1.DUCTWORK (580D036-150) Ð Secure vertical discharge ductwork to roof curb. For horizontal discharge applica- tions, attach ductwork to unit, or ®eld-supplied ¯anges can be attached to horizontal discharge openings and all duct- work attached to ¯anges.
2.DUCTWORK (579F180-300) Ð Ductwork should be at- tached to the curb on all units. Interior installation may pro- ceed before unit is set in place on roof. If ductwork will be attached to the unit, do not drill in condensate drain pan area Ð leaks may result. See ®gures on page 66 for in- formation on ®eld-installed concentric ductwork when applicable.
3.TO CONVERT DURABLADE ECONOMIZER FROM VER- TICAL DISCHARGE TO HORIZONTAL DISCHARGE
(580D036-150):
1.Remove economizer to gain access to return duct opening.
2.Move the horizontal discharge duct opening covers to the vertical discharge openings.
3.Rotate economizer 90 degrees (until the economizer motor faces the condenser section).
4.Rotate the barometric relief damper 90 degrees (econo- mizer only).
5.Install block-off plate over the opening on the access panel.
NOTE: Parablade economizer is for vertical discharge units only.
4.THRU-THE-CURB SERVICE CONNECTIONS (579F180- 300) Ð Roof curb connections allow ®eld power wires, con- trol wires, and gas supply to enter through the roof curb opening.
5.THRU-THE-BOTTOM SERVICE CONNECTIONS (580D036-150) Ð An accessory kit is required for proper installation of thru-the-bottom connections.
6.THERMOSTAT Ð Use of 2-stage cooling thermostat is rec- ommended for all units. A 2-stage cooling thermostat is required on units with accessory economizer to provide integrated cooling.
7.HEATING-TO-COOLING CHANGEOVER Ð All units are automatic changeover from heating to cooling when auto- matic changeover thermostat and subbase are used.
8.AIRFLOW Ð Units are draw-thru on cooling and blow-thru on heating.
9.MAXIMUM AIRFLOW Ð To minimize the possibility of con- densate blow-off from evaporator, air¯ow through units should not exceed 500 cfm/ton on size 036-240 units, and 11,250 cfm on size 028 units.
10.MINIMUM AIRFLOW Ð The minimum air¯ow for cooling is 300 cfm/ton on size 036-240 units and 280 cfm/ton on size 300 units. Refer to Heating Capacities and Ef®ciencies table on page 7 for minimum air¯ow cfm for heating on size 180-300 units.
11.MINIMUM AMBIENT COOLING OPERATION TEMPERA- TURE (580D036-150) Ð The cooling temperature for size 036-150 standard units is 25 F. With accessory Motor- master control units can operate at outdoor temperatures down to −20 F.
12.MINIMUM AMBIENT COOLING OPERATION TEMPERA- TURE (579F180-300) Ð Units are designed to operate at outdoor temperatures down to 40 F for 579F180, 35 F for 579F216 25 F for 579F240, and 48 F for 579F300. To op- erate at lower outdoor-air temperatures, see Price Pages or contact your local representative for appropriate accessory combinations for speci®c applications.
13.MAXIMUM OPERATING OUTDOOR-AIR TEMPERA- TURE Ð For cooling, this temperature is 115 F on size 036- 180 units, 125 F on size 216-300 units.
14.HIGH ALTITUDE Ð A change to the gas ori®ce may be re- quired at high altitudes. Refer to Altitude Compensation charts on pages 53 and 54.
15.MINIMUM TEMPERATURE Ð Air entering the heat ex- changer in heating must be a minimum of 50 F continuous and 45 F intermittent.
16.INTERNAL UNIT DESIGN Ð Due to the internal unit de- sign (draw-thru over the motor), air path, and specially de- signed motors, the full horsepower (maximum continuous bhp) listed in the Physical Data table and the notes follow- ing each Fan Performance table can be utilized with ex- treme con®dence.
Using motors with the values listed in the Physical and Fan Performance Data tables will not result in nuisance tripping or premature motor failure. The unit warranty will not be affected.
