Frost fans have become the central element in most frost protection strategies. They use the warmer air in the inversion layer to protect a crop from frost damage. The frost fan is angled slightly downwards to pull this inversion layer down to ground level, to protect the crop from frost damage.
Frost fans are turned on before a frost occurs, usually 0.5 to 1.5°C above freezing. There is documented proof that turning on frost fans early and shutting them down late, results in considerably better crop protection performance. It is recommended that growers use this procedure, even when the temperature drops below freezing for several hours, and it may appear to be a 'lost cause'. Substantial crop salvage has been achieved with a “slow-freeze-slow-thaw” even under severe frost conditions.
In severe conditions, the use of orchard heaters in conjunction with frost fans strengthens the useable inversion layer which the frost fan then mixes and distributes over the crop, thereby providing better protection.
The initial expense of protecting a large area with frost fans can be significant, but the cost of capital, maintenance and operation is comparatively lower than other types of frost protection systems. Calculate the ROI on installing FrostBoss® C49 machine/s by running your numbers through the FrostBoss® ROI calculator.
Depending on the type of crop, geography, local climate and crop layout, a single frost fan will provide protection for about 6 - 8 hectares. Multiple frost fan installations will increase the effective coverage of individual fans.
