Carrier MODU-PAC 50DF - Manual (Page 4)

Factory-installed options and
accessories offer flexibility to
application
field-installed
most any
Modulating outdoor air control
package (economizer) — Even when
outdoor air temperatures are low, many
installations still require cooling. The
economizer uses the cool outside air to
provide this cooling. Saves energy,
reduces compressor wear and tear and
lowers operating costs.
The economizer contains these
energy saving features:
•
Electronic control logic balances
the conditioned space demand against
the cooling system output. Ensures that
the economizer modulates to correct
position or closes to minimum position
to maintain a stable temperature in the
conditioned space. Never too much or
too little cooling.
The control logic also integrates
economizer cooling with mechanical
cooling. If outdoor enthalpy permits,
economizer acts as first stage of cooling.
If conditioned space requires more
cooling, economizer works in conjunc­
tion with mechanical cooling to maintain
required indoor temperature.
The integrated system supplies only
the amount of mechanical cooling
necessary.
• Low-leakage dampers limit infiltra­
tion. Rated by the manufacturer at 3%
with 3-in. wg pressure differential.
• Spring return damper motor auto­
matically closes the outdoor air dampers
in the event of a power failure. (Option
or Accessory)
Two-speed indoor fan option —
Substantial energy cost savings can be
obtained because fans automatically
operate at low speed during most cool­
ing operating hours. High speed is used
only if and when necessary to maintain
comfort conditions.
A 4-stage electronic logic panel
selects the most efficient fan speed and
compressor stage to satisfy room de­
mand.
Economizer performance is
optimized by utilizing low-speed opera­
tion except when space conditions
require the additional capacity of high­
speed “free cooling”.
The two-speed option is available in
either standard or alternate motor
sizes. All control and power wiring are
factory installed; thus, costly field wiring
and adjustments are not necessary.
The two-speed fan motors are 2
winding (4 pole/6 pole) with rpm’s of
1760/1170.
Power exhaust — Coupled with the
economizer, up to 75% of the return air
can be exhausted. Also, eliminates
over-pressurization of the building.
Designed for use with bottom duct
connection arrangements. Used only
with economizer. (Option or Accessory)
Electric heaters — Three factory-
installed and one field-installed heating
capacity are available. Factory wired for
2-stage heat. Outdoor air thermostats
can be added to provide additional
stages as required. Branch circuit pro­
tection is built in on each unit. (Option
or Accessory)
Bag filter — Extended surface media
provides high filtration of 50% (NBS
Dust Spot Test). Filter frame permits
use of field-supplied bag filters to pro­
vide up to 95% filtering efficiency.
(Option only)
Alternate indoor fan motor and
drive provides increased perform­
ance for application requirements
beyond standard unit operation range.
(Option only)
Energy management kit—Additional
energy savings occur thru the use of
the multi-feature energy management
kit which contains a setback/setup
module, a 7-day programmable clock
and morning warmup thermostat.
During unoccupied periods, the set­
back/setup module provides a select­
able amount of heating setback and
either cooling shutdown or a selectable
amount of cooling setup
The 7-day clock controls unit opera­
tion in and out of the setback/setup
modes. Clock contains a 10-hour spring
carryover for continuous operation
during power failures. Re-programming
is not necessary.
A 5-hour bypass switch provides unit
operation during unoccupied modes.
The clock and bypass switch are con­
tained in an attractive remote control
panel which installs in a convenient
location. Six status lights on the panel
indicate system operating modes.
The morning warmup thermostat
senses return air temperature and saves
energy by keeping the outdoor air
damper closed until morning warmup
is complete. Avoids using energy to
warm cold outside air. (Option or
Accessory)
REMOTE CONTROL PANEL
(Control Box)
SETBACK/SETUP MODULE 7-DAY CLOCK