Circulation Fans

Circulation Fans


Circulation fans are one of the most important accessories for a greenhouse. Circulation fans have several different functions all of which help the plants. The main goal of a circulating fan is to create an even flow of air throughout the greenhouse, in addition there are many other benefits of  circulation fans.

  1. Removes air stratification. When the air within a greenhouse stratifies, consequently it becomes stagnant. The air moves in one direction and does not promote healthy growth for the plants. The fan circulates air in the greenhouse.
  2. Helps to control air temperature. As the air moves within the greenhouse, the temperature is adjusted. There are no “temperature spots” when the air is moving. The ambient temperature of the air and room will reach the hot and cold corners of the greenhouse, therefore creating a healthy growing environment.
  3. Promotes air quality. This is perhaps the best function of a circulation fan. The air moves with a circulating fan which cuts down on the growth of fungus. Stagnant air allows fungus and disease to grow. Properly moving air is like providing fresh air which cuts down on disease outbreaks within the greenhouse environment.
  4. Dries the leaves of the plants which also minimizes disease. Flowers, such as orchids, cannot have water on their leaves, so a circulation fan is a must in this type of greenhouse. As the air moves, carbon dioxide moves as well, helping to promote new growth on the plants.


Solar Innovations® offers several sizes of circulation fans to provide the correct amount of moderate air flow in your greenhouse. A Solar Innovations® representative can help you determine the correct size and quantity of fans your greenhouse requires.

All of the circulation fans offered by Solar Innovations® include a manual speed control to adjust the air flow from 20% to 100% of the fan’s output or to turn the fan off completely. The controls are encased in a water-resistant electrical enclosure with approved connectors to withstand the high moisture greenhouse environment. The fans come with a solid mount for attaching. The mount allows the fan to circulate so it does not get entangled in chains as a suspended system often does.

For an additional cost, we also offer one of the finest and most reliable automatic single staged thermostats. It has a wide temperature range with a narrow operating differential. The automatic thermostat is enclosed in a code-approved, moisture-resistant housing.

These low maintenance circulation fans will provide the needed air flow within the greenhouse without increasing the overall structure maintenance required of the owner.

Attributes of Circulation Fans

Description HP Volts RPM CFM
8″ VK Circulation fan 1/100 115 1,550 466
12″ PA Circulation fan 1/10 115/230 1,725 2,600
20″ PA Circulation fan 1/3 115/230 1,725 6,000
  • Baked-on white epoxy fan guard.
  • Moisture-resistant variable speed motor.
  • Fan holes are larger than traditional basket fans and provide double the circulation of traditional models.
  • Heavy-duty statically balanced blades.
  • Low noise levels
  • Rigid motor mount provides for easy installation.
  • The fan’s heavy-duty bearing motors are maintenance-free and highly energy efficient.

Circulation Fan Placement
Most vendors recommend that the set of circulation fans be placed facing one another on opposite ends of the greenhouse.  Also, if a structure is over 60 feet long, it is recommended that circulation fans are installed in the same pattern, but for adequate circulation, the greenhouse should be divided and an additional set of circulation fans should be inserted.

Hooded Fans

Description Watts Rough Dimensions Depth Amps CFM Weight
TC1000 High 110 12 1/2″ X 27 1/2″ 2 1/2″ 1.5 50 16
TC1000 Low 50 12 1/2″ X 27 1/2″ 2 1/2″ 73 800 16

Hooded cooling fans are installed near the ridge of a structure. This placement allows the fans to remove the hottest air at the ridge first and then continue to cool the remaining space. The unit is operated by a manual control or thermostat. Hooded fans are available in standard Bronze, White, and Sandstone, and include a wall mounted thermostat. (Typically used in sunroom applications.)

Intake Louvers and Exhaust Fans

Intake Louvers and Exhaust Fans work hand-in-hand. Often times called shutter fans, these accessories help to promote a healthy greenhouse atmosphere. These units have two main functions: to cool a greenhouse and to exchange air.

Description HP Volts RPM Amps CFM Weight (lbs.) Rough-In Size
12″ shutter fan 1/30 115 1550 0.7 760 12 12 5/8″ Sq.
16″ shutter fan 1/10 115/230 1725 1.3/0.65 1250 21 16 5/8″ Sq.
20″ shutter fan 1/3 115/230 1725 3.8/1.9 3122 31 20 5/8″ Sq.
12″ intake louver 115 12 5/8″ Sq.
16″ intake louver 115 20 5/8″ Sq.
20″ intake louver 115 16 5/8″ Sq.
22″ intake louver 115 22 3/4″ Sq.

The intake louver is placed in the lower half of a greenhouse wall; the lover opens to let fresh air into the greenhouse. Air can also come into the greenhouse by way of opened windows. The incoming air is used to cool the greenhouse temperature and to promote the circulation of fresh, clean air.

Heat naturally rises, and the air eventually stagnates at the greenhouse’s ridge. This is when exhaust fans come into play. After the greenhouse reaches a certain temperature, the exhaust fan pulls hot air out of the greenhouse and circulates fresh air back into the environment. This cycle is continued as deemed necessary to maintain the balance of temperature and air flow within the greenhouse.

Both the intake louver and the exhaust fans engage when the greenhouse reaches a predetermined temperature. Precipitation sensors prevent the units from opening when rain or snow is falling. The greenhouse typically utilizes these accessories in the summer when the temperature is elevated within the greenhouse. Cooling the greenhouse interior to a minimum of the outside temperature is achievable with an intake and exhaust fan. Further cooling will require supplemental cooling devices such as an evaporative cooler.

Although summer is the primary season for the use for these items, there are times during the winter when the greenhouse may overheat from direct sunlight penetration. During those times, it is useful to have an intake louver and exhaust fan.

Please note: The units themselves are not insulated and it is a good idea to insulate against harsh winters with foam or a panel for protection.

It is important to note that if a greenhouse is insulated, an exhaust fan and intake louver are not often required. Insulated glass choices and the increase in glass technology will control the temperature and air flow, with additions of circulating fans. If the greenhouse is single pane, then an exhaust fan is a very good piece to consider incorporating into your greenhouse.

We would be happy to assist you or answer any questions. Please contact 800-618-0669 or e-mail us at

Additional Accessories