Application Data - Bryant LEGACY 582K Product Data

Application data

Minimum operating ambient temperature (cooling)
In mechanical cooling mode, your Bryant rooftop unit can
safely operate down to an outdoor ambient temperature of 40°F
(4°C). It is possible to provide cooling at lower outdoor ambi-
ent temperatures by using less outside air, economizers, and/or
accessory low ambient kits.
Maximum operating ambient temperature (cooling)
The maximum operating ambient temperature for cooling
mode is 115°F (46°C). While cooling operation above
115°F (46°C) may be possible, it could cause either a reduction
in performance, reliability, or a protective action by the unit's
internal safety devices.
Multiple motor and drive packages
Some applications need larger horsepower motors, some need
more airflow, and some need both. Regardless of the case, your
Bryant expert has a factory installed combination to meet your
application. A wide selection of motors are available, factory
installed, to handle nearly any application.
Stainless steel heat exchanger (582K units only)
The stainless steel heat exchanger option provides the tubular
heat exchanger be made out of a minimum 20 gage type 409
stainless steel for applications where the mixed air to the heat
exchanger is expected to drop below 45°F (7°C). Stainless steel
may be specified on applications where the presence of air-
borne contaminants require its use (applications such as paper
mills) or in area with very high outdoor humidity that may
result in severe condensation in the heat exchanger during cool-
ing operation.
Minimum mixed air temperature (heating) (582K units only)
Using the factory settings, the minimum temperatures for the
mixed air (the combined temperature of the warm return air and
the cold outdoor air) entering the dimpled, gas heat exchangers
are shown in the following table.
MINIMUM TEMPERATURE FOR MIXED AIR
TEMPERATURE
ALUMINIZED
50°F (10°C) Continuous
45°F (7°C) Intermittent
Operating at lower mixed-air temperatures may be possible, if a
field-supplied, outdoor air thermostat initiates both heat stages
when the temperature is less than the minimum temperatures
listed above. Please contact your local Bryant representative
for assistance.
Minimum and maximum airflow (heating and cooling)
To maintain safe and reliable operation of your rooftop, operate
within the heating airflow limits during heating mode and cool-
ing airflow limits during cooling mode. Operating above the
max may cause blow-off, undesired airflow noise, or airflow
related problems with the rooftop unit. Operating below the
min may cause problems with coil freeze-up and unsafe heating
operation. Heating and cooling limitations differ when evaluat-
ing operating CFM, the minimum value is the HIGHER of the
cooling and heating minimum CFM values published on page 7
and the maximum value is the LOWER of the cooling and heat-
ing minimum values published on page 7.
STAINLESS STEEL
40°F (4°C) Continuous
35°F (2°C) Intermittent
Heating-to-cooling changeover
Your unit will automatically change from heating to cooling
mode when using a thermostat with an auto-changeover feature.
Airflow
All units are draw-though in cooling mode and blow-through in
heating mode.
Outdoor air application strategies
Economizers reduce operating expenses and compressor run
time by providing a free source of cooling and a means of
ventilation to match changing application needs. In fact, they
should be considered for most applications. Also, consider the
various economizer control methods and their benefits, as well
as sensors required to accomplish your application goals.
Please contact your local Bryant representative for assistance.
Motor limits, break horsepower (BHP)
Due to internal design of Bryant units, the air path, and spe-
cially designed motors, the full horsepower (maximum contin-
uous BHP) band, as listed in the Fan Performance tables, can
be used with the utmost confidence. There is no need for extra
safety factors, as Bryant motors are designed and rigorously
tested to use the entire, listed BHP range without either nui-
sance tripping or premature motor failure.
Propane heating (582K units only)
Propane has different physical qualities than natural gas. As a
result, propane requires different fuel to air mixture. To opti-
mize the fuel/air mixture for propane, Bryant sells different
burner orifices in an easy to install accessory kit. To select the
correct burner orifices or determine the heat capacity for a pro-
pane application, use either the selection software, or the unit's
service manual.
High altitude heating
High altitudes have less oxygen, which affects the fuel/air mix-
ture in heat exchangers. In order to maintain a proper fuel/air
mixture, heat exchangers operating in altitudes above 2000 ft
(610 m) require different orifices. To select the correct burner
orifices or determine the heat capacity for a high altitude appli-
cation, use either the selection software, or the unit's service
manual.
High altitudes have less oxygen, which means heat exchangers
need less fuel. The new gas orifices in this field-installed kit
make the necessary adjustment for high altitude applications.
They restore the optimal fuel to air mixture and maintain
healthy combustion on altitudes above 2000 ft (610 m).
NOTE: Typical natural gas heating value ranges from 975 to
1050 Btu/ft at sea level nationally. The heating value goes
3
down approximately 1.7% per every thousand feet elevation.
Standard factory orifices can typically be used up to 2000 ft
(610 m) elevation without any operational issues.
Sizing a rooftop
Bigger is not necessarily better. While an air conditioner needs
to have enough capacity to meet the design loads, it does not
need excess capacity. In fact, excess capacity typically results
in very poor part load performance and humidity control.
Using higher design temperatures than ASHRAE recommends
for your location, adding "safety factors" to the calculated load,
are all signs of oversizing air conditioners. Oversizing the air
conditioner leads to poor humidity control, reduced efficiency,
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