Description
Modular Air Handling Solutions for Commercial, Industrial & Specialized Applications
Air Handling Units (AHUs) are configurable HVAC systems designed for air treatment, filtration, cooling, heating, humidity control and air distribution. The NEXA AHU range can be configured according to airflow requirements, application conditions and project-specific engineering requirements.
Key Features
- Airflow configurations from approximately 1,500 to 260,000 m³/h
- Modular and project-specific configuration
- Cooling coil configurations
- Heating coil options
- Primary, bag and HEPA filtration options
- Fan sections
- Heat recovery sections
- Humidification options
- Silencing sections
- Dampers and mixing sections
- Special-purpose sections
- Project-specific dehumidification and heat-recovery configurations
AHU Applications
The technical guide provides selection guidance for applications including:
- Normal comfort HVAC
- Outdoor AHUs
- 100% fresh-air / DOAS systems
- Healthcare and hospital applications
- Food-processing facilities
- Pharmaceutical and cleanroom environments
- Humidified AHUs
- Low-temperature process applications
- Non-critical extract systems
Airflow & Indicative Dimensions
The reference data covers airflow from 1,500 m³/h to 260,000 m³/h.
The preliminary sizing table provides internal and external casing dimensions based on approximately 2.5 m/s face velocity. External TBA dimensions are based on internal dimensions +50 mm, while TBC dimensions are based on internal dimensions +100 mm.
Important: These dimensions are preliminary planning references. Final AHU dimensions must be confirmed through the selected manufacturer’s certified drawing.
Configuration Options
Filtration
- Primary filter
- Medium-efficiency filter
- Bag filter
- HEPA filter
- Primary + bag filter
Cooling
Cooling coil configurations with approximately 1–10 coil rows are covered in the configuration reference.
Heating
- Heating coil
- Electric heater
Humidity Control
- Steam humidifier
- Wet-film humidifier
- Water-mist humidifier
Air Treatment
- Spray section
- Evaporation & cooling
- Dehumidification
- Heat recovery
- Self-purification high-efficiency cartridge filtration
- Infrared section
Air Movement
Fan-section lengths vary depending on fan type, duty and arrangement.
EN 1886 Casing Performance
The AHU technical guide discusses four important EN 1886 casing performance parameters:
D Class – Mechanical Strength
| Class | Relative Deflection |
|---|---|
| D1 | ≤4 mm/m |
| D2 | ≤10 mm/m |
| D3 | >10 mm/m |
D1 represents a stiffer casing construction suitable for higher-pressure or critical applications, while D2 is identified as the normal minimum recommendation.
T Class – Thermal Transmittance
| Class | Thermal Transmittance |
|---|---|
| T1 | ≤0.50 W/m²K |
| T2 | >0.50–1.00 W/m²K |
| T3 | >1.00–1.40 W/m²K |
| T4 | >1.40–2.00 W/m²K |
| T5 | >2.00 W/m²K |
Lower T classes represent better thermal insulation performance.
TB Class – Thermal Bridging
| Class | Thermal Bridging Factor |
|---|---|
| TB1 | 0.75–1.00 |
| TB2 | 0.60–0.75 |
| TB3 | 0.45–0.60 |
| TB4 | 0.30–0.45 |
| TB5 | <0.30 |
Thermal bridging is particularly important around doors, joints, frames, cooling-coil sections, cold-air sections and humidifier sections.
L Class – Casing Air Leakage
| Class | −400 Pa | +700 Pa |
|---|---|---|
| L1 | 0.15 L/s·m² | 0.22 L/s·m² |
| L2 | 0.44 L/s·m² | 0.63 L/s·m² |
| L3 | 1.32 L/s·m² | 1.90 L/s·m² |
L1 represents the lowest leakage category in the table, while L2 is described as the normal acceptable minimum for standard comfort applications.
Application-Based Selection
The guide provides the following selection examples:
| Application | T | TB | L | D |
|---|---|---|---|---|
| Normal comfort AHU | T3 | TB3 | L2 | D2 |
| Outdoor hot/humid AHU | T2 | TB2 | L2 | D2 |
| 100% fresh air / DOAS | T2 | TB2 | L1 | D1/D2 |
| Hospital / healthcare | T2 | TB2 | L1 | D1 |
| Food processing | T2 | TB2 | L1 | D1 |
| Pharmaceutical / cleanroom | T1/T2 | TB1/TB2 | L1 | D1 |
| Low-temperature process | T1 | TB1 | L1 | D1 |
These are selection recommendations, not guaranteed classifications for every AHU.
Engineering & Selection
AHU selection should consider:
- Installation location
- Maximum positive and negative static pressure
- Internal air temperatures
- Ambient dry-bulb temperature
- Ambient humidity and dew point
- Required thermal performance
- Thermal bridging and condensation risk
- Required casing leakage
- Mechanical strength
- Inner-skin material and thickness
- Hygiene and corrosion requirements
- Manufacturer-certified performance
Technical Documentation
The guide references EN 1886 for AHU mechanical performance and Eurovent Recommendation 6/18 2022 for AHU quality criteria.
Technical Disclaimer
The information provided is intended for preliminary engineering and selection guidance. Final AHU dimensions, configuration, performance and casing classifications must be confirmed against the project requirements and the selected manufacturer’s certified technical documentation. The values in the reference tables should not be treated as guaranteed specifications for an individual AHU model.
Important
The PDF does not provide individual model numbers, cooling capacities, fan power, electrical specifications, weights, exact product configurations or complete model-specific datasheets. Those details should be obtained from the relevant manufacturer/product documentation rather than invented from this guide.
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