Cross-Flow Fan Assembly Without a Motor: 620mm OEM Kit

What the OEM asked us to supply

An HVAC OEM asked for a 620mm cross-flow fan assembly for a new range of high-end fan coil units. Then came the unusual part: they wanted it without a motor.

They based the request on one of our standard models. Furthermore they asked for pricing on a sample plus a 1,000-unit batch.

Why an OEM asks for half a fan

This is a deliberate strategy rather than an oddity. The customer had already standardized on one motor and drive across their line. Consequently a complete fan would have introduced a second motor type, with its own spares, documentation and supplier.

The mechanical constraints

• First, the kit had to match the LW-65620-01 drawing exactly, at 646mm overall length.
• Second, the cross-section was limited to 112 by 100 mm to fit their slim chassis.
• Above all, the 8mm shaft dimensions mattered, since they were designing their own coupling around it.

Their performance target came from the base model, which gives roughly 722 m3/h at 53 Pa. They intended to meet or beat that using their own higher-efficiency motor.

Supplying the cross-flow fan assembly as a kit

No new product was needed here. Instead the job was taking a proven cross-flow fan assembly apart carefully, then documenting the seam.

Confirming the aerodynamics suited the job

First we checked the application against the assembly. The 65mm aluminum impeller uses forward-curved blades, which give a wide, laminar flow at low static pressure. In short, that is the right profile for fan coil units and trench heaters, where quiet matters as much as volume.

Meanwhile no alternatives were put forward, since the request was definitive and the reasoning behind it was sound.

The drawing became the contract

So the real work shifted to documentation. The mechanical drawing we issued acts as an interface control document, and both sides depend on it.

It specifies the 8mm shaft, the material callouts and the exact inlet and outlet geometry. Aluminum keeps the impeller inertia low. Meanwhile iron side plates give a rigid mounting face for whatever bracket the customer designs.

The housing scroll follows our standard cross-flow fan assembly geometry, which keeps turbulence and noise down. Consequently the customer inherits that development rather than repeating it.

What shipped

Here the deliverable was the LW-65620-01 cross-flow fan assembly: impeller, housing and shaft, ready for their motor. They kept the electromechanical integration, which is what they wanted to own. Meanwhile they skipped months of aerodynamic testing they did not.

Technical Specifications

The reference performance rows below assume a motor. In other words they describe what the aerodynamics can do, rather than what ships in the box.

Technical Documentation

LW-65620-01 Specification Sheet

Meanwhile the specification sheet provides precise mechanical dimensions, material callouts, and mounting interface details for the LW-65620-01 fan assembly, essential for system integrators and mechanical design engineers.

Here the image shows the top and side-view orthographic projections of the cross-flow fan housing and impeller, useful for quick visual reference during procurement and initial layout planning.

Why the OEM bought components from us

Not every supplier will sell a component instead of a finished product. We will, and here is why that matters.

• We supply sub-assemblies willingly. Forcing a bundled fan on an OEM who has already standardized their motors adds inventory complexity and cost for them. Supplying the core aerodynamic parts instead is simply the more useful answer.
• Quotes and drawings in days. The enquiry was for a 1,000-unit batch rather than a sample, so it needed a binding price quickly. Our light development route produced final drawings and a firm quote within days.
• The aerodynamics come pre-proven. Because the cross-flow fan assembly is factory matched and tested to AMCA 210/211 and ISO 5801 methods, the OEM started from a known quantity. All they had to add was rotation.
• Direct factory pricing. The 1,000-unit price came in materially below a comparable assembly from European manufacturers. On a component that goes into every unit they build, that difference compounds fast.

Browse the cross flow fan range, or the cross flow impeller section. Airflow testing follows AMCA 210.

Questions about the kit

What is the lead time for 1,000 units?

Standard make-to-order lead time for a cross-flow fan assembly like this runs 15 to 25 days from purchase order confirmation. This particular batch was scheduled for 25 days. Meanwhile customers on a frame agreement who send rolling forecasts can get inside 7 days, since we build against the forecast rather than the order.

Can you supply performance curves at other speeds?

Yes. The reference point is 722 m3/h at 1800 RPM, measured in our AMCA 210/211 test lab. From that we generate a family of P-Q curves at other speeds using the fan affinity laws. Usually that data is exactly what an engineer needs to pick the right motor.

How does a motor mount to this assembly?

Drive comes through the 8mm steel shaft extending from the impeller. The engineering drawing gives exact shaft dimensions and the hole pattern on the iron side plates. Most customers design a simple bracket and couple directly, although a pulley drive works too.

Will you still guarantee performance if we fit our own motor?

We guarantee the aerodynamics, which is what we control. Airflow at a given shaft speed is ours to stand behind. What the fan delivers in your product depends on your motor, your coupling and your system resistance, so those figures remain yours to verify.