POSITIVE HEATING AND VENTILATION OF PLASTIC GREENHOUSES WITH AUTOMATICALLY CONTROLLED EQUIPMENT
One fan with a capacity of one air exchange per minute at 1/8" statec pressure, is used to circulate internal air, distribute hot air from the vented hot air furnace and ventilate by introducing cooler exterior air into the greenhouse. All air passes over the roof and mixes with the internal air before it reaches the plant bed area. In this manner chilling or drying of plants and soil is eliminated.
Plants grown in greenhouses controlled by this system have been remarkably uniform, high yielding and relatively free of areal plant diseases. A high degree of uniformity of temperature and relative humidity is obtained.