How To Install Fans In A Greenhouse?

Install a ventilation fan on the back wall of your greenhouse, cutting a hole near the roof large enough for the fan to fit. Use a fan encased in waterproof housing with an air-activated vent and orient it to blow air out of the greenhouse. Cover the accessible portion of the fan with a screen. Regular air exchange is essential for crop growth and promoting a healthy temperature range.

There are several methods, tools, and tactics growers use to achieve proper ventilation, but the best operations often involve using a thermostat and greenhouse fan. Properly position the fan for maximum efficiency, perform regular maintenance, and utilize a thermostat for optimal performance. Solar fans can be installed at various cost points, such as Amazon, Lowe’s, or Lowe’s.

Greenhouse ventilation fundamentals include vents, fans, and automated systems. Fan systems work best if the draw is less than 150 feet, and most greenhouses require fans on one end wall with louvers placed in the opposite direction. For horizontal airflow fans, place them diagonally opposite corners. For greenhouses longer than 50 feet, more fans may be needed.

When using fans for air exchange, pull the air through the full length of the structure to avoid hot air pockets. Install the shutter mount exhaust easily using a hardware kit. Control the temperature with a thermostat and circulation fans to keep air from becoming too hot.

How many fans do you need 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.

How to set up fans in a greenhouse?

To ensure optimal airflow in a greenhouse, position the fan to flow over and through the plant canopy, with the bottom of the fan or louver about 3 feet above the floor. The fan and vent motors are typically controlled by thermostats, which can have a wide differential between the off and on positions, potentially leading to high electric bills. To check the accuracy of a thermostat, turn the control dial and calculate the difference between the on and off positions.

To get the most accurate temperature control, locate thermostats near the center of the greenhouse at plant height. Aspirating with a 40-60 cubic feet per minute squirrel cage blower or muffin fan will provide a more representative sample of air to the thermostat. When purchasing new fans, select those tested in accordance with Air Movement and Control Association (AMCA) standards, as fan output varies significantly between manufacturers.

What is the best way to circulate air in a greenhouse?

Active ventilation is the use of equipment to force air into or out of a structure, with fans being the primary method. Circulating fans are often used in passively ventilated structures to assist air movement. The most effective approach is to pull air through the entire structure to avoid hot air pockets. Fans placed higher in the greenhouse are more effective for cooling. However, active ventilation systems have limitations in their capacity to quickly exchange large volumes of air, and inadequate design specifications can lead to poor air circulation and overheating problems.

To ensure correct capacity and installation, select fans in consultation with the manufacturer and an independent expert. Ventilation fans should have sufficient capacity to completely replace the air in the greenhouse every minute.

At what temperature should I vent my greenhouse?

To effectively cool a greenhouse exceeding 84 degrees Fahrenheit, open the door and ensure all vents and louvres are open. Automatic vents and louvres automatically maintain the greenhouse’s optimal temperature throughout the day, allowing you to adjust the temperature as needed. Investing in greenhouse blinds can protect your greenhouse from direct sunlight on warm days, and pairing them with adequate vents and louvres can help cool it down effectively.

For a more cost-effective solution, attach shading material internally or use shading paint directly onto the greenhouse glass. However, this can be difficult to install and remove daily. Most automatic openers can be adjusted to open at different temperatures, allowing you to choose the best solution for your plants.

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 do you ventilate a greenhouse without losing heat?

To maintain a healthy greenhouse, close side vents at night to maintain interior warmth and keep roof vents open to allow slight venting of rising warm air. Insulated shutters and automatic louvers can help reduce cold air in colder weather. This is especially important for tropical plants that need to stay warm all night and during colder seasons. Adjust ventilation according to seasonal changes, as maintaining perfect temperatures and humidity levels in summer may cause plants to overheat in spring and fall. Venting out hot air for hot days can lead to frost damage in winter.

Does a greenhouse need ventilation at night?

The ideal temperature for a greenhouse is 75-85 degrees Celsius during the day and 60-70 degrees Celsius at night. In winter, this temperature decreases to 60-70 degrees Celsius and around 45 degrees Celsius. If your greenhouse exceeds these recommendations, you need to vent it. Greenhouse ventilation is crucial for maintaining a healthy and productive growing environment, regulating temperature, humidity, and carbon dioxide to oxygen ratios. Proper ventilation helps optimize the structure throughout the year, extending the growing season and producing the highest yields at the best quality.

A good ventilation system regulates temperature, controls pests, maintains fresh air levels, and aids in pollination, especially with self-pollinators like greenhouse tomato varieties. In summary, greenhouse ventilation is essential for maintaining a healthy and productive growing environment, ensuring optimal growth and quality.

Should I leave the greenhouse door open at night?

To ensure optimal greenhouse ventilation, use a maximum-minimum thermometer to monitor the temperature and be alert for signs of plant damage. Open doors and vents on sunny days, and temporarily remove panes to help during heat waves. Fit automatic vent openers to ensure roof vents open even when you’re not around, but remember that it takes time for the wax to expand. Provide alternative ventilation such as doors and side vents to prevent damaging temperatures. In changeable weather, vents and doors may need to be partially open to limit sudden temperature increases. Larger greenhouses may require automated ventilation and shading.

Shading is usually required from mid-spring until early autumn to release some heat but limits the light plants receive. Use only the minimum amount of shading to keep temperatures below 25-27ºC (77-81ºF), allowing as much light in as possible, especially for edible plants like tomatoes. Sun-loving plants like succulents may not need shading, but providing shade can make the greenhouse more pleasant.

How important is a fan in a greenhouse?

Circulation fans, also known as horizontal airflow (HAF) fans, are essential for maintaining consistent temperatures and reducing humidity in greenhouses. They promote air circulation, prevent stagnant air, and supply carbon dioxide, essential for plant health. Exhaust fans, on the other hand, are used to remove hot, stale air from the greenhouse, preventing mold and mildew. The optimal placement of fans in a greenhouse depends on the specific needs of the plant and the desired airflow. By following these guidelines, greenhouse fans can be strategically placed to maximize efficiency and maintain plant health.

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.

What are the two types of fans used in a greenhouse?

When choosing a fan for your greenhouse, consider the specific needs of your plants. Two common types of fans are circulation fans and exhaust fans. Circulation fans provide even air distribution, ensuring consistent temperatures and reducing humidity variations. They prevent stagnant air and supply carbon dioxide, essential for plant health. Exhaust fans, on the other hand, are used to remove hot, stale air from the greenhouse, removing excess heat and humidity, especially during summer months.

Proper ventilation helps prevent mold, mildew, and other environmental issues that can negatively impact plant health. The best place to place a fan in a greenhouse depends on the specific needs of your plants.