Grain store specialist Evans and Pearce has developed a simple, low-cost system to turn existing cooling fans into automated units capable of switching on and off only as required.
Called Grain Fan Assist, the system sees each fan fitted with a small control box that takes a feed from an ambient air temperature sensor and a spear-mounted grain temperature probe.
This clever controller monitors the difference in air and crop temperatures and then triggers the fan to kick in every time the air is cold enough to effectively cool the grain. As external temperatures rise, the fan will then switch itself off, avoiding warmer air being blown through the crop, undoing the good work done previously.
Operators can set the desired kick-in point simply via blister buttons and a digital display on the front of the box. This is known as differential grain cooling – a technique that has been shown by the AHDB to reduce energy usage by up to 40%.*
Grain Fan Assist can be fitted to new or existing fans and requires little, if any, input from an electrical contractor. Growers simply send their fans to Evans and Pearce where their qualified installers fit the control boxes – the approximate cost is £250 per fan, depending on spec.
Any number of cooling fans can be equipped with this simple set-up. In addition, if the store is fitted with additional extraction fans to draw clean air into the building, the system can be further enhanced with Extraction Fan Assist. This wirelessly detects when any of the grain ventilation fans kick in to trigger the main extraction unit into life. When they shut down as ambient air temperatures rise, the big fans in the roof stop too, avoiding electricity being used unnecessarily. (All Grain Fan Assist control boxes are fitted with a wireless transceiver to enable them to communicate with the Extraction Fan Assist system should it be purchased at a later date).
A variant of this system is the Multi Fan Hub – a wall-mounted control panel that will trigger up to eight individual three-phase fans into life automatically as probes in the grain detect a temperature differential suitable for cooling.
The big benefit of all three of these systems is they provide a low-cost option for automation so fans are only running when the conditions for cooling are optimal. In a conventional situation, fans will often be switched on as a matter of course in the evening and switched off in the morning regardless. This takes no account of ambient air temperatures and the fact that air blown through the heap may actually increase grain temperatures if above the required differential. Aside from unnecessary energy usage, this can also put crop quality at risk with higher crop temperatures increasing insect pest activity.