Nicotra Gebhardt Alternative
— The Naming-Mirror Guide

If you've been specifying Nicotra Gebhardt commercial centrifugal fans — AT series for belt-driven double-inlet, DD for direct-driven, RDH for backward-inclined high pressure, RZR for true airfoil efficiency, ADH for asymmetric outlet — this guide is the practical second-source answer.

It's also a guide that's been quietly missing from the industry for some time. Most "Nicotra alternative" search results either point at boutique replacement-parts suppliers (high price, limited inventory) or generic OEMs that match performance but not dimensions, which forces full system redesign. Neither is what an HVAC OEM, AHU integrator, or facilities engineer actually needs.

What's needed is a fan that drops into the existing scroll housing, on the existing bolt pattern, with the existing belt geometry, and meets the same duty point. That is what the LONGWELL commercial centrifugal line is built for. The proof is in the naming.

§ 01Why Choose LONGWELL as an Alternative to Premium European Fan Brands

Nicotra Gebhardt has been a benchmark in commercial and industrial centrifugal fans for over three decades. The AT series alone has been in continuous production since the early 1990s. There is no engineering case for replacing Nicotra parts on technical grounds — they work.

The case is commercial. Three forces are pushing AHU OEMs and HVAC integrators to qualify a second source:

• Lead time exposure. Mid-size AT and RDH parts from Nicotra now quote 12-20 weeks against historical 4-6 weeks. For OEMs operating to-order production, this is a planning constraint that affects quoted delivery to end customers.
• Cost pressure. Where European-manufactured fans previously represented 6-9% of an AHU BoM, recent supply tightening has pushed this toward 12-15%. For mid-market OEMs competing against integrated package suppliers, the gap is large enough to lose tenders.
• BoM single-source risk on tender submissions. Many institutional and governmental procurement specifications now require "alternative source identification" as a tender requirement. Naming a single brand on a BoM has become a procedural disadvantage.

The right second source is not the cheapest — it's the one that minimizes engineering re-work when activated. Dimensional drop-in is worth more than the next 5% off the price.

§ 02AT Series — belt-driven double-inlet (the 35-year workhorse)

The Nicotra AT series is the most-specified family in commercial AHU. Forward-curved impellers, galvanized scroll, double inlet, belt drive — the configuration has not meaningfully changed in 35 years because it does not need to. Sizes run from AT 7/7 (small office VRF box) to AT 30/28 (industrial process AHU).

LONGWELL's AT 7-7L through AT 18-18LK directly mirrors Nicotra's AT 7/7 through AT 18/18 — same wheel diameter, same scroll dimensions, same mounting bolt circle. The L suffix denotes LONGWELL's standard variant; LK denotes the low-noise variant with optimized blade angle and reinforced scroll dampening for noise-sensitive applications (libraries, hospitals, hotel guest-room AHUs).

The smaller sizes (7-7 through 12-12) target compact AHU and FCU applications. Mid-range (15-11 through 18-18) covers the bulk of commercial AHU specifications. The LK variants offer 3-6 dB(A) noise reduction at the cost of approximately 5% lower peak efficiency — the right trade for hospital, hotel, and library environments.

§ 03DD / DDM Series — direct-driven forward-curved

For applications where belt-drive maintenance is unwelcome — fan coil units, compact AHU, embedded HVAC modules — Nicotra DD and DDM (Direct Drive Motorized) series provide forward-curved impellers mounted directly on the motor shaft. LONGWELL's DDK and SDDK series follow the same architecture with the same dimensional sequence.

The match here is less perfectly mirrored than AT, because Nicotra uses inch-based wheel naming (e.g., DDM 10/10) and LONGWELL uses mm-based naming (DDK225, DDK280, DDK315, etc.), but the dimensional series and motor-class progression align cleanly. The cross-reference table maps each Nicotra DDM size to its LONGWELL DDK equivalent.

The advantage of LONGWELL DDK is depth of motor selection: each diameter is offered in 4 to 6 motor variants (YDW0.25-4 through YDW7.5-6), allowing finer power matching to the specified duty point than Nicotra's standardized DDM motor offerings. For OEMs working at the edge of a duty point — where Nicotra's "next size up" forces over-specification — LONGWELL's denser motor matrix can save 10-20% energy at deployment.

