Carrier MODU-PAC 50DF - Manual (Page 20)

50DF
Guide Specifications
BASE UNIT
Unit shall be of a one-piece air-to-air electric cooling and
electric heating unit and shall be mounted on a full perimeter
roof curb.
Total cooling capacity of the unit shall be__________ Btuh or
greater, and sensible capacity shall be_______ Btuh or greater
at conditions of:________ cfm evaporator air entering unit
at_____ wet-bulb,_______ dry-bulb and condenser entering
air temperature of_______dry-bulb.
Heating capacity of the system shall be__________ kw
Unit cabinet shall be constructed of galvanized steel,
bonderized and coated with baked enamel.
Compressor system — The unit shall contain serviceable
hermetic compressor(s) with service valves, suitable vibra­
tion isolators, crankcase heater(s), sight glass(es) and
filter drier(s).
Coils shall be aluminum plate fins mechanically bonded to
copper tubes. They shall be of an intertwined design for
equal circuit loading and full active coil on part load opera­
tion to assure proper treatment of conditioned air.
115-volt convenience outlet shall be sized to handle a
small power load or service light.
Controls shall contain a solid-state logic panel providing:
ability to accept parallel inputs from multiple dual set point
thermostats, 2-position on/off outputs for staged heating/
cooling control. Shall utilize electronic space sensor in con-
junction with discharge thermostat for stable operation,
and contain adjustable outdoor air thermostat to lock out
mechanical cooling when outdoor air is below its setting
Pre-installcd tracks shall be provided on non-electrically
heated units to accommodate a field-installed hydronic coil.
Fans and motors — The indoor air fans shall be of the
forward-curved centrifugal Class I type, belt driven by
a______ hp motor. The outdoor air fan(s) shall be of the
propeller type, each directly driven by a_______ hp inherently
protected motor.
Electric heaters shall have a total output of____________Btuh
Each heater assembly shall include circuit breakers, auto­
matic resetting limit switches and heat limiters for primary
and secondary over-current and thermal protection.
Safety controls — Cooling section shall be protected by
fusible plug, low and high pressurestat, compressor motor
overloads, and a timing device which will prohibit the
compressor motor from being subjected to starting current
more than once every 5 minutes.
Unit connections — Heating and cooling power wires in
the unit shall be powered by single-point terminal connec­
tions. All utility connections shall be routed thru bottom of
unit. Alternate openings in sides of unit shall also be
provided.
Dimensions — The unit casing shall have width of not
more than______ in., length of not more than________ in., and
height of not more than________inches
9^'
Options and accessories
Belt-driven centrifugal power exhaust, coupled with
the economizer, to exhaust up to 75% return air. (Option
or Accessory)
Bag filters with 50% efficiency (NBS Dust Spot Test). Bag
filter rack shall accept filter of up to 95% efficiency. (Option)
Indoor fan motor and drive to provide higher fan output
when job requirements exceed standard fan capacity.
(Option)
Two-speed indoor fan option shall provide economical
indoor fan operation based on conditioned space demands.
Economizer (when supplied) and compressor operation
shall be integrated with 2-speed fan control to supply
optimum cooling performance and energy savings.
Roof curb — Roof curb shall be of same manufacture as
unit, shall support unit and provide a watertight enclosure
to protect ductwork and utility services. Curb design shall
comply with NRCA requirements. (Accessory)
Suction pressure unloader shall provide capacity control
for reduced compressor capacity at light loads. (Accessory)
Head pressure control — An outdoor air fan speed
control to permit unit to operate down to -20 F shall be
provided. (Accessory)
Outdoor air thermostats shall be provided for additional
staging of electric heaters. (Accessory)
Modulating outdoor air control package (economizer)
shall provide “free cooling” with outside air without com­
pressor operation. The package shall:
• Contain low leak dampers rated at 3% at 3-in. static
pressure.
• Contain spring return motor to close dampers during
power failure.
• Be capable of integrated (simultaneous) economizer
cooling and mechanical cooling.
• Utilize room demand signal, enthalpy changeover and
discharge air sensor for damper control. (Option or
Accessory)
Energy management shall provide energy-saving settings
for unoccupied periods. It shall include these components:
• Setback/setup module providing a selectable amount of
heating setback or cooling setup or shut down.
• Morning warmup thermostat to hold outdoor air
dampers closed until return air temperature exceeds the
selected set point.
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