An alternate system runs on the fog or fine mist injected into the intake air stream. Although a number of commercial systems can be found, growers can assemble and install their own system utilizing a high pressure piston pump and fog nozzles. The essential components are shown in Fig. 1. A two-stage system controlled by a two- stage thermostat enables more water to be applied on excessively warm, shiny days. Temperature settings ought to be 5-10°F apart.

Algae development in the pads can become a problem that will reduce the effectiveness of the system and result in accelerated deterioration of the pads. The addition of an algaecide to the water supply can help in control.

It really is desirable, especially in hard water areas, to add a wetting agent to the water to obtain additional uniform wetting of the pads. A commercial materials or liquid household detergent at the price of 2 tablespoons per 100 gallons can be used.

Water for the pads should be clean and lower in mineral Greenhouse Exhaust Fan content to prevent clogging and coating of the pads. A pump, pipes and gutters are accustomed to recirculate the drinking water. A flow rate 113 gallon per minute per linear foot of pad program ought to be provided to assure adequate wetting.

In the most common cooling system (fan and pad), the fans draw air through wet pads that prolong the length of 1 endwall or sidewall. Aspen and covered cellulose are common pad materials that always have life of one to 3 years. Approximately one sq . foot of pad are is necessary for 20 square foot of floor area.