Engineering Reference Case Profile · AHU and Ventilation Units
AHU and Ventilation Units · EC Plug Fans, Wide Turndown, Potted Electronics
Compiled from LONGWELL’s real correspondence with air-handling-unit builders, residential ventilation manufacturers and HVAC integrators in Belgium, Russia, the USA, Belarus, the Netherlands and the Gulf. In this segment the fan is rarely rejected on airflow. It is rejected on what happens at the edges — running at 400 rpm without stalling, starting at −40 °C, surviving condensation on the driver board, and not feeding voltage back into the customer’s controller.
About this case profile: This profile is compiled from real LONGWELL project correspondence in this segment. Customer names and customer-specific unit prices are withheld; company names and branding have been removed from the photographs. Model references and selection requirements are drawn from historical project materials. Datasheet ratings, customer requirements and measured results have different scopes; use the approved documents for the exact model and revision before ordering. Named references are available under NDA on project qualification (sales@longwellfans.com).
1 · Challenge
- Turndown, not top speed. A residential ventilation terminal needed continuous running down to 400–500 rpm. Applying a low control voltage from standstill risks the motor failing to start or losing sync — a control-strategy problem, not a fan-curve problem.
- Cold start. One industrial AHU programme specified −40 °C to +70 °C, well outside the standard −25 °C…+60 °C envelope, with condensation risk on the driver board every time the unit cycles.
- Electrical isolation. On an outdoor precision-cooling programme, an AC voltage appeared between the 0–10 VDC control input and GND and damaged the customer’s main control board. A fan that can destroy the controller it is wired to is a warranty problem for the whole machine.
- Neutral supply. European OEMs require no supplier identification anywhere — not on the fan, not on the label, not on the carton — plus specified lead lengths, insulation class marking and EMC reports on file.
- Documented life, not claimed life. Buyers in this segment ask for bearing life calculations to ISO 281 and accelerated test evidence, not a datasheet sentence.
- Nameplate exactly equals paperwork. A single character difference between the nameplate and the specification, invoice or packing list stops the shipment at customs.
2 · Solution architecture
Selection in this segment runs on four axes at once: aerodynamic duty, control behaviour across the whole speed range, environmental hardening of the electronics, and document/label compliance. LONGWELL supplies the LWBE3G and LWBD3G backward-curved EC range and the LWAE3G EC axial range, with PCB potting, control-input isolation, neutral labelling and bearing-life reporting as defined options rather than special requests.
Review the installation envelope
Mounting patternUse the hole positions and support details together.Depth + inletCheck motor clearance and the inlet arrangement.Lead + revisionKeep the cable configuration with the approved drawing.
Selections and hardening options supplied into this segment
| Model / option | Key ratings | Control & environment | Role |
|---|---|---|---|
| LWBD3G160-060PM-01 | 24 V DC backward-curved centrifugal fan. Request the specification and performance data for the exact revision. | Confirm minimum stable speed, startup behaviour, material and lead length for the selected configuration. | Residential and window ventilation terminals |
| LWBE3G310-102NT-24 | 3 ph 380 VAC EC backward-curved | Cross-reference replacement selection | Industrial AHU and equipment ventilation |
| LWBE3G280-138NT-03 | EC backward-curved | Cold-climate requirement with PCB potting under review; confirm the qualified temperature range for the exact configuration. | Cold-climate industrial AHU |
| LWBE3G280-102PS-07 | Datasheet-listed ratings: 230 VAC, 50/60 Hz; maximum airflow 3,193 m³/h; nominal input power 500 W. These values do not describe a combined operating point. | Confirm the approved drawing, curve and control configuration for the full model before selection. | Candidate for central ventilation and filtration selection review |
| LWBE3G400-188PT-07 | EC backward-curved, bracket-mounted | 0–10 VDC / PWM / RS485 | Large central ventilation units |
| LWAE3G500SS-5PEW-10 | Datasheet-listed ratings: 220 VAC, 50/60 Hz; maximum airflow 8,858 m³/h; maximum static pressure 225 Pa; nominal input power 498 W. These are separate ratings, not a combined operating point. | Confirm the operating temperature range and control-input isolation for the exact revision. | Outdoor and precision AHU condenser sections |
| LWAA6D800S-7GB-01 | AC external-rotor axial, high volume | — | Bulk air change and exhaust sections |
| PCB compound potting | Option on EC driver boards | Moisture, dust and vibration protection; specified as default for cold and humid climates | Hardening option |
| Neutral OEM supply | No supplier marking on product, label or carton | Custom lead length, Class F marking, EMC report on file | European OEM requirement |
3 · Ratings and verification requirements
Datasheet maxima are separate ratings and must not be combined into a duty point. Request the selected model's approved specification, applicable test method and supporting test record. Energy savings and payback depend on measured baseline power, the proposed fan's power at the same duty, operating hours, electricity price and installed cost; no project saving or payback result is claimed here.
