ACiQ Square To Round Duct Adaptors For Package Units (NPDUCFLG002A00)
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Key features
- Designed specifically for package unit square or rectangular duct flange connections
- Transitions from rectangular opening to round duct collar for flex or rigid round duct
- Factory-formed sheet metal construction for consistent fit and reduced air leakage
- Compatible with standard package unit supply and return flange configurations
- Eliminates the need for field-fabricated transitions at the unit connection point
- Sold as part of ACiQ's package-unit accessory line for matching system components
About this system
The ACiQ Square To Round Duct Adaptor (NPDUCFLG002A00) is a sheet-metal transition fitting designed to connect the square or rectangular supply and return openings on a rooftop or ground-mounted package unit to standard round ductwork. Package units consolidate the entire heating and cooling system into a single outdoor cabinet, and the duct connections at the unit are almost always rectangular flanged openings. Wherever the installer is transitioning to round flex duct or spiral round trunk lines, an adaptor like this one bridges that geometry gap cleanly and without field fabrication.
This fitting suits contractors and DIY-capable homeowners who are installing, replacing, or reconfiguring ductwork on a packaged HVAC system and need a code-friendly, factory-formed transition rather than a hand-cut sheet-metal patch. It is not a standalone comfort product and carries no efficiency, tonnage, or refrigerant rating of its own. Its value is entirely practical: a properly fitted, leak-resistant transition that reduces air-side pressure drop compared to a poorly formed field connection, and that fits flush against standard package-unit flanges.
The NPDUCFLG002A00 is a straightforward sheet-metal transition fitting that does one job: connecting a package unit's rectangular duct opening to round ductwork. It is neither remarkable nor flawed on its own merits, and its usefulness depends entirely on whether its dimensions match your specific package unit and round duct size. Confirm measurements before ordering.
Overall score is the average of the five ratings above.
What we like
- Factory-formed construction is more consistent than most field-fabricated transitions
- Sold as a matched accessory for ACiQ package units, reducing fitment guesswork on those systems
- Reduces pressure drop compared to improvised sheet-metal transitions
- Straightforward installation that fits within standard duct connection workflows
- Priced as a value accessory without dealer markup typical of distributor-sourced fittings
Trade-offs
- Dimensional compatibility must be verified against your specific package unit model before purchase
- No independent testing data or airflow ratings are published for this specific adaptor
- ACiQ's direct-sale model means local HVAC supply houses may not stock replacements if a fitting is damaged
- Sheet-metal gauge and sealing quality cannot be independently confirmed from published specs alone
What homeowners and pros say about ACiQ
Because this is a duct fitting rather than a full HVAC system, owner commentary specific to this part is limited. What installers do say about ACiQ accessories generally is that fitment on ACiQ-branded package units tends to be consistent, which is the primary thing you want from a transition adaptor. ACiQ’s broader brand has earned largely positive early reviews for responsive customer support when something does not arrive as expected, and that matters for an accessory like this where a wrong-size fitting can stall an installation. Consumer Reports has not yet ranked ACiQ due to insufficient long-term data, so there is no independent reliability score to cite for the brand’s accessories either.
The documented concerns that follow ACiQ as a brand are worth keeping in mind even for a simple fitting: the undisclosed manufacturer makes it harder to cross-reference part numbers or find equivalent fittings at a local supply house, and the direct-sale model means you are not walking into a distributor to pick up a replacement on a Saturday. The specific failure modes flagged for ACiQ HVAC equipment, including questions about capacitor longevity, coil construction, and long-term compressor reliability, do not apply directly to a sheet-metal adaptor, but they are a fair reminder that ACiQ is a newer brand still building its service and parts infrastructure. For a passive fitting like this one, that is a lower-stakes concern than it would be for a compressor-bearing product.
Sources: Consumer Reports heat pump ratings, HVACDirect on the ACiQ brand, AHRI Directory of Certified Product Performance, U.S. DOE appliance and equipment efficiency standards.
How it compares
| Brand | Comparable model | SEER2 | Stage | Price position |
|---|---|---|---|---|
| ACiQ | NPDUCFLG002A00 Square To Round Adaptor | N/A | N/A (duct accessory) | Value pick |
| Hart and Cooley | Universal Square-to-Round Duct Transition | N/A | N/A (duct accessory) | Comparable to slightly higher, widely available at supply houses |
| Tjernlund | Sheet Metal Square-to-Round Transition Fitting | N/A | N/A (duct accessory) | Comparable, available through HVAC distributors |
| Deflecto | Dryer Box and Duct Transition Fittings (round collar series) | N/A | N/A (duct accessory) | Lower to comparable, broad retail availability but not always HVAC-grade gauge |
Competitor rows are comparable single-stage units at similar efficiency; price is relative position, not a quote.
Questions about this system
Will this adaptor fit my specific ACiQ package unit model?
ACiQ designs this fitting to match its own package unit flange dimensions, but you should confirm the square or rectangular opening size and the round collar diameter against your unit's submittal sheet before ordering. Not all package unit tonnages use the same duct opening size.
Can I use this adaptor on a non-ACiQ package unit?
Possibly, but only if the rectangular flange dimensions match. Package unit duct openings are not universally standardized, so measure your unit's supply and return flanges and compare them to the adaptor's listed dimensions before purchasing.
Do I need to seal the joints after installation?
Yes. Industry best practice and most energy codes require mastic sealant or UL-listed foil tape at all duct connections, including this transition. Sheet-metal-to-duct joints are common air leakage points if left unsealed.
What gauge sheet metal is this adaptor made from, and does it matter?
ACiQ does not publish the gauge specification for this fitting. Heavier gauge metal is more resistant to deformation during installation and over time, so if the gauge is not confirmed, inspect the fitting on arrival for rigidity before installing.
If this fitting gets damaged or I need a replacement, can I find one locally?
Because ACiQ sells direct rather than through local supply houses, this specific fitting may not be available at a local HVAC distributor. You would likely need to reorder through ACiQ directly, so it is worth having a spare on hand for larger installations.