Differences Between Axial and Radial Fans: What and Why?
Many growers try to save on the chosen fan right at the start by picking the cheapest possible fan, assuming that the chosen fan doesn't matter. Especially when it provides the required m3 per hour.
Unfortunately it's not that simple. Fans differ in many ways and behind that is, of course, mathematics and physics, which I will not present here, and if you want, you can google it. ;-)
Practical outputs divide fans into AXIAL (sometimes nicknamed toilet fans) typically represented by the TT and TD series and RADIAL, which are further divided into fans with forward-curved blades, backward-curved blades and radially terminated blades.
Axial TT fans are the cheapest you can find on the market and if you don't have ducting longer than 2 meters, don't kink it, don't use any silencers, filters (yes, even these "tubes" are actually a significant obstacle to airflow), or other components that obstruct airflow. Then with TT fans you'll operate fairly successfully for several grow cycles.
TD fans are the same, but they use better bearings. The fan is better protected against clogging and generally achieves a much longer lifespan than TT fans, which is reflected in the price. The airflow of an axial fan is specified at zero pressure.
One 90-degree bend raises the duct pressure by 10Pa and the performance of an axial fan drops by about 25%. If you add, for example, a filter, performance will drop another 25% and in addition to insufficient fan performance there is also a risk of inadequate cooling of the fan and burning the thermal fuse. (If this happens, the manufacturer knows the fan was operated improperly and will not accept the warranty.)
Another obstacle can even stop the airflow and the fan just "eats" power but does nothing.
Radial fans are, on the other hand, built for use in long ducts and by their principle generate pressure that "pushes" air through obstacles and bends. This does not, of course, mean that you can have infinitely long ducting or make a "snake" around the whole room and expect that airflow will not be affected. Performance drops are in percent units for each obstacle and under normal conditions, when you use a filter or silencers and have 2 bends in a 10-meter duct, you don't need to worry about the fan's performance or lifespan.
Radial fans also do not have, unlike axial ones, a problem with fragments of activated carbon from filters. These characteristics have made them popular not only among home growers.
Is anything unclear? Do you have a question? Write to us at info@higarden.cz We will gladly expand the article with relevant questions.