The coil power requirement is 20 VA. The external
electrical connection is made with a molded plug assembly.
This plug is connected to the Communicating Unitary Control
PCB (UC PCB) which contains a full wave rectifier to supply
direct current to the unloader coil.

COILS AND BLOWER COILS

MBVC blower cabinets are designed to be used as a two-piece
blower and coil combination and can be utilized with the CAUF,
CAPF, CAPFA and CAPT coils for upflow and downflow appli-
cations. The CACF and CHPF coils are designed for horizontal
applications. This two-piece arrangement allows for a variety
of mix-matching possibilities providing greater flexibility.
The MBVC blower cabinets use a variable speed motor that
maintains a constant airflow with a higher duct static. MBVC
blower cabinets are approved for applications with cooling
coils of up to 0.8 inches W.C. external static pressure. The
MBVC models allow airflow trimming of +/-10%.
All units are constructed with R-4.2 insulation. In areas of
extreme humidity (greater than 80% consistently), insulate the
exterior of the blower with insulation having a vapor barri-
er equivalent to ductwork insulation, providing local codes
permit.

DVPTC Multi-Position Air Handler

DVPTC is a multi-position, variable-speed air handler used
with R-410A and are available in 2 to 5 ton sizes with optional
3 kW to 25kW electric heat kits available for field installation.
The DVPTC unit's blower design includes a variable-speed ECM
motor and is compatible with heat pumps and variable-capaci-
ty cooling applications.
This appliance can be installed in the vertical or left horizontal
position without modification. The horizontal right and down-
flow positions require product modification. This product is de-
signed for zero inches (0 inches) clearance; however, adequate
access for service or replacement must be considered without
removing permanent structure. This unit can be installed on a
platform when deemed necessary.
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In an attic installation a secondary drain pan must be provid-
ed by the installer and placed under the entire unit with a
separate drain line properly sloped and terminated in an area
visible to the owner. This secondary drain pan is required in
the event that there is a leak or main drain blockage. Closed
cell insulation should be applied to the drain lines in uncondi-
tioned spaces where sweating may occur.
NOTE: DVPTC air handlers are factory-sealed to achieve a 2%
or less leakage rate at 1.0" water gauge external duct static
pressure.
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