Bryant 542J Heat Pump User Manual


 
3
INTEGRATED ECONOMI$ERS AND OUTDOOR AIR
Optional EconoMi$ers and manual outdoor-air dampers intro-
duce outdoor air which mixes with the conditioned air, improving
indoor-air quality and often reducing energy consumption.
During a first stage call for cooling, if the outdoor-air tempera-
ture is below the economizer control changeover set point, the
discharge-air sensor modulates the economizer outdoor-air
damper open to take advantage of free cooling provided by the
outside air. When second-stage cooling is called for, the com-
pressor is energized in addition to the economizer. If the
outdoor-air temperature is above the changeover set point, the
first stage of compression is activated and the economizer stays
at vent position.
Accessory upgrade kits allow for either outdoor air enthaply
changeover or for more precise differential enthalpy control.
Units can also utilize the factory or field-installed EconoMi$er.
The EconoMi$er is microprocessor controlled and incorporates
a parallel, opposed-blade gear driven damper system. In addi-
tion, it has a spring return built into the damper actuator to pro-
vide reliable close-on-power-loss. The EconoMi$er comes
equipped with up to 90% barometric relief capability for high
outdoor airflow applications on 036-120 units only. Optional
field-installed Barometric Relief package is available for use on
150,180 size units.
In addition, the EconoMi$er two-stage power exhaust acces-
sory can be utilized to help maintain proper building pressure
(036-120 units only). Single stage power exhaust is available for
unit sizes 150,180 as a field-installed accessory.
For units without economizer, year-round ventilation is
enhanced by a manual outdoor-air damper. On 036-120 units, a
25% or 50% manual damper is available as a field-installed
accessory. Unit sizes 150,180 are equipped with a standard
manual 25% damper.
SERVICE OPTIONS
Servicing a rooftop unit has never been easier with the new
factory-installed service options for these rooftop units. These
options include the following:
Hinged access panels are provided for the filter/indoor-fan
motor, compressors, indoor fan, and control box areas. Quick
access to major components is accomplished by simply
unlatching and swinging open the various panels. Each
hinged panel is permanently mounted to the unit, thereby
eliminating the concern of a dropped or wind-blown panel
puncturing delicate roof materials. The 4 extended access
panels are also equipped with ‘‘tie back’’ retaining devices to
hold the door in the open position while servicing the unit.
An external, covered, 115-v Ground Fault Interrupt (GFI)
receptacle is provided as a convenient power source for drills,
lights, refrigerant recovery units, or other electrical service
tools. Simply connect the outlet to a field-supplied and prop-
erly fused branch circuit power supply.
An integral non-fused disconnect switch within the rooftop unit
reduces installation time, labor and material costs. Safety is
assured by an interlock which prevents access to the control
box unless the switch is in the OFF position. In addition, the
externally mounted handle incorporates power lockout capa-
bility to further protect service personnel.
INDOOR-AIR QUALITY BEGINS WITH BRYANT ROOFTOPS
Sloped condensate pans minimize biological growth in rooftop
units in accordance with ASHRAE (American Society of Heat-
ing, Refrigeration, and Air Conditioning Engineers) Standard
62. Two-inch filters with optional dirty filter indicator switch pro-
vide for greater particle reduction in the return air. The face-split
evaporator coils improve the dehumidification capability of stan-
dard units, maximize building humidity control.