OPA 650RKTB
Packaged Reverse Cycle R410A
Air Cooled Air Conditioner
GENERAL
This OPA 650RKTB Outdoor Unit must be
installed in accordance with all national and
local safety codes.
CONFIGURATIONS
The OPA 650RKTB is supplied in one of
two standard configurations :
1. Horizontal supply/return air with box
mounting channel (RKTBH), or
2. Downward supply air with box mounting
channel (RKTBU).
REFRIGERATION SYSTEM
General
The OPA 650 has two independent
refrigeration circuits and two compressors
to provide the flexibility and economy of
two stage operation, i.e. utilising one or
two circuits as conditions vary, plus the
advantage of staggered starting.
Each refrigeration system has been
charged with 9.5 kg each of HFC-410A
(R410A) refrigerant. Tapping points are
provided to measure discharge and suction
operating pressures.
Compressors
The compressors are directional scroll
type. The compressor lubricant is polyol
ester oil (POE). Note, this oil absorbs
moisture quickly if exposed to open air.
On commissioning, the compressors must
be checked for correct rotation (refer Start
Up Procedure). A time delay prevents
simultaneous starting of the compressors.
ECONOMISER (Option)
If the outdoor air temperature or heat
content preferably, is below that of the
return air the fresh air damper opens and
the return air damper closes to provide the
first stage of cooling. A spill air facility in
the building may be necessary for when
the return air damper is closed. The fresh
air damper should return to minimum
setting and the return air damper open
before compressors are allowed to operate
to provide further cooling. A low limit
thermostat is fitted to prevent compressors
operating with a mixed air-on coil
temperature below 18°C; resets at 20°C.
This is by-passed during heating mode.
INSTALLATION
Positioning
Refer to dimension diagrams for minimum
clearances. If multiple units are to be
placed side-by-side then allow at least 2 m
between coil faces.
Installation &
Maintenance
Mounting
The unit should be fastened to a firm flat
horizontal base using the holes supplied in
the mounting channels.
When the unit is being installed on a roof it is
recommended that the unit is installed on a
substantial structure with vibration isolating
springs beneath the unit. These springs are
not supplied with the unit.
Flexible duct connections are recommended
between the supply and return ducts and
the unit.
Condensate Drain
The condensate drain should be 'U' trapped
outside the unit. The trap should have a
vertical height of at least 100 mm. The drain
should have a slope of at least 1 in 50 and
must not be piped to a level above the unit
drain pipe (refer Fig. 3).
Electrical Requirements
Electrical work must be done by a qualified
electrician. The outdoor unit must be wired
directly from a distribution board by means
of a circuit breaker or H.R.C. fuse, and a
mains isolator provided - preferably close to
the unit.
Note: DO NOT USE REWIRABLE FUSES.
The OPA 650 is provided with a 24V AC
control circuit for a thermostat, on/off switch
and/or time clock.
The control transformer 240V primary
voltage is used for countries with 230-240V
power supply. For countries with supply
voltages 200-220V, change the primary
voltage on the transformer to 208V.
Standard units are suitable for use with
thermostats with either manual Heat/Cool
selection or automatic changeover subject to
the contact ratings of the thermostats.
A 24 hour power supply to the compressor
crank case heaters is required, otherwise the
warranty is void.
CHECK TESTS
1. Leave the on/off switch in the off position
and close the mains isolating switch.
A four hour delay period is required to
allow the crankcase heaters to drive any
liquid refrigerant out of the compressor oil.
Bypass the crankcase heater thermostat
(CCHT) for this period only.
2. Check that the shipping blocks beneath
each compressor have been removed
and that each compressor is secure on its
mounts.
3. Check that all fan motors are free running.
4. Check that the thermostat is correctly
wired to the unit and is set at the desired
temperature.
5. Check that the air filters have been
correctly installed if fitted.
6. Check air diffuser dampers are open if
appropriate.
START UP PROCEDURE
Use the supplied Commissioning Sheet to
help you complete the following procedure:
1. After the four hour delay period has
expired, switch on the unit. Ensure the
crankcase heater thermostat has been
reconnected.
2. Check the supply voltage between each
phase and neutral.
3. Compressors fitted are directional. Check
for correct rotation. If rotation is incorrect
the compressor will not pump, be noisy,
and will draw minimal current. To correct
motor rotation, change the phasing at
the main power terminal. If changing the
phasing, check the indoor air fan then
runs in the correct direction also.
4. Measure the current draw on each phase
to the compressor motors and measure
the current draw of each fan motor.
Check all readings against the specified
values in the wiring diagram.
5. Fit R410A compatible gauges and
measure the suction and discharge
pressures of both refrigeration circuits.
6. Check that the outdoor air fan motors are
running smoothly.
7. Test the operation of the reversing valve
by running the unit in both the heating
and cooling mode.
8. Check the indoor unit's fan belt tension
after 20 mins of operation and adjust if
necessary (refer Commissioning Sheet).
9. Check the supply air flow at each outlet.
10.Check the tightness of all electrical
connections and sign the check label.
11.Touch up any outdoor unit paintwork
damage to prevent corrosion.
SETTING SUPPLY AIR FLOW
Consult OPA 650 Technical Data pamphlet
for details of airflow/duct static pressure, if
required.
If the indoor air returning to the unit is
regularly expected to be above 50%RH,
then the coil face velocity should be limited
to be 2.5 m/s or less (refer Air Handling
graph in Technical Data pamphlet).
High humidity levels can occur in tropical or
subtropical conditions, and/or when heavily
moisture laden fresh air is introduced.
Select a fan speed that avoids water carry-
over problems.
In a free blow or low resistance application,
beware of exceeding the fan motor's full
load amp limit (refer wiring diagram).
