Forward-Curved Centrifugal Blower for AHU OEM: 4-Pole, 220V Case Study

What the AHU maker specified

A customer engineering team came to us wanting five forward-curved centrifugal blower models for a new modular range of air handling units. Airflow ran from 884 m3/h at the bottom up to 9,885 m3/h at the top.

Helpfully, the power needs were laid out precisely, which is always a good sign.

• First, three models at 1.1, 1.5 and 2.2 kW, all on single-phase 220V.
• Then a 2.2 kW and a 3.0 kW model on three-phase 220V.
• 4-pole motors across the whole range, since 2-pole was explicitly rejected.
• Lastly, a full pack of specs, drawings in PDF and DWG, and a quotation.

Why the 4-pole line matters

Basically that single line tells you what kind of kit this is. A 4-pole motor turns at roughly 1450 RPM on 50Hz, whereas a 2-pole turns at about 2900 RPM.

Halving the speed cuts noise a lot, since fan noise climbs steeply with tip speed. The trade is pressure. Indeed a 2-pole motor makes far more of it from the same frame.

Choosing 4-pole means the customer values quiet over squeezing maximum pressure from the smallest housing. In commercial HVAC, that is usually right.

The 220V three-phase line is worth noting too, since 380V is far more common. Evidently it points at one regional market, or one class of commercial job.

Matching five forward-curved centrifugal blower models

Fortunately the brief was clear enough to skip exploring and go straight to matching products. Internally it ran as minor development, meaning documents and a quotation against existing models.

The 4-pole requirement narrowed it immediately

Specifically it pointed at our LWFDF-11 forward-curved centrifugal blower series, built for jobs where noise matters as much as airflow.

Certainly a 2-pole motor could have made higher pressure from a similar frame. However, it costs noise that commercial HVAC kit cannot afford. The customer had already made that call, and our team agreed it was right for an AHU.

Mapping five combinations

Usefully, each of the five power and voltage pairings mapped to a model in the same series.

• 1.1 kW single-phase 220V: LWFDF-11-3.2A-1.1-4P-1-001
• 1.5 kW single-phase 220V: LWFDF-11-4.5A-1.5-4P-1-001
• 2.2 kW single-phase 220V: LWFDF-11-5A-2.2-4P-1-001
• 2.2 kW three-phase 220V: LWFDF-11-5A-2.2-4P-3-001
• 3.0 kW three-phase 220V: LWFDF-11-5.6A-3-4P-3-001

Meanwhile IP44 protection and a steel double-inlet housing suit a sheltered spot inside an AHU chassis. That is where all five will live.

Afterwards the project manager gathered the approved documents. Five sets of drawings and specs went through technical review before costing and quotation. In short, that is how a five-model package gets answered fast without anyone guessing.

Technical Specifications

Five models are covered below. Note the speed row reads 1450 RPM throughout. That is the whole point of asking for a 4-pole forward-curved centrifugal blower.

Technical Documentation

LWFDF-11-3.2A-1.1-4P-1-001.pdf
The document contains the full technical specification and dimensional drawing for the 1.1kW model, essential for mechanical integration and performance verification.

LWFDF-11-4.5A-1.5-4P-1-001.pdf
Procurement and engineering teams use this specification sheet for the 1.5kW single-phase unit to confirm system compatibility.

LWFDF-11-5A-2.2-4P-1-001.pdf
Here the file provides all necessary data for the 2.2kW single-phase blower, including the performance curve and installation dimensions.

LWFDF-11-5A-2.2-4P-3-001.pdf
The specification sheet for the 2.2kW three-phase version is critical for electrical system designers and panel builders.

LWFDF-11-5.6A-3-4P-3-001.pdf
This document outlines the performance envelope and physical characteristics of the largest unit in this request, the 3.0kW blower.

Why one supplier covered the range

For an OEM building a new product line, the supplier choice runs well past the component itself.

• A five-model package, quickly. Our library of standard documented products let the team return five specification sheets, five drawings and a quotation in a very short time, which moved the customer own development along with it.
• One family covered everything. Five different power, voltage and phase pairings all came from the LWFDF-11 forward-curved centrifugal blower series. Consequently the OEM sources its whole fan lineup from one vendor, which simplifies the bill of materials and keeps design consistent across the range.
• A real price gap. Making the parts ourselves puts us materially below European rivals for the same AC motor technology. In commercial HVAC, that feeds straight into the customer own competitiveness.

Browse our forward-curved centrifugal fan range, or the AHU fan section. Efficiency requirements are published by ASHRAE in Standard 90.1.

Questions about control and voltage

Can these be speed-controlled with a VFD?

The three-phase models can, because their induction motors suit an external drive. That gives precise airflow control and helps against standards such as ASHRAE 90.1. The single-phase models cannot. Where you want integrated variable speed, take our SmartEC series with 0-10V or PWM control built in.

What is the lead time for 500 mixed units?

Standard catalog products like these run 30 to 45 days after order confirmation. We hold safety stock on core components, which helps a first mass production run for a new OEM partner. Exact timing is confirmed against production scheduling when the order is placed.

Is a 380V three-phase version available?

Yes. This project needed 220V three-phase. However, the LWFDF-11 forward-curved centrifugal blower series covers all standard voltages, including 380V/50Hz and 480V/60Hz. Motor voltage is a normal configuration option, and common voltages are often stocked. A genuinely custom winding would follow the standard 90-day NPI cycle.

Why does pole count change the noise so much?

Because pole count sets the synchronous speed, and fan noise climbs steeply with blade tip speed. Doubling the poles roughly halves the RPM, which drops the noise a long way. You lose pressure in exchange. Consequently the right choice depends on whether your system is pressure-limited or noise-limited.