Horizontal Air Flow (HAF) fans and their sisters (HVF) High Velocity Fans are essential parts of a greenhouse heating and cooling system. HAF Fans and HVF Fans are also known as circulating fans.
Circulating fans increase airflow throughout the greenhouse
These fans help move the air through the greenhouse, so when positioned properly they can eliminate hot spots and cold spots. When buying your airflow fans, meet with your greenhouse specialist to discuss the optimum layout. If this is a new range we can design the HAF or HVF layout during the greenhouse planning stage.
If the fans are needed to help with an existing airflow plan we can work together to determine which fans will best achieve the desired results and how to place them through the greenhouse.
The typical layout for HAF/HVF fans is a staggered zigzag pattern through the greenhouse
The optimal placement of fans really depends on your greenhouse layout. For instance a fan and pad cooled greenhouse with the pads on the endwall would be better served to zig zag the HAF fan pattern, keeping air movement following a linear pattern similar to when the exhaust fans are operating.
Place your HAF/HVF fans at the height most beneficial to your plants
Most plants do not like high velocity air blowing directly on them. You should plan in advance so that this doesn’t happen. Will you be growing hanging baskets in your greenhouse? Will your “lower greenhouse crop” grow into the wind path of your fans? The fans should be placed above the top level of your lower crop and below the lowest level of any trailing material growing from your hanging baskets.
Control All Circulating fans in relationship to the rest of your ventilation
Controlling when you are using your HAF fans and HVF fans is also essential. If you are using exhaust fans to pull the air through cooling pads, circulating fans running may be working against the exhaust fans and need to be shut off when exhaust fans are running.
They can also potentially reduce the efficiency of natural ventilation if the airflow is working against the natural flow of air out of the roof vents.
Since you want all your ventilation components working together, the ideal situation is to have them controlled by an environmental computer. Of course environmental computers come with different price points and with various levels of complexity. GGS works with several different suppliers of environmental computers and would be happy to assist you in determining which product is best for you.
Not All Circulating fans are the same
At GGS we carry several different makes of HAF fans and HVF fans. Depending on the application, the layout, and the preferences of the grower we suggest different fans. Blade pitch affects noise as well as air flow; size effects air volume and speed; and of course there are voltage considerations as is the case with anything electrical.