Bryant 549C manual Integrated Economizers And Outdoor-Airdampers, Service Options

INTEGRATED ECONOMIZERS AND OUTDOOR-AIR DAMPERS

Available as options or accessories, economizers and manual outdoor-air dampers introduce 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 mixed-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 compressor is energized in addition to the economizer. If the outdoor-air tem- perature is above the changeover set point, the first stage of compression is activated and the economizer damper stays at minimum position.

Accessory upgrade kits allow for control by differential dry-bulb temperature (outdoor vs return), outdoor air enthalpy changeover, or more precise differential enthalpy control.

Units can be equipped with different economizer options to meet specific controls applications. The factory-installed or field-installed EconoMi$erIV and EconoMi$er2 are available. The EconoMi$erIV is used with the standard rooftop unit controls and includes an industry standard, stand-alone, solid- state control. The control can be used with a CO2 sensor for DCV (demand control ventilation) operation. For direct digital control (DDC) applications, the EconoMi$er2 can be operated using a third party controller. The EconoMi$er2 includes 4 to 20 mA actuator capability for demand control ventilation applications.

All economizers incorporate a parallel blade, gear driven damper system for efficient air mixing and reliable control. In addition, the standard damper actuator includes a spring return to provide reliable closure on power loss. The economizers for sizes 024-120 are equipped with up to 100% barometric relief capability for high outdoor airflow operations. Economizers for unit sizes 024-120 are available, factory-installed, for vertical return only. Economizers for unit sizes 150 and 180 are compat- ible for vertical or horizontal return. An optional field-installed barometric relief package is available for 150 and 180 size units.

In addition, single-stage power exhaust is available as a field- installed accessory for EconoMi$erIV to help maintain proper building pressure.

For units without economizer, year-round ventilation is enhanced by a manual outdoor-air damper. On size 024-120 units, a 25% or 50% manual damper is available as a field- installed accessory. Unit sizes 150 and 180 are equipped with a 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 (549B, 549C and 542J only) are pro- vided 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 Standard 62. Two-inch filters with optional dirty filter indicator switch provide for greater parti- cle reduction in the return air. The face-split evaporator coils improve the dehumidification capability of standard units, maxi- mize building humidity control.

Optional proportional reacting CO2 sensor is available with the EconoMi$erIV outdoor air damper option/accessory to aid the IAQ benefits.

3