44
SS-SVX10H-EN
Start-Up
Electromechanical Controls
The 24–volt, electromechanical controls feature a
control transformer and contactor pressure lugs for
power wiring. 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 H
HE
EA
AT
T, C
CO
OO
OL
L or A
AU
UT
TO
O. The system should
operate normally.
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OT
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General
Operation of the system cooling (and optional heating)
cycles is controlled by the position of the system switch
on the room thermostat. Once the system switch is
placed in either the H
HE
EA
AT
T or C
CO
OO
OL
L position, unit
operation is automatic. The optional automatic
changeover thermostat, when in the A
AU
UT
TO
O position,
automatically changes to heat or cool with sufficient
room temperature change.
Evaporator Fan (Indoor Supply Air)
The evaporator fan is controlled by an O
ON
N//A
AU
UT
TO
O
switch on the room thermostat. With the switch
positioned at A
AU
UT
TO
O and the system operating in the
cooling mode, fan operation coincides with the cooling
run cycles. If the system is equipped with heat and is
operating in the heating mode while the fan switch is at
A
AU
UT
TO
O, fan operation coincides with the heating run
cycles. When the fan switch is positioned at O
ON
N, fan
operation is continuous.
Cooling Mode
With the disconnect switch in the O
ON
N position, current
is supplied to the compressor sump heater(s), phase
monitor and control transformer. The sump heater(s)
supplies heat to the compressor(s) during the “
“O
Offff”
”
cycle. The phase monitor looks at the incoming power
to verify that there is no reversed phase, no phase
imbalance, and no loss of phase. If the phase monitor
detects any of these three conditions, it will shut off
control voltage. The transformer steps down the line
voltage to 24V for the low voltage control circuit. When
the room thermostat system switch is positioned at
C
CO
OO
OL
L and the fan switch is at A
AU
UT
TO
O, the compressor
contactor energizes on a call for cooling. 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.
ReliaTel Controls
The ReliaTel™ Control 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 “
“O
Offff”
” and “
“O
On
n”
” timing to
increase reliability, performance and to maximize unit
efficiency. Upon power initialization, the RTRM
performs self-diagnostic checks to ensure that all
internal controls are functioning. It checks the
configuration parameters against the components
connected to the system. The system LED located on
the RTRM module is turned “
“O
On
n”
” within one second
after power-up if all internal operations are okay.
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
H
HE
EA
AT
T, C
CO
OO
OL
L or A
AU
UT
TO
O. The system should operate
normally.
N
NO
OT
TIIC
CE
E
E
Eq
qu
uiip
pm
me
en
ntt D
Da
am
ma
ag
ge
e!!
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En
nssu
urre
e tth
he
e d
diisscco
on
nn
ne
ec
ctt ffo
orr tth
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nd
do
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orr a
aiirr h
ha
an
nd
dlle
err iiss
ccllo
osse
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orre
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ng
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ysstte
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on
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Control Cooling Mode
For Zone Sensor Control
When the system switch is set to the C
CO
OO
OL
L position
and the zone temperature rises above the cooling
setpoint, the RTRM energizes the compressor
contactor, provided the high and low pressure and the
discharge temperature limit 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.
