12
OAU-SVX006E-EN
General Information
Overview of Manual
Note:
One copy of this document ships inside the control
panel of each unit and is customer property. It must
be retained by the unit’s maintenance personnel.
This booklet describes proper installation, operation, and
maintenance procedures for air cooled systems. By
carefully reviewing the information within this manual
and following the instructions, the risk of improper
operation and/or component damage will be minimized.
It is important that periodic maintenance be performed to
help assure trouble free operation. A maintenance
schedule is provided at the end of this manual. Should
equipment failure occur, contact a qualified service
organization with qualified, experienced HVAC technicians
to properly diagnose and repair this equipment.
Model Number Description
All products are identified by a multiple-character model
number that precisely identifies a particular type of unit.
An explanation of the alphanumeric identification code is
provided (refer to
“Model Number Descriptions,” p. 9
use will enable the owner/operator, installing contractors,
and service engineers to define the operation, specific
components, and other options for any specific unit.
When ordering replacement parts or requesting service,
be sure to refer to the specific model number and serial
number printed on the unit nameplate.
Unit Nameplate
A Mylar
®
unit nameplate is located on the unit’s corner
support next to the control box. It includes the unit model
number, serial number, electrical characteristics,
refrigerant charge, as well as other pertinent unit data.
Compressor Nameplate
The nameplate for the compressors are located on the side
of the compressor.
Unit Description
Before shipment, each unit is leak tested, dehydrated,
charged with refrigerant and compressor oil, and run
tested for proper control operation.
The condenser coils are aluminum fin, mechanically
bonded to copper tubing.
Direct-drive, vertical discharge condenser fans are
provided with built-in thermal overload protection.
The Outdoor Air Unit Main Unit Display and ReliaTel™
Control Module (RTRM) are microelectronic control
systems. The acronym RTRM is extensively throughout
this document when referring to the control system
network.
The Main Unit Display and the RTRM are mounted in the
Main Control Panel. The Main Unit Display and RTRM
receive information from sensors and customer binary
contacts to satisfy the applicable request for ventilation,
cooling, dehumidification and heating.
Indoor Fan Failure Input
The Indoor Fan Failure Switch (IFFS) is connected to verify
indoor fan operation.
When there is a call for the indoor fan to be energized, the
differential pressure switch, connected to the Main Unit
Display, must prove airflow within 30 seconds or the Main
Unit Display will shut off all mechanical operations, lock
the system out and send a diagnostic alarm to the Unit
Display. The system will remain locked out until a reset is
initiated through the MCM via the Alarm Reset Function on
the Unit Display.
Low Pressure Control ReliaTel Control
This input incorporates the compressor low pressure
control (CLP 1/2) of each refrigeration circuit and can be
activated by opening a field supplied contact installed on
the OAUTS.
If this circuit is open before the compressor is started, the
ReliaTel™ control will not allow the affected compressor to
operate. Anytime this circuit is opened for 1 continuous
second during compressor operation, the compressor for
that circuit is immediately turned “Off.” The compressor
will not be allowed to restart for a minimum of 3 minutes
should the contacts close.
If four consecutive open conditions occur during the first
three minutes of operation, the compressor for that circuit
will be locked out, and a manual reset will be required to
restart the compressor.
Refrigerant Circuits
For 10–20 ton units, one refrigerant circuit shall
incorporate a standard 4- or 6-row coil. All circuits shall
have thermal expansion valves (TXVs), service pressure
ports, and refrigerant line filter driers as standard. An area
will be provided for replacement suction line driers.
Refrigerant circuit one (1
st
Stage) is equipped with a
factory installed and preset refrigerant capacity control
(RCC) to prevent evaporator coil temperatures below
approximately 38°F (114 lb suction). The refrigerant
capacity device is not installed when the unit is equipped
with a digital scroll or variable speed compressor.
High Pressure Control ReliaTel Control
The compressor high pressure controls (CHP 1/2/3/4) are
wired in series between the compressor outputs on
RTRM1 (CHP 1/2) and RTRM2 (CHP 3/4) and the
compressor contactor coils. If one of the high pressure
control switches opens, the respective RTRM senses a lack
of current while calling for cooling and locks the
compressor out.
