TTA-SVN03A-EN
17
Unit Start-Up
Once the unit is properly installed and
pre-start procedures are complete,
start the unit by turning the System
Switch on the indoor thermostat to
either HEAT, COOL or AUTO. The
system should operate normally.
CAUTION
Ensure the disconnect for the indoor
air handler is closed before operating
the system. Operating the indoor unit
without the indoor fan energized, can
cause unit trip-out on high pressure
control and/or liquid flood back to the
compressor.
Sequence of Operation
ReliaTel
TM
Control
Unit Model Number Digits 9 and
10 = 0R, 0T, OU or OW
The ReliaTel Controls is a
microelectronic control feature, which
provides operating functions that are
significantly different than
conventional Electromechanical units.
The ReliaTel Refrigeration Module
(RTRM)
uses Proportional/Integral
control algorithms to perform specific
unit functions that govern the unit
operation in response to application
conditions.
The RTRM provides compressor anti-
short cycle timing functions through
minimum
“Off”
and
“On”
timing to
increase reliability, performance and
to maximize unit efficiency. Upon
power initialization, the RTRM
performs self-diagnostic checks to
insure that all internal controls are
functioning. It checks the
configuration parameters against the
components connected to the system.
The Light Port LED located on the
RTRM module is turned
“On”
within
one second after power-up if all
internal operations are okay.
ReliaTel Control Cooling Mode
When the system switch is set to the
COOL
position and the zone
temperature rises above the cooling
setpoint, the RTRM energizes the
compressor relay coil located on the
RTRM. When the compressor relay
contacts close, the compressor
contactor coil is energized provided
the low and high pressure controls
are closed. When the compressor
contacts close, the compressor and
the outdoor fan motor start to
maintain the zone temperature to
within ± 2 F of the sensor setpoint at
the sensed location.
On units with dual circuits, the second
stage of cooling is initiated as a result
of the Proportional/Integral control
algorithms calling for additional
cooling.
For Thermostat Control:
When the room thermostat system
switch is positioned at
COOL
and the
fan switch is at
AUTO
, the RTRM
energizes the compressor relay coil
located on the RTRM during a call for
cooling. When the compressor relay
contacts close, the compressor
contactor coil is energized provided
the low and high pressure controls
are closed. When the contacts of the
compressor contactor close,
operation of the compressor and
condenser fan begins. The evaporator
fan contactor also energizes on a call
for cooling and initiates evaporator
fan operation.
On units with dual circuits, the second
stage of cooling is initiated as a result
of the 2-stage thermostat calling for
additional cooling.
Note:
Irregular unit operation may
occur when the unit is
controlled with a triac-
switching thermostat. Please
review the approved
thermostat vendor list for all
recommended relay-switching
thermostats.
ReliaTel Control Evaporator Fan
Operation
When the fan selection switch is set to
the
AUTO
position, the RTRM
energizes the evaporator fan relay coil
approximately 1 second after
energizing the compressor contactor
coil in the cooling mode. In the
heating mode, the RTRM energizes
the evaporator fan
relay coil
approximately 1 second before
energizing the electric heat
contactors. The RTRM de-energizes
the evaporator fan relay coil
approximately 60 seconds after the
cooling requirement has been
satisfied to enhance unit efficiency.
When the heating cycle is terminated,
the evaporator fan relay coil is de-
energized at the same time as the
heater contactors. When the fan
selection switch is set to the
ON
position, the RTRM keeps the
evaporator fan relay coil energized for
continuous fan motor operation.
ReliaTel Control Heating
Operation
When the system switch is set to the
HEAT
position and heating is
required, the RTRM energizes the Heat
1 relay coil. When the Heat 1 relay
contacts close, the first stage electric
heat contactor is energized. If the first
stage of electric heat cannot satisfy
the heating requirement, the RTRM
energizes the Heat 2
relay coil. When
the Heat 2
relay contacts close, the
second stage electric heat contactor is
energized. The first and second stages
of heat are cycled
“On”
and
“Off”
as
required to maintain the zone.
System Start Procedure
ReliaTel™ Controls