What’S The Point Of Putting Greenhouse Fans?

Mounting fans above the crop canopy or along the sidewalls ensures efficient air movement throughout the entire growing area. Exhaust fans should be positioned at one end of the greenhouse slightly above bench level to maximize cooler air at the plants. Open vents and doors and use fans to provide air circulation, encourage healthy plant growth, and keep diseases away. Many fans are located at the opposite end of the greenhouse from the electric distribution box. Wiring should be large enough to keep the fan systems working best if the draw is less than 150 feet. For most greenhouses, this means installing the fans on one end wall with louvers placed in the opposite end. In longer houses, the fans should be placed 30-50 feet apart.

To choose a greenhouse fan system, consider key factors such as fan size, CFM (cubic feet per minute) rating, and fan placement. Utilizing a thermostat-connected fan will increase your greenhouse’s energy efficiency, lower your electricity bills, and give you peace-of-mind. Place the first fan 10-15 feet from one end wall to boost air coming from the corner. The remaining fans are usually located 30-50 feet apart. In longer houses, the fans should be located along the sidewalls so they can draw air in through louvers in both ends. Intake shutter area should be at least 1¼ times the fan area. Shutters should be mounted on the opposite endwall or sidewall from the fans to minimize hot air loss due to friction.

Ideally, exhaust fans should be placed towards the roof of the greenhouse, opposite the door. If your particular greenhouse does not allow for adding exhaust fans, consider using a fan-powered system to improve the greenhouse’s overall success.

How to cool a greenhouse with a fan?

Positioning fans strategically in your DIY greenhouse kit creates a gentle breeze that keeps the air flowing and prevents stagnant hot spots. This not only cools down the temperature but also keeps humidity at bay, reducing the risk of plant diseases. With eight techniques to keep your greenhouse cool and plants happy, including providing shade, enhancing ventilation, incorporating water features, and using cool tech like electronic cooling systems and fans, your DIY backyard greenhouse will be the coolest spot in town.

What is the best airflow for a greenhouse?

Base or roof vents in greenhouses are crucial for maintaining a healthy environment. They should be left open during warm weather and can be automated with solar openers. If the greenhouse has the option to add extra vents, it is often beneficial. Ideally, at least one large vent should be placed near the roof to allow heat to escape. Multiple vents around the perimeter near the base should also be placed for cross-ventilation, where cool air enters the greenhouse through the base and flows towards the top vents. This method maximizes the circulation achieved by vents alone, allowing plants to receive a consistent supply of carbon dioxide.

Where should fans be placed?

High ceilings require a powerful fan to maintain a comfortable temperature. Cold air is naturally heavier than warm air, settling near the floor while hot air occupies higher spaces. Placing a fan in a room disrupts this balance and can force cooler air to move where it wants. Place the fan facing the opposite wall from where most activity takes place, driving the air to the surface and cooling the space. If lower temperatures are your main goal, choose a fan lower to the ground to capture the refreshing chilliness.

Opening a window for fresh air can be unpleasant due to too much heat, bugs, and noise. Box fans or window fans can help by circulating fresh air faster and cooling down the heat. Box fans with Weather-Shield® can be used rain or shine, but should be moved from the window during heavy rains and winds to avoid damage. Window fans work even better at circulating fresh air from outside, with fans like the 16″ Window Fan with E-Z-Dial Ventilation fitting securely and tightly in the open window. Twin fans, like the Electrically Reversible Twin Window Fan with Remote Control, can simultaneously pull fresh air in while pushing out stale air, creating a crisp and clean circulating air.

Where should a circulator fan be placed?

Circulation fans should be evenly spaced along the center line of a house, within a few inches of the ceiling, directing air towards the end walls. They should be installed parallel to the ceiling and prevented from blowing air towards the floor. Most circulation fans should be installed between 40-60 inches on center. It is recommended against installing fans in a “racetrack” pattern, as it can create excessive air movement near the side walls, potentially creating drafty conditions for birds and disrupting inlet air flow patterns.

Additionally, placing fans near the side may not fully mix hot air collected near the ceiling peak with the rest of the house air. In houses using partial house brooding, half the circulation fans should be directed towards the end wall and the other half towards the brooding curtain. Circulation fans near the center of the brooding area should be positioned approximately 20 feet apart, with the ideal placement being within 40 feet of the end wall and brooding curtain.

What is the airflow pattern in a greenhouse?

