Evaporative cooling (Sometimes referred to as “Swamp Coolers”) is probably the best way to reduce greenhouse temperature. The principle is simple. As the exhaust fans blow air out of one end of the greenhouse, they draw in moist air from the other end. As the moist air moves through the greenhouse, some of the water vaporizes, absorbing heat in the process. Moisture is supplied at the end opposite the fans with an evaporative cooler that drips water through an absorbent material such as aspen pads, cellulose or a synthetic fiber media (commonly called “cooler pads” or “wet pads”).

All incoming air passes through this wet media. Any water that drips through the pad media is collected into the water pan at the bottom. Water is recirculated by a small water pump through a plastic line from the pump in the water pan back to the top of the cooler pads.

There needs to be a provision for replacing water that is evaporated by the air passing through the cooler pads. This is usually done with a 1/4″ copper or plastic water line to the float valve that is mounted in the cooler. This line can be installed from a garden hose bibb or sillcock located near the greenhouse to the cooler float valve.

Evaporative cooling is more effective when the air outside the greenhouse has a low relative humidity. As the relative humidity of the outside air increases, this technique becomes less effective. But so long as the relative humidity is less than 100 percent, this method will have some cooling effect on the air.

Champion Window Model Coolers
&
Phoenix Window Model Coolers

Are An Excellent Choice For Cooling Your Greenhouse
They Are Completely Factory Assembled
With A Two Speed Motor, Supply Grill, Switch
And Pump Kit

They Have An Electrical Cord And Plug And Use 115 Volt Electricity
Installation Instructions Are Shipped With The Coolers

Evaporative Cooler Service Tips