Low-speed requirement
400–500 rpm
Project requirement; verify startup and continuous running for the chosen control revision.
Control response record
Voltage + speed
Use the sample test record for the exact control revision, with supply voltage and load conditions stated.
Bearing-life evidence
Model + conditions
Request the applicable calculation and test basis, with bearing type, temperature and load stated.
Environmental qualification
Temperature + condensation
Confirm the qualified range and test conditions for the potted-board configuration.
Select at the required duty point
Airflow + pressure + power
For LWBE3G280-102PS-07, confirm all three together on the approved curve for the exact configuration. Maximum airflow and maximum static pressure are separate ratings.
Datasheet maximum airflow
8,858 m³/h
Archived LWAE3G500SS-5PEW-10 rating. Confirm input power at the selected duty point.
Impeller material
PA66+GF30%
Glass-filled polyamide, balanced for low-speed stability
Neutral packaging
No supplier marking
Product, label and carton — standard for European OEM supply
4 · How these programmes run
Duty and turndown definedAirflow and static pressure are agreed together with the lowest speed the machine has to hold. In this segment the low end is what fails, so it is written down first.
Control behaviour testedSpeed is measured at defined control-voltage points and the curve is issued. Where low-voltage starting is marginal, a start-high-then-ramp-down strategy is recommended in writing.
Environmental hardening decidedAmbient range, condensation exposure and vibration decide whether the driver board is potted. For cold or humid climates it is proposed by default rather than on request.
Interface protection reviewedConfirm the applicable control interface, isolation, grounding and defined fault tests for the exact fan and controller combination.
Documents assembledISO 281 bearing life calculation, EMC report, insulation class, IP class and neutral-label artwork are prepared before the first shipment, not after the first audit.
Nameplate and paperwork reconciledBefore despatch the nameplate is checked character by character against the specification, invoice and packing list. This step exists because skipping it once cost a customs hold.
5 · Engineering lessons carried forward
- In ventilation units the low end of the speed range is the risk, not the top. Ask for the minimum running speed at the enquiry stage, measure it, and issue the speed-versus-control-voltage curve rather than a single duty point.
- When starting at low control voltage is unreliable, evaluate a start-high-then-ramp-down strategy against the required minimum speed before selecting different hardware. Confirm the result on the intended control revision.
- Offer PCB potting by default for cold or humid climates. Condensation on an unprotected driver board is the failure mode behind a large share of field returns in this segment, and it is cheap to prevent at build time.
- Protect the control interface in both directions. An internal fault must never put voltage back onto the customer’s 0–10 V line; the documented response to such an incident should identify the board revision, isolation changes, sample verification and return or replacement records.
- European OEMs buy the paperwork as much as the fan. ISO 281 bearing life with an accelerated test report, an EMC report, Class F marking and genuinely neutral labelling remove most of the objections before they are raised.
- Check the nameplate against the invoice and packing list before packing. One extra character on a printed model number is enough for customs to reject the entry.
- When a customer reports an electrical fault, ask for video of the actual wiring and test. It shortens diagnosis dramatically and avoids shipping replacement units against a wrong hypothesis.
6 · Project evidence
Every item below is a real project thread from LONGWELL’s own correspondence. Each carries an anonymised case reference, the counterparty described by industry and buying role only, an evidence grade, the actual dates from first contact to close, the length of the email thread and, where an invoice is on file, the order value band. Customer names, domains, brand artwork and unit prices are withheld — including from the photographs. Evidence grade A means controlled documents or test reports are on file for that thread; grade B means a structured enquiry and specification are on file. Order value bands are read from the proforma or commercial invoice held on file for that thread and are rounded to a band; the invoice currency is shown as invoiced. A band is only given where the invoice currency is unambiguous — 20 of the threads on these pages carry one. Unit prices are never published.
