Multi-tube offset pre-insulated HVAC ducting technology

An HVAC ductwork assembly comprising a first duct and a second duct, the first duct having opposed first and second ends and a central span extending between the first and second ends of the first duct, the first duct comprising an inner composite tube and an outer composite tube, the inner composite tube having an interior metal wall, a primary foam wall, and an exterior metal wall, the outer composite tube having an interior metal wall, a secondary foam wall, and an exterior metal wall, the inner composite tube being nested inside the outer composite tube in an end-offset configuration characterized by the inner composite tube projecting beyond the outer composite tube at the first end of the first duct whereas at the second end of the first duct the outer composite tube projects beyond the inner composite tube, such that the first end of the first duct defines a male detent having a radially-outward-facing metal engagement face projecting axially beyond the interior metal wall of the outer composite tube of the first duct whereas the second end of the first duct defines a female detent having a radially-inward-facing metal engagement face projecting axially beyond the exterior metal wall of the inner composite tube of the first duct;

• the second duct having opposed first and second ends and a central span extending between the first and second ends of the second duct, the second duct comprising an inner composite tube and an outer composite tube, the inner composite tube of the second duct having an interior metal wall, a primary foam wall, and an exterior metal wall, the outer composite tube of the second duct having an interior metal wall, a secondary foam wall, and an exterior metal wall, the inner composite tube of the second duct being nested inside the outer composite tube of the second duct in an end-offset configuration characterized by the inner composite tube of the second duct projecting beyond the outer composite tube of the second duct at the first end of the second duct whereas at the second end of the second duct the outer composite tube of the second duct projects beyond the inner composite tube of the second duct, such that the first end of the second duct defines a male detent having a radially-outwardly-facing metal engagement face projecting axially beyond the interior metal wall of the outer composite tube whereas the second end of the second duct defines a female detent having a radially-inwardly-facing metal engagement face projecting axially beyond the exterior metal wall of the inner composite tube;
• the first duct and the second duct being joined together by a connection characterized by the male detent of the first duct being received in the female detent of the second duct, such that the connection comprises a radial inner interface and a radial outer interface, the radial inner interface being located between the primary foam wall of the inner composite tube of the first duct and the primary foam wall of the inner composite tube of the second duct, the radial outer interface is located between the secondary foam wall of the outer composite tube of the first duct and the secondary foam wall of the outer composite tube of the second duct, the connection comprising first and second beads of sealant positioned at locations that are spaced apart both axially and radially, the first bead of sealant positioned at the radial inner interface, the second bead of sealant positioned at the radial outer interface.