Are you “throwing” money away with your HAF fan purchase?
Two of the biggest benefits of proper airflow include temperature uniformity, and decreased disease risk in plants. By having proper airflow, you minimize temperature differences in your greenhouse that can lead to decreased yield in affected areas. Furthermore, the uniform airflow allows for air to get past the canopy which reduces difference between leaf surface temp and air temp and increases nutrient uptake by promoting transpiration during lighted hours. One of the most common methods used is HAF fans, or horizontal airflow fans. There are countless horizontal airflow solutions available to growers on the market.
At times, the perception in the market is that all fans move air, and more or less all fans are the same. In this situation, the up front cost of the fan becomes the highest priority for the decision of which fan to choose. When only the price of buying fans is compared, the value of different fan options can be overlooked. Installation costs, electrical, and operating costs can yield benefits in total cost of ownership that may mean the total cost of ownership for more expensive fans are lower. In some cases, even the initial implementation of fans can be lower for a fan that has a higher price than another.
Efficient airflow design in greenhouses can focus on a fan’s “throw” to optimize the design for performance and energy efficiency. The principle is simple, the more throw a fan has per watt consumed, allows for fewer fans to be used in the overall design. This leads to benefits such as reduced installation costs and reduced operating costs.
Figure 1: Fan layouts for a 250’ greenhouse comparing the number of fans needed for each type of fan.
Shrouded fan vs cage fan…
A shrouded fan has a round cover around the fan instead of a cage. This prevents air from dispersing around the fan which increases the efficiency of the fan and also directs the flow of air forward. This allows for the shrouded fan to push air further than a traditional cage fan, reducing the need for additional fans.
Figure 2: An unshrouded cage fan vs a shrouded Holland heater fan.
Does size matter?
The answer is yes and no, but mostly no. If you are comparing two fans from the same line from one manufacturer, a larger fan will move more air. But, when we are comparing the throw of a fan, not all 16” fans will have a further throw than all 12” fans. So, when you are comparing size, compare the throw distance over the diameter of the fan. Throw is a much better indicator of the number of fans needed.
Here at Total Energy Group we have the tools to give growers a better picture of the total cost of ownership of your fans. By assessing your current HAF solution we are able to show you the difference in cost over time by switching to one of our solutions. Please reach out to us if you are interested in having your HAF fans reviewed.