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RTU Open Protocol Controller —
Connect the rooftop to
an existing BAS without needing complicated translators or
adapter modules using the RTU Open controller. This new con-
troller speaks the 4 most common building automation system
languages (BACnet 1 , Modbus 2 , N2, and LonWorks 3 ). Use this
controller when you have an existing BAS.
Condensate Overflow Switch (Factory-Installed
Option) —
This sensor and related controller monitors the
condensate level in the drain pan and shuts down compression
operation when overflow conditions occur. It includes:
• Indicator light - solid red (more than 10 seconds on water
contact - compressors disabled), blinking red (sensor dis-
connected)
• 10 second delay to break - eliminates nuisance trips from
splashing or waves in pan (sensor needs 10 seconds of con-
stant water contact before tripping)
• Disables the compressor(s) operation when condensate plug
is detected, but still allows fans to run for Economizer.
Power Exhaust with Barometric Relief —
Superior
internal building pressure control. This field-installed acces-
sory or factory-installed option may eliminate the need for
costly, external pressure control fans.
Low Ambient Controller —
The low ambient controller is a
head pressure controller kit that is designed to maintain the unit’s
condenser head pressure during periods of low ambient cooling
operation. This device should be used as an alternative to econo-
mizer free cooling, not when economizer usage is neither appro-
priate nor desired. The low ambient controller will either cycle
the outdoor fan motors or operate them at reduced speed to main-
tain the unit operation, depending on the model. This controller
allows cooling operation down to 0°F (–18°C) ambient condi-
tions.
Motorized 2-Position Damper —
The new Bryant 2-posi-
tion, motorized outdoor air damper admits up to 100% outside
air. Using reliable, gear-driven technology, the 2-position
damper opens to allow ventilation air and closes when the roof-
top stops, stopping unwanted infiltration.
Manual OA Damper —
Manual outdoor air dampers are an
economical way to bring in ventilation air. The dampers are
available in 25% versions.
2-Speed Indoor Fan Motor System —
Bryant’s 2-Speed
Indoor Fan Motor System saves energy and installation time by
utilizing a Variable Frequency Drive (VFD) to automatically
adjust the indoor fan motor speed in sequence with the units
cooling operation. Per ASHRAE 90.1 2016 standard section
6.4.3.10.b, during the first stage of cooling operation the VFD
will adjust the fan motor to provide 2 /
3
of the total cfm estab-
lished for the unit. When a call for the second stage of cooling is
required, the VFD will allow the total cfm for the unit established
(100%). During the heating mode the VFD will allow total
design cfm (100%) operation and during the ventilation mode
the VFD will allow operation to
2
/
3
of total cfm.
Compared to single speed indoor fan motor systems, Bryant’s 2-
Speed Indoor Fan Motor System can save substantial energy,
25%+*, versus single speed indoor fan motor systems.
*Data based on .10 ($/kWh) in an office application utilizing
Bryant’s HAP 4.6 simulation software program.
The VFD used in Bryant’s 2-Speed Indoor Fan Motor System
has soft start capabilities to slowly ramp up the speeds, thus elim-
inating any high inrush air volume during initial start-up. It also
has internal over current protection for the fan motor and a field
installed display kit that allows adjustment and in depth diagnos-
tics of the VFD.
This 2-Speed Indoor Fan Motor System is available on models
with 2-stage cooling operation with electrical mechanical or
RTU Open, Multi Protocol controls. Both space sensor and con-
ventional thermostats controls can be used to provide accurate
control in any application.
The 2-Speed Indoor Fan Motor System is very flexible for initial
fan performance set up and adjustment. The standard factory
shipped VFD is pre-programmed to automatically stage the fan
speed between the first and second stage of cooling. The unit fan
performance static pressure and cfm can be easily adjusted using
the traditional means of pulley adjustments. The other means to
adjust the unit static and cfm performance is to utilize the field
installed Display Kit and adjust the frequency and voltage in the
VFD to required performance requirements. In either case, once
set up, the VFD will automatically adjust the speed between the
cooling stage operations.
Alternate Motors and Drives —
Some applications need
larger horsepower motors, some need more airflow, and some
need both. Regardless of the case, your Bryant expert has a fac-
tory-installed combination to meet your application. A wide
selection of motors and pulleys (drives) are available, factory-
installed, to handle nearly any application.
Barometric Hood —
For Horizontal Economizer applica-
tions where relief damper is installed in duct work. This kit pro-
vides the needed protection.
Differential Enthalpy Sensor —
The differential
enthalpy sensor is comprised of an outdoor and return air
enthalpy sensors to provide differential.
Wall or duct mounted CO
2
Sensor —
The IAQ sensor
shall be available in duct or wall mount. The sensor provides
demand ventilation indoor air quality (IAQ) control.
Time Guard II Control Circuit —
This accessory pro-
tects your compressor by preventing short-cycling in the event
of some other failure, prevents the compressor from restarting
for 30 seconds after stopping. Not required with PremierLink,
RTU Open, or authorized commercial thermostats.
Propane Conversion Kit —
Convert your gas heat rooftop
from standard natural gas operation to Propane using this field-
installed kit.
High Altitude Heating —
High altitudes have less
oxygen, which affects the fuel/air mixture 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 application, 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
1. BACnet is a registered trademark of ASHRAE (American Soci-
ety of Heating, Refrigerating and Air-Conditioning Engineers).
2. Modbus is a registered trademark of Schneider Electric.
3. LonWorks is a registered trademark of Echelon Corporation.