Understanding ventilation

Photo courtesy of Pinnacle Climate Technologies

When air is cooled and circulated properly throughout your structure, chances for disease decrease. Therefore, if you’re looking to cool and keep fresh air within your greenhouse, an evaporative cooling system may be the way to go.

Here, Brad Gaddy from Pinnacle Climate Technologies, the manufacturer of Schaefer fans, provides some insight into how an evaporative cooling system works, how it is different than a HVAC system and more.

Greenhouse Management: How can evaporative cooling suit your ventilation needs in a greenhouse?

Brad Gaddy: Depending on relative humidity, evaporative cooling can cool up to 30 degrees at the pad wall. However, the cooling effect will diminish the farther the air must travel.

GM: How does this differ from a traditional HVAC system?

BG: Air conditioning is a more complex and more expensive method of cooling. It needs more components such as a coil, condenser and compressor to make it work. It also relies on a refrigerant, like R-22. AC costs more to operate than evaporative cooling, which traps the heat in water. An AC unit is also a dehumidifier and is not affected by high relative humidity like a wet wall can be.

GM: How can evaporative cooling needs vary depending on your climate?

BG: Humidity is the main factor. If the humidity is high, the less effective it is. The drier the air, the more the system will cool.

“Ask yourself questions, such as, ‘How hard is the water? How much particulate is in the water?’ for your specific operation. Those things can reduce the life of the filter and pads by clogging them up.”

GM: What is their lifespan, and how are they serviced?

BG: This depends on water quality. Ask yourself questions, such as, “How hard is the water? How much particulate is in the water?” for your specific operation. Those things can reduce the life of the filter and pads by clogging them up. It is recommended that you let the pads dry at the end of the growing season and gently clean them to remove debris. Check the filter often and bleed the system off weekly to introduce fresh water.

GM: In what ways does exhaust equipment couple with evaporate cooling systems?

BG: Exhaust fans are placed at the opposite end of the structure from where the wet wall is. They pull air through the pads, which are soaked with water. The heat in the air is trapped by the water, thus resulting in cooler air leaving the system.