Residential ventilation terminal — 24 V fan and low-speed control review
- LWBD3G160-060PM-01 was considered for the 24 V residential ventilation application. Confirm the full specification revision, mounting plate and lead configuration before using its ratings for selection.
- The requirement was continuous running down to 400–500 rpm. Evaluate startup and ramp-down behaviour on the chosen sample, and use its revision-specific speed-versus-control record for programming. A low-speed requirement is not an acceptance result.
- Confirm the bearing specification and applicable life calculation or test evidence for the final fan revision, including temperature, load and the definition of the reported life metric.
- Supplied fully neutral — no supplier identification on the product, label or carton.
Cold-climate industrial AHU — temperature requirement and driver-board protection
- Cross-reference of an incumbent European model answered with LWBE3G310-102NT-24, matched on airflow, static pressure and 3-phase 380 VAC supply.
- The LWBE3G280-138NT-03 project discussion included a −40 °C to +70 °C requirement and compound potting for driver-board protection. Confirm the approved configuration and relevant environmental test evidence before adopting that operating range.
- The engineering lesson was written down: for high-latitude sites the standard −25 °C…+60 °C envelope is not enough, and potting should be proposed rather than waiting to be asked.
AHU terminal — potting upgrade after a field failure, plus customs-grade labelling
- Select the replacement at the required airflow and static pressure together, then confirm input power, speed and noise for the same operating point in the selected model's test record.
- Two failed units were returned for teardown. Diagnosis led to full compound potting of the EC driver board to raise moisture and corrosion resistance.
- A nameplate printing discrepancy was corrected and a compliant specification reissued so the shipment cleared customs; EAC marking and the QC PASS check mark were added to the nameplate template as mandatory items.
Outdoor precision AHU — control-input isolation and a full return/replace cycle
- The archived LWAE3G500SS-5PEW-10 datasheet lists 220 VAC, 50/60 Hz, maximum airflow 8,858 m³/h, maximum static pressure 225 Pa and nominal input power 498 W. These separate ratings do not define one operating point. Confirm the selected revision, operating temperature and required duty point.
- In cold conditions a voltage appeared between the 0–10 VDC input and GND and damaged the customer’s main board. Failed samples were stripped and the fault reproduced under simulated conditions; the control board was re-engineered with proper circuit isolation and protection, and revised samples were sent for on-site verification.
- The original model was taken back and settled, and LWAE3G450SS-5MEW-03 was supplied as the replacement so the customer’s production and service programme continued.
Central ventilation and filtration — high static pressure on a compressed schedule
- LWBE3G280-102PS-07 is a 230 V AC, 50/60 Hz EC backward-curved centrifugal fan. Its datasheet lists a maximum airflow of 3,193 m³/h and nominal input power of 500 W. Maximum airflow and maximum static pressure are separate ratings, not a combined operating point. Selection requires the confirmed curve for the exact model and configuration, with airflow, static pressure and input power checked together at the required duty point. LWBE3G400-188PT-07 was also included in the original selection record.
- LWAA6D800S-7GB-01 AC external-rotor axial fans covered the high-volume exhaust sections.
- Delivered on EXW terms across the Chinese New Year shutdown by issuing exact pallet dimensions (90×90×174 cm and 112×112×… cm) and gross weights early, so the customer’s forwarder could book space before the holiday.
Existing LONGWELL product photo used for this ventilation reference profile. This is a 160 mm product example, distinct from the 280 mm model drawing above.
Testing process: what to agree for your sample
Datasheet maxima are separate ratings and must not be combined into a duty point. Request the selected model's approved specification, applicable test method and supporting test record. Energy savings and payback depend on measured baseline power, the proposed fan's power at the same duty, operating hours, electricity price and installed cost; no project saving or payback result is claimed here.
Documentation for an AHU selection review
RLM series reference catalog
Reference for the separate RLM assembly family. It is not the approval sheet for the LWBE3G280 model shown above.
View RLM series catalog (PDF)Request the selected-model package
Ask for the full model and suffix, approved outline drawing, duty-point curve, control definition and supporting test records relevant to your application.
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