VRE 500 Air Recirculation Fan

Controlled Air Recirculation for Storage Rooms and Greenhouses

The VRE 500 is an axial air recirculation fan designed to maintain continuous air movement inside vegetable storage facilities and greenhouses. Its main task is not to replace the primary ventilation system, but to keep the internal air mass moving between full ventilation cycles. This supports more uniform temperature distribution, reduces stagnant zones and helps prevent moisture from condensing on walls, ceilings and structural elements.

In a large storage chamber, temperature and humidity are rarely distributed perfectly evenly. Warm air rises, colder layers remain near the crop or floor, and poorly ventilated corners can retain moisture. A correctly positioned recirculation fan creates a long directed air stream that mixes these layers and reduces local differences without introducing additional outdoor air.

Operating Principle

The VRE 500 uses a 500 mm axial impeller and an aerodynamically shaped housing to generate an air flow of up to 8,800 m3/h. The fan creates an effective air throw of approximately 45-50 metres, allowing a limited number of units to support circulation across long storage rooms or greenhouse bays.

Recirculation is especially valuable when the main supply and exhaust ventilation system is operating intermittently. The fan keeps chamber air moving during holding periods, helps transfer heat and moisture toward the active air-handling zones and reduces the risk of isolated pockets with different temperature or relative humidity.

Why Internal Air Movement Matters

• Temperature equalization: continuous mixing reduces differences between upper and lower air layers and between separate parts of the room.
• Condensation control: moving air accelerates moisture evaporation from walls and ceilings and reduces persistent wet surface zones.
• Fewer stagnant areas: the long air stream supports circulation in zones that are not reached effectively by the main ventilation system.
• More stable crop conditions: improved air distribution helps the storage-control system maintain a more consistent microclimate around the stored product.
• Support for greenhouse climate: recirculation improves temperature uniformity and limits local humidity accumulation around plants and structural surfaces.

Engineering Features

The fan combines a specially matched motor and impeller with an aerodynamic casing. The housing is made from polypropylene, while the impeller and blades use composite materials. These materials are suitable for humid agricultural environments and help protect the assembly from the corrosive effects associated with storage rooms and greenhouse operation.

The motor has IP67 protection. This level of enclosure protection is important in facilities where high humidity, condensation, dust and periodic cleaning can affect electrical equipment. A protective grille limits access to the rotating impeller while allowing the fan to maintain the required air flow.

Technical Specifications

• Model: VRE 500
• Impeller diameter: 500 mm
• Airflow: 8,800 m3/h
• Effective air throw: 45-50 m
• Motor power: 0.37 kW
• Supply voltage: 220 V
• Rotational speed: 1,500 rpm
• Motor protection: IP67
• Housing material: polypropylene
• Impeller and blade material: composite material

Placement and System Integration

Fan performance depends on placement as much as on nominal airflow. Units should be positioned so their air streams support the general circulation pattern rather than oppose each other or create short circulation loops. The layout must consider room length, ceiling height, crop loading method, racks or containers, structural columns and the location of supply and exhaust openings.

In vegetable storage rooms, recirculation fans can be coordinated with the main ventilation, refrigeration, heating and humidity-control strategy. In greenhouses, they can operate according to temperature and humidity conditions or as part of a scheduled circulation mode. The required number of fans and mounting positions should be selected for the actual facility geometry and operating scenario.

Typical Applications

• Potato, onion, carrot and cabbage storage rooms.
• Bulk and container vegetable storage facilities.
• Greenhouses and protected-crop production buildings.
• Agricultural rooms with long spans or persistent stagnant-air zones.
• Facilities where condensation forms on ceilings, walls or structural elements.

Engineering Result

The VRE 500 provides a practical way to improve internal air distribution without continuously running the full ventilation system. When the fans are correctly selected and positioned, they help stabilize temperature, reduce surface condensation and make the overall microclimate-control system more predictable.

Recirculation does not replace correctly sized supply, exhaust, cooling or heating equipment. It complements those systems by ensuring that conditioned air reaches the occupied volume more evenly and that local microclimate differences do not remain unnoticed between control cycles.