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25VNA4: Installation Instructions
WARNING
!
ELECTRICAL HAZARD - HIGH VOLTAGE
Failure to follow this warning could result in personal injury or death.
Elecrical components may hold charge. DO NOT remove control box
cover for 2 mintues after power has been removed from unit.
PRIOR TO TOUCHING COMPONENTS:
Verify zero (0) voltage at inverter connections shown on inverter cover.
Input Filter Board
The input filter board connects the line voltage to the VFD. The input
filter board ensures the inherent electrical noise generated by VFD does
not affect other electronics in the household and contains fuses to protect
against excess input current.
Reactors
There are either 1 or 2 reactors per model. These reactors are large
inductors and must be connected to the VFD to operate.
Variable Speed Compressor
This unit contains a high-side variable speed compressor that has a wide
operating range. Some models contain variable speed rotary
compressors while others contain variable speed scroll compressors. All
of the variable speed compressors operate on 300VDC provided by the
inverter. This compressor can only be operated by the specific inverter
supplied with the unit.
CAUTION
!
EQUIPMENT DAMAGE HAZARD
Failure to follow this caution may result in equipment damage.
Do not attempt to apply line voltage directly to the compressor. This
will destroy the compressor
Time Delays
The unit time delays include:
• Five minute time delay to start cooling or heating operation when
there is a call from the user interface. To bypass this feature,
momentarily short and release Forced Defrost pins.
• Five minute compressor re-cycle delay on return from a brown-out
condition.
Heating Electronic Expansion Valve (EXV-H)
This unit uses an electronic expansion valve for refrigerant metering in
the heating mode. The control board drives the EXV to its proper
position based on the operating mode and conditions.
Vapor Injection Electronic Expansion Valve (EXV-VI)
Some models in this product family contain a secondary EXV for
controlling the vapor injection circuit. This circuit is comprised of a
brazed plate heat exchanger (BPHE), an EXV (EXV-VI) and
interconnecting tubing. The PCM drives this EXV closed except for in
high ambient cooling and low ambient heating in efficiency mode. The
control of the vapor injection circuit allows greater capacity and
efficiency than when not operational.
BLDC Inverter-Controlled Fan Motor
The fan motor included in this unit is a Brushless DC motor with an
integrated control module. The control module is supplied DC voltage
from the VFD. The speed command is provided from the VFD through
a 0-5V signal. The commanded speed is determined by the PCM and is
communicated through Modbus to the VFD. The motor cannot be
connect to line voltage. Fan motor speed varies based on outdoor
ambient temperature and compressor speed. The fan motor will not
operate during defrost and may cycle off and on if extremely low airflow
is desired.
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
Pressure Equalization Valve (PEV)
The PEV is located at the discharge of the compressor and the inlet to the
accumulator. The purpose of the PEV is to prevent the compressor from
starting with a high pressure differential, which can cause compressor
damage. Occasionally the unit may experience a brief starting delay
while the PEV equalizes pressure before startup.
High Pressure Switch
This unit contains a high pressure switch to protect against high pressure
conditions. This switch must be closed for the VFD to be powered.
Outdoor Pressure Transducers
There are two pressure transducers installed on this unit. One is located
at the discharge of the compressor and the other is located at the suction
of the compressor. These are labeled as "P1" and "P2" on the PCM and
the connection to the control board can be interchanged without
impacting the pressure measurements or system control.
transducers have a range from 0 to 620 psig and are used for system
protection, calculating superheats, and diagnostics.
Stator Heater Operation
This unit has an internal stator heating function.
windings will occasionally be energized during the OFF cycle to start the
stator heat operation, thus maintaining a sump temperature that is
essential for compressor reliability. The compressor will not run during
this process. PCM software version 5.0 or above is required for stator
heat operation.
Infinity Controlled low ambient cooling
This unit is capable of low ambient cooling down to 0F (-17.8C) with
Low Ambient enabled on the Infinity Control. A low ambient kit is not
required.
The Infinity Control provides an automatic evaporator coil freeze
protection algorithm that eliminates the need for an evaporator freeze
thermostat. The only accessory that may be required is wind baffles in
locations which are likely to experience cross winds in excess of 5 miles
an hour. This generally occurs only on roof and open area applications.
Low ambient cooling must be enabled in the User Interface setup. The
outdoor unit fan will cycle on and off based on outdoor coil temperature,
outdoor air temperature, and suction pressure measurements to keep the
compressor running at the proper conditions.
Defrost
This user interface (UI) offers 5 possible defrost interval times: 30, 60,
90, 120 minutes, or AUTO. The default is AUTO.
Defrost interval times: 30, 60, 90, and 120 minutes or AUTO are
selected by the Infinity Control User Interface (dip switches are not
used.)
AUTO defrost adjusts the defrost interval time based on the last defrost
time as follows:
• When defrost time <3 minutes, the next defrost interval=120 minutes.
• When defrost time 3-5 minutes, the next defrost interval=90 minutes.
• When defrost time 5-7 minutes, the next defrost interval=60 minutes.
• When defrost time >7 minutes, the next defrost interval=30 minutes.
The control board accumulates compressor run time when the coil
temperature is below 32°F. When accumulated run time approaches the
selected defrost interval a defrost is initiated. Upon initial power up the
first defrost interval is defaulted to 30 minutes. Remaining intervals are
at selected times. Defrost is only allowed to occur when the coil
temperature is below 35°F.
Defrost termination will occur when the OCT reaches a predetermined
temperature. This temperature varies based on unit model and OAT. If
maximum allowable defrost time has expired and OCT has not reached
the predetermined temperature, the system will resume heating
operation.
NOTE: Compressor speed during defrost varies based on outdoor
conditions and unit model
15
These
The compressor
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