Carrier MODU-PAC 50DF - Manual (Page 5)

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Barometric relief damper operates
automatically to help exhaust excess
air during economizer operation. Ac­
cessory comes partially assembled for
easy installation.
Roof curb supports unit and frames
roof opening. Provides a strong, water­
tight interface between unit and roof.
Once curb is set in place, the unit may
be rigged at any time — no need to
schedule around the roofer. Design
complies
with National Roofing
Contractors Association (NRCA)
requirements.
Outdoor air thermostat allows addi­
tional staging of electric heat. Multiple
thermostats permit as many stages of
control as there are heaters in the unit.
Suction pressure unloader package
— Additional staging, beyond the stand­
ard 2 stages of capacity control, can be
accomplished with field-installed suc­
tion
pressure actuated compressor
unloaders. (024 size is excluded, uses a
standard electric unloader.)
Motormaster® head pressure con­
trol modulates the speed of outdoor air
fan motor to maintain correct con­
densing temperature at low outdoor air
temperatures.
Permits operation to
-20 F, if required.
Electronic temperature sensing —
Three
electronic sensing/transmitting
devices are available to meet your
specific application requirements. Each
transmitting
device contains dual
(heating/cooling) set point adjustment
levers concealed under a locking cover.
Light emitting diodes (LED’s), also con­
cealed under the cover, allow diagnostic
checkout of control system from the
transmitting device. The choices are:
• Thermostat with integral sensor —
A traditional application. Both the
temperature set points and the sensing
device are contained in one device
installed in the conditioned space.
• Transmitter with remote sensor —
The transmitter contains the tempera­
ture set points and LED’s under its
cover. In this application, a remote wall-
mounted sensor is installed in the con­
ditioned space and the transmitter is
installed in a restricted-access area.
Eliminates unauthorized adjustment of
conditioned space temperature.
• Thermostat or transmitter on subbase
—provides
manual COOL-AUTO.-
HEAT-OFF system switching and
AUTO.-ON fan switching from a con­
venient location. Recommended for
units without energy management kit.
FANS MOTORS
I____
PO’WER EXHAUST FANS AND MOTORS
THERMOSTAT OR
TRANSMITTER
REMOTE
SENSOR
UNLOADER PACKAGE MOTORMASTER CONTROL