Greenhouse Circulation Equipment
In a Nepenthes greenhouse, circulation equipment is mandotory. Air circulation keeps down the occurance of mold, and is also responsible circulating air from the heater. During normal operations it keeps hot and cold spots from developing during the day and night.
In small greenhouses a small fan is usually sufficient for circulation. (Note: a small fan is not sufficient for cooling.) In larger structures, the use of one or more HAF (high air flow) fans are re required. HAF fans are about 2 feet wide. The blades of the fan aren't turned significantly, which causes a large amount of air to be slowly circulated. In greenhouses that are longer than 20', 2 HAF fans are used for about every 20' of width. So a greenhouse that is 20'x50' would use 2 HAF fans. Greenhouses which are twice as long (20'x100') would use 4. A 40'x100' greenhouse would use 8, and so on.
Above: A 20'x40' greenhouse setup. The two HAF fans are set flow air opposite of each other. This causes the air in the greenhouse to circulate in a clockwise manner.
Above: The HAF fan configuration for a 20'x100' greenhouse.
Above: The HAF fan configuration for a 40'x100' greenhouse. This setup causes two rotating airflows. The left airflow circulates clockwise, and the right airflow circulates counter-clockwise.
HAF fans are usually inexpensive. Costing around $100 a piece, they are a low maintenance item that lasts a long time. They use a relatively small amount of electricity. In a very humid and moist Nepenthes greenhouse, they can eliviate the instance of mold, which would occur if there was no air circulation.
The HAF fans should run continuously except when the exhaust fan is on.