§ 04RDH Series — backward-inclined high pressure

The RDH naming convention is preserved verbatim between Nicotra and LONGWELL. Both lines run RDH 280 through RDH 1000 — backward-inclined sheet steel blades, double-inlet, belt-driven, sized for high-pressure applications (long duct runs, dense filter packs, smoke extract).

Nicotra's RDH range extends to 290,000 m³/h and 3,500 Pa at the largest 1000mm size. LONGWELL's RDH-R range covers the same dimensional series with comparable performance envelope at mid sizes (280-560mm), with the largest sizes (630-1000mm) targeted for industrial process and stadium HVAC applications.

§ 05RZR / RLM E Series — true airfoil for highest efficiency

This is the segment where naming diverges but architecture aligns. Nicotra's RZR series uses hollow-section true airfoil backward-curved blades — the highest-efficiency centrifugal blade geometry available, used in premium AHU specifications and FFU plug-fan systems. LONGWELL's equivalent is the RLM E series, with "E" denoting the airfoil ("E" for Eccentric airfoil profile).

Both lines use identical sheet metal manufacturing approaches: stamped airfoil blade shells, welded to the hub plate, dynamically balanced to ISO 1940 grade 6.3 (or grade 2.5 for premium variants). The dimensional series matches: RZR 280, 355, 450, 560, 630, 710, 800, 900, 1000 → RLM E-280, E-355, E-450, E-560, E-630, E-710, E-800, E-900, E-1000.

For high-efficiency AHU specifications — where the customer is willing to pay a 15-25% premium over a standard backward-curved fan to gain 5-8 percentage points of static efficiency — RZR/RLM E is the right segment. LONGWELL's blade tooling for this series was developed specifically against Nicotra RZR aerodynamics as the design benchmark.

§ 06ADH Series — asymmetric outlet high pressure

The ADH (Asymmetric Outlet) family is the most specialized of the commercial centrifugal product lines. Forward-curved blades, asymmetric scroll outlet for compact duct integration, used where standard scroll geometry doesn't fit the installation envelope. Nicotra's ADH 200 through ADH 1000 finds direct LONGWELL counterparts in ADH-L (small sizes 200-250) and ADH-R (mid-to-large sizes 280-1000).

Naming preservation: both lines use ADH as the family prefix, with size numbers following directly. ADH 400 → ADH-R 400, ADH 560 → ADH-R 560, and so on. Mounting flange dimensions match Nicotra's standard.

§ 07The complete naming-mirror table

Below is the consolidated cross-reference for the Nicotra Gebhardt commercial centrifugal range, organized by series. For comprehensive specifications including airflow curves, sound power data, and motor selection guidance, request the full Excel database via the application engineering channel.

★ Indicates the most-specified sizes in commercial AHU applications. Complete database covers 26 Nicotra cross-references plus 25 ebm-papst, 5 Ziehl-Abegg, 2 Rosenberg, and 1 Siemens — request via sales@longwellfans.com.

§ 08How to validate a LONGWELL alternative for Nicotra

For AHU OEMs and HVAC integrators evaluating LONGWELL as a Nicotra second source, the validation path is shorter than for most cross-brand substitutions because the dimensional architecture aligns from the start.

Step 1 — Specification sample, one size

Pick the most-used Nicotra size on the current BoM (most often AT 15/15, AT 18/18, or RDH 450/560). Request a LONGWELL engineering sample. Lead time is 1-3 days from Yuyao to Europe or North America. Mount in the same scroll housing; verify bolt pattern, shaft height, belt geometry.

Step 2 — Duty-point measurement

Test in your existing AHU test rig at design duty point. For belt-driven fans, the relevant performance metrics are airflow at duty pressure, total efficiency, and A-weighted sound power. LONGWELL publishes performance data in accordance with AMCA 210 and DIN 24166 standards — the same testing standards Nicotra uses.

Step 3 — Comparative test report (optional)

For OEMs requiring documented evidence of equivalence, LONGWELL's application engineering team produces side-by-side test reports comparing the LONGWELL fan against the original Nicotra part at three duty points (design, +10%, -10%). These reports are released under NDA to qualifying OEMs.

Step 4 — Pilot production

Initial pilot order (typically 20-50 units) at standard 15-30 day lead time. LONGWELL holds the most-specified Nicotra-cross-reference SKUs in serial production, with finished goods inventory at Yuyao for fast pull.

§ 09Frequently asked questions