An alternate system uses a fog or good mist injected in to the intake air stream. Although many commercial systems are available, growers can assemble and install their own system using a high Greenhouse Exhaust Fan pressure piston pump and fog nozzles. The basic components are proven in Fig. 1. A two-stage system controlled by a two- stage thermostat allows more water to be applied on excessively warm, shiny days. Temperature settings ought to be 5-10°F apart.
Algae development in the pads may become a problem that will decrease the effectiveness of the system and lead to accelerated deterioration of the pads. The addition of an algaecide to the water supply will help in control.
It really is desirable, especially in hard drinking water areas, to add a wetting agent to the water to obtain additional uniform wetting of the pads. A commercial material or liquid home detergent at the rate of 2 tablespoons per 100 gallons may be used.
Water for the pads ought to be clean and lower in mineral content to avoid clogging and coating of the pads. A pump, pipes and gutters are accustomed to recirculate the water. A flow rate 113 gallon per minute per linear foot of pad system should be provided to guarantee adequate wetting.
In the most typical coolant system (fan and pad), the fans draw air through wet pads that prolong the length of one 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.