22
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 Electro-mechanical 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
For Zone Sensor Control:
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
TM
Controls
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