INSTALLATION INSTRUCTIONS
R
−
410A Split System Heat Pumps
428 01 1703 01
9
Specifications subject to change without notice.
Unit is factory charged for 15ft (4.57 m) of lineset. Adjust
charge by adding or removing 0.6 oz/ft of 3/8 liquid line
above or below 15ft (4.57 m) respectively.
For standard refrigerant line lengths (80 ft/24.38 m or less),
allow system to operate in cooling mode at least 15 minutes.
When operating with the Observer Wall Control in
communicating mode make sure that indoor airflow is set to
the final operating selection (Eff 325, Eff 350, Comfort,
Maximum) during charging. If conditions are favorable, check
system charge by subcooling method. If any adjustment is
necessary, adjust charge slowly and allow system to operate
for 15 minutes to stabilize before declaring a properly
charged system.
If the indoor temperature is above 80
F (26.67
C), and the
outdoor temperature is in the favorable range, adjust system
charge by weight based on line length and allow the indoor
temperature to drop to 80
F (26.67
C) before attempting to
check system charge by subcooling method as described
above.
If the indoor temperature is below 70
F (21.11
C), or the
outdoor temperature is not in the favorable range, adjust
charge for line set length above or below 15ft (4.57 m) only.
Charge level should then be appropriate for the system to
achieve rated capacity. The charge level could then be
checked at another time when the both indoor and outdoor
temperatures are in a more favorable range.
NOTE
: The Observer Wall Control has a staging timer, to
override the staging timer for charging in high
−
stage create
at least a 5 degree difference between room and set point
temperatures and hold the “Cool To” button for 10 seconds
on the thermostat home screen.
NOTE
: If line length is beyond 80 ft (24.38 m) or greater than
20 ft (6.10 m) vertical separation, See Long Line Applications
Guideline for special charging requirements.
Heating Tech Label
To check system operation during heating cycle, refer to the
Heating Tech Label on outdoor unit. This label indicates
whether a correct relationship exists between system
operating pressure and air temperature entering indoor and
outdoor units. If pressure and temperature do not match on
chart, system refrigerant charge may not be correct. Do not
use label to adjust refrigerant charge.
SYSTEM FUNCTIONS AND SEQUENCE OF
OPERATION
The *CH9 and *CH6 models utilize either an Observer
Communicating Wall Control or a 2-stage cooling thermostat.
With a call for first stage cooling, the outdoor fan and
low-stage compressor are energized. If low-stage cannot
satisfy cooling demand, high-stage is energized by the
second stage of the indoor thermostat. After second stage is
satisfied, the unit returns to low-stage operation until first
stage is satisfied or until second stage is required again.
When both first stage and second stage cooling are satisfied,
the compressor will shut off. When a 2-stage unit is operating
at low-stage, system vapor (suction) pressure will be higher
than a standard single-stage system or high-stage operation.
When the outdoor ambient is more than 100
F (37.8
C), the
outdoor fan will continue to run for one minute after
compressor shuts off, this reduces pressure differential for
easier starting in the next cycle.
With non-communicating (non-Observer) systems, with first
stage of cooling, Y1 and O are powered on; and with second
stage of cooling, Y1, Y2, and O are on. For these systems,
with first stage of heating Y1 is on and for second stage of
heating, Y1 and Y2 are on. When the reversing valve is
energized, O is powered on.
Communication and Status Function Lights
Green communications (COMM) Light (Only with
Observer Communicating Wall Control)
A green LED (COMM light) on the outdoor board indicates
successful communication with the other system products.
The green LED will remain OFF until communications is
established. Once a valid command is received, the green
LED will turn ON continuously. If no communication is
received within 2 minutes, the LED will be turned OFF until
the next valid communication.
Amber Status Light (STATUS)
An amber colored STATUS light is used to display the
operation mode and fault codes as specified in the
troubleshooting section. See Table 3 for codes and
definitions.
NOTE
: Only one code will be displayed on the outdoor unit
control board (the most recent, with the highest priority).
Utility Interface with Non-Communicating
Thermostat
The utility curtailment relay should be wired in the Y2
thermostat lead. This allows a power utility device to interrupt
high stage compressor operation during peak load periods. If
the utility requires control of low stage compressor operation
a second utility curtailment relay should be wired in the Y1
lead.
NOTE
: Utility curtailment is not available when operating in
communicating mode. To apply utility curtailment with the
Observer Wall Control you must use a daughter board kit to
convert the control signals to standard thermostat signals.
Compressor Operation
The basic scroll design has been modified with the addition
of an internal unloading mechanism that opens a by-pass
port in the first compression pocket, effectively reducing the
displacement of the scroll. The opening and closing of the
by-pass port is controlled by an internal electrically operated
solenoid. The 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.
Modulation is achieved by venting a portion of the gas in the
first suction pocket back to the low side of the compressor,
thereby reducing the effective displacement of the
compressor.
Full capacity is achieved by blocking these vents, thus
increasing the displacement to 100%. A DC solenoid in the
compressor controlled by a rectified 24 volt AC signal in the
external solenoid plug moves the slider ring that covers and
uncovers these vents. The vent covers are arranged in such
a manner that the compressor operates at approximately
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.
NOTE
: 67% compressor capacity translates to approximately
75% cooling capacity at the indoor coil. The compressor will
always start unloaded and stay unloaded for five seconds even
when the thermostat is calling for high
−
stage capacity.
Crankcase Heater Operation
The crankcase heater is de-energized when the compressor
is running. The crankcase heater is energized when the
compressor is off and the ambient is less than 42
F. When
the ambient temperature is between 65
F and 42
F the
crankcase heater is energized 30 minutes after the
compressor is turned off. When the ambient is above 65
F
