An alternate Greenhouse Auto Vent system runs on the fog or good mist injected in to the intake air stream. Although many commercial systems are available, growers can assemble and set up their own system utilizing a high pressure piston pump and fog nozzles. The basic components are demonstrated in Fig. 1. A two-stage system managed by a two- stage thermostat allows more water to be applied on excessively warm, bright days. Temperature settings ought to be 5-10°F apart.
Algae development in the pads may become a problem which will decrease the effectiveness of the machine and result in accelerated deterioration of the pads. The addition of an algaecide to the drinking water supply will help in control.
It really is desirable, especially in hard water areas, to include a wetting agent to the drinking water to obtain additional uniform wetting of the pads. A commercial material or liquid household detergent at the price of 2 tablespoons per 100 gallons can be used.
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 used to recirculate the drinking water. A flow rate 113 gallon each and every minute per linear foot of pad system should be provided to assure adequate wetting.
In the most typical 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 1 to three years. Approximately one sq . foot of pad are is necessary for 20 square ft of floor area.