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(information reproduced from www.backyardgardener.com)
Misting Guidelines
Apply mist only during daylight hours to avoid excessive humidity at night, which encourages disease. Remember, when the greenhouse cools at night, the relative humidity will rise even with the misting system off. Use a 24-hour timer to shut off the misting system 2 hours before sundown.
Cooling
Shading and ventilation are required during summer to prevent a greenhouse from seriously overheating, but it is evaporative cooling from a misting system which can actually cool the greenhouse to a comfortable level.
Humidity Control
When a greenhouse warms up and venting begins, essential moisture is lost with the vented air. Plants lose moisture more rapidly and begin to wilt. A misting system can provide needed moisture to maintain a healthy humidity level of 50 to 70%.
Design for Cooling & Humidity Control
Use one 2 or 3 gph nozzle for every 12 to 14 sq. ft. of greenhouse floor. Install nozzles under the benches to avoid soaking plants on the benches. Nozzles will operate pointed in any direction - up, down, sideways or 45° angle. Control this type of system with a humidistat.
Overhead Watering
Many foliage plants, tropicals and subtropicals can be watered and fertilized by an overhead misting system. Use 2 gph nozzles installed as high as possible. Control this system with a short-cycle timer.
Propagation/Orchid Misting
Maintain a higher level of humidity (60 to 70%) for healthier plants. Protect seedlings and cuttings from fatal water stress. Imitate orchid's natural environment. Control with a short-cycle timer:
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How Does It Work?
(information from www.mistcool.com) |
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MIST&COOL™ Outdoor Cooling Systems employ evaporative cooling to effectively cool and condition the environment. Using our proprietary misting nozzles, an ultra fine mist is introduced into the environment which interacts with the air to cool, clean, humidify and to repel flying insects. |
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Maximum number of nozzles that can be used
at different water pressures: |
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½ Professional System |
3/8" Do-It-Yourself System |
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Water Pressure |
Max. # of Nozzles |
Water Pressure |
Max. # of Nozzles |
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25 psi |
6 |
30 psi |
6 |
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40 psi |
18 |
40 psi |
18 |
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50 psi |
30 |
50 psi |
30 |
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70 psi |
42 |
70 psi |
46 |
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180 psi |
54 |
90 psi |
62 |
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250 psi |
58 |
100 psi |
62 |
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120 psi |
106 |
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Our heaviest duty system is designed to work with house pressures and pump aided pressures up to 250 psi. Higher pressures produce more water volume and an even finer mist that evaporates more efficiently. |
This system is designed for optional installation flexibility and maximum number of nozzles at pressures up to 125 psi. Besides normal patio applications, this system works exceptionally well in greenhouse applications. *Normal house pressures range between 35 psi and 90 psi. |
Evaporative Cooling Principle
By forcing water through our specially designed misting nozzles, we create a fog of ultra fine water droplets with an average size of 50 microns or less. These tiny water droplets quickly absorb the energy (heat) present in the environment and evaporate, becoming water vapor (gas). The energy (heat) used to change the water to a gas is eliminated from the environment, hence the air is cooled.
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Cooling Efficiency |
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Maximum Potential Cooling
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Relative humidity, the amount of moisture in the air compared to the maximum amount of moisture the air could absorb at the same temperature, is a crucial factor in determining cooling potential. The lower the relative humidity, the more water can be vaporized, and hence, the more heat can be removed. Evaporative cooling can be used in most geographical locations. This is because when temperatures reach their peak during the day, relative humidity is normally at its lowest. |
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The graph above shows potential cooling at different temperatures and levels of humidity. To calculate potential cooling using misting, find the relative humidity for the day, follow that to the curve that is closest to the outdoor temperature, then read the potential temperature drop on the bottom line of chart. (Example: 30% humidity (a), 100° temperature (b) = 26° potential temperature decrease ©.) |
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