Bryant COMMERCIAL SINGLE PACKAGE ROOFTOP GAS HEAT/ELECTRIC COOLING 581B - Manual (Page 61)

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GUIDE SPECIFICATIONS (cont)
I. Controls and Safeties:
1. Unit Controls:
Unit shall be complete with self-contained low-
voltage control circuit protected by a fuse on the 24-v
transformer side.
2. Safeties:
a. Unit shall incorporate a solid-state compressor
protector which provides anti-cycle reset capabil-
ity at the space thermostat, should any of the
following standard safety devices trip and shut off
compressor.
1) Compressor overtemperature, overcurrent.
2) Loss-of-charge/low-pressure switch.
3) Freeze-protection thermostat, evaporator coil.
4) High-pressure switch.
The lockout protection shall be easily discon-
nected at the control board, if necessary.
b. Heating section shall be provided with the follow-
ing minimum protections:
1) High-temperature limit switches.
2) Induced draft motor speed sensor.
3) Flame rollout switch.
4) Flame proving controls
J. Operating Characteristics:
1. Unit shall be capable of starting and running at 125 F
ambient outdoor temperature, meeting maximum
load criteria of ARI Standard 210/240 or 360 at ±10%
voltage.
2. Compressor with standard controls shall be
capable of operation down to 25 F ambient outdoor
temperature.
K. Electrical Requirements:
All unit power wiring shall enter unit cabinet at a single
factory-predrilled location.
L. Motors:
1. Compressor motors shall be cooled by refrigerant
passing through motor windings and shall have line
break thermal and current overload protection.
2. Indoor blower (evaporator-fan) motor shall have per-
manently lubricated bearings and inherent
automatic-reset thermal overload protection.
3. Totally enclosed condenser-fan motor shall have
permanently lubricated bearings and inherent
automatic-reset thermal overload protection.
4. Induced-draft motor shall have permanently lubri-
cated, sealed bearings and inherent automatic reset
thermal overload protection.
M. Special Features:
Certain features are not applicable when the features
designated by * are specified. For assistance in amending
the specifications, contact your local sales office.
1. Roof Curbs:
a. Formed galvanized steel with wood nailer strip
and capable of supporting entire unit weight.
b. Allows for installing and securing ductwork to curb
prior to mounting unit on the curb.
*2. Integrated Economizers:
a. Integrated integral-modulating type capable of
simultaneous economizer and compressor
operation.
b. Includes all hardware and controls to provide
cooling with outdoor air.
c. Equipped with low-leakage dampers not to
exceed 3% leakage, at 1 in. wg pressure differen-
tial (Durablade economizer).
d. Capable of introducing up to 100% outdoor air in
both minimum and fully open positions.
e. Equipped with a gravity relief sliding plate damper
(Durablade economizer). Damper shall close
upon unit shutoff.
f. EconoMi$er shall be equipped with a barometric
relief damper with up to 100% of return air (036-
072) or 90% of return air (090-150) relief. The
Durablade economizer is equipped with 30% of
return-air relief (036-150).
g. Designed to close damper during loss-of-power
situations with emergency power supply (Dura-
blade economizer) or spring return built into
motor (EconoMi$er).
h. Dry bulb outdoor-air thermostat protection shall
be provided as standard.
i. Durablade economizer is a guillotine-style
damper, and the EconoMi$er is a parallel blade
design.
3. 50% Manual Outdoor-Air Damper:
Manual damper package shall consist of damper,
birdscreen, and rainhood which can be preset
to admit up to 50% outdoor air for year-round
ventilation.
4. 25% Manual Outdoor-Air Damper:
Manual damper package shall consist of damper,
birdscreen, and rainhood which can be preset
to admit up to 25% outdoor air for year-round
ventilation.
5. 100% Two-Position Damper:
a. Two-position damper package shall include single
blade damper and motor. Admits up to 100% out-
door air.
b. Damper shall close upon indoor (evaporator) fan
shutoff.
c. Designed to close damper during loss of power
situations.
d. Equipped with 15% barometric relief damper.
6. 25% Two-Position Damper:
a. Two-position damper package shall include single
blade damper and motor. Admits up to 25% out-
door air.
b. Damper shall close upon indoor (evaporator) fan
shutoff.
*7. Solid-State Enthalpy Control:
a. For use with variable sliding economizer package
only.
b. Capable of sensing outdoor-air enthalpy content
(temperature and humidity) and controlling econ-
omizer cut-in point to have minimum heat content
air passing over the evaporator coil for most effi-
cient system operation.
*8. Differential Enthalpy Sensor:
a. For use with economizer only.
b. Capable of comparing enthalpy content (tempera-
ture and humidity) of outdoor and indoor air and
controlling economizer cut-in point at the most
economical level.
9. Outdoor-Air Enthalpy Sensor:
The outdoor-air enthalpy sensor shall be used with
the EconoMi$er device to provide single enthalpy
control. When used in conjunction with a return-air
enthalpy sensor, the EconoMi$er device will provide
differential enthalpy control. The sensor allows the
EconoMi$er controller to determine if outside air is
suitable for free cooling.
10. Return-Air Enthalpy Sensor:
The return-air enthalpy sensor shall be used with the
EconoMi$er device. When used in conjunction with
an outdoor-air enthalpy sensor, the EconoMi$er
device will provide differential enthalpy control.