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

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

It is desirable, especially in hard water areas, to add a wetting agent to the drinking water to obtain more uniform wetting of the pads. A commercial material or liquid home detergent at the rate of 2 tablespoons per 100 gallons may be used.

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

In the most typical cooling system (fan and pad), the fans draw air through wet pads that extend the length of one endwall or sidewall. Aspen and covered 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 feet of floor area.