TemperZone OPA 465RKTG-P, Installation & Maintenance

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3. REFRIGERATION SYSTEM
3.1 General
The OPA 465-960 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, one stage being digital for improved
control and system efficiency.
Each refrigeration system has been charged with
HFC-410A (R410A) refrigerant; refer wiring diagram
specification table for amount. ECO machines are
supplied with a mini PDG service interface tool fitted for
ease of service, maintenance and trouble shooting.
This charge is based on nominal capacity, nominal
conditions and nominal airflow and is sufficient under
these conditions to maintain a refrigerant superheat
of approximately 6 Kelvin. If the unit is installed in
subtropical or tropical conditions, has a high fresh air
content or has been installed with maximum supply
air quantity, the superheat should be checked and if
found to be above 6 Kelvin, refrigerant may need to
be added to the system to return the superheat to the
factory required state.
These readings should be taken with each stage
operating independently and after the
space has achieved conditions. The additional charge
should be recorded for future reference.
3.2 Compressors
The compressors are directional scroll type. The
compressor lubricant is polyolester 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.
3.3 Economiser (Option) - ECO Plus Version
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. The fresh air damper should return
to minimum setting and the return air damper open
before the 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.
4. WIRING
4.1 Electrical Requirements
Electrical work must be done by a qualified electrician.

DANGER LIVE ELECTRICAL CONNECTIONS. ONLY QUALIFIED
PERSONS WHO ARE COMPETENTLY TRAINED SHOULD
PERFORM SERVICE AND MAINTENANCE TASKS.
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 ECO is provided with a 24VAC control circuit
thermostat (TZT Optional), on/off switch and/or time
clock, field supplied and fitted. The control transformer
240V primary is used for countries with 230-240V
power supply. Alternatively control can be via a Modbus
connection.
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.
4.2 Unit Controller (UC6)
The temperzone Unit Controller 6 (UC6) is the
successor to the OUC4 controller. The UC6 provides
increased capability and flexibility in indoor-, outdoor-
and packaged units. The complete controller combines
the µPC controller board from Carel plus an interface
board to connect temperzone standard sensors and
plugs. The UC6 receives requests such as “Unit On/Off”,
“Start 1 or 2 compressors”, “Activate HEAT (Reverse
Cycle)” and transfers these requests to the outputs after
enforcing safety timers. The UC6 ensures unit safety by
continuously monitoring input signals such as pressures
and temperatures. Beside the normal controls and unit
safety the UC6 has many other functions, for example
head pressure control, capacity control, superheat
control, serial communications and more.
The Unit Controller provides system protection functions
such as coil frost protection, de-icing, high head pressure
and low suction pressure cut-out. It also protects against
rapid cycling of the compressor(s) and loss of refrigerant.
The UC6 regulates the superheat of the refrigeration
system by controlling the position of an electronic
expansion valve (EEV). Various methods of head
pressure control (or limiting) are employed in temperzone
units. The particular method used varies from model
to model, but is also handled by the Unit Controller.
In combination, these features deliver optimised
performance across a wide operating temperature range.
As a result of the UC6’s control of these inter-related
functions, the outdoor fans may take some time to start
rotating after each compressor start. They may also run
on when the compressor stops. The fans will stop during
a de-ice cycle and the speed will vary either smoothly,
or in steps, in order to protect against excessively low or
high head pressure.
Refer to temperzone for operation & fault diagnostics
information OR www.temperzone.biz .