How to Choose an Exhaust Fan for a Multi-Span Greenhouse: Key Points on Installation and Maintenance
1. Why Install Exhaust Fans in a Multi-Span Greenhouse
A multi-span greenhouse has a large space and good airtightness. Under summer sunlight, the temperature inside rises quickly, and moisture tends to accumulate. Natural ventilation through roof windows and side windows alone often cannot keep high temperature and high humidity under control. An exhaust fan combined with a wet curtain forms a "fan-wet curtain" cooling system, forcibly drawing hot air out of the greenhouse while drawing in fresh air cooled through the wet curtain. The cooling effect is much more obvious than natural ventilation. In addition, exhaust fans can reduce humidity inside the greenhouse, help air circulation, supplement carbon dioxide, and reduce disease occurrence, making them indispensable equipment in protected agriculture.
2. How to Choose and Install Exhaust Fans
For selection, the main considerations are the greenhouse area, the crops grown, and the local climate. Fan size should match the ventilation volume required by the greenhouse; choosing one too large wastes electricity, while choosing one too small provides insufficient cooling. It is generally recommended to ask the manufacturer or local agricultural technical personnel to calculate the air volume according to the greenhouse dimensions before determining the model. Installation position also matters: exhaust fans are usually installed on the gable wall at one end of the greenhouse, and the wet curtain is installed at the opposite end, forming an airflow route through the greenhouse. Between the air inlet and air outlet, try to avoid tall crops or partitions blocking the airflow. During installation, the frame must be well sealed to prevent air leakage and short-circuiting from affecting cooling performance. It is best to add protective mesh and bird netting on the outside of the fan to ensure safety without affecting air intake.
3. Key Points for Daily Use and Maintenance
Whether fans perform well depends on maintenance. Regularly clean dust, flying insects, and debris from blades, louvers, and protective mesh; when too much dust accumulates on the blades, air volume will drop noticeably. Regularly check belt tension and bearing lubrication, and if abnormal noise or increased vibration is found, stop the machine promptly for inspection and repair. Because humidity in the greenhouse is high, the motor and wiring must be treated for moisture and corrosion protection to avoid electrical leakage hazards. When not in use for a long time, cut off the power supply and cover the protective hood properly. Before use the following year, run it idly for a few minutes first, and put it into formal operation only after confirming normal operation. As for equipment prices and purchase subsidies, policies and standards vary by region, so consult the local agricultural machinery authorities for specifics, and refer to the published subsidy catalog.
Overall, although the multi-span greenhouse exhaust fan may seem inconspicuous, it directly affects the temperature, humidity, and crop harvest inside the greenhouse. With reasonable selection, proper installation, and diligent maintenance, this ventilation and cooling system can truly deliver results and safeguard protected cultivation.