Can a 40 Ton Rooftop Unit Reuse the Existing Roof Curb?

Yes. In many rooftop HVAC replacement projects, the existing roof curb may be reused if the new equipment dimensions and air openings are compatible.

However, large-capacity RTUs from different manufacturers or different product generations may have different cabinet footprints, supply openings and return-air openings.

Possible Replacement Solutions

• Direct replacement using compatible curb dimensions
• Custom curb adapter
• Supply and return duct transition
• Modified curb arrangement
• New rooftop curb when required

The replacement review should compare:

• Existing curb length and width
• Supply-air opening
• Return-air opening
• Downflow or horizontal airflow arrangement
• New unit footprint
• Equipment weight
• Roof structural conditions