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I-Control Systems
The A55 Unit Controller provides all control function for
the rooftop unit. Default operation requires a standard
room thermostat or direct digital controller (DDC). The A55
can also control the unit from a zone temperature sensor.
The A55 Unit Controller is a network controller when dai-
sychained to the L Connection® Network Control System.
PC with Unit Controller PC software installed.
J-Smoke Detectors A171, A172, A173
-
stalled option. The smoke detectors can be installed in the
supply air section (A172), return air section (A171), or in
both the supply and return air section. Smoke detection
control module (A173) is located below the control pan-
el. Wiring for the smoke detectors are shown on the tem-
perature control section (C) wiring diagram in back of this
manual.
K-Blower Proving Switch S52
The blower proving switch monitors blower operation and
locks out the unit in case of blower failure. The switch is
N.O. and closes at .15” W.C. (3.3 Pa) The switch is mount-
ed on the middle left corner of the blower support panel.
Wiring for the blower proving switch is shown on the tem-
perature control section (C) wiring diagram in back of this
manual.
L-Dirty Filter Switch S27
-
is shown on the temperature control section (C) wiring di-
agram in back of this manual.
M-LP / Propane Kit
Units require two (one for each gas heat section) natural
to LP/propane kit. The kit includes one gas valve, eleven
the natural to LP gas changeover kit installation instruc-
tions.
The indoor air quality sensor monitors CO2 levels and
reports the levels to the A55 Unit Controller. The board
adjusts the economizer dampers according to the CO2
levels. The sensor is mounted next to the indoor thermo-
stat or in the return air duct. Refer to the indoor air qual-
ity sensor installation instructions for proper adjustment.
Wiring for the indoor air quality switch is shown on the
temperature control section (C) wiring diagram in back of
this manual.
O-Optional UVC Lights
The Healthy Climate
®
germicidal light emits ultraviolet
microbial life forms (viruses, bacteria, yeasts and molds)
in the air. UVC germicidal lamps greatly reduce the growth
and proliferation of mold and other bio-aerosols (bacteria
and viruses) on illuminated surfaces. Germicidal lamps
are NOT intended to be used for removal of active mold
growth. Existing mold growth must be appropriately re-
moved PRIOR to installation of the germicidal lamp. Refer
closely to UVC light installation instruction warnings when
servicing units.
when excessive condensate collects in the drain pan. The
-
ler (A55) through DI-3. When the switch opens, the Unit
and restart the unit (if the switch has closed). The Unit
Controller has a three-strike counter before the unit locks
switch to open three times per thermostat demand. If the
unit locks out, a reset of the Unit Controller is required af-
ter the switch has closed to restore unit operation.
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