4. Ductwork
1. Attaching Downflow Ductwork to The Roof Curb (below 5.0RT)
Supply and return air flanges are provided on the roof curb for easy duct installation. All duct work
must be run and attached to the curb before the unit is set into place.
2. Ductwork construction guidelines
Connections to the unit should be made with three-inch canvas connectors to minimize noise and
vibration transmission.
Elbows with turning vanes or splitters are recommended to minimize air noise and resistance.
The first elbow in the ductwork leaving the unit should be no closer than three times blower diameter to
avoid turbulence and back pressure.
3. Attaching Horizontal Ductwork to the Unit
All conditioned air ductwork should be insulated to minimize heating and cooling duct losses. Use
minimum of 2" of insulation with a vapor barrier. The outside ductwork must be weather proofed
between the unit and the building.
When attaching ductwork to a horizontal unit, provide a flexible water tight connection to prevent noise
transmission from the unit to the ducts. The flexible connection must be indoors and molded out of
heavy canvas.
Note: Do not draw the canvas taut between the solid ducts.
IMPORTANT(below 5.0RT)
To convert to downflow, remove covers from the downflow supply and return air opening(painted side
out) and secure with sheet metal screw (see Figure 3)
Note:
SUTTLY OPENING
1. Remove the screw nearest to the
opening and pull the panel firmly toward
the outside of the unit to disengage the
back attachment.
HORIZONTAL RETURN
AIR COVER
HORIZONTAL SUPPLY
AIR COVER
RETURN OPENING
2. Remove right hand screw and move
panel to the right or remove both
screws.
7
Figure 3