Unit Start-Up; Sequence Of Operation; Reliatel™ Controls; Reliatel™ Controls - Constant Volume (Cv) - Trane YSC036G Installation, Operation And Maintenance Manual

Unit Start-Up

Sequence of Operation

Units are offered with two control options,
electromechanical or ReliaTel™.
Note: Refer to the unit nameplate: If the 9th digit of the
model number = R, proceed with the ReliaTel™
Controls section within this chapter. If the 9th digit
of the model number = E, proceed with the
Electromechanical Controls section within this
chapter.
Note: The optional condensate overflow switch (COF)
will shut the unit down if the float is raised and the
switch is closed.
ReliaTel™ Controls
ReliaTel™ Controls - Constant Volume
(CV)
ReliaTel™ control is a microelectronic control feature,
which provides operating functions that are significantly
different than conventional electromechanical units. The
master module is the ReliaTel™ refrigeration module
(RTRM).
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 LED located on the RTRM module is turned "On"
within one second after power-up if all internal operations
are okay.
ReliaTel™ Control Cooling without an
Economizer
When the system switch is set to the "Cool" position and
the zone temperature rises above the cooling setpoint
control band, the RTRM energizes the (K9) relay coil
located on the RTRM. When the K9 relay contacts close,
the compressor contactor (CC1) coil is energized provided
the low pressure control (LPC1), high pressure control
(HPC1) and discharge line thermostat (TDL 1) are closed.
When the CC1 contacts close, compressor (CPR1) and the
outdoor fan motor (ODM) start to maintain the zone
temperature to within ± 2ºF of the sensor setpoint at the
sensed location.
If the first stage of cooling can not satisfy the cooling
requirement, the RTRM energizes the (K10) relay coil
located on the RTRM. When the (K10) relay contacts close,
the compressor contactor (CC2) coil is energized provided
RT-SVX21AC-EN
the low pressure control (LPC2), high pressure control
(HPC2) and discharge line thermostat (TDL 2) are closed.
When the CC2 contacts close, compressor (CPR2) starts to
maintain the zone temperature to within ± 2ºF of the
sensor setpoint at the sensed location.

Three-Stages of Cooling

Note: High efficiency units only.
When the unit is configured for three-stage cooling, and
the system switch is set to the cool position and the zone
temperature rises above the cooling setpoint control
band, the RTRM energizes the (K10) relay coil located on
the RTRM. When the (K10) relay contacts close,
compressor contactor (CC2) is energized. This is the
smaller of the two compressors (CPR2). This staging order
is opposite standard staging order.
If the first stage of cooling can not satisfy the cooling
requirement, the RTRM energizes the (K9) relay coil and
de-energizes the (K10) relay coil on the RTRM.
Compressor contactor (CC1) is energized, bringing on the
larger of the two compressors (CPR1). Compressor
contactor (CC2) is de-energized, turning off the smaller
compressor.
If the second stage of cooling can not satisfy the cooling
requirement, the RTRM keeps the (K9) relay coil energized
and energizes the (K10) relay coil. Compressor contactors
(CC1) and (CC2) are energized, and both compressors
(CPR1 and CPR2).
Lead/Lag is disabled with three-stage cooling. A unit
configured for three-stage cooling and controlled with a
thermostat will operate as a two-stage unit.
ReliaTel™ Control Evaporator Fan
Operation (for Gas Units)
When the fan selection switch is set to the "Auto" position,
the RTRM energizes the (K6) relay coil approximately 1
second after energizing the compressor contactor coil
(CC1) in the cooling mode. In the heating mode, the RTRM
energizes the (K6) relay coil approximately 45 second after
gas ignition. Closing the (K6) contacts on the RTRM
energizes the indoor fan relay (F) coil to start the indoor fan
motor (IDM).
The RTRM de-energizes the fan relay (F) approximately 60
seconds after the cooling requirement has be satisfied to
enhance unit efficiency. When the heating cycle is
terminated, the indoor fan relay (F) coil is de-energized
approximately 90 seconds after the heating requirement.
When the fan selection switch is set to the "On" position,
the RTRM keeps the indoor fan relay coil (F) energized for
continuous fan motor operation.
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