1.CONDENSATE DRAIN PAN — A sloped condensate drain pan is supplied on all units. The condensate pan must be externally trapped. Condensate drains are located on both the bottom and end of the unit.
2.DUCTWORK — All ductwork must be attached to flanges. If no flanges are present, they must be field supplied. Secure vertical discharge ductwork to roof curb. For hori- zontal discharge applications, attach ductwork to flanges. Field-supplied flanges can be attached to horizontal dis- charge openings and all ductwork attached to flanges.
3.TO CONVERT FROM VERTICAL DISCHARGE TO HORI- ZONTAL DISCHARGE (Durablade Economizer Only):
a.Remove economizer/two-position damper to gain access to return duct opening.
b.Move the horizontal-discharge duct opening covers to the vertical discharge openings.
c.Rotate economizer 90 degrees (until the economizer/ two-position damper motor faces the condenser section).
d.Rotate the barometric relief damper 90 degrees.
e.Install block-off plate over the opening on the access panel.
4.THERMOSTAT — Use of 2-stage cooling thermostat is recommended for all size 036-072 units equipped with economizer.
5.HEATING-TO-COOLING CHANGEOVER — All units are automatic changeover from heating to cooling when auto- matic changeover thermostat and subbase are used.
6.AIRFLOW — Units are draw-thru on cooling and blow-thru on heating.
7.MAXIMUM AIRFLOW — To minimize possibility of conden- sate blow-off from evaporator, airflow through units should not exceed 500 cfm/ton.
8.MINIMUM AIRFLOW — Minimum airflow for cooling is 300 cfm/ton.
9.MINIMUM AMBIENT OPERATING TEMPERATURE — Minimum ambient operating temperature for size 036-150 standard units is 25 F. With accessory Motormaster® or Motormaster II control, units can operate at outdoor tem- peratures down to –20 F.
10.MAXIMUM OPERATING OUTDOOR-AIR TEMPERATURE
—Maximum outdoor-air operating temperature for cooling is 125 F.
11.HIGH ALTITUDES — These may require a change to the gas orifice. Refer to Altitude Compensation tables on page 43.
12.MINIMUM TEMPERATURE — Minimum temperature of air entering the dimpled heat exchanger is 50 F continuous and 45 F intermittent.
13.MOTOR DATA — Due to Bryant’s internal unit design (draw-thru over the motor), air path, and specially designed motors, the full horsepower (maximum continuous bhp) listed in the Physical Data table and the notes following each Fan Performance table can be utilized with extreme confidence.
Using Bryant motors to the values listed in the Physical Data, Fan Performance, and Evaporator-Fan Motor Data tables will not result in nuisance tripping or premature motor failure. In addition, the unit warranty will not be affected.
14.THRU-THE-BOTTOM CONNECTIONS — The accessory thru-the-bottom connections are needed to ensure proper connections when routing wiring and piping through the basepan and roof curb. This accessory is used for electric and control power only.
15.PERFECT HUMIDITY™ DEHUMIDIFICATION PACKAGE
—This option provides greater dehumidification by further subcooling the hot liquid refrigerant leaving the condenser coil. The Perfect Humidity package consists of a subcooling coil located on the leaving-air side of the evaporator coil.
The location of the coil in the indoor airstream enhances the latent capacity of the 581B rooftop units by up to 40%.
Many buildings suffer damage or have poor indoor-air qual- ity due to overly humid conditions. Building humidity must be controlled for the following reasons:
a.INDOOR-AIR QUALITY — Humidity is a major factor in the growth and propagation of mold and mildew in a building. The mold and mildew can spread quickly and grow in carpets and ductwork and on walls, and often causes cases of sick building syndrome. This syndrome can lead to employee absenteeism due to illness, lower worker productivity, and increased health care costs. The American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) recommends that relative humidity levels in buildings be maintained below 70%.
b.COMFORT LEVELS — High humidity levels cause the occupied space to become uncomfortable, because humidity interferes with the body’s natural cooling pro- cess (evaporation at the skin surface).
c.HUMIDITY DAMAGE — Humidity causes property damage, such as stained wallpaper and ceiling tiles. Humidity can also damage books and artwork, and create strong odors in carpets. In addition, humidity can contribute to unacceptable product quality in industrial processes.
d.IMPROPER VENTILATION — Buildings in hot and humid geographical areas cannot be properly ventilated due to high humidity levels outdoors, resulting in poor indoor-air quality.
e.EQUIPMENT INEFFICIENCY — Humidity can cause inefficient operation of refrigerators and freezers.
f.INCREASED ENERGY COSTS — Because of high humidity levels and less comfortable conditions, ther- mostat set points are lowered to force the HVAC (heat- ing, ventilation, and air conditioning) equipment to run longer and work harder to lower the humidity levels. Also, in an attempt to control humidity, system design- ers typically oversize HVAC equipment and add reheat capability to get the desired latent capacity. This results in higher initial equipment costs, as well as increased energy expenses throughout the life of the unit.
Applications
There are many different rooftop unit applications that are susceptible to problems caused by high humidity levels. Some common applications include:
a.RESTAURANTS — The kitchen areas of restaurants have many humidity-producing activities, such as dish washing and cooking.
b.SUPERMARKETS — High humidity levels cause ineffi- ciency in operation of refrigeration and freezer systems.
c.MUSEUMS AND LIBRARIES — Humidity can damage books and artwork.
d.GYMNASIUMS, LOCKER ROOMS, AND HEALTH CLUBS — Shower areas and human perspiration cause uncomfortable occupied space conditions.
e.HOT AND HUMID CLIMATES — The southeastern United States is a good example of this application. The Perfect Humidity dehumidification package becomes particularly useful when increased amounts of the hot and humid outdoor air need to be brought into the build- ing for proper ventilation.
16.PERFECT HUMIDITY DEHUMIDIFICATION PACKAGE DESIGN EFFECTS — To fully understand the operation of the Perfect Humidity dehumidification package, refer to the pressure enthalpy curve, and analyze the Perfect Humidity package effects on the refrigerant in the rooftop unit. The pressure enthalpy curve shows the refrigerant cycle for a 581B rooftop unit.
