6" 90 Degree Round-to-Oval Boot

Lukjan Round-to-Oval Boot (OB7506) — 6″ Ø Round to Oval Transition, 90° Elbow, 9″ Length, 10-1/4″ Depth

The OB7506 is a transition boot that converts airflow from a 6-inch round duct to an oval or rectangular opening via a 90° sweep. It’s typically used where a round duct must feed into an oval register box or oval ductwork with a right-angle turn.

• Model / Part Number: OB7506 (Lukjan round-to-oval boot) — catalogued by Lennox as “Oval to Round Boot Elbow 6″ × 6″, 90°” (i.e. round-to-oval / oval-to-round) :contentReference[oaicite:0]{index=0}
• Configuration: 90° elbow, round inlet transitioning to oval / rectangular outlet
• Round duct connection: 6 inch diameter
• Boot length (throat / elbow sweep length): 9 inches (nominal) — the distance along the elbow path from round inlet to oval outlet plane
• Depth (projection / major manifold dimension): 10-1/4 inches (10.25″) — the outward depth or “face height” of the oval outlet opening
• Material: Galvanized steel (common for HVAC duct fittings) — likely manufactured in standard sheet metal gauge (e.g. 30 gauge) unless otherwise specified
• Finish: Hot-dip galvanization or G-series galvanized coating (to inhibit corrosion in indoor HVAC applications)
• Weight (estimated): ~0.5 lb (by analogy to analogous Lukjan boots) — actual value depends on gauge and exact dimensioning
• Applications:
  • Used where a 6″ round duct must feed into an oval register boot or duct with a right-angle change.
  • Useful in installations where space constraints require oval output and the round duct must turn 90° to feed it.
• Installation / connection notes:
  • Mount the round duct to the round inlet, using screws, rivets, or cleat tabs as standard.
  • Ensure the oval outlet aligns with matching oval receiver / register frame or duct opening.
  • Seal all seams and joints with foil HVAC tape or duct mastic to ensure airtightness.
  • Avoid sharp bends immediately before or after the elbow to limit pressure drop and turbulence.
  • Deburr interior edges where possible to improve airflow smoothness.

Technical & Performance Notes

• The round-to-oval transition will inherently alter cross-sectional shape; ensure that the oval outlet provides equivalent or greater cross-sectional area compared to the round inlet to avoid excessive velocity or pressure drop.
• The 10.25″ depth indicates a relatively long output footprint, which can help smooth airflow transition but requires enough space behind the register or duct opening.
• Galvanized steel provides durability in typical indoor HVAC environments; inspect periodically for corrosion in humid or exposed installations.
• The elbow curvature (90° sweep) should be gradual to minimize losses; extremely sharp internal bends should be avoided if possible.
• When designing the system, include allowances for the transition’s pressure drop in the duct calculations (elbows and transitions generally incur extra losses relative to straight duct).