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Greenhouse Ventilation Fans

Greenhouse ventilation is a topic before it is a product: a greenhouse must lose heat and humidity on a sunny day, gain fresh air for the crop, and hold a steady climate overnight. This page covers the ventilation topic first, and the fan families the manufacturer’s pages list for greenhouses second — the topic section is a guide, not a product claim.

Greenhouse ventilation as a topic

Searches for greenhouse ventilation return guides, tips and videos alongside fan listings, because the question most growers start with is how a greenhouse breathes, not which fan to buy. The basics are the same as any ventilated building: hot air rises and must leave at the top, fresh air must enter low or at the far end, and the air must actually move across the crop rather than short-circuiting from one opening to the next. A roof exhaust fan is the exit at the top of that circuit. Whether one fan or several, and where the inlets sit, depends on the house length, the crop height, and the climate — and no source page publishes a greenhouse sizing rule, so this page states none. The guide section below sets out the questions; the fan tables further down give the verified figures to answer them with.

What growers ask about first

• How hot the house gets at midday in the local climate, and how much of that heat the ventilation must remove — a question for the grower, not a figure any fan page states.
• Where fresh air enters, and whether the inlet path keeps the airflow moving across the crop instead of over it.
• Whether the crop needs steady air movement overnight as well as heat removal by day, which changes how many fans run and when.
• Whether humidity control matters as much as temperature — in a closed house overnight, humid air is the problem, and the exhaust and intake must be planned for it.
• Whether thermostat control is wanted: search terms name greenhouse fans with thermostats, but no source page lists a thermostat model, so thermostat control is a question to ask, not a feature to assume.

The fan families the source pages list for greenhouses

The slope page lists greenhouses among its agricultural applications, and describes its fan as serving factories, poultry houses, greenhouses and warehouses in Southeast Asia's climate. The elbow page lists greenhouses among its agricultural applications, alongside large-scale farms and poultry and livestock. The two families give the grower a real choice: the slope models run at 28,000 and 45,000 m³/h with a waterproof dome-shaped cap, a wind deflector and a 1.9-metre awning against rain; the elbow models run from 28,000 to 45,000 m³/h with PVC shutters against flies and backflow, a smooth-surfaced FRP housing described as UV and weather resistant, and noise figures from 55 to 65 dB. Both families run on 380 or 220 V at 50 Hz. The FRP housings suit the humid air of a greenhouse, and the shutters on the elbow family matter where insects must be kept out of the house. The full tables are on the FRP page.

Shutters, awnings and the crop

Two small features deserve a grower's attention because they protect the crop rather than the fan. The elbow family's PVC shutters close against flies and backflow when the fan stops, which keeps insects out and keeps cold or humid air from flowing back into the house overnight. The slope family's 1.9-metre awning sheds rain away from the fan and the roof opening, which matters on a greenhouse roof where a leak lands on the crop. Neither feature appears as a headline specification, and both are stated on their own family pages as features, not as guarantees — but for a growing building they are the difference between a fan that ventilates and a fan that also protects the house when it is off.

What to send with a greenhouse inquiry

• The house length, width and height, the crop, and the local climate — the facts a sizing answer actually needs.
• The roof openings available, and the voltage at the fan positions: 380 or 220 V, 50 Hz for slope and elbow models.
• Whether thermostat or staged control is wanted, and what control equipment the house already has — no thermostat model is listed on the source pages.
• The inlet arrangement: where fresh air enters, and whether it can be kept open and clean through the season.
• MOQ, lead time and warranty, which no source page states and which must be confirmed before payment.

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