An alternate system uses a fog or great mist injected into the intake air stream. Although several commercial systems are available, growers can assemble and install their own system utilizing a ruthless piston pump and fog nozzles. The basic components are shown in Fig. 1. A two-stage system controlled by a two- stage thermostat allows more water to be employed on excessively warm, Greenhouse Auto Vent bright days. Temperature settings ought to be 5-10°F apart.

Algae growth in the pads can become a problem that will decrease the effectiveness of the machine 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 drinking water to obtain additional uniform wetting of the pads. A commercial materials or liquid household detergent at the rate of 2 tablespoons per 100 gallons can be used.

Drinking water for the pads ought to be clean and low in mineral content to prevent clogging and coating of the pads. A pump, pipes and gutters are used to recirculate the drinking water. A flow rate 113 gallon per minute per linear foot of pad system should be provided to make certain adequate wetting.

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