Packaged Rooftop Air Conditioners Manual

15RT-PRC010-EN

Duct Design

It is important to note that the rated

capacities of the rooftop can be met only

if the rooftop is properly installed in the

field. A well-designed duct system is

essential in meeting these capacities.

The satisfactory distribution of air

throughout the system requires that

there be an unrestricted and uniform

airflow from the rooftop discharge duct.

This discharge section should be straight

for at least several duct diameters to

allow the conversion of fan energy from

velocity pressure to static pressure.

However, when job conditions dictate

elbows be installed near the rooftop

outlet, the loss of capacity and static

pressure may be reduced through the

use of guide vanes and proper direction

of the bend in the elbow. The high

velocity side of the rooftop outlet should

be directed at the outside radius of the

elbow rather than the inside as

illustrated in Figure AC-5.

Figure AC-4 — Unit Placement

Figure AC-5 — Duct Design

1. 20-40 ton models have only one outdoor air intake.

50 - 75 ton models have two outdoor air intakes.

2. 90-130 ton models have two outdoor air intakes on

the backside of the unit and one small air intake at

the end of the unit.

Proper

Improper

Application

Considerations