Framed AC Centrifugal Fan for AHU: 17,893 m3/h Case Study

What the HVAC manufacturer asked for

An HVAC system maker asked for a 630mm backward-curved framed centrifugal fan, built into a custom mounting bracket. They referenced an existing specification, our LWBA6D630-188NT-01.

That model runs on 380V, 50Hz, and it gives 12,360 m3/h at 494 Pa. Meanwhile the change they wanted was the frame, shown by a photograph of a similar fan inside an aluminum extrusion.

That photograph tells you where it is going. Namely a larger build. Most likely a commercial air handler, or else a plenum for a fan wall.

• An ambient range of at least -25C to +60C, both ends.
• Compliance with EN 60335-1, since appliance safety applies.
• A complete factory-built module, so their production line stays simple.
• Lastly, data verifiable to AMCA 210/211, for accurate system modeling.

Notably, the request was for one sample only. Evidently this is an OEM at prototype stage. Above all, they need something they can install this month.

Choosing a framed centrifugal fan instead

Certainly we could have built a custom frame around the NT-series fan they named. However, that path opens a 90-day NPI cycle, with new drawings, tooling and validation attached.

Frankly, for a customer wanting a sample now, both time and cost are real obstacles.

The catalog already had the answer

So our engineers proposed a standard high-volume model instead, the LWBA6D630-188PT-06-00.

Usefully it arrives already built inside an 800 by 800mm steel frame. Consequently the core requirement is met with no NPI work at all.

And it performs considerably better

Notably the substitute is not merely equal. It gives 17,893 m3/h of airflow against 720 Pa of pressure.

Set beside the 12,360 m3/h and 494 Pa of the original, that is over 40% more air and far more pressure. For an OEM still drawing their AHU, that headroom is genuinely useful. It absorbs tighter filters or more duct later, without a redesign.

What drives it

Specifically a 400V three-phase external rotor motor, with Class F insulation and IP54 sealing, built to run non-stop in commercial buildings.

None of that is exotic. In short, the right answer sat on the shelf already. Finding it was worth more than engineering a new one.

Technical Specifications

These figures cover the framed centrifugal fan we proposed, not the one requested. Compare them with the original, which gave 12,360 m3/h and 494 Pa.

Technical Documentation

The complete technical specification sheet for the proposed LWBA6D630-188PT-06-00, including performance data, mechanical drawings, and wiring diagrams, is available for review by design engineers. Download Technical Datasheet.

Here the document shows the customer’s initial reference model, the LWBA6D630-188NT series, which was used as the baseline for the project brief.

The customer-provided photograph illustrates the requirement for the fan to be delivered within a modular mounting frame.

Why standardizing beat customizing

Four things followed from standardizing rather than customizing.

• No NRE, no waiting. Picking a standard framed centrifugal fan with the bracket already on it removed the tooling charge and the long wait a custom build brings. The result performs better, and it costs materially less than a European module.
• A sample immediately. Moving to a catalog item meant we shipped from stock. Consequently their engineers began fitting it weeks earlier than a 90-day NPI would allow.
• Curves that support system modeling. We validate every figure, the 720 Pa maximum included, to AMCA 210/211 and ISO 5801. Consequently the numbers behind your calculations and energy model are independently checkable.
• Modules, not just parts. We build whole framed centrifugal fan units. The 800 by 800mm frame drops into an AHU plenum quickly, which takes labor out of their final assembly.

Browse our backward-curved centrifugal fan range, or the AHU fan section. Test methods are published by AMCA International.

Questions about the substitution

We asked for the NT-01. Why did you propose a different model?

Because the PT-06-00 is a framed centrifugal fan already carrying the 800mm bracket you wanted, which removes custom development cost entirely. It is also a real upgrade: over 40% more airflow at 17,893 against 12,360 m3/h, and 720 Pa against 494 Pa. That gives your HVAC design more room to move.

It is an AC fan. Can we still control the speed?

Yes. The 400V three-phase motor suits an external variable frequency drive, which is the usual control method in modern AHUs. Where you want integrated smart control instead, we also build EC versions with 0-10V, PWM and Modbus RS485 on our SmartEC platform.

What is the lead time in production quantities?

For a standard make-to-order HVAC product like this, 100 to 500 units run 15 to 25 days from purchase order confirmation. Under a frame agreement with a rolling forecast we set up a stock program, which supports shorter delivery schedules again.

Is more headroom actually worth having?

Usually yes, provided you can control the fan. Filters load over time, and installed ductwork rarely matches the drawing. Consequently a fan sized exactly to the calculated duty has nowhere to go. With a VFD, extra capacity costs nothing to carry, and it saves a redesign later.