Freestanding greenhouses use a circular horizontal air pattern, while gutter-connected ranges use a more efficient method. Fans should be placed near the center of the air mass, 7-8 feet above the floor for floor or bench crops, and below or above the basket level for hanging baskets. Support can be provided by truss or collar tie. For hanging baskets, fans should be below or above the basket level for the least resistance and to prevent drying of foliage.

Fans should be located below the energy curtain to maintain temperature uniform at night. The HAF system should be operated 24 hours a day, except when exhaust fans are on or vents are open. A relay can be added to switch fans off when the ventilation system activates. Operating cost for small fans is about $0. 25 per day at a 10 cent/kilowatt electricity rate.

Where should I put my fan in my indoor greenhouse?

In order to ascertain the volume of air that must be removed from a room on a minute-by-minute basis, it is first necessary to calculate the volume of the room in question and then to determine the CFM of exhaust fans that are required for the space in question.

Where should greenhouse circulation fans be placed?

The optimal fan location for a greenhouse is in the center of the air mass being moved. Freestanding greenhouses should be located 1/4 of the width of the greenhouse from the sidewall, while gutter-connected greenhouses should be in the center of the bay. The first fan should be 10-15 feet from one endwall to boost air coming around the corner. Subsequent fans should be 30-50 feet apart, with the last fan at least 50 feet from the endwall.

The height of the fan is not critical, but it is best located above head height to get it out of the way. If the house contains hanging baskets, a location a couple of feet above or below them is best.

Short circuiting of the air stream across the house before it reaches the next fan can occur with a poor installation. To check this, use a smoke bomb or fogger, and watch the movement of the fans after airflow has stabilized. Incense sticks can also be used to detect turbulence in the airflow.

Control of the fan circuit is crucial, as fans with 1-10-1-15 horsepower draw about 100 watts of electricity. Up to 15 fans can be placed on one 20-amp circuit. The HAF system should run continuously during the fall, winter, and spring, with an on/off switch and a power relay. If a controller or computer manages the environment, the HAF fans should be operated during heating, set point, and low stage ventilation modes.

What kind of fan is best for a greenhouse?

Fan classifications include centrifugal and axial flow, based on the direction of air flow through the impeller. Axial flow fans, such as propeller fans, duct fans, vane axial fans, and disc fans, are used for general ventilation applications and grain drying. They are tested in accordance with AMCA (Air Moving and Conditioning Association) Standard 210, which specifies procedures and setups for testing various types of fans. This ensures that fans of different manufacturers and types are rated and compared using the same basis of testing and performance data.

Fan laws relate the performance characteristics of geometrically similar series of fans, involving variables such as fan size, rotational speed, volume flow rate, static pressure, horsepower, and mechanical efficiency. These laws help determine requirements when changing the volume capacity of a fan for a given system. The new operating point for a given fan can be determined from fan laws, which show that volume flow rate (CFM) varies directly as fan speed (N), static pressure (SP) varies as the square of fan speed, and horsepower (HP) varies as the cube of fan speed.

How many fans should you have in a greenhouse?

For larger houses, use two fans to stage cooling in two or three levels. For a 30′ x 96′ greenhouse, two 36″, 1/2 hp fans would be sufficient to move 10, 080 CFMs of air. To calculate shutter size, divide the total CFMs by 600, which is an air velocity number. Smaller shutter openings create more air velocity and more of a breeze, while larger openings create lower air velocity and less of a breeze. For example, a 30′ x 96′ greenhouse with two 36″, 1/2 hp fans would require 34. 36 square feet of opening, so two 51″ shutters, two 45″ shutters, and one 30″ gable shutter are recommended.

Do fans lower humidity in greenhouse?

Greenhouse fans are used to create airflow within a greenhouse, helping to control humidity levels by directing air towards different areas and dense foliage. However, fans alone do not remove water vapor or reduce absolute humidity in the growing space. Various fans, including vertical fans and air circulators, can improve air movement in large spaces and combat humidity build-up. However, fans do not reduce the amount of water vapor found in the greenhouse, and in a saturated environment with 100 relative humidity, fans will not reduce the humidity level.

How far apart are greenhouse fans?

In order to optimize air circulation around corners in greenhouses, the initial fan should be situated at a distance of 10-15 feet from one endwall. This should be followed by the installation of 30-50 feet of additional fans, with the final fan positioned at a minimum distance of 50 feet.